[Influence of sleep bruxism on dislodgement of dental restorations]

This study investigated the correlation between strength of sleep bruxism and dislodgement of dental restorations, by both using the facet index of occlusal splint for sleep bruxism and measuring the dislodgement rate of dental restorations.

Subjects consisted of 422 patients with 3673 dental restorations (inlay, crown, jointed crowns, and bridge) referred to the hospital from 1976 to 2004 who were randomly selected from 912 patients. All patients wore an occlusal splint during sleep. Ink was placed on the occlusal part of the splint and the strength of sleep bruxism was evaluated by the wearing away of the ink and indentation on the splint (Ikeda's method). The subjects were classified into the following four groups according to the evaluation: B-0: no facet on the splint, B-1: slight facet with wearing of the ink but no indentation on the splint, B-2: slight indentation on the splint, and B-3: notable indentation on the splint, and then the dislodgement rate between the groups was compared. The mean evaluation time in each patient was 10.1 years.

The rate of patients with dislodgement was B-1: 12.7%, B-2: 35.1%, and B-3: 43.8%. The dislodgement rates of categorized restorations in groups B-1, B-2, and B-3 15 years after the placement were, restorations: 9%, 18%, and 24%, inlay: 19%, 24%, and 32%, and crown: 5%, 12%, and 13%, respectively.

It is proved that the evaluation method using the facet index of occlusal splint for sleep bruxism is a reliable means of estimating how long the restoration will last. The results showed that sleep bruxism influences the dislodgement of restorations. To protect restorations, it might be effective to control the load from sleep bruxism.