Is it normal for a piece of tooth to break off spontaneously?

Question

While brushing my teeth, I noticed that a small piece of my second incisor on the right was missing. I have no idea how that happened. I can't remember biting on anything hard. I'm 64 years old. Is it normal for a piece of tooth to suddenly break off? What could be the cause? C. E. in L. 

Short answer

If a tooth is already damaged, a part of the tooth may actually break off spontaneously. Such pre-damage can be caused in particular by teeth grinding at night and/or during the day, which leads to cracks in the teeth, among other things, and by cracks forming in older dental fillings.

It is actually possible for a part of a tooth to break off spontaneously or for eating a soft food (e.g. a croissant) to be enough to cause a tooth fracture. However, it is only possible for a tooth to break off without a proportionate external impact if the tooth is already damaged. 

There are two main possible causes of pre-damage. 

Teeth grinding 

The most common cause is teeth grinding (bruxism). Grinding means rubbing the upper and lower jaw teeth together without food between the teeth. This involves much greater forces than chewing food. When grinding, forces of up to 70 kg can be developed directly between the teeth. In addition, people who are predisposed to grinding (approx. 20% of the population) grind their teeth very frequently over a 24-hour period. People who grind their teeth usually do so unconsciously and therefore unnoticed at night, but also during the day (60% of predisposed people only grind during the day!) Grinding often only becomes noticeable through pain in the jaw muscles (they become overloaded and thus inflamed), through the teeth becoming shorter over the years or through the breaking off of parts of teeth. The repeated application of force causes cracks in the teeth, which progressively develop further and further until only a minimal connection holds the two parts together. Often only a very small amount of force is then required to complete the crack and cause the part of the tooth to break off. 

Ageing of the fillings 

Dental fillings are another possible cause. Artificial fillings, like natural teeth, are subject to an ageing process in the mouth. After years, it is quite possible that an older filling can eventually break and be lost due to gradual cracking. This can happen more frequently if teeth with extensive fillings are subject to grinding. Tooth fractures and also filling fractures are much more common in such teeth. 

Author: Dr. med. dent. Jürg Eppenberger
Published in: Neue Luzerner Zeitung on July 18, 2007