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Clinical performance of monolithic and veneered zirconia three-unit posterior FDPs: A five-year multicenter randomized controlled trial.

AIM: This randomized controlled clinical study compared monolithic, partially veneered, and fully veneered zirconia FDPs over a 5-year period with respect to survival, technical and biological complications, and patient-reported outcome measures (PROMs). MATERIALS AND METHODS: Sixty-four patients requiring three-unit posterior FDPs were randomly allocated to monolithic (MONO-FDP), partially veneered (PV-FDP), or fully veneered (FV-FDP) groups. All FDPs were fabricated from 4 mol% Y₂O₃ partially stabilized zirconia (4Y-TZP). Follow-up examinations were conducted at baseline, 1, 3, and 5 years. Technical parameters were evaluated using modified USPHS criteria. Periodontal measurements (PPD, BOP, PI) and patient satisfaction were assessed at all time points. RESULTS: A total of 63 FDPs were evaluated at baseline, 57 at 3 years, and 54 at 5 years. Survival at 5 years was 94.7% for MONO-FDPs, 100% for FV-FDPs and 100% for PV-FDPs. Technical complications occurred exclusively in PV-FDP (33%) and FV-FDP (38%) groups and consisted of minor, polishable chipping; no chipping or fractures were recorded in MONO-FDPs (0%) with statistically significant difference between MONO-FDP and the other two groups (p ≤ 0.014). Biological parameters remained stable across all groups, with no significant differences in PPD, BOP, or PI. PV-FDPs and FV-FDPs tended to receive more favorable professional color ratings, whereas PROMs were similar among the groups. CONCLUSIONS: All three FDP designs-monolithic, partially veneered, and fully veneered-fabricated from 4Y-TZP zirconia demonstrated excellent 5-year clinical performance. Technical complications were limited to PV- and FV-FDPs and consisted of minor chipping. Biological outcomes and patient satisfaction were similar across groups. CLINICAL SIGNIFICANCE: The five-year outcomes suggest that veneered, partially veneered, and monolithic FDPs can be used with high clinical reliability; however, restorations incorporating veneering ceramic may present an elevated risk of ceramic chipping.

Humans

Marginal fit and five-year outcomes of posterior monolithic zirconia restorations: A randomized paired and observational clinical study.

OBJECTIVES: The aim of this study was to evaluate the marginal fit and five-year clinical performance of posterior 5 mol% yttria-partially stabilized zirconia restorations. A randomized paired comparison with lithium disilicate crowns was performed for marginal fit. METHODS: A total of 65 posterior restorations were placed in 38 patients, including 32 zirconia crowns, 17 lithium disilicate crowns, and 16 zirconia partial coverage restorations. In the randomized paired comparison, 17 patients received one lithium disilicate crown and one zirconia crown. Additional zirconia crowns (n=15) and zirconia partial coverage restorations (n=16) were included in a prospective observational cohort. The primary outcome was marginal fit within the randomized cohort. Marginal and internal fit were assessed using the replica technique. Marginal and internal gap values were compared using the Wilcoxon signed-rank test; clinical outcomes were analyzed descriptively, and Kaplan-Meier estimates were calculated for survival and complication-free survival. Clinical performance was assessed using CDA criteria, periodontal parameters, complication recording, and patient-reported outcomes. Clinical examinations were performed at baseline and at 12, 24, 36, 48, and 60 months. RESULTS: Mean marginal gap values at the crown margin were 46 ±33 µm for lithium disilicate crowns and 50 ±32 µm for zirconia crowns (p>0.05). No restoration required replacement, resulting in 100% restoration survival after a median follow-up of 60 months (range: 57-64 months). Most complications were biological or functional, including endodontic, periodontal, occlusal, and proximal-contact-related events. One zirconia partial coverage restoration exhibited a small ceramic fracture managed by polishing. The Kaplan-Meier probability of complication-free survival was 76.4% for zirconia crowns, 66.7% for lithium disilicate crowns, and 87.5% for zirconia partial coverage restorations. CONCLUSIONS: In the randomized paired comparison, 5 mol% yttria-partially stabilized zirconia crowns showed marginal gap values similar to lithium disilicate crowns. All restorations remained in situ during the observation period. Lower complication-free survival was mainly related to biological and functional events and should be interpreted separately from restoration survival. CLINICAL SIGNIFICANCE: Clinical evidence for posterior 5 mol% yttria-partially stabilized zirconia restorations remains limited. This study provides mid-term clinical data on crowns and partial coverage restorations. In the randomized full-crown comparison, marginal fit was similar to that of lithium disilicate crowns, supporting the clinical consideration of monolithic zirconia restorations for posterior teeth.

Humans