Cavities, Plaque, and Tooth Decay

What causes a cavity?

Your mouth is a busy place. Bacteria - tiny colonies of living organisms are constantly on the move on your teeth, gums, lips and tongue. Having bacteria in your mouth is a normal thing. While some of the bacteria can be harmful, most are not and some are even helpful.

Certain types of bacteria, however, can attach themselves to hard surfaces like the enamel that covers your teeth. If they're not removed, they multiply and grow in number until a colony forms. More bacteria of different types attach to the colony already growing on the tooth enamel. Proteins that are present in your saliva (spit) also mix in and the bacteria colony becomes a whitish film on the tooth. This film is called plaque, and it's what causes cavities.

(From www.healthyteeth.org)

How does Plaque cause a cavity?

The hard, outside covering of your teeth is called enamel. Enamel is very hard, mainly because it contains durable mineral salts, like calcium. Mineral salts in your saliva help add to the hardness of your teeth. Mineral salts, however, are prone to attack by acids. Acid causes them to breakdown.

The plaque that forms on your teeth and doesn't get washed away by saliva or brushed away by your toothbrush, produces acid as it eats up sugar. This acid is produced inside the plaque and can't be easily washed away by your saliva. The acid dissolves the minerals that make your tooth enamel hard. The surface of the enamel becomes porous - tiny holes appear. After a while, the acid causes the tiny holes in the enamel to get bigger until one large hole appears. This is a cavity. It's important to see your dentist before a cavity forms so that the plaque you can't reach with your toothbrush or floss can be removed.

What about sugar?

Sugar plays a harmful role in tooth decay. The bacteria that form together to become plaque, use sugar as a form of energy. They multiply faster and the plaque grows in size and thickness. Some of the bacteria turn the sugar into a kind of glue that they use to stick themselves to the tooth surface. This makes it harder for the bacteria to get washed away with your saliva.

Severe Dental Decay

However, sugar is not the only culprit! 2

We feed the bacteria in our mouth everytime we eat carbohydrates. These come in two types:

Sugars
Cooked starch - like bread and biscuits, which are broken down to sugars by an enzyme in the saliva. The bacteria in the mouth then treat them as though you had eaten plain sugar. Sweets like cake and candy are not much worse for your teeth than bread, biscuits, potato chips, fruit salad, and a glass of milk.

To the bacteria in your mouth, sugar is sugar, no matter what package it comes in. So candy is as bad as, or as good as, apples for the teeth.

Recent research shows that some candy is potentially less destructive to the teeth than bread, biscuits and some fruits (apples, bananas) which were previously considered safe or even protective against cavities, may actually promote tooth decay.

Two important factors affecting tooth decay are: 2

How often you eat: The mouth normally contains a wide variety of bacteria. These bacteria take advantage of food whenever it is available. So they become active whether you eat a full meal or just a small snack, and they remain active - producing acids that can cause cavities - for about 30 minutes after you eat. This is how frequent eating contributes to tooth decay, and can be easily modified by exerting a bit of self-control.
How long a particular food stays in the mouth after you eat it: The most commonly thought of sticky foods are chocolates. The chocolate is mostly sugar that dissolves in saliva and is cleared from the mouth fairly quickly. However, foods like biscuits and potato chips stay longer in the mouth than chocolates. This is because these do not dissolve in saliva and clear the mouth until they have been broken down into simpler sugars by the enzymes in the saliva. This process is likely to take hours, and in the meantime, the bacteria have a feast and secrete acids, which destroy the enamel of your teeth.

Why does it take so long to hurt?

Nerve fibers, the way that pain is sent through the body, aren't present in tooth enamel. While the acid is attacking the enamel, you can't feel a thing. Once the acid has begun to create a cavity and attacks the dentin under the enamel, the nerve fibers begin to send out a message that something is wrong. But by then, you have tooth decay. That's why it's important to have regular, preventive dental check-ups. Don't wait until it hurts!

Between Meal Snacks- are they OK?

As long as children are not eating all day long and are brushing properly with a fluoride toothpaste, we can stop nagging them about snack selection.

For those of us who are now using a fluoride toothpaste, even the issue of frequency of eating has become less significant than it was in the past. Concepts concerning diet and cavities have changed dramatically. Today there is decreasing emphasis on dietary counseling as the most effective strategy to prevent cavities in children. The traditional advice to avoid sticky sweets and between-meal snacks is being relaxed for most cavity-free children who are exposed to fluoride and comprehensive dental care. Many children need snacks daily to help meet their nutritional needs, and parents should choose and offer snack-foods accordingly.

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Resources

1. Unless otherwise noted, content and graphics from www.healthyteeth.org and developed by the Nova Scotia Dental Association. Text has been reformatted to enhance viewability. To visit this site directly (and leave Doctors Corner) select link above. This is an excellent noncommercial site providing basic but very useful information on various dental topics.

2. http://www.drjay.com

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