What is bruxism?

Bruxism is a muscular behaviour — a form of extreme use of the dento-maxillary apparatus.

Part of the professional literature does not consider bruxism pathological, but in my understanding it is quite the opposite — it is a situation that deserves to be addressed.

It takes multiple forms, but the most frequent are:

• Grinding — usually nocturnal. Considered without pathological significance in children up to the age of 12-14.
• Clenching — an isometric contraction. Frequent both during the day and at night.

Normal use of the dento-maxillary apparatus:

• at a meal we use today, on average, 20-35 kgf/cm2
• for a raw carrot or a quince we need around 70 kgf/cm2
• over a two-hour meal, the teeth are in contact for less than 2 minutes
• across a whole day, total tooth-to-tooth contact amounts to 15-20 minutes

In bruxism:

• forces can reach 400-500 kgf/cm2
• bruxism can last many hours, sometimes 16-18 hours a day

The muscles directly involved in bruxism

What are the effects of bruxism?

When a structure is overloaded, it can give way:

A. At the level of the parts

The teeth can show abrasions — wedge-shaped lesions at their base.

B. At the level of the joints

1. The temporomandibular joint, located in front of the ear, where the mandible engages the base of the skull. Its suffering shows in multiple ways, among which I mention:
   • clicking and cracking on closing/opening the mouth
   • pain in the area, with or without the closing/opening movement
   • limited mouth opening
   • tinnitus
2. The many hinges between teeth and bone (the periodontium), leading to periodontal disease. I believe that, before being genetic or bacterial in origin, periodontal disease is the result of incorrect use of the dento-maxillary apparatus.

What other signs are associated with bruxism?

• headaches from the temples to the back of the head
• back pain, especially between the shoulder blades

These usually appear after more tiring days. Sometimes the patient wakes up with them — or is woken up by them.

Why does bruxism appear?

I leave the list of triggers open and will mention the ones I have identified as most likely.

Grinding

The masticatory engram — the piece of cortex responsible for chewing — is the trigger.

• In children, as a compensatory mechanism: the natural abrasion is missing, because today's food is too soft.
• In adults, as a mechanism for increasing chewing efficiency by increasing the tooth-to-tooth contact surfaces, when the teeth are not well enough aligned or dental work is not fitted finely enough.

Between the teeth we can feel a "high spot" starting from one tenth of the thickness of a hair. When you receive a restoration (a filling, a crown and so on), the only "presence" should be felt at the tongue and/or cheek — and in no case at the level of the teeth. The finest analyst of the situation is the patient and, unfortunately, not the doctor — the doctor has no tools capable of detecting those dimensions.

Clenching

It is part of the primordial "Fight or Flight" mechanism, meant to increase the mechanical strength of the face in a fight with the bear — or with the neighbour. A serious blow across the face with the mouth open can end in a fractured mandible. Unfortunately, the part of the brain responsible for this mechanism does not know how to tell the difference between fighting the bear and a moved deadline — or a light jog taken by choice rather than necessity.

So stress and/or concentration and determination are the triggers for this type of bruxism.

With enough repetition of the triggers, bruxism can become a bad habit. That is: it appears without the trigger being present.

How can I treat bruxism?

Classically the solution is a night guard or, more recently, botox injected into the muscles. In my experience these have a limited success rate, most likely because they carry no guarantee that the behaviour changes — and muscles, if you use them, rebuild themselves.

I believe the real solution is changing the muscular behaviour. That takes time and exercise, but it carries the guarantee that, once learned, it shelters the dento-maxillary apparatus from exaggerated muscular stress.

If you find this approach interesting, you can find on X the exercise I recommend to my patients.