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Everything You Need to Know About Cavities (But Were Afraid to Ask)

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Dental cavities are considered a disease caused by bacteria "pooping" in your mouth after you've had a meal.

by Dr. Burhenne

Everything You Need to Know About Cavities (But Were Afraid to Ask)

I will never forget my visits to the dentist as a child. Around three to four days before the visit, I would begin a crash program in oral hygiene. I would vigorously brush and floss five times a day and forgo my beloved after-school snack: a Butterfinger.

The night before the appointment, I would suddenly become deeply religious and pray for a cavity-free check-up.

Needless to say, my last minute flossing and brushing did not work, and the dentist found the results of my most consistent behavior — that of benign neglect — the next day at my dental appointment. How “fortunate” I was to be able to have had my cavities filled that same day since the dentist “fortunately” had a last minute opening.

It was only after becoming a dentist that I understood what a cavity actually was and what caused them.

But a cavity doesn’t need to be so mysterious, even to a 10-year-old.

The earliest theory of tooth decay was that a worm drank the blood of the teeth and fed on the roots of the jaws. This theory was common to all early civilizations from Babylon in the Euphrates River Valley to the Shang Dynasty in 1000 B.C. China.

Turns out that “worm” theory wasn’t too far from the truth.

What Is a Cavity?

Dental cavities are considered a disease. Even though they’re preventable, cavities are the most common chronic disease in children and adolescents. If you’re an adult, it doesn’t mean you’re out of the woods. 9 out of 10 adults over the age of 20 have had one or more cavities, according to the CDC.

A cavity is best described as a hole in your tooth. This hole is caused by acid erosion from the bacteria in your mouth that break down foods and produce tooth enamel-destroying acid.

The result: nerves in your teeth become exposed. Tooth pain is some of the worst pain out there, so this exposed nerve can make you feel pain or sensitivity when you eat or drink.

If you feel pain near the root of your tooth, chances are you may have some form of tooth decay and should see your dentist.

How Cavities Form in the Mouth

The process is complex and some aspects are still not completely understood.

There isn’t any one thing that causes a cavity, rather, cavities are caused by a “perfect storm” of several factors at play in your mouth.

There are four main factors involved in the creation of a cavity:

  1. Your teeth and saliva, which set the “stage” for bacteria to feast
  2. The bacteria in your mouth
  3. The food you eat
  4. The frequency, or number of times, the first three factors overlap on this “stage”

First, for a tooth to be susceptible to decay, the bacteria must adhere themselves to the tooth. They do this by combining with proteins in saliva and food debris, forming a layer which is known as plaque. Plaque, taken from the French verb plaquier (to plate), coats the tooth with these bacteria. They consume the food with which they come into contact (the same food you eat) and often digest it within 15 minutes. Bacteria are very fond of easily digestible foods such as saltine crackers, Goldfish crackers, potato chips, sugary foods and anything processed.

However, the bacteria in your mouth are extremely disappointed with foods like broccoli. The cellulose is very difficult for them to digest. When the bacteria do get together to feast, they feast on junk food.

Soon after a meal, of course, bacteria have to “go to the bathroom” just like any other organism — and they “go” in your mouth. They do this by excreting an acid, which, if concentrated in one area, can actually dissolve the calcium in a tooth. This is known as an “acid attack”. If a small colony of plaque remains attached to one aspect of a tooth for a certain period of time, this little colony will cause a hole to form in the tooth structure. Every acid attack constitutes a small removal of tooth enamel. Yes, you read that right — cavities are formed by bacteria pooping in your mouth.

Surprisingly, the tooth is able to re-mineralize these dissolved areas if given ample opportunity to do so. If the colony of plaque is removed or even temporarily dislodged, the acid attack will not occur in the same place, allowing the tooth some time to recalcify the depleted area. Of course, this is the role brushing and flossing play in prevention of cavities; mechanical removal of the plaque facilitates the health of your teeth.

The typical “acid attack” during the waking hours is tempered by the presence of saliva in our mouths. The saliva, being much less acidic, dilutes the acid, reducing its strength and therefore it effectiveness in dissolving teeth. However, many of us do not realize that our mouths stop producing saliva after we have fallen asleep, allowing the bacteria to inflict their severest attack to the teeth. This is why your dentist recommends flossing and brushing before bedtime. If the plaque is dislodged from the teeth before this dangerous period occurs, at least the “acid attack” is rendered less effective.

Imagine a misbehaved dog peeing on the wood floor of your home. The acid in that waste will slowly erode the soft wood floor. However, buffering that acid with lots of water would reduce the acid attack on the wood. This is exactly how saliva protects your teeth.

Even if all the plaque is not dislodged, the teeth are able to fend for themselves in other ways. A tooth, while rebuilding itself, will take up fluoride and incorporate it into its crystalline structure. Fluoride is much more resistant to being dissolved by subsequent “acid attacks.” Hence, topical fluoride (not the fluoride in our water supply) can help protect against cavities.

How Cavities Are Treated

Cavities are fairly simple to treat in a visit to the dentist. The basic treatment is a filling, which involves drilling away the decayed part of the tooth and replacing that hole or “cavity” with a strong filling made of porcelain, silver, gold, or amalgam.

More extensive decay requires more advanced techniques like crowns and root canals.

How to Prevent Cavities

Now that I’m a dentist, I know why that last-minute flossing as a kid was a futile attempt at preventing cavities. Fortunately, I made it to adulthood with only four cavities that needed to be filled. Candy bar indulgences gave way to a sensible diet and I brush and floss all year long now. Dentists are human after all. We can get cavities just as often as any one else.

Consistency in caring for your teeth is the one crucial ingredient in maintaining dental health. 

Notice how I said “maintaining”? The goal is preventing disease, because once you have it, it’s hard to reverse. Maintaining the good oral health we are all born with is much easier than letting it go and then treating it.

The key is to prevent plaque from building up through teeth cleanings and proper brushing and flossing.

Today, as an adult and as a dentist, I see many children (and many adults) practicing the same last-minute tactics I practiced years ago. Some things never change. Perhaps, after work tomorrow, I’ll have just one…just one Butterfinger.

Mark Burhenne DDS

read next: Foods to Eat—And Foods to Avoid—to Heal Cavities Naturally

Tired of cavities?

In 3 super easy steps, I'll show you how to hardly ever get another cavity without drastically changing your diet.

Dr. Mark Burhenne DDS

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