Occlusal features are not a reliable predictor of bruxism

The aim of this investigation was to estimate the contribution of occlusion to differentiate bruxers from non-bruxers.

Participants in the study were 160 patients consecutively selected among 20-30 year old patients attending the Section of Prosthetic Dentistry for conservative care. The presence of bruxism was clinically and anamnestically investigated. In each patient the following occlusal features were recorded: retruded contact position-intercuspal position slide length, vertical overlap, horizontal overlap, unilateral posterior crossbite, incisor dental midline discrepancy, mediotrusive interferences, laterotrusive interferences. A stepwise logistic regression model was used to identify the significant associations between occlusal features and bruxism.

Diagnosis of bruxism was made in 67/160 subjects (41.8%). Differences between sex were not significant (p=0.814). Among the 8 occlusal variables included in the logistic regression analysis, those remaining in the final model were laterotrusive interferences (OR 2.47) and anterior open-bite (OR 0.88). This model showed good specificity (87%) but an unacceptable sensitivity (26.9%) to predict bruxism (accuracy=61.6%). Therefore, multivariate analysis did not lead to an improvement in bruxism predictability with respect to univariate analysis, which revealed that the presence of bruxism was significantly associated with laterotrusive interferences alone (p=0.040), and not with unilateral cross-bite (p=0.208), anterior open-bite (p=0.202), deep-bite (p=0.572), large horizontal overlap (p=0.261), dental midline discrepancy (p=0.519), mediotrusive interferences (p=0.119), slide >or=2 mm (p=0.857).

According to our findings the contribution of occlusion to differentiate bruxers from non-bruxers is very poor. Infact, only laterotrusive interferences seem to be significantly associated with bruxism.