175 Grange Avenue
P. O. Box 629
Molalla, OR 97038
Phone: 503-829-9374
Fax: 503-829-9375
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About Cavities
What's In Your Mouth?
To understand what happens when your teeth
decay, it's helpful to know what's in your mouth naturally. Here are a few of
the elements:
Saliva — Your
mouth and teeth are constantly bathed in saliva. Although we never give much
thought to our "spit," this simple fluid is remarkable for what it
does to help protect our oral health. Saliva keeps teeth and other oral tissues
moist and lubricated, washes away some of the food particles left behind after
we eat, keeps acid levels in the mouth low, and protects against some viruses
and bacteria by carrying immunoglobulins and other substances important for
immunity.
Pellicle —
Certain proteins in saliva (glycoproteins) are absorbed by the surface of our
teeth. This creates a microscopically thin, clear coating on the teeth called
"acquired pellicle." The pellicle starts forming immediately after
you brush your teeth, and, within a few minutes, you can feel that slippery,
moist feeling on your teeth. The pellicle helps shield the teeth against acid
that can cause caries. However, the pellicle also forms a prime surface for
bacteria and other microorganisms that lead to the development of plaque.
Plaque — Plaque
is the scourge of the mouth. It appears as a soft, gooey substance that sticks
to the teeth a bit like jam sticks to a spoon. It is, in fact, colonies of
bacteria, protozoa, mycoplasmas, yeasts and viruses clumping together in a
gel-like organic material. Also in the mix are bacteria byproducts, white blood
cells, food debris and dead body tissue. Plaque grows when more bacteria join
in, when the bacteria already there start to multiply, or when bacteria
byproducts and food debris accumulate. Plaque starts forming immediately after
a tooth is cleaned. It builds up to measurable levels after about one hour and
takes an average of seven days to fully mature. As it matures, more and more
different types of microorganisms appear, the plaque thickens and gum
inflammation begins. Plaque that forms on the crowns of the teeth, the part
that shows above the gums, is called supragingival plaque; plaque under the
gums is called subgingival plaque.
Calculus — If
left alone long enough, plaque begins to mineralize and harden into calculus,
also known as tartar. Calcium, phosphorus and other minerals from saliva become
incorporated into the plaque, form crystals and harden the plaque structure.
Plaque begins to mineralize within 24 hours and it is fully hardened and
transformed to calculus within 12 to 20 days. Then, new plaque forms on top of
existing calculus and this new layer can also become calcified. For that
reason, calculus is usually found in layers.
Bacteria — We all
have many different strains of bacteria in our mouths. Some bacteria are good
for us because they help control populations of more destructive bacteria. When
it comes to decay, Streptococcus mutans is the bacterial strain that does the
most damage. It attaches easily to teeth and produces a lot of acid. Another
common acid-producing bacteria, lactobacillus, is less destructive because it
can attach only to plaque, not to the tooth itself. A third type of bacteria,
actinomyces also plays a role in tooth decay. Other bacteria cause periodontal
disease and include porphyromonas gingivalis, prevotella intermedia and
bacteroides forsythus.
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How Your Teeth Decay
If you never ate any food and brushed your teeth
twice a day, the decay process would never get started. But the minute you put
food in your mouth, the sequence begins.
In a clean mouth, the pellicle, a
microscopically thin, clear coating on the teeth formed by certain proteins in
the saliva, starts forming immediately after brushing. Soon after,
microorganisms attach themselves to the pellicle and begin to form plaque on
the teeth.
Illustrations: How A Tooth Decays
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White Spots
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Enamel Decay
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Acid from bacteria in the mouth has started to leach minerals
from the enamel in a process called "demineralization." This
earliest stage of decay is reversible.
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Demineralization continues. Enamel starts to break down.
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Dentin Decay
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Pulp Involvement
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The decay reaches into the dentin where it can spread and
undermine the enamel.
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If decay is left untreated, it will reach the tooth's pulp,
which contains nerves and blood vessels. The pulp becomes infected. An
abscess can form in the tissues.
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At this point, mouth tissues and plaque have a
pH of about 6.2 to 7.0. pH is a measure of acidity or alkalinity on a scale of
1 to 14. A pH of 7 indicates a substance is totally neutral, neither acid nor
alkaline. Lower numbers on the scale indicate a substance has more acid and
higher numbers mean the substance is more alkaline. At a normal pH of 6.2 to
7.0, the mouth is close to neutral and no damage is being done to the teeth. If
the pH drops below 5.5, the enamel that covers the portion of the tooth above
the gums starts to demineralize, which means it loses some of the minerals in
its structure and begins to break down. Between a pH of 5.5 and 6.0, the acid
can begin to destroy the roots of the teeth under the gum line.
So how do our mouths become acidic? That's where
the sugar connection comes in. And it's not just candy and ice cream we're
talking about. All carbohydrate foods, as they are digested, eventually are
broken down into simple sugars: glucose, fructose, maltose and lactose. Some of
this digestion begins in the mouth with digestive enzymes in saliva. Foods that
break down into simple sugars in the mouth are called fermentable
carbohydrates. These include the obvious sugary foods, such as cookies, cakes,
soft drinks and candy; but also bread, crackers, bananas, potato chips and
breakfast cereals.
The process of digestion begins in the mouth.
The sugars created by that process are used by the bacteria, which form acids
as a byproduct. These acids cause the mouth's pH to drop and begin to dissolve
the mineral crystals inside the teeth.
The longer the pH remains lower than 5.5, the
more acid damage will be done. Therefore, carbohydrate foods that tend get
stuck to teeth tend to do more acid damage. Teeth with a lot of nooks and
crannies, such as molars, are more likely to trap food and are therefore more
susceptible to caries. Plus, every time you eat a fermentable carbohydrate, the
pH of your mouth remains below 5.5 for up to several hours, depending on the
quality of your saliva. People who sip soft drinks or sweetened coffee
throughout the day or who eat many small carbohydrate snacks will have an
acidic mouth almost constantly.
What's worse is that bacteria love sugar, and
they thrive and multiply in an acid environment. So the more sugar you eat, the
more acidic your mouth and the more bacteria will grow. The more bacteria you
have, the more acid will be produced when you eat sugar. The cycle builds on
itself, creating an ever more destructive environment for teeth.
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Types And Stages Of Decay
When acids first start dissolving the tooth, a
white spot appears on the enamel. This is where the demineralization has begun
to weaken the enamel and start a cavity inside the tooth. At this stage, the
tooth can remineralize and fix the weakened area itself with the help of
minerals in saliva. But if the decay continues and breaks through the surface
of the enamel, the damage is permanent. The decay must be cleaned out and the
cavity filled by a dentist. Left untreated, the decay will continue. It has been
known to eat away at a tooth all the way through the enamel, through the dentin
and down to the pulp of the tooth.
In young children, teeth that have just recently
emerged have weak enamel and are highly susceptible to acid decay. Acute
caries, which destroys enamel quickly, is common in children and young adults.
This type of decay can eat through enamel and leave a large cavity in a matter
of months.
Older adults sometimes have chronic caries,
cavities that don't seem to progress or progress at a very slow rate. They will
tend to be darker in color because the edges get stained from normal eating and
drinking.
Root caries is more common in older adults than
in younger adults for a couple of reasons. Older adults are more likely to have
gums that have receded from years of hard brushing or periodontal disease. That
can higher risk of decay. Older adults also have higher incidences of dry mouth
(xerostomia), which increases the risk of decay.
Recurrent caries is decay that forms beneath
fillings or other restorations, like crowns. Sometimes, bacteria and food
particles can slip into a tooth if a filling hasn't been placed properly or if
the filling cracks or pulls away from the tooth enough to leave a gap.
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Preventing Cavities
Oral hygiene is necessary to prevent cavities.
To prevent your teeth from decaying, you can do two things — reduce the amount
of bacteria in your mouth, and strengthen your teeth's defenses. Although you
can never totally get rid of bacteria in your mouth, you can reduce it greatly
by brushing at least twice a day and flossing at least daily, and regular
professional cleaning (every 6 months). X-rays may be taken yearly to detect
possible cavity development in high risk areas of the mouth.
Chewy, sticky foods (such as dried fruit or candy)
are best if eaten as part of a meal rather than as a snack. If possible, brush
the teeth or rinse the mouth with water after eating these foods. Minimize
snacking, which creates a constant supply of acid in the mouth. Avoid constant
sipping of sugary drinks or frequent sucking on candy and mints.
Some prescription mouthwashes can help prevent
decay by reducing the number of bacteria in the mouth. Chewing sugarless gums,
especially those with xylitol, can help prevent decay by increasing the flow of
saliva, which has antibacterial properties.
Fluoride is the best resource available for
protecting teeth from decay and healing early acid damage. Fluoride strengthens
teeth by penetrating the tooth structure and replacing lost minerals to repair
acid damage. Sealants, which provide a protective coating over the tops of
vulnerable molars and premolars, block bacteria and acids from sticking in the
tiny grooves on the chewing surfaces of these teeth. And general good nutrition
will keep the quality of saliva high enough to protect against acid and provide
minerals for remineralization.
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