Ceramic crowns and sleep bruxism: 3-year results of a randomized controlled trial

OBJECTIVE: To evaluate whether sleep bruxism (SB) influences the occurrence of technical complications and affects the survival and success of monolithic lithium disilicate (LiDi) or zirconia (Zir) molar crowns over 3 years. MATERIALS AND METHODS: In this prospective clinical study, 109 patients requiring a single molar crown were assessed for SB using a structured questionnaire, clinical examination, and a portable electromyography device (BruxOff). Based on SB status and randomized crown material allocation, patients were assigned to four groups: LiDi-SB (n = 27), LiDi-no SB (n = 21), Zir-SB (n = 21), and Zir-no SB (n = 24). Protective occlusal guards were not permitted. Follow-up examinations were performed at 1 week, 6 months, and 1, 2, and 3 years after cementation. Differences in technical complications, survival, and success rates were analyzed using Fisher's exact test (α = 0.05). RESULTS: No technical complications occurred in any group. Survival rates were 96.3% for LiDi-SB and 100% for LiDi-no SB (95% CI difference: -0.1828 to 0.1481; p > 0.999), and 95.2% for Zir-SB and 95.8% for Zir-no SB (95% CI difference: -0.2190 to 0.1940; p > 0.999). Success rates were 81.5% for LiDi-SB and 95.2% for LiDi-no SB (95% CI difference: -0.3590 to 0.1450; p = 0.211), and 85.7% for Zir-SB and 95.8% for Zir-no SB (95% CI difference: -0.3390 to 0.1530; p = 0.326). CONCLUSION: Within a 3‑year observation period, sleep bruxism showed no detectable impact on the incidence of technical complications or on the survival and success of monolithic LiDi or Zir molar crowns. This study was registered on ClinicalTrials.gov (NCT03039985).