Multicenter Prospective Clinical Study on Chairside-Fabricated Partial Crowns: 5-Year Results for Lithia-Zirconia Glass-Ceramic Restorations.

Objectives: Clinical evaluation of chairside-fabricated lithia-zirconia glass-ceramic (LZGC) partial crowns (CCPCs) in a multicenter practice-based study.

Materials and methods: Seventy-one patients were restored with 92 adhesively luted CCPCs (Cerec SW 4.2/Cerec MC XL/Celtra Duo) in three private dental clinics (C1-C3). Time-dependent (Kaplan-Meier) survival rates (SVR) and success rates (SCR) were calculated. The following possible covariates of SVRs and SCRs were evaluated in a Cox regression model: Restoration position (premolar/molar), luting material (Variolink/Calibra), and operator (C1-C3).

Results: Seventy-three CCPCs were placed in 59 patients and were included in the study (mean observational period: 58.0 ± 15 months). Four complete failures (two tooth fractures, one restoration fracture, and one endodontic failure) were recorded. All failures and interventions occurred in one of the three centers (5-year SCR: C1 + C2: 100%; C3: 71%; 95% confidence interval: [0.55; 0.87]). Additionally, three biological, and two technical complications required clinical intervention to maintain function, and all occurred in C3. Restorations placed in C1 and C2 showed a significantly reduced risk for failure/intervention (hazard ratio = 0.103, p = 0.026) compared with restorations placed in C3.

Conclusions: LZGC CCPCs showed good five-year clinical performance. However, SVRs and SCRs were significantly influenced by the operator. Additional clinical data are required for a more detailed investigation of this effect.