What is a Cavity?

Dr. Kyle Hornby

I am a Dentist in Kitchener, ON, and each week I like to explore a question that I commonly get at my Family Dental office. This week, I'd like to discuss what cavities are, how they form, and what you can do to prevent them.

Cavity repair is by far the most common treatment delivered at dental offices. However, what cavities are, what they feel like, and how they're repaired is still generally misunderstood. Perhaps we Dentists can be doing more to explain these kinds of things to our patients.

Today, I'm going to give you a crash course in cavities so you can better understand treatment recommendations from your Kitchener Dentist.

What is a Cavity?

"Cavity" is what most patients commonly call tooth decay or dental caries. Early in my career, I often used the term "tooth decay" and most patients would ask "well, is that a cavity then?". Now, I just say cavity.

What's tricky is that most cavities are not actually cavitated. They're not always noticeable holes. As tooth decay progresses to a severe state, it weakens the tooth. Then, one day, the patient bites down and the enamel over top of or around the decay crumbles and breaks. Only at this point is the cavity truly a hole or "cavity".

Most tooth decay/cavities are caught early before a noticeable hole develops. So, you may not always feel a hole in your tooth when your Kitchener Dentist tells you that you have a cavity.

Cavities are painful...right?

Not always. In fact, I'd estimate that 95% of cavities or greater are totally asymptomatic. The diagnosis often surprises patients. Most say "Wow, I don't feel anything there".

This is another fact that makes dealing with cavities tricky. People are often reluctant to undergo treatment if they're not in pain. People are often reluctant to allow for routine x-rays if they're not in pain. And, routine x-rays enable early detection and treatment of cavities before they become large and sometimes painful.

Just so we're on the same page, I completely understand the logic people use when thinking about cavities and routine x-rays. My hope with the information I provide is that people will better understand what tooth decay is and how it progresses so that they can make good decisions about their oral health!

What do I do if I have pain from a cavity?

If you have tooth pain, it's not always easy to know if it's because of a cavity. One thing you can try is to use oil of cloves in the are where you are experiencing symptoms. Oil of cloves contains ingredients that act to settle down the nerve in your tooth and these ingredients can work their magic even when applied to the outer surface of your tooth!

If you find that pain persists, they your symptoms may have a different cause.

In both cases, it's best to call your Kitchener Family Dentist to arrange an exam or "check up".

What's inside a cavity?

A cavity or "tooth decay" starts when bacteria start to consume food and plaque left on your teeth after each meal. The bacteria produce acid as a byproduct of gaining fuel from these bits of food. The acid softens and dissolves your teeth and this is the process of tooth decay.

If you sample the softened material within a cavity, you find that it contains softened tooth structure, different kinds of bacteria, and often protein and sugars from food. So, inside the cavity, bacteria have lots of fuel to stay alive, they continue to produce acids, and the tooth decay progresses. Eventually, without treatment, the tooth weakens and breaks to yield a cavity.

How do you treat or eliminate a cavity?

Most people know that if they have a cavity, they will need a dental filling. But, how does this help?

At your dental filling appointment, your Kitchener Dentist will numb the tooth so that they can clean the cavity. They use a drill and high pressure water spray to break up, dissolve and remove the soft material inside the cavity. Once your Dentist removes decay material and bacteria, they are left with a cleaned hole or void. The base of this area is made up of decay-free, healthy tooth structure. The Dentist then places a white filling to repair the hole or void.


Hopefully, this brief look at cavities has been helpful to you. The main take home messages are:

  1. What is commonly referred to as a "cavity" is known to Dentists as "tooth decay" or "dental caries". If you hear these other terms, you can interpret this as having a "cavity".
  2. Most cases of tooth decay or cavities don't result in an actual cavitation or "hole" in your tooth. Instead, most cases of tooth decay involve a soft or tacky spot on your tooth.
  3. In most cases, cavities don't cause pain.
  4. Cavities begin when bacteria digest plaque and food debris, produce acid, and this acid then dissolves your tooth enamel and dentin.
  5. Your Kitchener Dentist repairs a cavity by cleaning out and eliminating decay. The Dentist then fills the hole with a white filling.

In some cases, where the cavity is deep and close to your tooth's nerve, you may require root canal treatment. This eliminates post-operative pain and removes bacteria that may have reached the nerve space. Following root canal treatment, a dental crown would be necessary to reinforce your tooth.

Additionally, you can find a useful article from the American Dental Association on Tooth Decay here.

Thank you for reading today's post! Reach out if you have any questions.

By Dr. Kyle Hornby, Dentist in Kitchener

If you would like to have your teeth examined or you think you might have a cavity, give us a call at (519) 576-8160 or request a consult with me here.

Our Kitchener Dental Clinic is centrally located in downtown Kitchener and provide dentistry to Kitchener, Waterloo, Cambridge, Breslau, Elmira and surrounding areas.

This article is meant to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your Kitchener Dentist or other qualified healthcare provider with any questions you may have regarding a dental condition or treatment.

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