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.