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All 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:
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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.
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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.
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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.
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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.
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.
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.
If tooth decay
is a location on a tooth where its mineral content has been dissolved away
and a hole has formed (a process called demineralization), how does this
action occur? The answer is, the demineralization of a tooth is caused by
acids, acids that are created by certain types of bacteria that live in
our mouths.
Bacteria are living organisms just like we are. As you
know, humans consume food and produce waste products that are subsequently
excreted. Bacteria do the same thing. The bacteria that are capable of
causing cavities (mutans streptococci and lactobacilli) consume sugars as
food (glucose, sucrose, fructose, lactose, or cooked starches). The waste
products these bacteria create from having consumed these sugars are the
acids (especially lactic acid) which cause a tooth's demineralization
(tooth decay formation).
The bacteria that live in our mouths eat
when we do. So, as we ingest foods which contain sugars (such as soda,
candy, milk, and even fruits and vegetables or the juices made from them)
the bacteria get a meal too, and within minutes they start producing the
acids which cause tooth decay.
- Factor in the formation of
tooth decay :
-
When oral bacteria consume sugars
they produce the acids which cause tooth demineralization (tooth decay
formation).
- Cavity prevention suggestion
:
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The smaller amount of sugars you
consume, or the fewer times you consume sugars, or the shorter the
amount of time a concentration of sugars is allowed to persist in your
mouth, the less acid which will be produced oral bacteria.
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Use artificial sweeteners
rather than natural sugars.
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Reduce the amount of time
sugars remain in your mouth. Brush and floss, or at least rinse,
promptly after consuming sugary foods.
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Don't continually snack on or
sip on sugary foods and beverages over prolonged periods. Eat or drink
them fairly promptly and then clean your teeth.
Oral bacteria and dental plaque:
location, location, location.
Everyone's mouth is inhabited by bacteria, in fact a single human
mouth can contain more microorganisms than there are people on planet
Earth. While you can't sterilize your mouth you can minimize your
potential for the formation of tooth decay. This is done by way of not
allowing the bacteria that are present to form organized colonies on the
surface of your teeth. These colonies are called "dental plaque".
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Dental plaque not only provides living
quarters for bacteria but it also helps to hold the acid produced by these
bacteria up against the tooth's surface. Take a look at our diagram to the
left. Acids created by bacteria that lie near the surface of the dental
plaque will possibly seep out off the plaque's surface and into our
mouths. This acid will get diluted, buffered, and/or washed away by saliva
and the foods we eat and drink and isn't the acid that will be especially
instrumental in actually forming tooth decay. |
The acid which will demineralize a
tooth and hence cause tooth decay formation is the acid which seeps in the
other direction, on through the plaque down to the tooth's surface. This
acid will be held right up against the tooth and because down at this
depth there is less dilution, buffering, or washing away by saliva the
acid will be in very concentrated form (a pH of 4 or lower).
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Factor in the formation of
tooth decay :
-
Decay occurs in those areas where
dental plaque lies on a tooth's surface.
-
Cavity prevention suggestion
:
-
Brush and floss often and
effectively.
-
Brush and floss after every
meal or snack.
-
Take the time to be thorough
with your brushing and flossing. Those places where you don't clean
well are exactly the same locations where cavities will be most likely
to occur.
As time goes by the buffering
agents found in saliva can penetrate through dental plaque and neutralize
the acids which are present, however this can take as long as two or more
hours.
-
Factor in the formation of
tooth decay :
-
Acid formation, and hence
demineralization and tooth decay formation, begins within minutes of the
bacteria receiving a sugary meal. It can take up to several hours for
saliva to penetrate the layer of dental plaque and neutralize these
acids.
-
Cavity prevention suggestion
:
-
Brush and floss promptly after
eating so to make sure the dental plaque has been cleaned off the
surface of your teeth.
- The amount of demineralization that
the acids can cause is related to the age of the dental plaque that is
present. The age of dental plaque relates to its thickness, chemical
nature, and what types of bacteria inhabit it. In response to an identical
exposure to sugars, plaque which is only a few hours old will produce much
less tooth demineralization than plaque which is several days old.
- Factor in the formation of
tooth decay :
-
The longer the plaque has been
present, the more capable it is of causing tooth damage.
- Cavity prevention suggestion
:
-
Brush and floss often and
effectively. Take the time to be thorough with your brushing and
flossing.
-
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.
Preventing Cavities
(Prevention)
To prevent your teeth from decaying,
you can do two things — reduce the amount of bacteria in
your mouth, and strengthen you teeth's defenses.
Although you can never totally get rid of bacteria in
your mouth, you can reduce it greatly by
brushing regularly and flossing daily, seeing your
dentist and dental hygienist twice a year for a thorough
cleaning and check-up, and by reducing the number of times
each day that you eat fermentable carbohydrates or drink
sugary drinks.
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. |
