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31 Jan 2021 | Australasian Dental Practice

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Essential messages: Discussing abfractions and toothbrush abrasion

By Dr Michael Sernik

Dentistry is a business of repetition. Yesterday is often a preview of tomorrow and we find ourselves saying the same sorts of things again and again. What we say can become automatic speeches, not because we've tried to memorise them, but because we've just said them so often. There are many Essential Messages that we need to deliver to patients and they should be short and clear.

Since most of us just keep repeating the same sorts of things for years, it's not a bad idea to pause and reassess your Essential Messages from time to time.

One common topic that comes up is related to the loss of cervical tooth structure. Typically, we discuss one of two related aspects:

  • Their sensitivity in the cervical area to cold or touch; and
  • The visible loss of tooth structure in that area.

Many dentists will get bogged down as they try to explain these topics. This is particularly the case when they talk about abfractions and toothbrush abrasion. Let's look at each topic.

Toothbrush abrasion

Telling the patient to "brush more" and then telling them that they have "brushed away their enamel" has inherent conflicts in logic, i.e. you need to brush more but not too much.

There are several reasons to doubt the toothbrush abrasion theory.

  1. Sometimes, we'll see some decay associated with the area that is being over-brushed. It's difficult to reconcile these two processes happening simultaneously;
  2. The removal of tooth structure by brushing has never been duplicated in any vitro tests; and
  3. The hardness of tooth enamel is higher than stainless steel. Toothbrush bristles simply cannot mechanically wear away enamel. We'll discuss the role of toothpaste in a moment.


The theory is that when patients bite hard, they bend the tooth and the enamel flakes off in the cervical region. This leads, somehow, to the dentine disappearing in the cervical area.

There are several reasons to doubt this process.

  1. Out of the tens of thousands of teeth studied from prehistoric times, there has never been a single case of abfraction being found. This is the case, notwithstanding the fact that the forces applied to many of these teeth in prehistoric man would have been far greater than the pressures applied by modern man;
  2. It's difficult to explain an abfraction when the tooth in question has no opposing tooth;
  3. The removal of the enamel happens only on the buccal surfaces. Yet the forces on upper teeth tend to cause compressive forces on the buccal and flexural forces on the buccal of the lower teeth;
  4. The abfraction process has never been replicated in any study; and
  5. The removal of dentine cannot be explained by these occlusal forces.

Let's postulate for a moment that the cause of non-carious cervical lesions is related to two possible factors:

  1. We know that saliva has a buffering effect on tooth structure. The buccal surfaces are drier than the lingual surfaces because the lips and cheeks reduce saliva flow in these areas; and
  2. We know that tooth structure can be softened by acid and that if the tooth is brushed with toothpaste, the brushing can remove the softened tooth structure. There are many examples of abrasion by habits such as running string around teeth in native peoples as part of weaving activities and tooth picks or tobacco pipes wearing away tooth structure.

Mouths in modern man are probably drier and more acidic.

  1. In past times, our foods were more fibrous and required more mastication which in turn stimulated more saliva;
  2. Many medications cause a reduction in saliva flow; and
  3. Modern processed foods interact with bacteria and are more acidogenic.

What could you could say to patients?

If you get bogged down trying to explain all the differences of opinion within the profession, you probably won't be helping the patient much. Chances are, they'll leave more confused. Only give patients usable advice that will help them, regardless of what your theories are.

To explain the cervical loss of tooth structure, I explain that:

  1. The lips and cheeks tend to prevent saliva from washing the outside surfaces of the teeth. Saliva buffers the acids and the dry tooth structure is more acidic;
  2. Our modern diet of processed foods and sugar cause the bacteria to produce more acids;
  3. Modern medicines often reduce saliva; and
  4. The acid softens the tooth structure. When we brush the softened structure with toothpaste, this can remove some of the protective tooth enamel and then the softer dentin can be brushed away due to the toothpaste.

My Essential Message: If you woke up and your mouth feels dry, the outside of the teeth will be softened by the acids, so don't just brush with toothpaste immediately after you wake up. You should rinse with bicarbonate of soda, which will buffer the acids. Then have breakfast, which will stimulate more saliva and finally, brush thoroughly. Don't use toothpaste. Just brush with a good quality soft brush and water. Then clean interproximally. During the day don't snack on processed foods or drink soft drinks because that will increase the acid in your mouth.


When discussing cold or touch sensitivity, I explain that the outer part of the tooth is covered with protective enamel which has no nerves in it. But underneath the enamel, the tooth structure can transmit signals into the centre of the tooth. Unlike the rest of the body, teeth have just one type of nerve. That nerve only transmits pain. A light touch doesn't signal touch; a hot drink doesn't signal heat and the cold drink doesn't signal cold. The nerves in teeth only transmit pain signals.

We are all conditioned to assume that if we feel pain then there is something wrong. But in the case of teeth, it just means that we are stimulating the pain nerves inside the teeth. Imagine standing on ice with bare feet. It would hurt, but the pain doesn't mean we need to treat the feet. It just means we need to reduce the stimulus with shoes. So in the case of this type of sensitivity, we just need to protect the surface of the tooth.

At the moment, I don't believe anyone has come up with definitive proof as to how non-carious cervical lesions occur but we don't need to share our confusion and doubts with patients. The benefit of the explanations given are that the instructions are clear and there are no inherent conflicts in logic. Following these protocols will not cause the patient any harm.

About the author

Dr Michael Sernik is the creator of Channel D, dental videos designed to trigger conversations that will grow your practice. Simplicity in patient communications matters. Channel D is also perfect for treatment rooms. It plays silently and will trigger conversations on Dental topics that matter to you. Visit and use Code MA56 to start your trial.

SernikSpeak is a new program offering online communications training for dental practices. If you're interested in finding out about the new SernikSpeak Communications program, just go to and register your interest.

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