What causes cavities?

This is the first of our series of blogs! We get a lot of common questions from parents concerning their children’s oral health. Most common questions include topics such as trauma, cavity process, cavity prevention, fixing cavities, and child anxiety in the office.  Today, we will start with one of the most common questions we get on a daily basis: What causes a cavity?

Our mouths are full of hundreds of types of bacteria. They live on our teeth, gums, and tongue.  Some of these bacteria are helpful, but some can be harmful, such as those that play a role in the tooth decay process.

Tooth decay is the result of an infection with certain types of bacteria that use sugars in food to make acids. Over time, these acids can make a cavity in the tooth.

Dental plaque—a sticky, colorless film of bacteria—uses foods and drinks that contain sugar or starch (such as milk (regular and chocolate), bread, cookies, candy, soda, juice, and many others) to eat away at the tooth; this is called decalcification. Whenever we eat or drink something that contains sugar or starch, the bacteria use them to produce acids. These acids begin to eat away at the tooth's hard outer surface, or enamel.

Fortunately, there are protective factors against cavities: minerals in our saliva (such as calcium and phosphate) plus fluoride from toothpaste, water, and other sources. This team helps enamel repair itself by replacing minerals; this is called remineralization.  The teeth are in a constant state of demineralization and remineralization, and our goal is to minimize the demineralizing factors, and increase our protective, remineralizing factors to keep cavities away.

A graph to explain this process of demineralization and remineralization is called the Stephan curve.

At Time = 0 the baseline pH of plaque is taken (approximately pH7). A sugary intake is consumed and the pH drops to around pH2-3. This is below the 'critical pH' of enamel (pH5.4). The critical pH is the pH below which enamel will begin to dissolve. Gradually over the following 30 minutes the pH of the mouth begins to return to neutrality and the dissolving of enamel ceases and the products of saliva can begin to remineralize any dissolved enamel. If sugar is frequently consumer throughout the day then the dissolving action of bacterial acids will probably lead to tooth decay.

An example showing frequency is more important than the quantity.  Let’s say you eat 4 pieces of your favorite candy all at once.  Your pH will drop, and potential demineralization of your teeth can occur for about 30 minutes.  Now, let’s say you eat 4 pieces, but eat one piece every 15 minutes… Now, demineralization of your teeth can occur for over an hour and a half (vs a half hour).  Hence, frequent snacking of sugary items is not recommended due to its high potential for causing cavities.

When a tooth is exposed to acid frequently -- for example, if you eat or drink often, especially foods or drinks containing sugar and starches -- the repeated cycles of acid attacks cause the enamel to continue to lose minerals. A white spot may appear where minerals have been lost. This is a sign of early decay.

Tooth decay can be stopped or reversed at this point. Enamel can repair itself by using minerals from saliva, and fluoride from toothpaste or other sources.

 But if the tooth decay process continues, more minerals are lost. Over time, the enamel is weakened and destroyed, forming a cavity. A cavity is permanent damage that a dentist has to repair with a filling.

 Tips for prevention:

1) Establish a dental home early!

                  -Newly erupted teeth, because of immature enamel, may be at higher risk for developing cavities. Evidence increasingly suggests that preventive interventions within the first year of life is critical. The American Academy of Pediatric Dentistry recommends the first dental visit to occur at age 1 in order to preserve your child’s best oral health.

2) Use fluoridated toothpaste

                  -The American Academy of Pediatric Dentistry recommends the current best practice is twice daily brushing with fluoridated toothpaste for all children. A smear or rice sized amount should be used for children less than 3 years of age.  A pea sized amount is appropriate for children age 3-6.

                  -Please contact us with questions or concerns regarding fluoride use in children

3) Limit between-meal snacks. This reduces the number of acid attacks on teeth and gives teeth a chance to repair themselves.

4) Save candy, cookies, soda, and other sugary drinks for special occasions

5) Limit fruit juice. Follow the Daily Juice Recommendations from the American Academy of Pediatrics (4-6 oz. per day in an open cup, not bottle or sippy).

6) Make sure your child doesn't eat or drink anything with sugar in it after bedtime tooth brushing. Your mouth dries out overnight, and decalcification can occur more significantly if the bacteria can use that sugar all night long!

Thank you for reading our blog. Please contact our office at 605-242-4700 with any questions or concerns regarding your child’s oral health!