Oral Health and Teledentistry Interest during the COVID-19 Pandemic

 
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
Journal of
              Clinical Medicine

Article
Oral Health and Teledentistry Interest during the
COVID-19 Pandemic
Magdalena Sycinska-Dziarnowska 1 , Marzia Maglitto 2 , Krzysztof Woźniak 1 and Gianrico Spagnuolo 2,3, *

                                          1   Department of Orthodontics, Pomeranian Medical University in Szczecin, Powstańców Wielkopolskich Street
                                              72, 70111 Szczecin, Poland; magdadziarnowska@gmail.com (M.S.-D.); krzysztof.wozniak@pum.edu.pl (K.W.)
                                          2   Department of Neurosciences, Reproductive and Odontostomatological Sciences, University of Naples
                                              “Federico II”, 80131 Napoli, Italy; mar.maglitto@gmail.com
                                          3   Institute of Dentistry, I. M. Sechenov First Moscow State Medical University, 119435 Moscow, Russia
                                          *   Correspondence: gspagnuo@unina.it

                                          Abstract: Background: The COVID-19 pandemic outbreak has significantly changed access to dental
                                          treatments. Methods: The data related to oral health and teledentistry topics were collected from the
                                          open database Google Trends. The analyzed material was collected from 19 June 2016 to 6 June 2021
                                          among anonymous search engine users. The following expressions were analyzed: “dental care”,
                                          “emergency dental care”, “oral health”, ”periodontitis”, “teledentistry”, “is it safe to go to the dentist”,
                                          and “COVID-19” and ”PPE dentist”. Results: During the first lockdown in 2020, a significant increase
                                          in “emergency dental care” phrase queries was detected, with a simultaneous decrease in regular
                                          “dental care” questions, as well as a peak in the queries for “periodontitis” preceded by lower interest
                                          in “oral health.” The number of searches stated for “teledentistry” increased during the time of the
         
                                   pandemic 5 times and for and “PPE dentist” 30 times. The risk of visiting the dental studio was seen
                                          in almost 40 times increase in the query “is it safe to go to the dentist.” Conclusions: The COVID-19
Citation: Sycinska-Dziarnowska, M.;
                                          imprinted a stigma on oral health care. In this difficult epidemiological situation, teledentistry might
Maglitto, M.; Woźniak, K.; Spagnuolo,
G. Oral Health and Teledentistry
                                          become a helpful solution.
Interest during the COVID-19
Pandemic. J. Clin. Med. 2021, 10, 3532.   Keywords: oral health; teledentistry; Google Trends; COVID-19 pandemic
https://doi.org/10.3390/
jcm10163532

Academic Editors:                         1. Introduction
Hans-Peter Howaldt and Sameh Attia
                                               In late June 2021, about 182 million COVID-19 cases were reported globally, with
                                          almost 4 million people deaths [1]. It seems very likely that the COVID-19 pandemic had
Received: 22 July 2021
                                          an impact on oral health-related behaviors. The stringent measures undertaken to limit
Accepted: 10 August 2021
                                          the spread of COVID-19 disease with social distancing rules made access to dental offices
Published: 11 August 2021
                                          more troublesome. The risk of contagion can be reduced by introducing teledentistry [2].
                                          Teleconsultation, which begins with an online triage, was a compromise that limited patient
Publisher’s Note: MDPI stays neutral
                                          access but also ensured effective treatment and relief from symptoms [3].
with regard to jurisdictional claims in
                                               According to some studies, routine dental care and emergency dental care have been
published maps and institutional affil-
iations.
                                          immensely influenced by the waves of COVID-19 [4–7]. The large impact of the COVID-
                                          19 pandemic on dentistry was shown in the study conducted by Soltani et al., in which
                                          as many as 659 articles published by dental journals were found in PubMed regarding
                                          implications of the COVID-19 pandemic in dentistry [8]. Moreover, many people did not
                                          want to visit the dental studios due to the fear of virus transmission. Moreover, as proved
Copyright: © 2021 by the authors.
                                          in many studies in pre-pandemic time, the prolonged lack of regular oral health check-
Licensee MDPI, Basel, Switzerland.
                                          ups may lead to periodontitis [9,10]. Another unprecedented situation happened during
This article is an open access article
                                          the COVID-19 pandemic. Greater demand for personal protective equipment (PPE) was
distributed under the terms and
                                          detected globally and led to a shortage in masks, gloves, and almost all PPE [11]. Difficult
conditions of the Creative Commons
Attribution (CC BY) license (https://
                                          access to PPE was significant and obvious in the early phase of the COVID-19 pandemic.
creativecommons.org/licenses/by/
                                          In order to minimize the viral spread risk during the current COVID-19 pandemic and
4.0/).

J. Clin. Med. 2021, 10, 3532. https://doi.org/10.3390/jcm10163532                                               https://www.mdpi.com/journal/jcm
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J. Clin. Med. 2021, 10, 3532                                                                                               2 of 12

                               post-pandemic times, the global project to define the best organization of dental offices was
                               conducted [12].
                                    Rapid changes in the epidemiological situation might be easily and strongly visible in
                               the surveillance of the more widely used search engines, for example, the Google search
                               engine, the most used engine with the vast majority of the market share, as much as
                               92.26% [13].
                                    The aim of this study was to analyze the impact of the COVID-19 pandemic on oral
                               health and the interest in teledentistry.

                               2. Materials and Methods
                                    The data for the study were collected from the open database—Google Trends (GT)
                               service among anonymous search engine users related to oral health and teledentistry
                               subjects [14,15]. Each data record represents a weekly worldwide number of queries
                               processed by Google engine and available according to the selected time period. In the
                               study, the analyzed material was collected from 19 June 2016 to 6 June 2021. All data
                               imported from GT represent queries were normalized to the time and location. The
                               resulting numbers are scaled on a range of 0 to 100, where 100 is the maximum number of
                               searches in a stated period of time. The following expressions were analyzed: “dental care”,
                               “emergency dental care”, “oral health”, “periodontitis”, “COVID-19” and ”PPE dentist”, as
                               well as the phrases “teledentistry” and “is it safe to go to the dentist”, were investigated to
                               check the interest for online consultations.
                                    The data analysis was divided into two sections. The first section provides the detailed
                               level description of data, its structure, and main samples characteristics needed in order to
                               perform further calculations. In the second section, the pairwise correlation between data
                               series was analyzed. For each time series data, the trend, cyclical, and random fluctuations
                               analyses were performed. The purposes of this section were as follows:
                               •    To present pairwise time series visualizations;
                               •    To perform time series decompositions indicating the trend, cyclical, and random fluctuations;
                               •    To analyze the cross-correlation between chosen time series pairs with statistically
                                    significant estimation;
                               •    To evaluate a pairwise of mutual influence (where possible).
                                     To estimate the dynamics rate (hereinafter), the comparisons of two mean rates for
                               two periods were made: first one for the period before the 22–23 January 2020, when the
                               World Health Organization (WHO) Director gathered an Emergency Committee to discuss
                               whether the new virus outbreak determined a public health emergency of worldwide
                               concern [16] (that refers to dates from 19 June 2016 to 19 January 2020 in our weekly split
                               data set) and the second one from 19 January 2020 to 6 June 2021. For simplicity, we further
                               refer to those periods as before and during the pandemic. In the study, we aimed to check
                               the time before the official pandemic onset, as the search engines may have shown some
                               interest in the subject before official regulations were made.
                                     For the qualitative and quantitative analysis of the correlation, the time series collec-
                               tions were divided into the following 4 pairs:
                               •    “Dental care”–“emergency dental”;
                               •    “Oral health”–“periodontitis”;
                               •    “Teledentistry”–“is it safe to go to the dentist”;
                               •    “COVID-19”–“PPE-dentist”.
                                    All statistical estimations with data visualizations were programmed by the “R”
                               programming language [17] with “R studio” version 1.4.1106 open-source software for
                               data science, scientific research, and technical communication [18].
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
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                                   3. Results
                                    3.1. Time Series Visualizations
                                   3.1. Time Series Visualizations
                                          A graphical illustration of time series was presented by a paired graph of the dynam-
                                         A graphical illustration of time series was presented by a paired graph of the dynamics
                                    ics of requests in the study period. For the purposes of analyzing the trend, cyclical, and
                                   of requests in the study period. For the purposes of analyzing the trend, cyclical, and
                                    random fluctuations, the time series were decomposed for each collection separately.
                                   random fluctuations, the time series were decomposed for each collection separately.
                                          The pairwise time series visualization of “dental care”–“emergency dental care” is
                                         The pairwise time series visualization of “dental care”–“emergency dental care” is
                                    presented in Figure 1a. The plot clearly shows a high proportion of uncertainty in demand
                                   presented in Figure 1a. The plot clearly shows a high proportion of uncertainty in demand
                                    fordental
                                   for   dentalservices
                                                servicesatatthe
                                                              thevery
                                                                  verybeginning
                                                                        beginningofof2020.
                                                                                      2020.This
                                                                                              Thisisisevidenced
                                                                                                       evidencedbybya asharp
                                                                                                                         sharpdecline
                                                                                                                                declineinin
                                    demand    for planned    dental procedures   with  a simultaneous      sharp  increase
                                   demand for planned dental procedures with a simultaneous sharp increase in demand       in demand    for
                                   for emergency ones. However, this phase had a short-term character, and during the1–
                                    emergency    ones.  However,     this phase had  a short-term     character,  and during   the next
                                    2 months,
                                   next         the structure
                                         1–2 months,            of demand
                                                      the structure         returned
                                                                       of demand       to its normal
                                                                                  returned              state. state.
                                                                                              to its normal

                                   (a)                                                                          (b)
       Figure
     Figure 1.1.Pairwise
                 Pairwisecomparison
                          comparisonofofweekly
                                         weeklyrequests
                                                 requestsduring
                                                          during2016–2021:
                                                                 2016–2021:(a)(a)“dental
                                                                                  “dentalcare”–“emergency
                                                                                           care”–“emergencydental
                                                                                                            dentalcare”;
                                                                                                                    care”; (b)
                                                                                                                         (b)   “oral
                                                                                                                             “oral
       health”–“periodontitis”.
     health”–“periodontitis”.

                                            Thepairwise,
                                          The    pairwise,time   timeseries
                                                                        seriesvisualization
                                                                                 visualizationofof“oral
                                                                                                      “oralhealth”–“periodontitis”
                                                                                                             health”–“periodontitis”isispresented
                                                                                                                                               presented
                                   ininFigure
                                         Figure1b.1b.TheTheplotplotshows
                                                                      showslargelargeinterest
                                                                                       interestgrowth
                                                                                                  growthwhenwhenregarding
                                                                                                                    regarding“periodontitis”
                                                                                                                                  “periodontitis”with with
                                     thepeak
                                   the     peakatatthe
                                                     thebeginning
                                                           beginningofofthe    theyear
                                                                                    year2020
                                                                                          2020with
                                                                                                 withstable
                                                                                                       stableand
                                                                                                               andslight
                                                                                                                     slightgrowth
                                                                                                                             growthininthe
                                                                                                                                         thenumber
                                                                                                                                               numberofof
                                     questionsasked
                                   questions       askedduringduringthe theanalyzed
                                                                              analyzedperiod.
                                                                                           period.TheThenumber
                                                                                                          numberofofqueries
                                                                                                                          queriesfor
                                                                                                                                   for“oral
                                                                                                                                        “oralhealth”
                                                                                                                                                health”isis
                                     more    stable.  A    peak    in  “periodontitis”      queries   was  detected     after
                                   more stable. A peak in “periodontitis” queries was detected after the hard lockdown and    the  hard  lockdown      and
                                   the
                                     thelower
                                           lowerinterest
                                                   interestininthe the“oral
                                                                        “oralhealth”
                                                                                 health”subject.
                                                                                           subject.
                                          Furthermore,
                                            Furthermore,the        pairwise,
                                                                 the  pairwise,  time  series
                                                                                    time        visualization
                                                                                           series  visualizationof “teledentistry”–“is
                                                                                                                    of “teledentistry”–“is it safe  to goto
                                                                                                                                                 it safe
                                   togothetodentist”    is presented
                                             the dentist”                  in Figure
                                                                 is presented           2a. Both
                                                                                   in Figure     2a.terms
                                                                                                     Both under
                                                                                                           terms consideration        rarely occurred
                                                                                                                    under consideration         rarely oc-
                                   incurred
                                       the pre-pandemic
                                               in the pre-pandemic time. Only        at theatbeginning
                                                                             time. Only                    of 2020
                                                                                               the beginning          diddid
                                                                                                                 of 2020    these  concepts
                                                                                                                               these  concepts  become
                                                                                                                                                   become
                                   widespread.
                                     widespread. The plot clearly shows a peak when the request for both terms reachesitsits
                                                      The     plot  clearly    shows    a peak    when   the   request    for both  terms   reaches
                                   maximum.
                                     maximum.The     Thedemand
                                                             demandfor   forthe
                                                                              the“teledentistry”
                                                                                   “teledentistry”term termthen
                                                                                                             thenbegins
                                                                                                                    beginstotodecline
                                                                                                                                declineexponentially
                                                                                                                                          exponentially
                                   until
                                     until the end of the period under review, reaching levels preceding thepandemic,
                                           the  end  of   the  period     under    review,   reaching   levels  preceding     the    pandemic,and  andthe
                                                                                                                                                        the
                                   expression
                                     expression“is   “isititsafe
                                                              safetotogogototothe
                                                                                thedentist”
                                                                                     dentist”isischaracterized
                                                                                                   characterizedbybysteady
                                                                                                                         steadydemand
                                                                                                                                  demandthroughout
                                                                                                                                             throughout
                                   almost
                                     almostallallofof2020,
                                                      2020,reaching
                                                                reachinglocallocalhighs
                                                                                    highsduring
                                                                                            duringperiods
                                                                                                      periodsofoflockdowns
                                                                                                                   lockdownsand   andexacerbations
                                                                                                                                       exacerbationsofof
                                   restrictions.
                                     restrictions. However, at the end of the period under review, requests forthis
                                                    However,         at the   end   of the  period    under   review,    requests   for   thisterm
                                                                                                                                                termalso
                                                                                                                                                       also
                                   reached     a minimum,         slightly    exceeding     pre-pandemic
                                     reached a minimum, slightly exceeding pre-pandemic levels.               levels.
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
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                                      (a)                                                                              (b)
                                     (a)                                                                (b)
       Figure 2. Pairwise comparison of weekly requests during 2016–2021: (a) “teledentistry”–“is it safe to go to the dentist”; (b)
             Figure 2. Pairwise
             2. Pairwise        comparison of weekly requests during 2016–2021: (a) “teledentistry”–“is it safe to go to the dentist”; (b)
                           comparison
      Figure
       “COVID-19”–“PPE      dentist”. of weekly requests during 2016–2021: (a) “teledentistry”–“is it safe to go to the dentist”;
             “COVID-19”–“PPE dentist”.
      (b) “COVID-19”–“PPE dentist”.
                                              The pairwise,
                                                The  pairwise,timetimeseries   visualizationofof“COVID-19”–“PPE
                                                                        series visualization       “COVID-19”–“PPE          dentist”
                                                                                                                        dentist”        is presented
                                                                                                                                  is presented   in    in
                                             The pairwise, time series visualization of “COVID-19”–“PPE dentist” is presented in
                                        Figure  2b.2b.
                                           Figure   Both
                                                       Bothexpressions
                                                              expressions came       intouse
                                                                             came into    useimmediately
                                                                                               immediately       with
                                                                                                              with  the the onset
                                                                                                                        onset  of theofpandemic.
                                                                                                                                        the pandemic.
                                       Figure 2b. Both expressions came into use immediately with the onset of the pandemic.
                                        TheThe
                                             demand
                                                demand  curve
                                                          curvefor for“COVID-19”
                                                                       “COVID-19” isischaracterized
                                                                                         characterized   byby
                                                                                                            thethe  presence
                                                                                                                presence        of three
                                                                                                                           of three  globalglobal
                                                                                                                                             highs highs
                                       Thethat
                                            demand     curve
                                                occurred        forjunction
                                                                     “COVID-19” is characterized           by the presence     of at
                                                                                                                                   three  global highs
                                        that occurred    atatthe
                                                              the junction of 2019–2020,
                                                                                 2019–2020,ininthethefirst quarter
                                                                                                        first      of 2020,
                                                                                                              quarter        and
                                                                                                                       of 2020,   andtheatjunction
                                                                                                                                            the junction
                                       thatofoccurred
                                              2020/2021,at which
                                                           the junction      of 2019–2020,
                                                                    corresponds    to         in the first pandemic
                                                                                                             quarter ofwaves.
                                                                                                                          2020, The
                                                                                                                                 and at the“PPEjunction
                                        of 2020/2021,    which corresponds          tothe
                                                                                       thetime
                                                                                            timeofofglobal
                                                                                                      global pandemic       waves. topic
                                                                                                                                       The topic “PPE
                                       of 2020/2021,
                                           dentist”     whichforcorresponds
                                                    standing         personal      to the equipment
                                                                               protective  time of globalwas  pandemic waves.
                                                                                                              characterized   by the  The topic
                                                                                                                                      greatest  de-“PPE
                                        dentist” standing for personal protective equipment was characterized by the greatest                        de-
                                       dentist”
                                           mandstanding        for personal
                                                  at the beginning       of the protective    equipment
                                                                                 pandemic; over     the nextwas1.5 characterized
                                                                                                                   years, the level by of the  greatest
                                                                                                                                           interest
                                        mand at the beginning of the pandemic; over the next 1.5 years, the level of interest
                                       demand    at the
                                           dropped        beginninguntil
                                                     exponentially,       of the
                                                                              the pandemic;     over under
                                                                                  end of the period     the next   1.5 years,
                                                                                                               review,  where the    level
                                                                                                                                it again     of interest
                                                                                                                                           reached
                                        dropped    exponentially,
                                           the pre-pandemic
                                                                        until the end of the period under review, where it again reached
                                                                 level.until the end of the period under review, where it again reached
                                       dropped    exponentially,
                                        the pre-pandemic level.
                                       the pre-pandemic level.
                                              3.2. Trends Analysis
                                        3.2.Trends
                                       3.2.   Trends   Analysis
                                                      Analysis
                                                  Regarding     the “dental care” time series, during the period under consideration, there
                                            areRegarding
                                                 two  periods the
                                              Regarding theof“dental“dental
                                                                    trend growthcare”Figure
                                                                              care”     timeseries,
                                                                                      time    series,   during
                                                                                              3a: the during
                                                                                                       first (more the
                                                                                                                  the   periodunder
                                                                                                                                under
                                                                                                                      pronounced)
                                                                                                                       period       from  consideration,    there
                                                                                                                                            the beginningthere
                                                                                                                                         consideration,
                                        are of
                                             two2018 to  the
                                                   periods    beginning
                                                              of  trend      of
                                                                           growth2019, and
                                                                                     Figure the   second
                                                                                                3a: the    (more
                                                                                                         first  (moresmoothed)  from
                                                                                                                         pronounced)
                                       are two periods of trend growth Figure 3a: the first (more pronounced) from the beginning        the  beginning
                                                                                                                                           from   the    of
                                                                                                                                                      beginning
                                            2020. to
                                        of2018
                                           2018    There   was   no downtrend
                                                      thebeginning
                                                           beginning            2019,during
                                                                            of2019,     andthe  thesecond
                                                                                              the   pandemic      period.
                                                                                                              (more        Regarding
                                                                                                                        smoothed)    fromthe “emergency
                                                                                                                                              thebeginning
                                                                                                                                                   beginningofof
                                       of         to the                  of           and        second (more         smoothed)    from     the
                                            dental
                                        2020. There care”
                                                Therewas    time
                                                         wasno      series
                                                               nodowntrend  (Figure
                                                                     downtrendduring  3b), the
                                                                                      duringthe  direction
                                                                                                 thepandemic is multidirectional
                                                                                                      pandemicperiod.              (with
                                                                                                                      period.Regarding
                                                                                                                               Regarding    local
                                                                                                                                               theups  and
                                                                                                                                                    “emergency
                                       2020.                                                                                                  the  “emergency
                                            downs) with a general upward trend. After reaching the minimum in 2018 through mid-
                                        dentalcare”
                                       dental     care” timeseries
                                                                 series(Figure
                                                                           (Figure3b), 3b), thedirection
                                                                                                  direction ismultidirectional
                                                                                                                    multidirectional(with (withlocal
                                                                                                                                                  localups
                                                                                                                                                        ups and
                                            2020, theretime
                                                          was a significant       increase,the
                                                                                             followed by aisshort-term       moderate decline      (proba- and
                                        downs)
                                       downs)      with
                                            bly during
                                                          a
                                                   with athe general
                                                           general       upward
                                                               generalupward
                                                                          lockdown).
                                                                                     trend.
                                                                                    trend.     After
                                                                                          An After
                                                                                              upward
                                                                                                       reaching
                                                                                                      reaching
                                                                                                         trend was
                                                                                                                     the  minimum
                                                                                                                    theobserved
                                                                                                                         minimum since
                                                                                                                                       in
                                                                                                                                      inthe 2018
                                                                                                                                           2018   through
                                                                                                                                                 through
                                                                                                                                               second
                                                                                                                                                            mid-
                                                                                                                                                       half mid-
                                        2020,
                                       2020,    there
                                            of there   was    a  significant
                                                      was a reached
                                                2020, which    significant        increase,    followed
                                                                                increase, followed
                                                                          its maximum       values at the   by
                                                                                                         by end  a  short-term
                                                                                                              a short-term       moderate
                                                                                                                              moderate
                                                                                                                   of the period                decline  (proba-
                                                                                                                                             decline (probably
                                                                                                                                  under review.
                                        bly during
                                       during          the general
                                                  the general            lockdown).
                                                                   lockdown).             An upward
                                                                                     An upward        trend trend
                                                                                                                waswas     observed
                                                                                                                      observed    sincesince
                                                                                                                                           the the   second
                                                                                                                                                second   halfhalf
                                                                                                                                                              of
                                        of 2020,
                                       2020,       which
                                               which         reached
                                                        reached          its maximum
                                                                     its maximum             values
                                                                                         values        at the
                                                                                                   at the  endend      of the
                                                                                                                  of the      period
                                                                                                                          period  under under    review.
                                                                                                                                             review.

                                            (a)                                                                  (b)
                      Figure 3. Decomposition of time series (month granularity): (a) “dental care”; (b) “emergency dental care”.

                                      (a)                                                                              (b)
                Figure3.3.Decomposition
               Figure     Decompositionof
                                        oftime
                                           timeseries
                                                series(month
                                                       (monthgranularity):
                                                              granularity):(a)
                                                                            (a)“dental
                                                                                “dentalcare”;
                                                                                        care”;(b)
                                                                                               (b)“emergency
                                                                                                   “emergencydental
                                                                                                              dentalcare”.
                                                                                                                     care”.
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                                           Regarding
                                            Regardingthe      the“oral
                                                                   “oralhealth”
                                                                            health”timetimeseries,
                                                                                              series,during
                                                                                                       duringthe theperiod
                                                                                                                       periodunder
                                                                                                                                 underconsideration,
                                                                                                                                           consideration,there   there
                                     are    Regarding         the  “oral health”       time   series,  during    the   period    under     consideration,       there
                                      are two periods of trend growth Figure 4a: the first (minor one) from the
                                          two    periods       of  trend     growth     Figure    4a:  the  first  (minor     one)    from     the beginning
                                                                                                                                                    beginning of    of
                                      are two
                                     2017   to theperiods
                                                      beginningof trend
                                                                      of     growth
                                                                          2018,    and   Figure
                                                                                         the      4a: the
                                                                                              second    (a   first (minor one)
                                                                                                           pronounced          one) from
                                                                                                                                      frommid-2018
                                                                                                                                              the beginning to      of
                                                                                                                                                                early
                                      2017 to the beginning of 2018, and the second (a pronounced one) from mid-2018 to early
                                      2017 to
                                     2020.      the beginning         of 2018,      and the second      (a pronounced         one) from mid-2018            to early
                                      2020. Periods
                                             Periods of   of growth
                                                               growth are  are followed
                                                                                 followed by  by periods
                                                                                                  periods of  of decline
                                                                                                                 decline withwith similar
                                                                                                                                    similar severity
                                                                                                                                               severity and and du-du-
                                      2020.
                                     ration.  Periods        of  growth       are  followed     by   periods     of  decline     with    similar    severity      and
                                      ration. Since
                                               Since the the beginning
                                                                beginning of     of the
                                                                                     the pandemic,
                                                                                          pandemic, aa negative
                                                                                                            negative trend
                                                                                                                         trend waswas recorded
                                                                                                                                          recorded withwith small
                                                                                                                                                                small
                                      duration.
                                     periods        Since the beginning             of the pandemic,       a negative      trend wasnorecorded         with small
                                      periods of of stabilization
                                                     stabilization with  with aa tendency
                                                                                     tendency to to smooth
                                                                                                     smooth out.out. There
                                                                                                                       There were
                                                                                                                                were no upward
                                                                                                                                             upward trends.
                                                                                                                                                         trends. In In
                                      periods ofthe
                                     mid-2021,        stabilization
                                                         level    of      with aistendency
                                                                     demand           close  to thetominimum
                                                                                                       smooth out.  valuesThere
                                                                                                                              for  were
                                                                                                                                   the      no upward
                                                                                                                                         period   under       trends.
                                                                                                                                                            review.
                                      mid-2021,
                                      In mid-2021,  the the
                                                          level    of demand
                                                                level   ofthedemand is close  to theto
                                                                                          is close    minimum
                                                                                                        theseries   valuesvalues
                                                                                                              minimum          for the for
                                                                                                                                         period
                                                                                                                                             the under
                                                                                                                                                  period     review.
                                                                                                                                                               under
                                     Furthermore,
                                      Furthermore,       regarding
                                                          regarding        the  “periodontitis”
                                                                                “periodontitis”      time
                                                                                                      time   series  (Figure
                                                                                                                      (Figure    4b),
                                                                                                                                 4b),  for
                                                                                                                                        for most
                                                                                                                                            most   of
                                                                                                                                                    of the
                                                                                                                                                        the  period
                                                                                                                                                              period
                                      review.
                                     under       Furthermore,
                                              review,      the   trend regarding        the  “periodontitis”       time    series   (Figure     4b), for    most    of
                                      under
                                      the     review,
                                          period      under       trend was
                                                            thereview,     was
                                                                             the
                                                                                 characterized
                                                                                  characterized
                                                                                  trend    was
                                                                                                    as
                                                                                                     as moderately
                                                                                                        moderately
                                                                                                characterized       as
                                                                                                                        growing
                                                                                                                         growing with
                                                                                                                        moderately     with   small
                                                                                                                                              small corrections
                                                                                                                                           growing    corrections
                                                                                                                                                      with     small
                                     and
                                      and short
                                           short declines.
                                                    declines.      Since
                                                                   Since    the
                                                                             the beginning
                                                                                  beginning     of
                                                                                                of 2019,
                                                                                                    2019,  there
                                                                                                            there has    been
                                                                                                                    has2019,     protracted
                                                                                                                          beenthere
                                                                                                                                  protracted     growth,
                                                                                                                                                 growth,      which
                                                                                                                                                               which
                                      corrections
                                     reached     its   and short
                                                      maximum          declines.
                                                                      during      the  Since   the
                                                                                        pandemic.   beginning
                                                                                                      At  the   end ofof  the   period    has
                                                                                                                                          under been   protracted
                                                                                                                                                   review,      there
                                      reached
                                      growth,     its
                                                 whichmaximum
                                                            reached    during
                                                                        its trend, the
                                                                              maximum   pandemic.
                                                                                            during     At  the   end
                                                                                                      the pandemic.    of  the  period
                                                                                                                            At the         under
                                                                                                                                     end oflevels  review,
                                                                                                                                               the period        there
                                                                                                                                                               under
                                     is a slight
                                      is a slight   decrease
                                                     decrease      in the
                                                                    in the    trend, inwhich,
                                                                                        which,   however,
                                                                                                 however,      exceeds
                                                                                                               exceeds     the   demand
                                                                                                                            theexceeds
                                                                                                                                 demandthe    levels  of   the    pre-
                                                                                                                                                       of thelevels
                                                                                                                                                                  pre-
                                      review,
                                     pandemic   there   is
                                                    period.  a  slight  decrease          the  trend,   which,    however,                       demand
                                      pandemic       period.
                                      of the pre-pandemic period.

                                   (a)
                                    (a)                                                                                (b)
                                                                                                                        (b)
     Figure 4. Decomposition of time series (month granularity): (a) “oral health”; (b) “periodontitis”.
     Figure 4. Decomposition  of time series
                 Figure 4. Decomposition   of(month  granularity):
                                              time series          (a) “oral health”;
                                                          (month granularity):        (b) health”;
                                                                                (a) “oral “periodontitis”.
                                                                                                   (b) “periodontitis”.
                                           Regarding
                                            Regarding the   the “teledentistry”
                                                                 “teledentistry” timetime series
                                                                                             series (Figure
                                                                                                     (Figure 5a),
                                                                                                               5a), until
                                                                                                                    until thethe second
                                                                                                                                  second half half ofof 2019,
                                                                                                                                                         2019,
                                     the  trend
                                      the trend waswas   an
                                                    was an   almost
                                                          analmost     flat
                                                              almostflat     curve,
                                                                         flatcurve, with
                                                                              curve,with   a  barely
                                                                                       witha abarely
                                                                                                barelynoticeable
                                                                                                         noticeable
                                                                                                       noticeable  increase,
                                                                                                                       increase,
                                                                                                                    increase,    which
                                                                                                                                    which
                                                                                                                                 which     is  replaced
                                                                                                                                                is replaced
                                                                                                                                            is replaced     by
                                                                                                                                                             by
                                     abysharp
                                          a sharp
                                      a sharp    growth
                                                 growth    phase
                                                      growth
                                                           phase   lasting
                                                                phase         about
                                                                          lasting
                                                                    lasting   about  a year.
                                                                                   about       The
                                                                                           a year.
                                                                                     a year.        growth    for
                                                                                                      The growth
                                                                                               The growth         the   specified
                                                                                                                     forspecified
                                                                                                               for the               period
                                                                                                                           the specified         was
                                                                                                                                      periodperiod     about
                                                                                                                                                 was aboutwas
                                     20
                                      20 points.
                                      about
                                         points.    Then,
                                                    Then, the
                                              20 points.     the growth
                                                            Then,            phase
                                                                    the growth
                                                                 growth             was
                                                                                    was replaced
                                                                             phasephase               by
                                                                                                      by aa moderate
                                                                                           was replaced
                                                                                          replaced                       decline
                                                                                                             by a moderate
                                                                                                             moderate     decline   phase,
                                                                                                                                 decline
                                                                                                                                    phase,      which
                                                                                                                                             phase,
                                                                                                                                                 which   con-
                                                                                                                                                       which
                                                                                                                                                          con-
                                     tinued
                                      continueduntil   the
                                                     until  end
                                                           the    of
                                                                end   the
                                                                       of   period
                                                                           the      under
                                                                               period   under review.
                                                                                                review. Similarly,
                                                                                                          Similarly, in
                                      tinued until the end of the period under review. Similarly, in the “is it safe tointhe
                                                                                                                           the “is
                                                                                                                                “isititsafe
                                                                                                                                         safe toto go
                                                                                                                                                    go to
                                                                                                                                                        to the
                                                                                                                                                           the
                                                                                                                                                            the
                                     dentist”
                                      dentist” time
                                                  time series
                                                        series (Figure
                                                                (Figure 5b),5b), until
                                                                                 until the
                                                                                       the second
                                                                                            second half
                                                                                                      half of
                                                                                                           of 2019,
                                                                                                              2019, the
                                                                                                                      the trend
                                                                                                                           trend   was
                                                                                                                                   was
                                                                                                                            trend was flataa flat
                                                                                                                                             flat  line
                                                                                                                                                   line  with
                                                                                                                                                         with
                                     aa zero
                                        zero value,
                                              value, which
                                                        which waswas replaced
                                                                        replaced byby aa phase
                                                                                         phase of of sharp
                                                                                                     sharp growth
                                                                                                             growth that
                                                                                                                       that lasted
                                                                                                                              lasted forforabout
                                                                                                                                        for   aboutaaayear.
                                                                                                                                             about       year.
                                                                                                                                                         year.
                                     The   growth      for
                                      The growth for the   the  indicated
                                                            the indicated      period
                                                                 indicated period       was
                                                                               period was     about
                                                                                        was about     40
                                                                                               about 40   points.
                                                                                                       40 points.   Then,    the
                                                                                                          points. Then, the growthgrowth
                                                                                                                                   growth phase phase gave
                                                                                                                                               phase     gave
                                                                                                                                                         gave
                                     way
                                      way to
                                      way   to aaa moderate
                                            to     moderate decline
                                                   moderate     decline phase,
                                                               decline      phase, which
                                                                           phase,   which lasted
                                                                                   which    lasted until
                                                                                            lasted   until the
                                                                                                    until   the end
                                                                                                           the  end of
                                                                                                                end   of the
                                                                                                                     of   the period
                                                                                                                         the   period under
                                                                                                                               period     under review.
                                                                                                                                          under     review.
                                                                                                                                                    review.

                                   (a)
                                    (a)                                                                                (b)
                                                                                                                        (b)
     Figure
      Figure5. Decomposition
                 Decompositionof time
                                   timeseries
                                        series(week
                                                (weekgranularity):
                                                      granularity):(a)
                                                                     (a)for
                                                                          for“teledentistry”;
                                                                              “teledentistry”;(b)
                                                                                                (b)for
                                                                                                     for“is
                                                                                                         “isitititsafe
                                                                                                                   safeto   go
                                                                                                                             gototothe
                                                                                                                                     thedentist”.
     Figure 5.5.Decomposition ofoftime series  (week granularity):  (a)  for “teledentistry”;  (b)  for “is       safe  totogo  to  the  dentist”.
                                                                                                                                        dentist”.
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J.J. Clin.
     Clin. Med. 2021, 10, 3532
                          x FOR PEER REVIEW                                                                                                            of 12
                                                                                                                                                     6 of 12

                                         The
                                         The trend
                                               trend line
                                                      line for
                                                           for both
                                                                both expressions
                                                                     expressions in
                                                                                  in Figure
                                                                                     Figure 6a,b—“COVID-19”
                                                                                             6a,b—“COVID-19” and   and “PPE
                                                                                                                         “PPE dentist”—
                                                                                                                                dentist”—
                                    repeats  the  pattern   of the previous  pair. Until mid-2019,   a horizontal
                                    repeats the pattern of the previous pair. Until mid-2019, a horizontal line at  line  at the
                                                                                                                             the 00 level
                                                                                                                                    level is
                                                                                                                                           is
                                    observed,    after  which   the annual  growth    phase  with  a maximum      increase
                                    observed, after which the annual growth phase with a maximum increase of up to 30 points  of  up  to  30
                                    points  is observed.
                                    is observed.           The growth
                                                   The growth     phase phase  is replaced
                                                                        is replaced         by a moderate
                                                                                     by a moderate          decline
                                                                                                      decline phase,phase,
                                                                                                                        whichwhich     con-
                                                                                                                                continues
                                    tinues until
                                    until the  endthe
                                                    of end  of the period
                                                       the period   underunder    consideration
                                                                           consideration         (the volume
                                                                                          (the volume          of decline
                                                                                                        of decline           for “COVID-
                                                                                                                      for “COVID-19”—
                                    19”—5    points,  for “PPE   dentist”—10
                                    5 points, for “PPE dentist”—10 points).    points).

                                  (a)                                                                            (b)
      Figure 6. Decomposition of time series
                Figure 6. Decomposition      (week
                                        of time    granularity):
                                                series           (a) for “COVID-19”;
                                                       (week granularity):            (b) for “dentist
                                                                           (a) for “COVID-19”;  (b) forPPE”.
                                                                                                        “dentist PPE”.

                                    3.3. Cyclical
                                    3.3. Cyclical and
                                                   and Random
                                                        Random Fluctuations
                                                                   Fluctuations Indications
                                                                                     Indications Analysis
                                                                                                      Analysis
                                          In the
                                          In the “dental
                                                  “dental care”
                                                             care” time
                                                                    time series
                                                                            series (Figure
                                                                                     (Figure 3a),3a), there
                                                                                                       there isis aa single
                                                                                                                     single negative
                                                                                                                             negative peakpeak of
                                                                                                                                                of average
                                                                                                                                                   average
                                    severity   in the  second    half   of 2018.    There     were     no positive      peaks
                                    severity in the second half of 2018. There were no positive peaks in the similar intensity. in  the  similar  intensity.
                                    When
                                    When regarding
                                            regarding the the “emergency
                                                               “emergency dental  dental care”
                                                                                           care” timetime series
                                                                                                            series Figure
                                                                                                                      Figure 3b,
                                                                                                                              3b, there
                                                                                                                                    there are
                                                                                                                                           are two
                                                                                                                                               two peaks:
                                                                                                                                                     peaks:
                                    the most pronounced at the beginning of the period (breaking through the 20 marks) and
                                    the  most   pronounced      at the   beginning       of the   period     (breaking     through     the 20 marks)     and
                                    slightly less
                                    slightly  less pronounced
                                                    pronounced in    in the
                                                                         the second
                                                                              second halfhalf ofof 2018
                                                                                                   2018 (approaching
                                                                                                           (approaching the   the 2020 marks).
                                                                                                                                        marks). Negative
                                                                                                                                                  Negative
                                    peaks
                                    peaks ofof similar
                                               similar intensity
                                                         intensity were
                                                                      were notnot observed.
                                                                                    observed.
                                          Regarding      the  “oral   health”
                                          Regarding the “oral health” time series time    series (Figure
                                                                                                   (Figure 4a),4a), there
                                                                                                                      there are
                                                                                                                             are several
                                                                                                                                   several cycles
                                                                                                                                            cycles ofof low
                                                                                                                                                         low
                                    severity breaking
                                    severity   breaking through
                                                            through the the 10-point
                                                                             10-point mark markin   inboth
                                                                                                        bothdirections.
                                                                                                               directions.Moreover,
                                                                                                                               Moreover,ininthe  the“perio-
                                                                                                                                                      “peri-
                                    odontitis” time series (Figure 4b), there are several peaks of average severity approaching
                                    dontitis”   time series (Figure 4b), there are several peaks of average severity approaching
                                    the 10-point mark in both directions. The most pronounced is the positive cycle at the end
                                    the 10-point mark in both directions. The most pronounced is the positive cycle at the end
                                    of the period under consideration.
                                    of the period under consideration.
                                          In the “teledentistry” time series (Figure 5a), there is one pronounced cycle with an
                                          In the “teledentistry” time series (Figure 5a), there is one pronounced cycle with an
                                    increase in the parameter of about 60 points, and there is one pronounced cycle with an
                                    increase in the parameter of about 60 points, and there is one pronounced cycle with an
                                    increase in the parameter of more than 40 points when describing the “is it safe to go to the
                                    increase in the parameter of more than 40 points when describing the “is it safe to go to
                                    dentist” time series (Figure 5b).
                                    the dentist” time series (Figure 5b).
                                          Two pronounced cycles are clearly visible in the “COVID-19” time series in Figure 6a—at
                                          Two pronounced cycles are clearly visible in the “COVID-19” time series in Figure
                                    the junction of 2019/2020 and in the first half of 2020, with an increase of about 35 points. No
                                    6a—at the junction of 2019/2020 and in the first half of 2020, with an increase of about 35
                                    pronounced negative peaks are observed. A series of peaks regarding the expression “PPE
                                    points. No pronounced negative peaks are observed. A series of peaks regarding the ex-
                                    dentist” at the junction of 2019/2020 with gains of more than 50 points is clearly visible. No
                                    pression “PPE
                                    pronounced         dentist”
                                                    negative       at the
                                                               peaks    werejunction
                                                                                recorded  of (Figure
                                                                                             2019/2020   6b).with gains of more than 50 points is
                                    clearly visible. No pronounced negative peaks were recorded (Figure 6b).
                                    3.4. Changes in Request Average during COVID-19 Pandemic
                                    3.4. Changes in Request Average during COVID-19 Pandemic
                                          The mean of “dental care” time series request rate in the pre-pandemic period has
                                    a rateThe
                                            of mean    of “dental
                                                79.9; during     the care”     time series
                                                                       pandemic,        the meanrequest    rate
                                                                                                        rate  was in increased
                                                                                                                      the pre-pandemic
                                                                                                                                    to 80.2. period
                                                                                                                                              Thus, hasfroma
                                    rate  of 79.9; during
                                    the pandemic      onset the     pandemic,
                                                               to the    present,the themean
                                                                                           “dental ratecare”
                                                                                                          was requests
                                                                                                                 increasedmean to 80.2.
                                                                                                                                      rateThus,   from the
                                                                                                                                           has remained
                                    pandemic onset
                                    particularly         to the present,
                                                    unchanged                 the “dental
                                                                    (the increasing        ratecare”    requests
                                                                                                  is about     0.4%).mean    rate has remained
                                                                                                                          Moreover,      the mean partic-
                                                                                                                                                      of the
                                    ularly unchanged
                                    “emergency      dental(the
                                                             care”increasing
                                                                    time series   rate   is about
                                                                                     request     rate0.4%).
                                                                                                        in theMoreover,
                                                                                                                pre-pandemic   the mean
                                                                                                                                     periodofhas
                                                                                                                                               thea “emer-
                                                                                                                                                     rate of
                                    gency   dental
                                    48.73, and       care”the
                                                 during      time  series request
                                                                pandemic,       the meanraterate
                                                                                               in the   pre-pandemic
                                                                                                    increased      to 52.6. period    has athe
                                                                                                                             Thus, from      rate  of 48.73,
                                                                                                                                                pandemic
                                    and
                                    onset to the present, the main rate of “emergency dental care” increased by 7.9%.onset
                                         during    the pandemic,      the   mean     rate  increased      to  52.6.   Thus,  from    the  pandemic      The
                                    to the of
                                    mean    present,   the health”
                                               the “oral     main rate    of “emergency
                                                                       time   series requestdental rate in care”    increased by 7.9%.
                                                                                                              the pre-pandemic               Thehas
                                                                                                                                        period     mean    of
                                                                                                                                                      a rate
                                    the  “oralduring
                                    of 62.0;    health” thetime  series request
                                                             pandemic,       the mean  raterate
                                                                                              in the    pre-pandemic
                                                                                                  changed                    periodfrom
                                                                                                                to 61.8. Thus,         has the
                                                                                                                                            a rate  of 62.0;
                                                                                                                                                pandemic
                                    during
                                    onset tothe
                                              the pandemic,
                                                   present, thethe     mean
                                                                   “oral         rate requests
                                                                           health”    changedmean    to 61.8.
                                                                                                            rateThus,    from particularly
                                                                                                                   remained      the pandemic      onset to
                                                                                                                                               unchanged
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J. Clin. Med. 2021, 10, x FOR PEER REVIEW                                                                                                            7 of 12

J. Clin. Med. 2021, 10, 3532                                                                                                                         7 of 12
                                    the present, the “oral health” requests mean rate remained particularly unchanged (the
                                    decreasing rate is about 0.3%). The mean of the “periodontitis” request rate in the pre-
                                    pandemic period has a rate of 35.7; during the pandemic, the mean rate changed to 41.1.
                                  (the decreasing rate is about 0.3%). The mean of the “periodontitis” request rate in the
                                    Thus, from the pandemic onset to the present, the main rate of “periodontitis” increased
                                  pre-pandemic period has a rate of 35.7; during the pandemic, the mean rate changed
                                    by 15.1%. Moreover, the mean of the “teledentistry” time series request rate in the pre-
                                  to 41.1. Thus, from the pandemic onset to the present, the main rate of “periodontitis”
                                    pandemic period has a rate of 4.3; during the pandemic, the mean rate changed to 21.4.
                                  increased by 15.1%. Moreover, the mean of the “teledentistry” time series request rate in
                                    Thus, from the pandemic onset to the present, the “teledentistry” requests mean rate char-
                                  the pre-pandemic period has a rate of 4.3; during the pandemic, the mean rate changed
                                    acterized by a 5 times increase. The mean of the request rate for the “is it safe to go to the
                                  to 21.4. Thus, from the pandemic onset to the present, the “teledentistry” requests mean
                                    dentist” time series in the pre-pandemic period has a rate of 0.8; during the pandemic, the
                                  rate characterized by a 5 times increase. The mean of the request rate for the “is it safe
                                  tomean
                                      go torate
                                            the changed      to 31.9.
                                                  dentist” time        Thus,
                                                                    series     from
                                                                           in the    the pandemic
                                                                                  pre-pandemic        onsethas
                                                                                                   period      to the present,
                                                                                                                  a rate of 0.8; the requests
                                                                                                                                  during the
                                    mean   rate  is characterized     by  an increase  of  almost 40  times.   The  mean
                                  pandemic, the mean rate changed to 31.9. Thus, from the pandemic onset to the present,   of the  “PPE  den-
                                    tist”
                                  the     requestmean
                                        requests    rate inrate
                                                             theispre-pandemic
                                                                    characterizedperiod     has a rateofofalmost
                                                                                    by an increase          0.8; during  the pandemic,
                                                                                                                   40 times.  The mean theof
                                    mean   rate  changed    to  24.0. Thus,   from  the  pandemic   onset   to  the present,
                                  the “PPE dentist” request rate in the pre-pandemic period has a rate of 0.8; during         the  “PPE den-
                                                                                                                                         the
                                    tist” request
                                  pandemic,     themean
                                                     meanraterateischanged
                                                                     characterized
                                                                              to 24.0.by  an increase
                                                                                       Thus,  from theofpandemic
                                                                                                           30 times. onset
                                                                                                                       Whentoregarding    the
                                                                                                                                the present,
                                    “COVID-19”
                                  the               timerequest
                                        “PPE dentist”      series, this
                                                                     meanexpression   did not exist by
                                                                            rate is characterized   before    the pandemic.
                                                                                                        an increase    of 30 times. When
                                  regarding the “COVID-19” time series, this expression did not exist before the pandemic.
                                   3.5. Cross-Correlation
                                  3.5. Cross-Correlation
                                         The time series pair “dental care”–“emergency dental” cross-correlation function
                                    plotTheis shown       in Figure
                                                 time series     pair 7a. Therecare”–“emergency
                                                                      “dental       are a number of significant         correlations onfunction
                                                                                                           dental” cross-correlation         both sides plotof
                                  is0.shown
                                        All significant
                                                 in Figure correlations
                                                               7a. There areare     positive,
                                                                                 a number     of from   whichcorrelations
                                                                                                 significant      it follows, onan both
                                                                                                                                     increase
                                                                                                                                           sidesinofone   pa-
                                                                                                                                                      0. All
                                    rameter leads
                                  significant              to an increase
                                                    correlations             in another.
                                                                     are positive,     from There
                                                                                              whichisit no     significant
                                                                                                           follows,          correlation
                                                                                                                      an increase     in oneatparameter
                                                                                                                                                 h = 0. Fur-
                                    thermore,
                                  leads             the time in
                                           to an increase       series pair “oral
                                                                   another.   Therehealth”–“periodontitis”
                                                                                       is no significant correlation  cross-correlation      function the
                                                                                                                           at h = 0. Furthermore,        plot
                                  time    seriesin
                                    is shown        pair    “oral7b.
                                                       Figure      health”–“periodontitis”
                                                                     The correlation magnitude      cross-correlation
                                                                                                            and the number function     plot is shown
                                                                                                                                  of significant          in
                                                                                                                                                     correla-
                                  Figure
                                    tions are7b. greater
                                                   The correlation     magnitude
                                                               on the left  side of 0. andThethemost
                                                                                                  number      of significant
                                                                                                        dominant               correlationsoccurs
                                                                                                                      cross-correlation        are greater
                                                                                                                                                       at h =
                                  on−2.the
                                         The leftcorrelation
                                                   side of 0. The    most dominant
                                                                 is positive,   indicating cross-correlation
                                                                                               that an above-average           h = −2.
                                                                                                                  occurs at value      ofThe
                                                                                                                                          “oralcorrelation
                                                                                                                                                  health” is
                                  islikely
                                      positive,     indicating
                                              to lead              that an above-average
                                                          to an above-average         value of value        of “oral health”
                                                                                                   “periodontitis”      about is    likely tolater.
                                                                                                                                 2 months       lead to   an
                                                                                                                                                       Addi-
                                  above-average          value   of “periodontitis”      about    2 months     later. Additionally,
                                    tionally, a below-average value of “oral health” is associated with a likely below-average          a below-average
                                  value     of “oral health”
                                    “periodontitis”         valueisabout
                                                                     associated
                                                                           2 months withlater.
                                                                                          a likely   below-average
                                                                                                Moreover,       the time“periodontitis”      value about
                                                                                                                          series pair “teledentistry”–
                                  2“is
                                     months
                                         it safelater.
                                                   to goMoreover,      the time
                                                            to the dentist”        series pair “teledentistry”–“is
                                                                               cross-correlation      function plot is itshownsafe toingoFigure
                                                                                                                                           to the7c.dentist”
                                                                                                                                                       There
                                  cross-correlation           function plot
                                    are a number of significant                is shown only
                                                                           correlations      in Figure
                                                                                                    on the7c.   There
                                                                                                             right  sideare
                                                                                                                          of a0.number     of significant
                                                                                                                                 All significant     correla-
                                  correlations        only onFinally,
                                    tions are positive.           the right
                                                                          theside
                                                                                timeofseries
                                                                                         0. Allpair
                                                                                                 significant     correlationsdentist”
                                                                                                      “COVID-19”–“PPE             are positive.     Finally,
                                                                                                                                            cross-correla-
                                  the   time    series    pair  “COVID-19”–“PPE            dentist”    cross-correlation
                                    tion function plot is shown in Figure 7d. There are a number of significant correlations   function    plot  is shown  on
                                  inboth
                                       Figure     7d.   There    are a number       of  significant    correlations     on  both   sides
                                            sides of 0. There is also a significant correlation at h = 0. All significant correlations     of 0.  There    is
                                  also
                                    are apositive,
                                            significant from correlation
                                                                which it at   h = 0. All
                                                                           follows,     an significant
                                                                                            increase incorrelations
                                                                                                            one parameter are positive,
                                                                                                                                leads to from     which itin
                                                                                                                                            an increase
                                  follows,      an   increase    in one  parameter       leads   to  an  increase    in another.
                                    another. An above-average value of “COVID-19” is highly likely to lead to an above-av-          An    above-average
                                  value
                                    erageofvalue“COVID-19”         is highlyabout
                                                       of “PPE dentist”         likely 4toweeks
                                                                                            lead tolater.
                                                                                                      an above-average         value of “PPE
                                                                                                             Since both expressions         existeddentist”
                                                                                                                                                       in GT
                                  about     4  weeks     later.  Since both   expressions      existed    in GT   searches
                                    searches for less than 2 years, the use of month granularity was impossible, which is why,for less  than  2  years,  the
                                  use   of   month      granularity     was
                                    in this case, a week granularity was used.impossible,      which    is  why,   in this  case,  a  week   granularity
                                  was used.

                                  (a)                                                                             (b)

                                                                 Figure 7. Cont.
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J. Clin. Med. 2021, 10, 3532
                        x FOR PEER REVIEW                                                                                                              8 of 12

                                 (c)                                                                              (d)
     Figure 7.
     Figure   7.Cross-correlation plots:
                  Cross-correlation      (a) “dental
                                      plots:         care”–“emergency
                                              (a) “dental                dental”dental”
                                                          care”–“emergency       (granularity: month); (b)
                                                                                          (granularity:    “oral health”–“periodon-
                                                                                                        month);   (b) “oral health”–
     “periodontitis” (granularity: month); (c) “teledentistry”–“is it safe to go to the dentist” (granularity:(d)
     titis” (granularity: month); (c) “teledentistry”–“is it safe to go to the dentist” (granularity: month);     “COVID-19”–“PPE
                                                                                                                month); (d) “COVID-
     dentist” (granularity:
     19”–“PPE               week).
                dentist” (granularity:  week).

                                  4. Discussion
                                     Discussion
                                          The aim of the study was to investigate the impact of the                     the COVID-19
                                                                                                                             COVID-19 pandemic on
                                  oral health and teledentistry subjects. To the best of our knowledge, this is one of the few
                                  studies [19,20] tracing
                                                       tracing thetheGTGTexpressions
                                                                            expressionsconnected
                                                                                             connectedwith withoral oralhealth
                                                                                                                           healthduring
                                                                                                                                     during  thethe
                                                                                                                                                  COVID-19
                                                                                                                                                     COVID-
                                  pandemic.
                                  19   pandemic.  TheThefirstfirst
                                                                noticeable   outcome
                                                                    noticeable    outcome of the
                                                                                               of research
                                                                                                   the researchwas wasa large   increase
                                                                                                                             a large          in emergency
                                                                                                                                        increase    in emer-
                                  dentaldental
                                  gency      care questions
                                                     care questionsaskedasked
                                                                           during      the spring
                                                                                  during              lockdown
                                                                                             the spring     lockdown  in 2020    withwith
                                                                                                                            in 2020       a simultaneous
                                                                                                                                                a simultane-
                                  decrease
                                  ous           in regular
                                         decrease    in regular dental   care
                                                                    dental     queries.
                                                                             care  queries.  Our
                                                                                               Ourresults
                                                                                                      resultsstrongly
                                                                                                                stronglyshow showthat thatthe
                                                                                                                                            the COVID-19
                                                                                                                                                  COVID-19
                                  pandemic had significantly influenced dental-care-seekingdental-care-seeking behavior. According     According to the
                                  recommendations and
                                  recommendations            and because
                                                                   because of of the
                                                                                 the fear
                                                                                        fear surrounding
                                                                                             surrounding the    the epidemic,
                                                                                                                     epidemic, peoplepeople were were averse
                                                                                                                                                       averse
                                  to be   outside    and   less   willing  to visit   dental   studios.   Moreover,
                                  to be outside and less willing to visit dental studios. Moreover, dental care was not    dental   care   was    not widely
                                                                                                                                                       widely
                                  available during
                                  available      duringthe theearly
                                                                 earlyphase
                                                                         phaseof of
                                                                                  thethepandemic,
                                                                                           pandemic,   with
                                                                                                          witha large    number
                                                                                                                   a large          of patients
                                                                                                                               number               expected
                                                                                                                                            of patients    ex-
                                  to seek    emergency        dental   service   only    when    urgent   care
                                  pected to seek emergency dental service only when urgent care was needed [5].   was    needed     [5].  In   line with   our
                                                                                                                                                       In line
                                  study,our
                                  with      thestudy,
                                                 outcomes       of the study
                                                         the outcomes           conducted
                                                                            of the              by FaccinibyetFaccini
                                                                                     study conducted              al. indicate
                                                                                                                            et al.that    during
                                                                                                                                    indicate     thatthe hard
                                                                                                                                                       during
                                  lockdown,       64.6%    of  dentists   carried   out   only  emergency       treatments,
                                  the hard lockdown, 64.6% of dentists carried out only emergency treatments, with 26.1%         with    26.1%    of  dentists
                                  stilldentists
                                  of     maintaining      the routine planned
                                                  still maintaining       the routine appointments,       and with 9.3%
                                                                                           planned appointments,                of dental
                                                                                                                              and   with 9.3% offices
                                                                                                                                                    of closed
                                                                                                                                                       dental
                                  for   the  duration     of  the  lockdown.      An    increase    in urgent    dental
                                  offices closed for the duration of the lockdown. An increase in urgent dental procedures  procedures        was   noted by
                                  44.1%
                                  was       of the
                                         noted    by dentists.
                                                      44.1% of the It occurred
                                                                       dentists. most      often most
                                                                                   It occurred      due to    the due
                                                                                                          often     lower     availability
                                                                                                                          to the                for a longer
                                                                                                                                  lower availability        for
                                  period     of time   for  regular    dental   care.    The  main    causes    of  emergency
                                  a longer period of time for regular dental care. The main causes of emergency appoint-             appointments        were
                                  toothache,
                                  ments     weredental       trauma,
                                                    toothache,     dentalor trauma,
                                                                            broken restorations          [21]. Similarly,
                                                                                         or broken restorations                 a study conducted
                                                                                                                         [21]. Similarly,       a study con- in
                                  Beijing, in
                                  ducted      China,    withChina,
                                                 Beijing,       2537 patients
                                                                       with 2537 involved
                                                                                      patientsin involved
                                                                                                  the study,inindicated
                                                                                                                   the study,  that   at the beginning
                                                                                                                                   indicated      that at theof
                                  the COVID-19 pandemic, 38% fewer patients sought dental emergency care than before.
                                  beginning of the COVID-19 pandemic, 38% fewer patients sought dental emergency care
                                  Dental problems and oral infection increased from 51.0% in the pre-pandemic period to
                                  than before. Dental problems and oral infection increased from 51.0% in the pre-pandemic
                                  71.9% during the COVID-19 pandemic period [5]. A finding in line with our study is that
                                  period to 71.9% during the COVID-19 pandemic period [5]. A finding in line with our
                                  the COVID-19 pandemic outbreak had strongly influenced the emergency dental services.
                                  study is that the COVID-19 pandemic outbreak had strongly influenced the emergency
                                  The large influence of COVID-19 disease on oral cavity was shown in the study conducted
                                  dental services. The large influence of COVID-19 disease on oral cavity was shown in the
                                  by Gherlone et al., as 83.6% of patients reported anomalies of the oral cavity, such as dry
                                  study conducted by Gherlone et al., as 83.6% of patients reported anomalies of the oral
                                  mouth or salivary gland ectasia, that lasted even up to 3 months after hospitalization due
                                  cavity, such as dry mouth or salivary gland ectasia, that lasted even up to 3 months after
                                  to COVID-19 [22].
                                  hospitalization due to COVID-19 [22].
                                          According to recent studies, people with serious medical conditions such as diabetes,
                                          According to recent studies, people with serious medical conditions such as diabetes,
                                  heart diseases, lung or kidney chronic disease, and older persons were at high risk for de-
                                  heart diseases, lung or kidney chronic disease, and older persons were at high risk for
                                  veloping more severe COVID-19 infection. On the other hand, poor oral health and hygiene
                                  developing
                                  may increase     more
                                                      the severe
                                                            risk ofCOVID-19
                                                                      developinginfection.       On the other hand,
                                                                                       the abovementioned            medical  poor    oral health
                                                                                                                                 problems.            and hy-
                                                                                                                                                  Therefore,
                                  giene    may    increase     the  risk of developing       the  abovementioned
                                  improving oral health among the whole population may lead to a lower risk of developing   medical     problems.      There-
                                  fore,   improving       oral   health  among      the   whole    population      may
                                  systemic diseases and, in this way, reduce the morbidity due to COVID-19 [9,23]. In      lead  to   a  lower    risk  of the
                                                                                                                                                           de-
                                  veloping
                                  study among   systemic
                                                      a groupdiseases
                                                                  of 568and,  in thisthe
                                                                          patients,      way,  reduce
                                                                                            higher   riskthe
                                                                                                           of morbidity
                                                                                                               intensive care  dueunit
                                                                                                                                     to COVID-19
                                                                                                                                           admission[9,23].
                                                                                                                                                         with
                                  In the   study   among      a  group   of 568  patients,    the  higher
                                  the need for assisted ventilation and worse disease outcomes, leading even risk  of  intensive     care  unit toadmission
                                                                                                                                                   the death
                                  with    the needpatients,
                                  of COVID-19          for assisted wasventilation
                                                                          associated and  withworse     disease outcomes,
                                                                                                periodontitis.       Similarly, leading
                                                                                                                                    COVID-19     even   to the
                                                                                                                                                     patients
                                  death    of  COVID-19         patients,  was   associated      with   periodontitis.
                                  with periodontitis had significantly higher blood levels of D-dimer and C-reactive protein Similarly,     COVID-19       pa-
                                  tients with periodontitis had significantly higher blood levels of D-dimer and C-reactive
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J. Clin. Med. 2021, 10, 3532                                                                                            9 of 12

                               and white blood cells [24]. After a lower level of interest in oral health was detected in
                               the number of queries asked in GT during the hard lockdown, in the conducted study, we
                               detected a peak in periodontitis questions and about a 15% interest growth in the subject.
                                     During the pandemic, telemedicine represented an opportunity to improve accessibil-
                               ity to medical treatments. According to some studies, teledentistry could be comparable to
                               face-to-face visits for oral screening, especially in areas with limited access to oral health
                               care. In fact, the identification of oral pathologies via teleconsultations is widely possible
                               and valid [25]. The online examination using intraoral scans may become helpful in de-
                               tecting dental problems. The remote assessment of intraoral scans can allow an efficient
                               screening and the correct triage of patients. Improved intraoral scans can provide even
                               three-dimensional images with true colors [26]. Nowadays, to minimize contact with the
                               patient and to ensure patient safety clinicians may follow up with patients online, for
                               example, through video calls. In the present study, a 5-time increase in query rates for
                               teledentistry during the COVID-19 pandemic was detected because of the anxiety to visit
                               the dentist. The query “is it safe to go to the dentist” increased the question rate during
                               the pandemic almost 40 times. It may indicate the usefulness of such a digital tool during
                               epidemiological threats. The screening for other chronic viral infections was previously
                               conducted in dental offices, for example, for HCV virus [27]; such easy, free-of-charge
                               prevention campaigns may use teleconsultation in the post-pandemic time.
                                     In addition, specific recommendations and lots of preventive measures against COVID-19
                               were undertaken in dental offices with infection control strategies. The urgent need for den-
                               tal emergency care required fast delivery of the appropriate PPE. The initial shortage and
                               distribution challenges of PPE was seen globally [11,28], as well as the large interest in PPE
                               connected with dentists was observed in our study, with a 30-time increase of requests mean
                               rate. The patient management protocols were applied to reduce the risk of infection and to
                               prevent the spread of the cross-infection, for example, clinical triage for patient screening
                               with a questionnaire on recent disease symptoms, body temperature measurement, avoiding
                               crowding in the waiting room, a hand sanitizer available to patients before entering the oper-
                               ating rooms, and the use of PPEs and oral rinses with hydrogen peroxide before the dental
                               treatment [29–32]. The WHO recommended the use of FFP3 masks according to the European
                               terminology or N100, according to the United States nomenclature [33]. Members of the
                               oral healthcare team should be acquainted with the COVID-19 transmission and preventive
                               measures, as the oral cavity is an important site for COVID-19 infection and a potential route
                               of virus transmission [34]. Cross-infection control measures should be applied to all patients
                               because asymptomatic COVID-19 persons may also need emergency dental treatment [35].
                                     This study has some limitations. Firstly, the analyzed data were collected from one
                               search engine; nevertheless, Google engine has nearly four billion users worldwide and
                               covers more than 90% of all queries on the internet, with near 7 billion queries per day. With
                               4.39 billion internet users worldwide, the number of Google users is globally nearly four
                               billion [36]. In our study, the GT request sample size for 5 years period is about big data
                               collections. Thus, the nature of the data and sample size is appropriate for the purpose and
                               nature of the study. Moreover, when considering the overlapping of expressions meaning,
                               in a small sample, it might be discussed as a limitation; however, the sample of expressions
                               gathered in the presented study is huge, the time of observation is long, and therefore,
                               it should not induce significant changes in results. Secondly, the study was carried out
                               globally, in order not to add too much manual categorization, by providing expressions in
                               different languages. When adding queries in many languages across countries, it becomes
                               more difficult to choose the best fitting expression used in a specific country. Finally, there
                               are no strict rules on how to analyze the GT in health care research [37]; on the other hand,
                               the GT data are recognized by the scientific community as a reliable source on the basis of
                               which scientific papers in various fields are published [38,39]. Because of the anonymized
                               approach of data collection, GT enables the analysis and forecasting of sensitive topics
                               especially in medicine [37,40–43]. Because of using the revealed and not stated users’
                               preferences, it is possible to obtain information that would be otherwise impossible to
Oral Health and Teledentistry Interest during the COVID-19 Pandemic
J. Clin. Med. 2021, 10, 3532                                                                                                        10 of 12

                                   collect. Moreover, GT offers a substantial promise for the global monitoring of diseases in
                                   countries that lack clinical surveillance but have sufficient internet coverage to allow for
                                   surveillance via digital epidemiology [44].

                                   5. Conclusions
                                   1.    Firstly, according to the search queries analysis from GT, the COVID-19 pandemic
                                         had a large impact on oral health problems;
                                   2.    Moreover, emergency dental care became more required during the onset of pandemic
                                         and hard lockdown than regular dental care;
                                   3.    Finally, teledentistry gained in popularity during the lockdowns according to globally
                                         asked questions in GT service.

                                   Author Contributions: Conceptualization, M.S.-D. and G.S.; methodology, M.S.-D.; software, M.S.-
                                   D.; validation, M.S.-D. and M.M.; formal analysis, M.S.-D.; investigation, M.S.-D.; resources, M.S.-D.;
                                   data curation, M.S.-D.; writing—original draft preparation, M.S.-D.; writing—review and editing,
                                   M.S.-D., K.W., M.M., and G.S.; visualization, M.S.-D. and M.M.; supervision, G.S. All authors have
                                   read and agreed to the published version of the manuscript.
                                   Funding: This research received no external funding.
                                   Institutional Review Board Statement: Not applicable.
                                   Informed Consent Statement: Not applicable.
                                   Data Availability Statement: The data presented in this study are available on request from the
                                   corresponding author.
                                   Conflicts of Interest: The authors declare no conflict of interest.

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