The Physiology of Cavities

By Premier Dental of Ohio

For many people, going to the dentist is a frustrating process.  They dread hearing the words, “You have a cavity.”  And the less you know about cavities, the more frustrating that is!  This post aims to help you understand the physiology behind cavities.  We believe you can have a positive impact on your own oral health by comprehending the cavity process.

The Anatomy of a Tooth

Before you can understand the cavity process, first you have to understand the anatomy of a tooth.  A tooth is not just one solid piece of enamel.  Its different components each play an important role in normal tooth function, and they each give in to cavities differently.


Enamel is the hardest substance in the human body.  It is harder than bone!  Moreover, it must be that hard in order for teeth to do their job properly.  Teeth must bear the physical force of chewing and the chemical forces of the foods and drinks to which we subject them.

Enamel covers the exposed surface of a healthy tooth.  It is relatively white in color (obviously, there are wide variations in tooth color).  Enamel protects the other anatomical features of the tooth by insulating them from the harsh world of the mouth . . . when enamel is healthy, that is.

Do not make the mistake of assuming that enamel is invincible.  It is not!  Enamel’s kryptonite: ACID.  In the same way acid etches glass, it will soften and weaken enamel.


Dentin makes up the majority of a tooth’s mass.  This core structure extends from the very tip of the root all the way to the enamel, and it surrounds the soft tissue inside the tooth.  Dentin is yellow in color and much softer than enamel.

The reason for the “softness” of dentin is the presence of tiny pores, called tubules.  These tubules are like tiny channels or pathways between the enamel and the hollow chamber inside the tooth.  These pathways are very important in the cavity process.


The root of each tooth is what anchors it into the jawbone.  The root is mostly dentin, and it is covered in a very thin layer of a structure called cementum.  Cementum provides a little insulation for the root, but that is not its primary goal.  The root should be covered in bone and gums, so it should not need the insulation.

Because cementum is so thin, it comes off the root surface very easily if gum recession exposes the root.  Tooth roots are very susceptible to cavities because they do not have the protective coating of enamel.


Pulp is the term we use to describe the soft tissue (nerves and blood vessels) that fill the hollow chamber inside a tooth.  All of the teeth are hollow, and the pulp tissue is what makes them “alive”.

The nerves and blood vessels connect to the rest of the nervous and circulatory systems in the body via a tiny hole in the tip of each root.  This tiny hole does not allow antibiotics to pass through, which is why infected teeth cannot be cured with only antibiotic therapy.

The Biology of Bacteria

Now that you understand the makeup of a tooth, we will move on to the bacteria that cause cavities.  Cavities are an infectious disease, caused by the multiplication and spread of bacteria.  Being an infectious disease, it is also a transmissible disease.  We transfer bacteria from one mouth to another by kissing and sharing eating utensils.

The mouth is home to over 300 different species of bacteria, some of which are actually good.  But the bad, cavity-causing bacteria can quickly override any good ones and wreak havoc on your teeth.

There are a few different strains of bacteria known to cause cavities, the most notable being Streptococcus mutans.  These bacteria form large colonies within dental plaque (that soft whitish stuff that collects on your teeth).  This is the reason that great oral hygiene, brushing and flossing regularly and properly, lowers your risk for cavities: it physically removes the bacteria from your mouth!

The Cavity Process

There are four essential ingredients in the cavity process:

  1. Teeth – Cavities break down the hard structure of a tooth.
  2. Bacteria – The bacteria produce the acid that weakens, softens, and eventually penetrates the tooth’s enamel.
  3. Sugar – Sugar, or more specifically any refined carbohydrate, provides the food source for the bacteria.
  4. Time – Cavities are not instant; they take time. The bacteria must stay in contact with the tooth for an extended amount of time to create a cavity.  This length of time is different for every person.  It varies based on the type of bacteria, the strength of the tooth’s enamel, and the pH of the mouth.

So in general, a cavity works like this.  Bad cavity-causing bacteria stick to a tooth via dental plaque.  Those bacteria eat sugar and produce acid.  The acid, when it has enough time to work, softens and weakens the enamel.

Eventually, the enamel’s solid coating breaks, allowing the bacteria access to the softer dentin underneath.  Once a cavity penetrates the enamel, it can progress much more quickly, working its way toward the nerve and blood vessels in the center of the tooth.  At this stage, we can stop the cavity and repair its damage with a filling.

If no intervention occurs and things keep moving, then the bacteria continues to spread and move toward the nerve and blood vessels inside the tooth.  This leads to toothaches and dental infections, sometimes even abscesses.  It also leads to expensive dental treatment to repair the situation!

How to Fight Cavities

We can fight cavities by addressing those four factors listed above.  Here are some great tips for ways you can stop cavities before they start!

  1. Teeth – Strengthen your teeth by using a fluoride toothpaste. If you need extra strength, ask your dentist for a prescription toothpaste or a professional fluoride treatment.  Research shows that fluoride makes enamel harder and less likely to give in to the acid attacks of bacteria.
  2. Bacteria – Reducing the amount of bacteria in your mouth goes a long way in the fight against cavities. Remember: these bacteria live inside dental plaque, so your goal is to remove all the plaque on your teeth.  This means you must be flossing every night before bed.  You must brush, with the appropriate technique, twice a day.  Adding an antiseptic mouthwash (try to stick with alcohol-free) will reduce the plaque in your mouth, too!
  3. Sugar – Cut it out. The less sugar you eat and drink, the less likely you are to get cavities.  Again, by “sugar”, we mean all refined carbohydrates.  Try to stick to complex carbs, proteins, and fats for great oral health.
  4. Time – You can affect the time factor of the cavity process by making sure you do not allow plaque to stay on your teeth for more than a day. Cleaning your teeth properly and consistently fights both the time factor and the bacteria factor of the cavity process.

More Questions about Fighting Cavities?

Call your nearest Premier Dental of Ohio location to schedule a consultation with one of our dentists.  We are all cavity experts!

Premier Dental Shop


View More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More ProductsView More Products

Join our 37,500+ patients who are maintaining healthy teeth and gums for life.

Find Your LocationSchedule online
Schedule Now