Background:
In dental practice, the diagnosis of bruxism is mainly based on clinical examination. This may results in a false positive or false negative bruxism diagnoses in comparison with the presence of bruxism by instrumental methods.

Aim:
Evaluating the effectiveness of clinical examination in the diagnosis of bruxism.

Material and methods:
The study material consisted of 13 patients examinated with polysomnography . On the basis of clinical and instrumental tests, the diagnosis of bruxism was made, depending on the diagnostic method used. On the basis of the PSG examination, definite bruxism was determined. The results of instrumental studies were compared with the results of clinical ones.

Results:
Definite bruxism was found in 70% of all patients (N = 13). The sensitivity and specificity of the bruxism diagnostic criteria included in the clinical examination were respectively 33.3% and 100% for the information on grinding and stiffness of the jaws after awakening and 44.4%, 100% for the muscle pain on palpation. Tooth abrasion and the white line were characterized by a sensitivity of 100% and a specificity of 25% and 50%, respectively

Conclusions:
In the presented study single symptoms are tests of much higher sensitivity and specificity then tests in form of a set of symptoms indicating possible or probable bruxism. Teeth abrasion or a white line on the cheek are symptoms confirming the presence of bruxism. A negative result of teeth grinding or stiffness of the jaws enquiry and the absence of muscle pain in palpation confirm the absence of bruxism.