How do you answer your patient when they ask you why their TMJ clicks? The truth is that the answer is not very clear, and there hasn’t been any consistent research to tell us why.
Temporomandibular disorders (TMDs) can present with pain, limited jaw mobility or clicking sounds. The most common thought is that malocclusion is the chief cause of TMDs, aside from an obvious episode of trauma. In fact, for years many dentists attempted to treat TMDs with occlusal adjustment or “selective grinding.” However, research fails to support this treatment. At first glance, its makes sense why dentists think that malocclusion can cause TMJ clicking. A posterior crossbite can cause an asymmetric condyle-fossa relationship, which in turn can cause disc displacement. However, a systemic review on this causal link was inconclusive. Therefore, until now, etiologies of TMDs remain unclear.
The largest and longest study was done to determine the etiologies of TMDs. In a 30-year birth cohort study, 1037 children were followed up to age of 45, in New Zealand. Various patterns of occlusion, habits and personality traits were examined to uncover any association with TMJ clicking.
The study finds that:
- About 20% or 1/5 of people show TMJ clicking by the age of 45.
- Abnormal occlusal features, present early in life, such as posterior crossbite are not associated with TMJ clicking later in life.
- Orthodontics or occlusal adjustments do not have any effect on reducing the occurrence of TMJ clicking.
- Personality was shown to have a great influence on clicking.
- Clenching was shown to have a high correlation with TMJ clicking.
- Negative self-reported personality traits such as stress as brought upon by catastrophizing behavior, depression and anxiety show a high correlation with TMJ clicking and other muscle related TMDs.
Interestingly, it was shown that an overbite has a negative association with TMJ clicking by the age of 45. Overbite is a feature of patients with hypodivergent facial patterns, with larger TMJ condyles, as compared to hyperdiverdent counterparts. It is possible that large condyles are less susceptible to mechanical stress than small condyles.
Dr. Kasra Eghbaldar – Toronto, Ontario