GUM LASER SURGERY
As of March 1999, two companies market the laser for dental
decay: Premier Laser Systems Inc., of Irvine, California, and
BioLase, of San Clemente, California.
The erbium:YAG laser essentially vaporizes decayed tooth
tissue. A stream of laser light that passes through a fiber
connected to a pencil-like hand piece is directed to the decay.
The laser hand piece looks like the standard hand piece and,
like the standard hand piece, must be used in a controlled
manner so that it doesn't slip and damage healthy tissue.
"The laser is a cutting instrument," says Susan
Runner, D.D.S., branch chief of dental devices in FDA's Center
for Devices and Radiological Health. "And like any cutting
instrument, dentists have to be careful any time they use
it. The laser has many of the same risks as the drill."
Another similarity between the dental drill and the laser
is that both use water and air to cool the tooth and clean
the surface during removal of decay. While dentists and patients
may wear eye protection during conventional treatment to protect
against the spray of water and particles, they must wear goggles
during the laser procedure to protect their eyes from straying
laser light.
The laser has several benefits over the hand piece: Because
laser treatment is usually painless, there is no need for
anesthesia--or anesthetic injections--in many patients, and
dentists do not have to wait until their patients' mouths
are numb to begin treatment. Also, the laser eliminates the
vibrating sensations of the high-speed hand piece
Also, compared with the standard hand piece, the laser can
work with better precision, saving more of the healthy tooth.
And when the laser procedure is done, patients do not have
to wait for the numbness and puffiness related to the use
of anesthesia to fade.
For many patients, especially those particularly fearful
of the dental drill, the laser has drawn rave reviews. "My
patients love it," says Edward Romano, a dentist in Morristown,
N.J., who has used the laser since 1997. "They say: 'I
can't believe it's so comfortable, that dentistry has come
this far.'"
However, the laser is not without its own shortcomings. For
one, it can't be used on teeth with fillings already in place.
According to Runner, there is the risk of damage to the tooth
because the filling heats up. Romano says silver fillings
also damage the laser tip. Also, studies show that the laser
procedure takes longer than the conventional method.
"The laser is really ideal for virgin teeth--for new
decay," Runner says. "Dental lasers is a growing
field, but they can't do everything. There's still a need
for the standard hand piece"
Another potential pitfall is expense. In December, Premier
Laser Systems was citing a list price of about $45,000 for
its Centauri laser. That includes training for the dentist.
The standard high-speed hand piece typically sells for around
$600.
Premier Laser estimates, however, that while the typical
laser procedure costs about $13 more on average than the same
drill procedure, the cost reductions of not using anesthesia
and having more time to spend with other patients could actually
save dentists about $70,000 over three years.
Still, some dentists say they are putting off buying a laser
for treating cavities, at least for the near future. "Our
position [in my dental practice] is that the laser looks promising,"
Harms says. "But we're not using it yet. We're waiting
for long-term studies and newer tools."
The other alternative to the traditional high-speed hand
piece is the air abrasion hand piece Air abrasion involves
the use of a high-pressured instrument similar to a tiny sandblaster.
A stream of tiny aluminum oxide particles cuts away the decay.
There is no heat and no vibration, and often, it can be used
without anesthesia. It also can be used to remove some fillings,
although it is not yet cleared for removing amalgams (silver-colored
fillings).
Harms, who uses air abrasion, says the technique is ideal
for small cavities and fillings in children, but she notes,
"It doesn't replace the drill."
Fillings
Once decay is removed, a filling is placed inside the cut-out
area to retain the tooth's shape and function, including chewing.
A variety of filling materials is available.
One of the oldest and most commonly used filling is amalgam,
a metal alloy of silver, tin, copper, and sometimes indium,
palladium and zinc that is mixed with about an equal amount
of mercury. FDA regulates amalgam alloy as a medical device.
According to a 11-98 article in the Journal of the American
Dental Association, dentists continue to use amalgam primarily
because it is inexpensive and durable and withstands the tremendous
forces of chewing. A 1993 U.S. Public Health Service report
on dental amalgam said that amalgam typically lasts from 8
to 12 years. Only gold alloy and metal-ceramic crowns last
longer up to 18 years.
Amalgam has drawn controversy in the past 10 years because
its critics contend that the mercury emits minute amounts
of vapor, causing a variety of health problems ranging from
multiple sclerosis and arthritis to mental disorders. However,
several investigations by the federal government and others
have not borne this out, and the use of amalgam is supported
by FDA, the National Institute on Dental and Craniofacial
Research, the American Dental Association, and other professional
organizations.
In a scientific literature review published in the 11-98
Journal of the American Dental Association, professors of
dentistry in the United States and China found that research
has not yet shown that mercury vapors escaping amalgams are
"in concentrations high enough to produce any detectable
effect on the body." The authors concluded that, contrary
to some dentists' current practice, "dentists cannot
ethically tell patients that amalgam is a health hazard and
that removal of restorations will benefit their health."
While amalgam remains the most commonly used dental filling,
its use does appear to be declining. According to the dental
association's journal article, the use of amalgam for filling
back teeth has dropped from 85% in 1988 to 58% in 1997. "The
use of amalgam will likely continue to diminish, and it will
eventually disappear from the scene," the journal article
said.
One reason for the decline is the introduction of new materials
that afford similar durability and strength as amalgam and,
unlike the silver-colored fillings, can be made to match the
color of a patient's teeth. "The aesthetics' side of
it is very important to many patients," Runner says.
However, using these materials--composites, glass ionomers,
and metal-ceramic crowns--can cost a patient from 1.5 times
to 8 times the cost of an amalgam restoration.
Prevention of Decay
Of course, much of the pain and expense of treating cavities
can be eliminated through preventive measures.
Many of these measures, says Dennis Mangan, Ph.D., chief
of the Infectious Diseases Branch of the extramural division
of the National Institute on Dental and Craniofacial Research,
are aimed at interrupting the decay process--for example,
eliminating the sugars that serve as a source of food for
bacteria in the mouth, eliminating the bacteria that feed
on the sugars, strengthening the tooth's enamel to make it
harder for acids to attack. Or, Mangan says, "It can
be some combination of all of them."
Some of the most successful preventive measures involve fluoride,
a mineral that occurs naturally in many foods and water. Fluoride
helps prevent decay by making the tooth more resistant to
acid attacks. It also has been found to reverse early decay
where acid has broken through the enamel by re mineralizing
the affected area.
To function effectively as an anti-decay substance, fluoride
should not only be applied to the teeth but ingested, as well.
The most important way in which fluoride is ingested is through
fluoridated public drinking water. Dental experts cite water
fluoridation, which began 50 years ago, as the main reason
for the decline in cavities in children since World War II.
In areas with inadequate or no water fluoridation, children
between 6 months and 16 years may need fluoride supplements.
A dentist can prescribe the correct dose.
Fluoride can be applied directly to teeth with the use of
fluoridated toothpastes and mouth rinses. Less-concentrated
rinses are available over-the-counter, while stronger concentrations
require a dentist's prescription.
Consumers need to be sure that children don't use fluoride
products without supervision because excess ingestion of fluoride
can cause defects in the tooth's enamel that range from barely
noticeable white specks or streaks to cosmetically objectionable
brown discoloration. The defects, known as fluorosis, occur
while the teeth are forming, usually in children under 6 years.
Although tooth staining from fluorosis cannot be removed with
normal hygiene, a dentist may be able to lighten or remove
these stains with professional-strength abrasives or bleaches.
Although excess fluoride intake can be toxic, most reported
adverse reactions involve vomiting, diarrhea and eye irritation.
Because fluoride is a drug, FDA requires toothpaste manufacturers
to include on the labels of fluoride toothpastes a warning
that the products should be kept out of the reach of children
under 6. In addition, because FDA requires all over-the-counter
oral drugs to bear an accidental-ingestion warning, toothpaste
labels also must carry a warning that instructs consumers
to contact a professional or a Poison Control Center if more
than the normal amount used for brushing is swallowed. This
labeling requirement took effect April 1997.
Another highly effective way to prevent cavities is sealants.
Plastic material that is usually applied to the chewing surfaces
of the permanent back teeth, sealants bond into the depressions
and grooves of the chewing surfaces, acting as a barrier to
plaque and acid.
According to the American Dental Association (ADA), sealants
are "virtually 100-percent effective at preventing tooth
decay." They can be used on the permanent teeth of both
children and adults.
Though sealants are considered to be most beneficial to children,
a 1996 study published in ADA's journal found that only 20
percent of school-aged children have dental sealants on their
permanent molars. Cost-wise, sealants average about half the
cost of a filling, according to the American Academy of Pediatric
Dentistry.
Another reason for the decline in dental caries can be attributed
to public education aimed at encouraging consumers to follow
good oral health practices at home and see a dentist regularly,
beginning as early as age 1.
"Most patients now know [they should] see a dentist
regularly," says Cleveland dentist Matthew Mecini, D.D.S.,
citing statistics that show that 50 to 55 percent of adults
actually follow that advice. "We [the dental community]
are doing a better job of educating the public on the need
for regular dental care."
What's Ahead
Efforts to reduce cavities don't end there. One of the most
promising preventives on the horizon is a vaccine-like product
against decay. In April 1998, British scientists reported
that they had developed a plant-based treatment, which, when
applied to the teeth, effectively prevented Streptococcus
bacteria, the main bacteria involved in tooth decay in humans,
from growing in the mouth for up to four months.
In the United States, researchers funded by the National
Institute of Dental and Craniofacial Research are studying
a similar preventive, known as "pl antibodies." Using
genetic engineering techniques, scientists transfer a gene
for antibodies specific for streptococci to the tobacco plant,
which produces large quantities of these antibodies. Antibodies
purified from the tobacco plant are then applied to the teeth
with a goal of preventing streptococci from adhering to the
teeth.
"The concept is good," Mangan says, but notes that
the high cost of genetic engineering and the bother of applying
the substance on a routine schedule may make the product somewhat
impractical.
Other research, he says, focuses on a vaccine that boosts
children's immune systems to prevent decay. The intent of
this experimental product is to stimulate the body's own production
of antibodies to prevent streptococci from adhering to the
teeth.
While these experimental products promise an even brighter
dental outlook for future generations, kids today can look
forward to a life of dental care that even their parents never
envisioned.
"If you can reduce the anxiety that often accompanies
dental treatment," FDA's Runner says, "that's a
very positive step, especially for children. That's where
a lot of these devices have the most potential--in children."
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How Decay Occurs
For most people, the first sign of a cavity is pain, but
the actual start of tooth decay begins much earlier, with
the accumulation of minute amounts of a sticky film, called
plaque, on the tooth's surface.
Plaque contains bacteria, which feed on carbohydrates in
the mouth. As a result of their feeding frenzy, the bacteria
produce acids, which can attack the tooth enamel--the outermost
layer of the tooth. If the plaque isn't removed, it continues
to build, creating more acid that continues to damage the
tooth enamel. There usually is no pain until the acids eat
through to the tooth's underlying dentin and pulp layers,
where the nerves are located. This decay, technically known
as dental caries, is the point at which treatment is needed
to prevent further tooth damage and loss.
Cavities usually form:
- in depressions and grooves of chewing surfaces
- between teeth
- on the root surfaces of people whose gums have receded
Dental decay usually occurs in the back teeth, where it
is more difficult to remove food debris and plaque. There
are two notable exceptions: early childhood decay in bottle-fed
babies and root decay in older adults.
Baby-bottle decay usually occurs in the upper front teeth
as a result of continuous feeding on sweet liquids, including
milk, formula and fruit juice. Nighttime use of a bottle is
the most dangerous because the sugars sit on the baby's teeth
for an extended time. Tooth loss can result, causing spacing
and development problems when the permanent teeth erupt.
"It's very nasty," says Cleveland dentist Matthew
Mecini, D.D.S. "You don't see it too often, but when
you do, it's severe. The amount of damage that can be done
to children's teeth in a short time is amazing."
Root decay occurs on the exposed root surfaces of older adults
whose gums have receded as a result of gum disease. Many types
of medicines older people typically use decrease saliva production,
which can aggravate the problem. Saliva is important in preventing
tooth decay because it can wash away food particles and bacteria
and help neutralize acids formed by bacteria in the mouth.
The first sign of a cavity forming may be a white spot that
in time may turn brown. Most patients, however, remain unaware
of the decay until it is well advanced. Common signs that
people notice include sensitivity of the tooth when exposed
to hot or cold and brief pain after eating a sugar-containing
food.
The dentist can diagnose decay with x-rays or by probing
the tooth with a sharp instrument. Decayed enamel or dentin
will feel soft.
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Healthy Habits to Help Prevent Cavities
See your dentist regularly. How often will depend on your
particular needs. Your dentist can advise you.
Brush your teeth regularly to reduce plaque buildup. Brushing
should last for about 2 to 3 minutes each time to make sure
you're reaching all teeth surfaces. Even though there are
many kinds of toothbrushes on the market, including electric
and sonic models, any will do, says Susan Runner, D.D.S.,
chief of FDA's dental devices branch. "The most important
thing about the brush is to use it and to have appropriate
instruction from your dentist or hygienist on how to use it,"
she says. The American Dental Association recommends switching
to a new brush every three to four months.
Use a fluoride-containing toothpaste. Check to make sure
there is fluoride in the product, because not all toothpastes
contain it. Three kinds of fluoride ingredients are allowed,
based on their effectiveness and safety, according to FDA's
final monograph on over-the-counter anti caries drug products,
which took effect in spring 1997. They are sodium fluoride,
sodium monofluorophosphate, and stannous fluoride. Toothpaste
manufacturers sometimes combine fluoride with other ingredients
that are said to reduce plaque and gingivitis (inflammation
of the gums). Although FDA has approved one such product,
Colgate's Total toothpaste, for helping to prevent cavities,
plaque and gingivitis, FDA has not determined the effectiveness
of many of the anti plaque and anti gingivitis ingredients.
Also, consumers should be wary of claims that a dental product
can do more than simply reduce tooth decay because, based
on current scientific knowledge, this is the only cavity-fighting
labeling claim FDA allows.
Floss daily. Like toothbrushes, any kind will do, as long
as you use it daily. Flossing helps reduce plaque buildup
in areas the toothbrush can't get to.
Eat a variety of foods, but eat fewer foods containing sugars
and starches between meals. The more often you eat foods with
sugars and starches and the longer these foods stay in your
mouth before you brush your teeth, the greater the risk for
tooth decay. Consider sugarless candy and gums made with certain
sugar alcohols because they may not promote tooth decay. |
