by Steven Shepherd, M.P.H.
Getting your teeth pulled because of a sore arm may sound
farfetched. But it happened more than once, says Saul
Schluger, D.D.S., professor emeritus at the University of
Washington's school of dentistry in Seattle.
Schluger has been involved in the treatment and study of gum,
or periodontal, disease for more than 50 years, and he recalls
that the patients in these cases were professional baseball
players who had the ill luck to have developed their dental
(and arm) problems when the "focal infection" theory of
periodontal disease was in vogue earlier this century.
The theory held that periodontal disease always worsened, could
only be stopped by pulling teeth, and that it could spread--not
only from one area of the gums to another, but to other parts
of the body. In the case of an affected ballplayer with a sore
arm, explains Schluger, it was considered possible that
migrating infection from the gums might be the cause of the
sore arm. To prevent further problems it was sometimes thought
best to simply pull the player's teeth.
For ordinary people, a more common scenario was the wholesale
pulling of teeth at the first sign of gum disease. The
reaction, says Schluger, was "almost Pavlovian. If you had gum
disease, you had your teeth out. It was the cause of a lot of
dentures."
Old Beliefs, New Data
Though the focal infection era is now behind us, its legacy
remains. Many older people are toothless and wearing dentures
for reasons now considered unnecessary. And many fears and
beliefs formed during that period continue to hold sway.
For instance, periodontal disease is commonly said to be
responsible for 70 percent of the teeth lost after childhood.
But, according to Brian Burt, Ph.D., a dental epidemiologist in
the School of Public Health at the University of Michigan, this
oft-repeated statement is based largely on a single study
conducted in the early 1950s. A more recent study published in
the January 1987 Journal of the American Dental Association
found that dental decay was the most common disease-related
reason for adult tooth extractions in the late 1970s and early
80s; only 9 percent were necessitated by periodontal disease.
Clearly, much has changed. So what is the threat of
periodontal disease today? And what can be done about it?
What Is Periodontal Disease?
In the broadest sense, periodontal disease can be considered
any form of ill health affecting the periodontium--the tissues
that surround and support the teeth. These include the gums
(or gingiva), the bone of the tooth socket, and the periodontal
ligament, a thin layer of connective tissue that holds the
tooth in its socket and acts as a cushion between tooth and
bone.
Inflammation or infection of the gums is called gingivitis;
that of the bone, periodontitis. These conditions can arise
for a variety of reasons. A severe deficiency of vitamin C can
lead to scurvy and result in bleeding, spongy gums, and
eventual tooth loss. And at least one periodontal disease--the
uncommon but highly destructive juvenile periodontitis--is
thought to have a strong genetic basis. But as the terms
periodontal disease, gingivitis, and periodontitis are most
commonly used, they refer to disease that is caused by the
buildup of dental plaque.
Plaque is a combination of bacteria and sticky bacterial
products that forms on the teeth within hours of cleaning. Its
source is the natural bacteria in the mouth, of which more than
300 different species have been identified. In small amounts
and when newly formed, plaque is invisible and relatively
harmless. But when left to accumulate, it increases in volume
(in large amounts, plaque can be seen as a soft whitish
deposit), and the proportion of harmful species in the plaque
grows.
Separating Gingivitis
The role played by plaque in the development of gingivitis was
demonstrated in the early 1960s. Dental researchers had people
stop brushing their teeth and let the plaque in their mouths
build up. Within two to three weeks signs of inflammation
appeared--redness, swelling, and an increased tendency to
bleed--and when brushing resumed, the inflammation went away.
Gingivitis is fairly common. Just about everybody, says Burt,
has it in some degree. A recent nationwide survey by the
National Institute of Dental Research, for example, found that
40 to 50 percent of the adults studied had at least one spot on
their gums with inflammation that was prone to bleeding.
At one time gingivitis and periodontitis were thought to be
different phases of the same disease, meaning that the sort of
inflammation detected in this study would lead inevitably to
periodontitis if left untreated. Yet, dental researchers no
longer believe this to be true. In the April 1988 Dental
Clinics of North America, National Institute of Dental Research
director Harald Loe, D.D.S., describes an ongoing study, then
in its 15th year, of Sri Lankan tea workers who practice no
oral hygiene. All have gingivitis--but not all have
periodontitis.
This and other studies with similar results have led dental
researchers to two conclusions. One, says dental
epidemiologist Ronald J. Hunt, of the College of Dentistry at
the University of Iowa, is that "gingivitis is not a
particularly serious disease." The other is that "gingivitis
and periodontitis are different disease entities."
From Periodontitis
Some people with gingivitis do, nonetheless, develop
periodontitis. The plaque that causes gingivitis is located at
or above the gum line and is referred to as supragingival
plaque. With time, areas of supragingival plaque can become
covered by swollen gum tissue or otherwise spread below the gum
line (where it is called subgingival plaque), and in this
airless environment the harmful bacteria within the plaque
proliferate. These bacteria can injure tissues through the
direct secretion of toxins. But they cause the greatest damage
by stimulating a chronic inflammatory response in which the
body in essence turns on itself, and the periodontal ligament
and bone of the tooth socket are broken down and destroyed.
This is similar to what happens in rheumatoid arthritis and,
like rheumatoid arthritis, periodontitis is now considered
primarily an inflammatory disease.
The bone destruction from periodontitis can be fairly even,
resulting in receding gum lines. But more often it causes deep
crevices between an individual tooth and its socket. These
crevices are called periodontal pockets, and just as it once
was thought that gingivitis inexorably progressed to
periodontitis, so it was once believed that shallow periodontal
pockets inevitably deepened, eventually becoming deep enough to
jeopardize the socket's support of the adjacent tooth.
Recently, however, dental researchers have collected
substantial evidence to support a theory called the burst
hypothesis. This theory states that periodontal bone loss is
not a steady process but results instead from periodic
flare-ups of infection and inflammatory response inside the
pocket. Writing in a 1988 issue of the Journal of Clinical
Periodontology, researchers from the British Medical Research
Council say this theory helps explain epidemiologic and
clinical findings that many, if not most, periodontal pockets
are not actively diseased. Rather, they are remnants of past
infections that the body has overcome. Further, not all
periodontal pockets inevitably deepen; some apparently
partially heal and get shallower.
What triggers a destructive "burst" inside a periodontal pocket
(or, for that matter, the transition from gingivitis to
periodontitis) is unknown. But, as described by these British
researchers, such events are most likely the result of
unfavorable fluctuations in the balance between the type,
quantity and location of bacteria in a person's mouth, the
ability to resist bacterial infection, and the unique
characteristics of an individual's inflammatory response.
Good News-Bad News
All this has something of a good news-bad news flavor to it.
The good news is that most of us have less to fear than we may
have been led to believe. Periodontal disease is often
described as almost universal--a disease that can or will
affect almost everyone and that can have "devastating"
results. But most such statements are based on studies that
are not only old (dating from the 1950s and early '60s) but
that also combine gingivitis and periodontitis under the single
heading "periodontal disease." More recent studies suggest
that only about 10 percent of adults have periodontitis severe
enough to possibly cause tooth loss. The percentage is lower
in younger people and higher in older people. Even among these
people, says epidemiologist Burt, it is unusual to have more
than a few affected teeth. In one 1985 study of nearly 55,000
Italians, among those who had what are considered deep
periodontal pockets the average number of affected teeth was
fewer than one.
The "bad" news generated by all this new research into the
causes and natural history of the periodontal diseases (as
gingivitis and periodontitis are now referred to collectively)
is that while most of us may be at lower risk than previously
thought, it is still impossible to say who is at high or low
risk individually. It can't be predicted who with gingivitis
will develop periodontitis or who with shallow periodontal
pockets will go on to develop deep pockets and possibly lose
teeth.
Researchers are, however, working rapidly on methods to make
such predictions. These techniques will involve tests of
immune function and the types of bacteria in a person's mouth.
Once available, they are expected to dramatically change
current approaches to the treatment of periodontitis.
Today, periodontitis is treated either by surgically
eliminating periodontal pockets or by cleaning affected tooth
roots in a process known as scaling and planing. The current
trend is towards the latter, and the ability to predict who is
susceptible to worsening disease could accelerate the move in
this direction. By one estimate, such predictions could make
90 percent of "pocket elimination" surgeries unnecessary.
Fighting Plaque
As yet, however, dentists can't make such predictions. And
because both gingivitis and periodontitis are caused by the
buildup of plaque, one dental maxim is as true now as ever: If
you want to keep your teeth you have to keep them clean.
Only a dentist can diagnose and treat periodontitis. And only
a dentist can remove the subgingival plaque responsible for
periodontitis and its worsening. Nonetheless, according to
Sebastian Ciancio, D.D.S., professor and chairman of the
Department of Periodontology at the School of Dental Medicine,
State University of New York at Buffalo, controlling the
buildup of plaque above the gum line helps control both the
quantity and harmful nature of plaque below the gum line. He
says an ideal plaque control program involves periodic
professional examinations and cleanings--"so you can start out
with a clean mouth"--coupled with good cleaning at home.
The most effective method of plaque control at home is brushing
and flossing. According to dental experts, most people don't
brush their teeth properly and frequently miss some areas of
their mouths, so it is a good idea to get instructions in
effective brushing from a dentist or dental hygienist. One way
to help determine how well you are brushing is through the use
of disclosing agents (available over-the-counter), which make
plaque easier to see.
As for toothbrush selection, studies show that soft bristles
are better than hard at removing plaque. Toothbrushes are also
less effective when splayed or matted and for this reason
should be replaced at the first signs of wear. These
considerations aside, virtually any toothbrush can be effective
if properly used and a choice can usually be made based on
personal preference or a dentist's advice.
There is a large and growing selection of dental flosses on the
market today. According to the August 1989 Consumer Reports,
which evaluated "anti-plaque" products, waxed and unwaxed floss
are equally effective. Flosses do vary in strength and
resistance to shredding, but as long as it doesn't break, the
kind of floss you choose is less important than how well you
use it--and whether you use it at all. Surveys show that fewer
than 20 percent of Americans floss their teeth daily.
Though flossing is the only effective way to clean between the
teeth, toothpastes can help in the removal of plaque from more
accessible tooth surfaces. This is not because they have
special "anti-plaque" ingredients, but because they contain
abrasives and detergents that aid in the mechanical removal of
plaque that occurs during toothbrushing. This is the source of
the "anti-plaque" statements made on some toothpaste labels.
Several toothpastes are also now being marketed for preventing
the buildup of "tartar." Tartar, which is plaque that has
calcified and hardened on the teeth, was once thought to
contribute to or even cause periodontal disease by physically
irritating the periodontal tissues. It is now considered far
less important, however, and, according to the January 1988
Journal of the American Dental Association, tartar control
toothpastes have a "cosmetic benefit" only. They have no
effect on gingivitis or periodontitis.
Theoretically, a toothbrush, floss, and toothpaste are all you
need to control supragingival plaque. Yet estimates are that
only 30 percent of the U.S. population clean their teeth
adequately using these mechanical means alone. For this
reason, dental researchers have been searching recently for
additional ways to help people control plaque. In particular,
this search has focused on mouthwashes.
There have been differences of opinion over the anti-plaque
claims made for various mouthwashes (see "Anti-Plaque
Mouthwashes" on page xx). But regardless of how effective a
mouthwash might be, Ciancio points out that not everyone needs
such products. "People who don't have periodontal problems
don't need an anti-plaque mouthwash," he says. "If you are
having problems--for instance, gums that bleed when you
brush--see your dentist. If an anti-plaque mouthwash is
recommended, what I advise is using the product for three to
six weeks to see what a clean mouth feels like. Then stop and
see if you can maintain that feeling with mechanical means
alone. If not, resume the mouthwash for another few weeks,
then try again to maintain a clean mouth mechanically."
This kind of conscientious effort at good plaque control holds
great promise. When combined with researchers' rapidly growing
knowledge about the causes of periodontal disease and how it
can best be treated, the future offers a realistic prospect,
says NIDR's director Loe, that "no one need ever lose a tooth
to periodontal disease."
Anti-Plaque Mouthwashes
The use of mouthwashes in the quest for a healthy mouth has a
long history. According to Irwin Mandel, D.D.S., professor of
dentistry at Columbia University's School of Dental and Oral
Surgery, an ancient Chinese text contains the first known
recommendation for the use of a mouthwash in the treatment of
gum disease: Rinse the mouth with urine.
In the intervening 5,000 years, urine (which from a healthy
person is sterile) has been used as a mouthwash in cultures
around the world. By lowering the acidity of the mouth it may,
says Mandel, help reduce the formation of cavities. But
against the periodontal diseases it's unlikely to have an
effect.
The modern era of mouthwashes might be said to have begun in
1920. It was then that Listerine, which had already been sold
for more than 40 years as a general antiseptic, was first
marketed as a remedy for bad breath. A new advertising
campaign for the product introduced the American public to the
term "halitosis" and its social undesirability. The pitch was
so successful it is now considered a classic.
Such promotional activities no doubt contributed to what Mandel
describes as a longstanding "disdain" of mouthwashes by members
of the dental and scientific communities. This view was
further reinforced by a widely held assumption that any effect
mouthwashes had against oral bacteria was only temporary. In
the early 1980s, however, studies began to appear suggesting
that some mouthwashes might indeed reduce supragingival plaque
and plaque-related gingivitis. There is no evidence that
mouthwashes can affect subgingival plaque or periodontitis.
A prescription product (trade name Peridex) containing the
antimicrobial chlorhexidine was approved by FDA in 1986 based
on studies showing that it reduced gingivitis by up to 41
percent. Chlorhexidine mouthwashes have long been used in
Europe, and a 1986 article in The Journal of Periodontal
Research called chlorhexidine "the most effective and most
thoroughly tested anti-plaque and anti-gingivitis agent known
today."
A month later the American Dental Association awarded Peridex
its "Seal of Acceptance"--the first ever granted a mouthwash by
the ADA. This seal (which can have considerable marketing
value and is probably most familiar as a result of its being
displayed on many brands of toothpaste) indicated that Peridex
had met a series of guidelines established by the ADA for
evaluating products making anti-plaque, anti-gingivitis claims.
In 1987 the ADA awarded its second (and so far only other)
Seal of Acceptance to a mouthwash for use in the reduction of
plaque and gingivitis. This seal went to Listerine, and its
manufacturer has since used the ADA seal in promoting the
product as a plaque-fighter. FDA, however, has not yet
approved Listerine for this use. In fact, FDA has sent letters
to the makers of Listerine and several other over-the-counter
(OTC) products making anti-plaque claims stating that in its
opinion the products are being marketed in violation of the
Federal Food, Drug, and Cosmetic Act and are "at risk of
regulatory action."
The basis for these letters is that no ingredient for use in an
OTC drug product has yet been recognized as safe and effective
for the prevention or reduction of plaque or gingivitis in
FDA's ongoing evaluation of OTC drug products. FDA therefore
considers as unproven claims that a product's ingredients have
such effects.
In part, the reason for this stance (and for the difference
between the actions of FDA and those of the ADA with respect to
Listerine) has to do with timing. Data concerning the claims
of the OTC anti-plaque, anti-gingivitis products were not
available until after FDA's review of OTC dental products was
well under way. Such data have since been submitted and in the
case of Listerine, says Jeanne Rippere, a microbiologist in
FDA's over-the-counter drug evaluation division, the
information is probably much the same as that presented to the
American Dental Association and on which the awarding of its
Seal of Acceptance was based.
In a continuation of its ongoing OTC drug review, FDA plans to
have a panel of non-government experts evaluate ingredients
that might be used in OTC drug products making anti-plaque and
anti-gingivitis claims. Steps are being taken to facilitate
this process, and it may begin within the next year. n
--S.S.
What About Baking Soda?
In the late 1970s and early '80s an oral hygiene program known
as the Keyes Technique was widely promoted in the United
States. Aimed at combatting plaque-related periodontal
diseases, the program included not only such conventional
advice as frequent professional cleanings, but also the
recommendation that patients apply to their gums and brush
their teeth with a mixture of salt, hydrogen peroxide, and
baking soda.
Laboratory studies showing these agents had some
effectiveness against harmful bacteria were the principal
basis for this recommendation. But critics pointed out that
what worked in the laboratory didn't always work in the
mouth. A study by the technique's proponents showed some
effectiveness in humans. However, it lacked a control group,
so it was impossible to say how the technique compared to more
traditional methods of oral hygiene. Furthermore, the
subjects in this study had been liberally treated with
antibiotics, so it wasn't known if the benefits they had
experienced were actually due to the baking soda brushing
regimen.
To resolve these issues, dental researchers at the University
of Minnesota, led by Larry Wolff, Ph.D., D.D.S.,
conducted a four-year study involving 171 adults with moderate
periodontitis. The study's design enabled the researchers to
compare the effectiveness of a baking soda, salt, and hydrogen
peroxide mixture with that of ordinary toothpaste. The
results, published in the January 1989 Journal of the American
Dental Association, showed that while the baking soda mixture
did help in the maintenance of oral health it was no more
effective than ordinary toothpaste.
Wolff and his colleagues also found that, compared to the
patients using ordinary toothpaste, those using the baking
soda regimen were three times as likely to stop following
their oral hygiene program because it was inconvenient.
Overall, they said, there was no evidence that a baking soda
brushing regimen "will contribute more toward periodontal
health than use of a commercial toothpaste, a toothbrush, and
dental floss."
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