Effects of working side interference on nocturnal bruxers

The present study aimed to test the effects of experimentally placed working side interference on nocturnal bruxers with regard to the health and chewing motor behaviors of the masticatory system. Thirteen asymptomatic nocturnal bruxers, nine males and four females, aged 18-31 years old, were selected according to the including criteria. A metal overlay was fabricated and bonded on the tips and lingual inclines of buccal cusps of the upper second premolar and first molar of the habitual chewing side. It discluded the eccentric contacts without disturbing the centric occlusion. A light emitting diode system was used to record the chewing motor behaviors before (W0), immediately after (W1), one day after (W2), one week after (W3), and one month after (W4) placement of the working side interference. The healthy states of masticatory muscles and TMJs were examined at each session. The results showed: 1. High overlay debonding rate (60%). Among five subjects who were observed over 25 days, 80% showed grinding facets, and 40% showed grade I mobility on the overlay opposing teeth. None of the subjects complained of muscle or joint pain in the one month follow-up period. 2. The chewing movements shifted toward the non-interfered side with narrowed and vertical chews after placement of overlays. Two major responded chewing patterns were found according to the results of statistical analysis. 3. Sixty-nine per cent of the subjects showed higher mean closing velocity than the mean opening velocity at the W0 session.(ABSTRACT TRUNCATED AT 250 WORDS)