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• Mouth - Body CONNECTIONS • The Facts and Fictions of INFLAMMATION • PREGNANCY and PERIODONTAL DISEASE • Linking DIABETES, OBESITY and INFECTION • Reflections from a SURGEON GENERAL • HEALTH POLICY of the Future • Blurring the DOCTOR-DENTIST Barrier A custom publication production in collaboration with the Procter & Gamble Company
The mouth speaks for the body.
We speak for the mouth.
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Together for the first time. 100 years of innovation, information, and expertise. This combined heritage,
Dedicated to uncovering coupled with a shared dedication to improving outcomes for dental
all the links between professionals and patients alike, puts the new company of Crest and Oral-B at
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whole-body wellness. Oral-B are passionately committed to evolving the field of oral health and its
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between oral and systemic health? Absolutely. Join us on the journey as we
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© 2006 P&G PGC-1713C OPAD06506 Dedicated to healthy lifesmiles
SCIENTIFIC AMERICAN PRESENTS
ORAL AND W HOLE BODY HEALTH
INTRODUCTION »
OUR MOUTHS, OURSELVES
As the relationship between the mouth and the rest
of the body becomes clearer, it is changing the way
3 dentists, doctors and patients view oral health.
BY SHARON GUYNUP
INVADERS
AND THE BODY’S DEFENSES
Gum disease illustrates how local infections may
have systemic consequences.
6 BY PHILIP E. ROSS
HEART HEALTH IN THE
INFLAMMATION AGE
Arterial plaques, once thought to be fatty deposits,
are a result of the inflammatory process.
12 BY PETER LIBBY
THE THREE-WAY STREET
OR AL AND WHOLE BODY HE ALTH
is published by S CIENTIFIC A MERICAN,
Two decades of biomedical and dental detective
INC ., 415 Madison Avenue, New York, work have linked obesity, diabetes and periodontal
NY 10017-1111. Copyright © 2006 disease.
by S CIENTIFIC A MERICAN, INC . All rights
reserved. No part of this issue may
be reproduced by any mechanical,
photographic or electronic process,
or in the form of a phonographic
18 BY ROBERT J. GENCO
recording, nor may it be stored in a
retrieval system, transmitted or INTERVIEW »
other wise copied for public or
pr i v a te us e w i thou t w r i t ten
BUZZ TALK WITH
permission of the publisher. MARJORIE K. JEFFCOAT
Subscription inquiries for The Dean of the University of Pennsylvania School of
S CIENTIFIC A MERICAN MAGAZINE:
U.S. and Canada (800) 333-1199;
23 Dental Medicine on the facts and fiction surrounding
oral health’s relationship to the rest of the body.
CREDIT
Other (515) 248-7684
b SCIENTIFIC AMERICAN PRESENTS: ORAL + WHOLE BODY HEALTH PROTCTOR & GAMBLE
A custom publication produced
in collaboration with CREST and ORAL-B
WHAT EVERY WOMAN
NEEDS TO KNOW
Growing evidence suggests that poor oral hygiene
during pregnancy can adversely affect the health
of newborns.
BY STEVEN OFFENBACHER 24
AS THE BODY AGES
When it comes to the complications of oral disease,
the elderly are particularly vulnerable.
BY FRANK A. SCANNAPIECO
30
INSIGHTS »
ORAL HEALTH
AROUND THE WORLD
Maurizio Tonetti, an oral health professional who
has worked in four different countries, offers some
thoughts on the future of global oral health.
35
PUBLIC POLICY & ORAL HEALTH »
A WHOLE NEW GAME
Governments, insurers, clinicians and the public
must all recognize the changing face of dental
medicine.
BY SHEILA RIGGS 36
INTERVIEW »
DISCUSSION WITH
DAVID SATCHER
The former U.S. surgeon general reflects on his
landmark report that put oral health on the national
agenda and the policy steps that still need to be taken.
40
CREDIT
w w w. s c ia m . c o m SCIENTIFIC A MERIC A N c
RESEARCH SNAPSHOT »
A custom publication produced in
A NOVEL APPROACH TO
collaboration with CREST & ORAL-B INFLAMMATION
PROJECT MANAGEMENT Understanding how the body “turns off” inflammation
Publication and Media Director : may yield new treatments for periodontal disease
42 and other inflammatory conditions.
Jeremy Abbate
Editorial Director: Sharon Guynup
Features Editor: Larry Katzenstein
BY THOMAS E. VAN DYKE
Art Director: Jeff Mellin
& CHARLES N. SERHAN
Illustrators: Matt Collins, Tami Tolpa,
Keith Kasnot
Custom Photography: John Soares PATH TO PREVENTION »
Production Consultant: Richard Hunt MOUTHFUL OF BUGS
Copy Editor: Michael Battaglia Pathogenic bacteria are a way of life.
Research: Anna Kline So, too,must be brushing and flossing.
BOARD OF ADVISERS
Robert J. Genco: Distinguished
Professor, Department of Oral Biology,
School of Dental Medicine, State
University of New York at Buffalo
46 BY ROBERT H. KAGAN
Jim Beck: Distinguished Professor,
Department of Dental Ecology, School
of Dentistry, The University of North
INTERVIEW »
Carolina at Chapel Hill THE ADA’S TAKE
Marjorie K. Jeffcoat: Dean, University of How the American Dental Association, the world’s
Pennsylvania School of Dental Medicine
leading dental organization, views the growing
49
Steven Offenbacher: Director, Center for
Oral and Systemic Diseases, University connections between a healthy mouth and a healthy
of North Carolina at Chapel Hill body — a conversation with Daniel M. Meyer.
Maurizio Tonetti: Chair, Division of
Periodontology, University of
Connecticut School of Dental Medicine
Thomas E. Van Dyke: Professor,
Department of Periodontology and
Oral Biology, Boston University
Goldman School of Dental Medicine A Message from the A MERICAN A CADEMY OF P ERIODONTOLOGY
SCIENTIFIC AMERICAN
EDITORS & PROJECT STAFF THE AMERICAN ACADEMY OF PERIODONTOLOGY (AAP) congratulates Procter & Gamble
Editor In Chief: John Rennie Professional Oral Health, Scientific American and all of the contributors to this special
Executive Editor: Mariette DiChristina
Managing Editor: Ricki L. Rusting supplement for providing in-depth and balanced information on the association between
News Editor: Philip M. Yam periodontal diseases and general health conditions.
Special Projects Editor: Gary Stix
Senior Editor: Michelle Press The AAP has been a leader in tracking periodontal and systemic research for over a decade.
Editors: Mark Alpert, Steven Ashley, The research results to date have been promising, and the prospect that periodontal
Graham P. Collins, Steve Mirsky,
George Musser, Christine Soares treatment may significantly improve general health outcomes is exciting. However, there is
Art Director: Ed Bell
still a great deal to learn about the impact of periodontal infection and infl ammation on
Associate Publisher, Production: general health. Additional research into these complex associations is essential if patients
William Sherman are to reap the benefi ts of improved health.
Production Manager: Christina Hippeli
Prepress and Quality Manager: Silvia Given the potential impact on diabetes, pre-term low birthweight, cardiovascular disease
De Santis and other conditions, we believe this research merits the investment and should be prioritized
Director of Ancillary Products: Diane
McGarvey by the National Institutes of Health and other funding agencies.
Associate Publisher, Circulation: The Academy and its member periodontists are proud to collaborate to advance oral and
Simon Aronin
Circulation Director: Christian Dorbandt systemic health. Readers are encouraged to visit www.perio.org for more information about
General Manager: Michael Florek periodontists and periodontal health.
Business Manager: Marie Maher
President and Chief Executive Officer:
Gretchen G. Teichgraeber — KENNETH A. KREBS, D.M.D.
Vice President and Managing Director,
CREDIT
International: Dean Sanderson President, American Academy of Periodontology
Vice President: Frances Newburg
d SCIENTIFIC AMERICAN PRESENTS: ORAL + WHOLE BODY HEALTH PROTCTOR & GAMBLE
INTRODUCTION
OUR MOUTHS, OURSELVES
As the interrelationship between the mouth and the rest
of the body becomes clearer, dental professionals, doctors
and patients will need to rethink the term “oral health”
BY SHARON GUYNUP
ORAL AND WHOLE BODY HEALTH 3
S I N C E T I M E I M M E M O R I A L , people have struggled to maintain adequate oral
health. As far back as a.d. 250, Kemetic Egyptians used myrrh and other antiseptic herbs to treat infected gums. The Nubians
that dwelt in the Nile River valley two centuries later drank beer as a palliative for unhealthy teeth; it may have worked well,
as it was brewed from grain contaminated with the same bacteria that produces tetracycline.
Lengthening teeth and receding gums have historically “oral-systemic link” emerges almost daily. For example, in
been considered a consequence of surviving into adulthood. May 2006 it was announced at an American Society for Mi-
(In his 1852 novel The History of Henry Esmond, Esq., Wil- crobiology meeting that researchers have identified genes in
liam Thackary used the expression “long in the tooth” to certain oral bacteria that allow the organisms to invade and
describe a middle-aged person.) The few teeth that didn’t de- infect human arterial cells. This certainly expands to the
cay in youth usually loosened with the passing years, as the discussion of the possible biologic pathways that might link
tissues supporting them were eroded by periodontal disease. the mouth and the heart (or other parts of the body). Addi-
Those teeth ultimately fell out. tionally, this year will see the results of two major studies
Today, people are living longer, and gum disease has sup- examining the relationship between oral disease and preg-
planted tooth decay as the most common cause of tooth loss nancy complications in expectant mothers.
in adults. The disease affects about 80 percent of Americans So what exactly is the connection between what happens
over age 65, according to the American Dental Association. in your mouth and your overall health? Some of the millions
At the turn of the last millennium, then–U.S. surgeon gen- of bacteria that lurk in our mouths (numbering more than all
eral David Satcher called periodontal disease the “silent the cells in our bodies) are the primary culprits—along with
epidemic” in his landmark report, Oral Health in America. the subsequent inflammation they cause. These microrgan-
Given the state of public health, good oral hygiene may prove isms form complex colonies of sticky plaque. This tenacious
to be more critical than just preserving your smile. A grow- plaque — what microbiologists call a “biofi lm” — is com-
ing body of research suggests that periodontal disease may posed of durable, coral reef–like structures, building up at the
play a role in a variety of systemic health problems as wide gum line and in between teeth.
ranging as diabetes, respiratory illness, pregnancy complica- Some of the approximately 500 species of bacteria in your
tions, and heart disease. mouth are not innocuous flora. They cause gingivitis, infect-
It is this body of research—and the attendant health pol- ing gums. Your immune system steps in to fight these invad-
icy implications it engenders—that is the subject of this cus- ers—gums become inflamed, and may bleed when you brush.
tom publication from Scien-
tific American, Oral and
Whole Body Health, pro- The fields of dentistry and medicine have traditionally
duced with the generous sup-
port of the Procter & Gam-
been worlds apart. But in light of the growing evidence
ble Company. Here we pres- pointing to links between oral and whole body health, this
ent, for the benefit of both separation of disciplines is slowly beginning to change.
health professionals and pa-
tients, the latest pieces in the
ever-growing puzzle of oral disease’s connection to systemic Interestingly, if this same type of infection appeared on a per-
health. You’ll hear from some of the pioneering researchers son’s arm or another body part, they would no doubt go run-
themselves about their ongoing explorations into the mouth- ning to the doctor for treatment—but bleeding, tender gums
body relationship. are often ignored.
Like any new area of scientific inquiry, some data paint a Untreated, this tenderness progresses into full-blown peri-
very clear picture while other results are still inconclusive. odontitis, and here the immune system shows its dark side.
Several studies, for example, have found that blood-sugar This simmering inflammation ulcerates gums and summarily
levels in diabetics with periodontal disease were significant- destroys the soft tissue and bone that anchors your teeth. It
ly reduced when the patients’ gum disease was treated. Oth- also sends inflammatory substances throughout the body.
ers, like the ones examining the connection between peri- Researchers are discovering that out-of-control inflamma-
odontal disease and heart conditions, have not yet uncovered tion may prove to be the engine that drives an ever-growing
a defi nitive causal relationship. But new information on this list of greatly feared, chronic illnesses from clogged arteries
4 ORAL AND WHOLE BODY HEALTH
and heart attacks to arthritis and cancer. This inflam- es on their Web site,
mation link is just one of a number of hypotheses ex- warning: “if you or
plaining how chronic oral infection may trigger or someone you know
intensify systemic diseases. had periodontal dis-
Another concern is that the microbial ecosystem in ease, diagnosed or
your mouth doesn’t just stay there. Stealthy, virulent undiagnosed, and ei-
bacteria overgrow in inflamed gum tissues; with each ther ignored or treat-
bite of food or stroke of a toothbrush, some of those ed unsuccessfully,
microbes can seep into your bloodstream, traveling to before or during the
distant parts of your body. The question is: can they set same time as any of the
up shop elsewhere and cause harm? It is known that some mentioned systemic dis-
of these bad bugs, when inhaled, can cause pneumonia, par- eases, you may be eligible
ticularly in the elderly. Some are also able to move through arter- for damages caused by these
ies to the uterus and have been found in the placenta. systemic diseases.” Although
BUGS WITH STAYING POWER: an extreme example, it embod-
clearly the mouth is in many ways the “gateway” to the Once thought to be a mere ies the confusion and hype sur-
rest of the body. However, this connection is often overlooked. congregation of pathogens, rounding this topic and under-
dental plaque is now known to
In the U.S., the fields of dentistry and medicine have tradition- be a dynamic – and tenacious – scores the need for objective,
ally been worlds apart. But in light of the growing evidence microbiological community credible analysis. And it ig-
pointing to links between oral and whole body health, this called a biofilm. nores the fact that oral disease
separation of disciplines is slowly beginning to break down. is complex.
The notion that dentists care for only gums and teeth, while For example, changing hormone levels can cause flare-ups
doctors look after everything else is being rethought. in women during pregnancy and while premenstrual—or in
There is a dawning realization that often it is a dentist or perio- those taking oral contraceptives. Other medications can also
dontist who first discovers a larger health problem, because of make gums more susceptible to infection, including antihis-
what they see in a patient’s mouth—and that doctors need to look tamines, antidepressants, cancer drugs, steroids, and espe-
at more than the tonsils when a patient opens wide and says “ah.” cially those that cause “dry mouth,” disrupting the mouth’s
P R E V I O U S P A G E P H O T O : J O H N S O A R E S M O U T H I M A G E S : C L I P A R T. C O M C O L L A G E I L L U S T R A T I O N : J E F F M E L L I N
For example, diabetics tend to develop periodontal disease at three bacterial ecosystem. Genetic, microbial, immunological and
to four times the rate of nondiabetics. If a dental professional sees environmental factors influence both the risk and progression
gum inflammation in someone who brushes and flosses regu- of infection. For example, the American Academy of Peri-
larly, they need to ask, “Have you checked your blood sugar odontology says that perhaps one third of Americans may be
lately?” Or, conversely, the doctor of a patient with uncontrolled genetically susceptible—making them up to six times more
blood sugar may need to refer them to a dental professional. likely to develop periodontal disease. It could be that in some
There is already a ripple effect in some sectors of the insur- cases these same factors or susceptibility might independent-
ance industry. Some insurers are finding it more cost-effective ly cause harm elsewhere in the body, creating a mere illusion
to include periodontal treatment among covered services for of oral-systemic causality.
diabetics and pregnant women. But if additional research so- Of course, one of the most important differences between
lidifies the links between gum disease and other chronic ill- periodontal disease and other systemic conditions is that the
nesses, sweeping changes will be needed to provide access to former has a known cause and is quite treatable. Dental profes-
care. This will be crucial for the segments of society—the poor sionals should never lose sight of the fact that they are address-
and the elderly—who are most at risk for oral disease as well as ing a disease that significantly contributes to disability and a
conditions such as heart disease and diabetes. It is a huge public lack of well-being in the population. This fact alone makes it
health issue: periodontal treatment and prevention can cost important to treat this condition, regardless of whether it might
between $100 and $1,000 annually per patient. contribute to other serious illnesses. And although no one
Over the past few years, newspapers, magazines and oth- should overstate the oral-systemic link, proffers Robert Genco,
er national media outlets have hyped numerous stories about a professor of oral medicine and microbiology at the Univer-
the possible systemic health risks of periodontal disease as sity at Buffalo, no one should underestimate what can happen
well as inflammation’s general link to a broad range of dis- if it’s ignored, either. While the mouth’s relationship to the rest
eases. Some articles have greatly exaggerated or oversimpli- of the body will certainly be a matter of public health, of patient
fied the connection, enough so that the expression “floss or awareness and of the changing roles among caregivers, it will
die” has become a standing joke among researchers. first and foremost be a matter of science. •
Even some opportunistic law fi rms have jumped on the
bandwagon. One in Arizona solicits potential malpractice cas- SHARON GUYNUP is editorial director of Oral and Whole Body Health.
ORAL AND WHOLE BODY HEALTH 5
>>
Gum disease illustrates how local infections may have systemic consequences
INVADERS
& THE BODY’S DEFENSES BY PHILIP E. ROSS
IF EVER THERE WAS A MAGIC BULLET —a drug so discriminating that it attacked
microbes while sparing healthy tissue— it would be the monoclonal antibody, a human-tuned
form of an immune molecule honed by eons of natural selection. Yet, as the world learned
this spring, when such an antibody nearly ic effects are nowhere better illustrated than
killed several subjects in a British clinical in chronic gum disease. Although it origi-
trial, even these drugs can cause serious side nates in a bacterial assault, some two thirds
effects. No one should have been too sur- of the damage is caused by the inflammatory
prised; the natural immune response also response to the perceived invader. What is
causes damage, which is why it fully mobi- worse, inflammation somehow communi-
lizes—in a process called inflammation— cates itself to distant points, explaining the
only when the enemy is at the gates. possible association of gum disease with oth-
In recent years, a lot of media attention er conditions: adult-onset (or type 2) diabe-
has been lavished upon the process of inflam- tes, premature birth, stroke and cardiovascu-
mation (including a cover story in Time mag- lar disease. However infection travels from
azine on this “silent killer”) as researchers the mouth to infl ame distant organs, it is
continue to uncover evidence linking it with clear that it turns the body against itself. In
other serious diseases. Whether or not in- the words of the cartoon character Pogo,
>> flammation turns out to be the “holy grail” of “We have met the enemy and he is us.”
medicine is yet to be seen. But inflammation’s Only a handful of the more than 500 spe-
problem of friendly fi re and potential system- cies of bacteria that live in the mouth are
6 ORAL AND WHOLE BODY HEALTH
S
INFECTION AND INFLAMMATION
in the mouth have been linked to a
variety of systemic conditions,
including pregnancy complications,
type 2 diabetes, heart disease and
stroke. While recent national media
coverage spotlighting inflammation
has spawned much interest in the
JOHN SOARES
topic, more research is needed to
uncover exactly how infection and
inflammation affect the body.
ORAL AND WHOLE BODY HEALTH 7MOUTH A PRIME LOCATION
The hard, non-shedding surface of the teeth and the nutrient-
INVADERS rich, oxygen-poor environment of the mouth provide ideal
conditions for the growth of oral bacteria. They easily attach
themselves to the tooth and gum. Of the over 500
The Progression of microorganisms that live in dental plaque, only a handful have
Periodontal Disease been implicated in gum disease.
implicated in gum disease. They are par- dead and dying neutrophils, and any the ligaments that anchor teeth in their
ticularly hard to eradicate because they cellular detritus that may litter the bat- sockets, loosening them until they at last
form biofilms: tough, many layered, tlefield. Meanwhile, the macrophages fall out. Nowadays this happens less fre-
mineral encrusted communities. Hud- secrete fatty acids and interleukin-1 quently; the patient notices the bleeding
dling in the deepest layers are the oxygen- (IL-1), a primary regulator of infl am- and goes to a dentist. The dentist or den-
shunning, or anaerobic, bacteria that ap- matory and immune responses, as well tal hygienist scrapes away inflammation-
pear to cause the most damage. as tumor necrosis factor alpha (TNF␣), riddled material and treats the infection
When bacteria come in contact with a protein that heightens inflammation. with antibiotics. Treatment, however,
gums, they secrete toxins that break The resulting mayhem may be likened cannot prevent the influx of bacteria.
down gum lining, creating a tiny ulcer. to urban warfare, with immune sol- The disease will recur if the patient does
The body’s bloodhounds, the neutro- diers running from house to house, not stick to a rigorous routine of brush-
phil cells, then attack these invaders. If tossing in grenades, spraying rooms ing, flossing, rinsing and dental clean-
they keep the biofi lm at bay, the battle with machine-gun fi re, all before ask- ings. And although the damage in peri-
reaches a standoff, termed gingivitis. If, ing who is friend and who is foe. No odontal disease is primarily the result of
however, the bacteria continue to ad- wonder the tissue breaks down. The the inflammatory process, it can only be
vance into the gums, the immune sys- ulcers sink deeper into the gum, creat- prevented or treated by addressing the
tem signals a higher state of alert, mo- ing a “periodontal pocket”; full-blown bacterial biofilm that is infecting the
bilizing macrophages (Greek for “big periodontitis begins. gums. What is worse, the chance of early
eaters”). These white blood cells swal- If the disease is allowed to progress, detection is lessened in those who are
low bacteria, along with the gorged, the advancing inflammation eats away most vulnerable—smokers. Just as to-
8 ORAL AND WHOLE BODY HEALTHTENACIOUS BUGS A HEATED STRUGGLE
Oral bacteria are particularly hard to eradicate because they form Continued defensive strikes by the immune system heighten
tough, many-layered, mineral-encrusted communities, known as inflammation as specialized white blood cells (macrophages,
biofilms. If untreated, these biofilms become lodged in the gingival as well as others) secrete inflammatory substances. This
crevices around the tooth. The immune system launches a defensive intense inflammation can ultimately break down gum tissue,
strike against these bacterial invaders by dispatching neutrophils. creating a periodontal pocket — the beginning of full-blown
The first signs of inflammation (redness, swelling) begin to appear. periodontal disease.
bacco smoke irritates the gums, height- neutrophils have trouble homing in on tomb fat in situ, creating atherosclerot-
ening inflammation, it also tends to mask bacteria, showering them with chemical ic plaque. This buildup, combined with
telltale bleeding. grenades called superoxides. “But instead inflammation, fattens the arterial wall,
Other factors that predispose people of destroying bacteria, they destroy the gradually restricting blood flow to tis-
to gum disease include bad oral hygiene periodontal ligament that ties the tooth to sues. Sometimes, for reasons that are
and an unlucky bequeathal of genes. the jaw,” says Charles N. Serhan, profes- not well understood, the thin layer of
One very invasive form of periodontal sor of anesthesiology at Harvard Medical tissue covering the plaque ruptures,
disease is found in just 0.1 percent of School. “It’s like rheumatoid arthritis, an spurring clots to form in a matter of
Americans, a distribution that indicates autoimmune disease where a lot of the minutes, often triggering a heart attack
a genetic component. People with these degradation of the synovium [the lining of or stroke. This is why the most com-
and other predisposing genes must work the joints] is done by neutrophils.” Serhan mon fi rst symptom of heart disease is
extra hard to care not only for their is looking for ways to shut down this ex- sudden death.
teeth but even for the artificial implants cessive immune response. If infection in the gums not only pre-
that may replace those teeth. Periodon- When inflammation strikes sites far cedes inflammation in the arteries, but
tal disease can strike the tissues sur- from the gums, it progresses there much encourages it, the question is how does
rounding implants as well. as it does in the mouth. In the lining of it happen. One theory holds that bacte-
Genetic variation is of particular in- the heart’s arterial wall, for instance, ria are the primary vehicles in commu-
M AT T COLLINS
terest because it may illuminate the mech- macrophages engulf whatever detritus nicating disease; another lays the blame
anisms that underlie all varieties of peri- they find, including fatty particles. on proinflammatory chemicals that leak
odontal disease. In one invasive form, When the macrophages die, they en- out of the gums and into the blood-
ORAL AND WHOLE BODY HEALTH 9stream. Direct inflammation currently valve. What if a similar weakness ex- sidered innocuous. Yet critics of the
holds sway, particularly in the popular ists in the arterial lining? bacterial-cause theory point out that
press. Still, there is evidence supporting Researchers have, in fact, found oral bacteria survive poorly in the
both theories, and each may explain traces of oral bacteria in arterial plaque. bloodstream. They also note that proin-
part of the problem. Yet as critics of the infection theory flammatory chemicals demonstrably
Oral bacteria can get into the blood- point out, the method they used to iden- leak from the gums into the blood-
stream. Robert Genco, a professor of tify the bacteria—a highly potent DNA stream, adding to the body’s inflamma-
oral medicine and microbiology at the amplification tool—cannot tell how tory burden. In a test tube, proinflam-
University at Buffalo, took moment-by- many bacteria were present in the matory agents from one group of cells
moment blood tests in healthy patients plaque or whether any of them were can spark a response in another group.
undergoing routine teeth cleaning. The alive when they entered it. Injecting proinfl ammatories into ani-
bacterial count spiked when cleaning be- Paul Ewald, an evolutionary biolo- mals also produces such a response.
gan, then fell back to normal less than a gist at the University of Louisville, has Some argue that these chemicals alone
minute after it was over—that is how fast been a leading advocate of the role of can explain the association of gum dis-
the body’s immune system rousts such infectious agents in chronic illnesses. ease and systemic illness.
invaders. Yet in people with periodontal He argues that gum disease fits into the Here is how it might play out. Imag-
disease, such bacterial inundations of the evolutionary model he has devised be- ine that there is some small irritation in
blood occur every time a loosened tooth cause it is chronic, widespread and of the wall of the coronary artery, per-
moves in its socket, providing many op- great antiquity, and therefore cannot be haps the result of chemicals absorbed
portunities for a stray bacterium to relo- simply the result of defective genes. from cigarette smoke or car exhaust. If
cate to some distant location. “If it were just a case of the immune the overall inflammatory burden is low,
Oral bacteria, once established else- system going haywire, you’d think that then perhaps these sites will remain
where in the body, are bad news. Genco natural selection would have weeded it quiescent. If, however, proinfl amma-
injected Porphymonas gingivalis, a out,” he says. “But if you are looking at tory chemicals have leached from the
main culprit in periodontal disease, un- actual combat between the immune sys- periodontal pocket into the blood-
der the skin of rodents and found that it tem and [an] infectious agent, you’d ex- stream, it might heighten local inflam-
mation in the artery, beginning the
process of atherosclerosis.
If infection in the gums not only precedes How do the two theories stack up? It
inflammation in the arteries, but encourages it, is not easy to say from the evidence now
the question is how does it happen? in hand, which comes mainly from ob-
serving correlations between gum dis-
ease and other diseases; either or both of
invariably produced fatal infections. “It pect it to be an evolutionary arms race, the proposed mechanisms could be re-
causes gross necrosis of skin and under- one that would never stabilize.” That sponsible. Take the evidence linking
lying tissue; if you inject into the belly, same arms race would have tuned the periodontal disease with premature
the intestines will be exposed,” he says. bacteria to a high pitch of virulence and birth, which could be caused by the in-
A rare, analogous condition has been invasiveness, hence their ferocious be- fection reaching the uterus or, alterna-
seen in humans, in which a dental infec- havior when ensconced in another part tively, by the release into the bloodstream
tion spreads down the neck to the area of the body. of such proinflammatories as prostaglan-
surrounding the carotid artery, where it Biologists are now investigating the din E2, a drug used by obstetricians to
digests tissue. possibility that many chronic illnesses, induce labor. There is also evidence that
Perhaps the most persuasive exam- once attributed to other causes, may in oral disease destabilizes blood sugar con-
ple of a secondary infection from oral fact stem from infection. Several strik- trol in diabetic patients, although the
sources comes from patients who have ing examples have been demonstrated mechanism remains unclear. It is known
mitral valve heart defects. Such pa- in the past two decades: Stomach ulcers, that high blood sugar contributes to gum
tients are warned to take antibiotics long attributed to stress, spicy food and disease and that all kinds of stress badly
before their dental appointments so genes, turn out to derive, almost always, impact diabetic control. Periodontal dis-
that tooth cleaning will not send bac- from the bacterium Helicobacter pylori. ease may put stress on the body by
teria to infect or inflame the valve, Cervical cancer, it is now known, can spreading bacteria, increasing the in-
which could destroy it or produce clots develop only in women who have been flammatory burden, or both.
that might block arteries. The critical infected by certain varieties of the hu- So, too, many treatments whose suc-
element here is the vulnerability of the man papillomavirus (HPV), long con- cess may seem to confi rm one theory or
10 ORAL AND WHOLE BODY HEALTHINFLAMMATORY MOLECULES
produced locally in tissue can
get into the bloodstream and
travel throughout the body.
FIGHTING INVADERS The inflammation-causing
bacteria can also infect blood
and travel to distant points.
THE IMMUNE SYSTEM INCLUDES, among other components, antimicrobial molecules and various phagocytes (cells that ingest and destroy
pathogens). These cells, such as dendritic cells and macrophages, also activate an inflammatory response, secreting proteins called cytokines that
trigger an influx of more defensive cells from the blood.
another turn out to be hard to interpret. We need interventionist studies to learn Genco notes that “the insurance com-
Aspirin, an anti-inflammatory, is used whether treating oral disease unmistak- panies are driven by economics, and
to reduce the risk of heart attack, but ably shows a preventative benefit against even though the science isn’t absolutely
again, no one can say that this proves heart disease. Such trials are needed to there yet, they are taking action.”
that inflammation, pure and simple, is justify any public investment in such The smart money, therefore, is bet-
the culprit. It could be that aspirin mere- treatment, and several are now planned ting on healthy gums. To keep them that
ly limits clotting. and in line for funding. way, there are no magic bullets, no
What is needed are large clinical tri- In the meantime, insurance compa- chemicals that can be added to drinking
als in which patients are divided, at ran- nies—which are used to basing policies water, as fluoride was added to stave off
dom, into two groups: one that gets on purely actuarial data—are respond- tooth cavities. There is no substitute for
treatment for periodontal disease, an- ing. This year, Aetna Dental announced brushing, flossing and regular dental
other that gets a placebo. Two such stud- the results of a study of policyholders visits. It should be easier to justify than
ies are trying to determine whether such that had both dental and health insur- in the past, for the dentist’s or hygien-
treatment alleviates the risk of prema- ance. It showed that treating periodon- ist’s ministrations may turn out to pro-
ture birth in women with gum disease. tal disease in heart patients lowered the tect not only your teeth, but, quite pos-
Another is testing whether antibiotic total cost of treating both conditions. sibly, the rest of you as well. •
treatment can alleviate heart disease. Yet,
TA MI TOLPA
even here, one must beware of the pos- PHILIP E. ROSS, a former S CIENTIFIC A MERICAN contributing editor, is currently the online
sibility that antibiotics themselves may editor of IEEE Spectrum, the magazine of the Institute of Electrical and Electronic
exert a subtle anti-inflammatory effect. Engineers. He has written for Forbes and Red Herring.
ORAL AND WHOLE BODY HEALTH 11It is clear that inflammation is linked to heart disease, and
that one of the body’s most common sources of inflammation
is periodontal disease. Does poor oral health contribute to
heart disease risk? Although the jury is still out while
scientists investigate this link, here is what we know about
inflammation’s role in atherosclerosis. | BY PETER LIBBY
HeartHealth
INFLAMMATION AGE
IN
THE
O N L Y A D E C A D E A G O, most physicians would have confidently described sometimes fail. It also highlights the
need for better prevention, detection
atherosclerosis as a plumbing problem: Fat-laden gunk gradually builds up on and treatment. In industrialized na-
tions, deaths from heart attacks and
artery walls. If a deposit (plaque) grows large enough, it closes off an affected strokes exceed those from cancer—and
they are also becoming more prevalent
“pipe,” preventing blood flow. Eventually, Such research has established in- in developing countries.
the blood-starved tissue dies. If that flammation’s key role in atherosclerosis.
happens in the heart or the brain, a heart This process—the same one that causes IGNITING TROUBLE
attack or stroke occurs. infected cuts to become swollen, hot we know that inflammation symp-
Few believe that tidy explanation and painful—underlies everything from toms reflect a pitched struggle on a mi-
anymore. Twenty years of research show the creation of plaques to their growth croscopic battlefield. After sensing
that arteries bear little resemblance to and rupture. (rightly or wrongly) a microbial inva-
pipes. They contain living cells that When microbes invade, inflamma- sion, certain types of white blood
communicate with one another and tion (literally meaning “on fi re”) fights cells—the immune system’s frontline
their environment. They also partici- infection. But with atherosclerosis, in- warriors—convene in the threatened
pate in the development of the fatty de- fl ammation proves harmful; our own tissue. There they secrete chemicals to
posits that grow within vessel walls— defenses bombard us with friendly fire, limit infection: oxidants that damage
few which actually shrink vessels to a just as they do in lupus and other auto- invaders and signaling molecules (in-
pinpoint. Most heart attacks and many immune disorders. This revised picture cluding proteins called cytokines) that
M AT T COLLINS
strokes stem from interior plaques that resolves two disturbing mysteries: why orchestrate the activities of defensive
rupture suddenly, spawning a blood clot many heart attacks strike without warn- cells. Their presence in tissue signifies
that blocks blood flow. ing and why preventative therapies an inflammatory response. >>
12 ORAL AND WHOLE BODY HEALTHCROSS-SECTION
OF HEALTHY
CORONARY
INFLAMMATION’S MANY ROLES
ARTERY INFLAMMATION—a central player in atherosclerosis—occurs when
white blood cells, the body’s first line of defense against infec-
Blood channel tion, invade and become active in tissue. These diagrams
depict atherosclerotic plaque growth in a coronary
Intima artery; the close-ups highlight some inflam-
matory processes triggered by elevated
Media low-density lipoprotein (LDL) in
the blood.
Adventitia
LOL
T cell Endothelial 1
Monocyte Adhesion
cell
Scavenger Foam
2
molecule receptor cell 3 Blood channel
INTIMA
Modified LOL
Chemokine
Plaque Thrombus
4 5
Microphage Inflammatory
Elastic tissue mediators
MEDIA Smooth muscle cells
BIRTH OF A PLAQUE PLAQUE
PROGRESSION
1 Excess LDL accumulates in
ar tery walls, undergoing
chemical changes. Modified
LDLs stimulate endothelial cells to
display adhesion molecules, which
2 Monocytes mature into active
macrophages in the intima;
with T cells, they produce
inflammatory mediators, including
cytokines that carr y signals
3 The macrophages display
“scavenger receptors” to help
ingest modif ied LDLs;
macrophages feast on them, filling
with frothy, fatty droplets. These
4 Inflammatory
molecules trigger further
plaque growth. A fibrous cap
develops over the lipid core when the
molecules induce smooth muscle
capture circulating monocytes (key between immune system cells and “foam cells” combine with T cells, cells to migrate to the intima surface,
players in inflammation) and T cells factors that promote cell division. comprising the fatty streak—early multiplying and producing a tough,
(immune cells). Endothelial cells atherosclerotic plaque. fibrous matrix that glues cells
also secrete “chemokines,” luring together. The cap makes the plaque
snared cells into the intima. larger and walls it off from the blood.
Cholesterol studies on both animals As LDLs accumulate, their lipids mature into active macrophages, ready
and cultured cells have elaborated in- oxidize—a corrosive process similar to to unleash their weapons against the
flammation’s role in atherosclerosis. Sci- the one that rusts pipes. Cells in the body’s enemies. These warriors set about
entists have long known that although blood vessel wall react to these changes clearing perceived invaders from vessel
we need cholesterol, excessive amounts by calling for reinforcements from the walls. Scavenger receptor molecules cap-
clog arteries. But until recently, no one body’s defense system. Adhesion mole- ture modified LDL particles and help
knew how this happened. Low-density cules on the endothelial cells that line macrophages “eat” them—until they’re
lipoprotein (LDL)—also known as bad vessels latch like Velcro onto mono- so full of fatty droplets that they look
cholesterol—is composed of fatty mol- cytes, inflammatory cells that normally foamy under a microscope, giving them
ecules (lipids) and protein. Its job: trans- circulate in the blood, attaching them to their “foam cell” nickname.
port cholesterol (another lipid) from its artery walls. Endothelial and smooth T lymphocytes (a type of white blood
source in the liver and intestines to other muscle cells inside vessels then secrete cell) also attach themselves to artery
organs. The trouble begins when LDLs chemokines—chemicals that attract walls, releasing cytokines that intensify
from the blood collect in the intima, the monocytes. Much as hounds track the inflammation. The fi rst visible athero-
interior wall of an artery. At low concen- scent of their prey, more monocytes fol- sclerotic lesion, a yellow “fatty streak,”
KEITH K A SNOT
trations in the blood, LDLs can pass in low the chemical trail into the intima. is a mix of foamy macrophages and T
and out of the intima; in excess, LDLs Stimulated by chemokines and other lymphocytes. These lesions are a precur-
become stuck in the cell matrix. substances, the monocytes multiply and sor of the complex plaques that later dis-
14 ORAL AND WHOLE BODY HEALTHPLAQUE RUPTURE
sel surface. Once there, they form a fi- channel. This also explains why bypass
5 Foam cells secr ete inf lammator y
subs tances that weaken the cap,
digesting matrix molecules and damaging
smooth muscle cells that normally repair it.
Foam cells may produce tissue factor, a potent
brous covering over the original plaque.
Underneath this cap, some foam cells
die, releasing their load of lipids.
surgery or therapies such as angioplasty
or stents that widen obstructed arteries
can ease angina—yet often fail to pre-
Atherosclerotic plaques usually ex- vent a heart attack. Even when blocked
clot-promoter. If the plaque ruptures, a clot
forms. A large clot can halt blood fl ow to the pand outward, not inward to block an arteries are treated, they often clog up
heart, causing a heart attack—the death of artery’s blood-carrying channel. When again fairly quickly—it seems that the
cardiac tissue. they do push in, blood flow to tissues is treatment itself elicits a robust inflam-
restricted, especially when arteries matory response.
Thrombus would normally expand. During exer-
Matrix-degrading
enzyme cise or stress, blood flow through a com- BEYOND BAD CHOLESTEROL
Cytokines that
disrupt smooth promised heart artery fails to meet the several other atherosclerosis risk fac-
muscle cells
Fibrous increased demand. This causes angina tors exhibit intriguing inflammatory fea-
cap
pectoris, a feeling of tightness or pres- tures: diabetes, for instance, elevates
sure usually under the breastbone. Nar- blood sugar levels, which can enhance
rowing in other arteries can cause pain- LDL’s inflammatory properties. Smoking
ful cramping of the calves or buttocks causes oxidants to form, possibly hasten-
during exertion. ing LDL oxidation—and fostering arte-
rial inflammation even in people with
CAUSING CRISES average LDL levels. Obesity contributes
only about 15 percent of heart at- to diabetes and vascular inflammation.
tacks are caused by large plaques that Conversely, high-density lipoprotein
block arteries. Autopsies have shown (HDL) seems beneficial; as levels of this
that most attacks occur after a plaque’s “good cholesterol” decline, the likeli-
fibrous cap ruptures, prompting a blood hood of suffering a heart attack goes up.
clot to develop over the break. Inflamma- HDL may achieve its beneficial effects
tion makes the cap vulnerable. My labo- in part by reducing inflammation, be-
ratory found that when stimulated by cause along with cholesterol, HDL
inflammatory chemicals, macrophages transports antioxidant enzymes that
secrete enzymes that degrade a cap’s break down oxidized lipids.
strong collagen fibers and stop smooth Given inflammation’s usual respon-
CUTAWAY VIEW OF ARTERY
AFFLICTED BY ATHEROSCLEROSIS muscle cells from extruding fresh colla- sibility in the body—blocking and elim-
gen to repair and maintain it. inating infectious agents—biologists
Clots form when blood seeps have wondered whether arterial infec-
through a fi ssure in a cap and coagu- tions might contribute to inflammation
figure arteries. Many Americans begin lates. Although our bodies produce sub- in the arteries. Recent studies suggest
plaque buildup as early as their teens. stances that can prevent or degrade that atherosclerosis can develop in the
blood clots, infl amed plaques release absence of infection. However, circum-
FUELING PLAQUE GROWTH chemicals that impede this clot-busting stantial evidence suggests that certain
when an inflammatory response in, machinery. If a clot does clear naturally microorganisms, such as herpes viruses
say, a scraped knee successfully blocks or with medication, the healing process or the bacterium Chlamydia pneumoni-
infection, macrophages release molecules may kick in once again, restoring the ae could induce or aggravate atheroscle-
that promote healing. A “healing” pro- cap but also enlarging the plaque by rosis. C. pneumoniae appears in many
cess is also part of the chronic, low-level forming scar tissue. Considerable evi- atherosclerotic plaques—and can trig-
inflammation that operates in athero- dence suggests that plaques grow in fits ger inflammatory responses.
sclerosis. But instead of restoring artery and starts as inflammation comes and Infections might also act from a dis-
walls, the process perversely remodels goes and as clots emerge and dissolve. tance, in an “echo effect.” When the
them, generating a bigger plaque. This new picture of atherosclerosis body fights infections, inflammatory me-
Recently, biologists have learned explains why many heart attacks seem diators can escape into the blood and
that both macrophages and cells within to come from out of the blue. Plaques travel to distant sites. Because the mouth
an inflamed vessel wall secrete sub- that rupture may not protrude very far can be a source of chronic infection, re-
stances that create a kind of scar tissue. into a blood channel—and may not searchers are exploring the potential im-
Smooth muscle cells migrate to the ves- cause angina or appear on images of the pact of gum disease. Infection from peri-
ORAL AND WHOLE BODY HEALTH 15EVALUATING THE DATA:
Could Periodontal Disease Increase the Risk for
Cardiovascular Disease? BY K AUMUDI JOSHIPURA
HEART DISEASE AND PERIODONTAL DISEASE have several loss-induced dietary
things in common. One of them is inflammation, which both narrows changes(e.g.,shunning
coronary arteries and breaks down the tissues that hold teeth in fruits, vegetables and
place. Could periodontal disease increase your risk for developing dietary fiber) that
heart disease, perhaps due to bacterial pathogens or inflammatory increase heart risks.
chemicals carried by the blood from the mouth to the heart? If so, The link between the
could you reduce your heart disease risk by preventing or treating two diseases may
periodontal disease? derive from factors that
Research suggests that there may be links between the two influence both. For
conditions. Animal studies in particular offer provocative evidence example, cigarette
that certain biologic pathways might allow one disease to influence smoking is a major risk
the other. Periodontal bacteria are found in the plaque deposits that factor for heart disease
narrow coronary arteries; inducing periodontal disease in rabbits and for periodontal
causes plaque accumulations in their coronary arteries. disease, and a genetic
Other evidence comes from observational human studies. The sus c ep tibili ty to
largest such study, the National Health and Nutrition Examination inflammation might
Survey (NHANES), involved 10,000 Americans between the ages of 18 cause someone to develop both diseases (see chart).
and 74. It found that people with periodontal disease were much more Although periodontal disease seems to be associated with heart
likely to be diagnosed with heart disease than those without disease, more studies are needed before we can say with certainty
periodontal disease. that one disease actually causes the other. Meanwhile, everyone
Not all studies have yielded similar results. For example, my colleagues should be conscientious about treating gum disease, but it is not yet
and I examined a group of health care professionals and failed to find an clear that doing so will protect you from heart disease. •
overall association. Interestingly, our study and several others did detect
a significant association between tooth loss (often a result of severe KAUMUDI JOSHIPURA is director of the Division of Dental Public
periodontal disease) and heart disease. So the “connection” between Health at the University of Puerto Rico and also teaches at Har-
periodontal disease and heart disease may be indirect, involving tooth- vard University.
odontal disease pumps a continuous flow measuring the heat of blood vessels (be- tion’s ability to ward off infection out-
of bacteria and cytokines into the blood- cause heat normally accompanies in- weighed its drawbacks. Today, as we live
stream. Bacteria also produce toxins that flammation); and altering existing im- longer, exercise less, eat too much, and
can trigger inflammatory responses. Cy- aging technologies, such as MRI or CT smoke, many of us suffer from inflam-
tokines and bacterial toxins can stimu- scans, to improve their ability to peer mation’s dark side—including its ability
late the white cells in atherosclerotic inside vessel walls. Scientists are trying to contribute to atherosclerosis and other
plaques, prompting plaque growth or to develop molecular imaging tech- chronic disorders. Scientists continue to
rupture. Despite these links between in- niques to “visualize” biological process- pursue a deeper understanding of in-
fection and atherosclerosis, current clin- es such as infl ammation, looking be- flammation’s role in atherosclerosis, and
ical evidence does not support the use of yond the anatomical features of blood to decipher the intricate interactions that
antibiotics to prevent recurrent compli- vessels. Geneticists are hunting for genes ignite and drive the inflammatory pro-
cations following a heart attack. that predispose some people to chronic cesses in the arteries. These insights
inflammation and atherosclerosis so should enable us to make further inroads
TOWARD EARLY DETECTION they can seek more aggressive monitor- against a disease with growing world-
noninvasive methods for identifying ing and treatment. wide impact that causes extensive dis-
vulnerable plaques might help pinpoint For most of human history, inflamma- ability and takes far too many lives. •
at-risk individuals who lack warning
signs of potential heart attack or stroke. PETER LIBBY, who earned his M.D. from the University of California, San Diego, is chief of
Ideas include testing for elevated levels cardiovascular medicine at Brigham and Women’s Hospital, Mallinkrodt Professor of
of C-reactive protein, a substance in the Medicine at Harvard Medical School, and co-editor of Heart Disease, a classic cardiology
blood that signifies acute inflammation; textbook (W.B. Saunders, 2001).
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Two decades of biomedical and dental detective work
have linked obesity, diabetes and periodontal disease
BY ROBERT J. GENCO
I N T H E E A R LY 19 6 0 S ,
researchers from the National Institutes of Health (NIH) journeyed to the parched desert
lands of the Gila River Indian Community in central Arizona to study the health of the Pima
Indians. In the course of routine medical exams, they made a startling discovery: the
Pima people proved to be fatter than any other group of people on Earth except for the
Pacific Nauru islanders. Nearly half of those over the age of 35 had type 2, or adult-onset
diabetes, eight times the national average. In order to survive in the desert, it seems that
their thrifty genes may have evolved to carefully conserve fat through times of drought and
famine. After World War II, when the tribe changed their traditional diet to an American
one, their fat intake rose from about 15 percent to a whopping 40 percent of calories—and
their genetic evolution backfi red. >>
18 ORAL AND WHOLE BODY HEALTHN O R T H W E S T E R N U N I V E R S I T Y L I B R A R Y, E D W A R D S . C U R T I S ’ S “ T H E N O R T H A M E R I C A N I N D I A N ,” 2 0 0 3
HISTORY INTERRUPTED:
When Arizona’s Pima Indians
adopted a fatty American diet,
their thrifty desert genes
backfired. Almost half of adults
over 35 developed type 2
diabetes—and also contracted
severe gum disease at twice the
normal incidence.
ORAL AND WHOLE BODY HEALTH 192 diabetes research from our studies
both on the Pimas and on the popula-
tion of Erie County in New York State,
along with research from around the
globe—Japan, Brazil, Chile, Finland,
Slovenia and other nations. In nearly all
of the studies, it was found that diabet-
ics suffered from more severe periodon-
tal disease that often appeared years or
even decades before it did in the general
population—and once a diabetic patient
had periodontal disease, their sugar
control worsened and they suffered fur-
ther complications, including nerve
damage and kidney disease.
We combined the results of these
studies and formulated a hypothesis
that we and others could begin testing.
This informational mosaic has given us
a reasonable understanding of how obe-
sity and diabetes are linked to infections
such as periodontal disease. It also re-
vealed a potential explanation of why
IN 1983, H. was healthy. Three years later, she suffered from out-of-control type 2 diabetes and diabetes is a significant risk factor for
severe gum disease, with abscesses ulcerating her gums and loose, shifted teeth. oral infection and inflammation—and
why it often leads to periodontal disease
As the NIH studies continued over clinics.) Diabetics fared the worst, with at a much earlier age than normal. Pa-
the following decades, the researchers twice the normal incidence of gum dis- tients with type 2 diabetes are twice as
delved into other health issues including ease—and much more severe oral infec- prone to periodontal disease as nondia-
kidney problems and heart disease. They tion than nondiabetic patients. betics, all other factors being equal.
also suspected that there might be a In 1983 we examined H, a 32 year- An important piece of this puzzle
higher than normal incidence of gum old woman who was extremely over- emerged 10 years ago during the Erie
disease. In 1981 the Dental Institute weight, but otherwise quite healthy. In County study, conducted in metropoli-
asked me to assess the periodontal health her follow-up exam two years later we tan Buffalo, N.Y. We discovered that
of the Pimas. At that time, I was in the were shocked to discover that her health obesity and periodontal disease were re-
midst of clinical studies at the University had deteriorated precipitously: she suf- lated. We collected information on both
at Buffalo Periodontal Disease Research fered from uncontrolled type 2 diabetes the general and oral health of 1,250
Center examining the body’s response to and had developed advanced gum dis- adults. After statistical adjustment for
bacterial infection in the mouth—so I ease. Abscesses ulcerated her gums, and other periodontal risk factors including
welcomed the opportunity to examine a her teeth were loose and had shifted out age, gender, socioeconomic status, smok-
very different population. I spent three of position, leaving large gaps between ing, diabetes and dental plaque, the rela-
days at the Gila River reservation con- her front teeth. Under normal circum- tionship remained strong: obesity ap-
ducting several dozen clinical exams. stances, the progression of this condi- pears to be an independent risk for peri-
Never before had I seen such severe, un- tion would have taken 15 to 20 years to odontal disease. Investigations by Nabil
treated periodontal disease. reach that level of infection. Bissada and his colleagues at Case West-
In 1982 we established our first den- Her case sparked a question that we ern University in Cleveland and by Toshi-
tal clinic in a trailer on the reservation, couldn’t answer. Could there possibly yuki Saito of Kyushu University in Fu-
run by Dr. Marc Shlossman, and initi- be a connection between obesity, diabe- kuoka, Japan, mirrored our findings.
ated a study to track the Pimas’ oral tes and oral infection? It took 21 years Another important clue surfaced in
health. Since then, we have examined of medical and dental detective work, the mid-1990s that helped to explain the
3,600 people, giving checkups every piecing together data from many sourc- role obesity plays in infection. We learned
two years. (Regular dental care was es, to understand this triangular rela- that fat tissue is not only a repository for
provided by the reservation’s dental tionship. We gathered the results of type fat cells but is increasingly viewed as a
20 ORAL AND WHOLE BODY HEALTHYou can also read
