Full-Zirconia Single Molar Implant-Supported Restorations With Angulated Screw Channel Abutments: 5-Year Results of a Prospective Case Series Study

Introduction: Full-zirconia (ZrO₂) restorations were introduced to address the most common complications in implant-supported restorations in the posterior region: fractures of the veneering. The aim of this prospective case series study was to evaluate full-ZrO₂ implant-supported restorations with angulated screw channel abutments (ASCs) in the molar region of the maxilla and mandible and their effect on hard and soft peri-implant tissues, and patient-related outcome measures (PROMs), during a 5-year follow-up period. 

Material and Methods: Patients with a single missing molar in the maxilla or mandible with sufficient bone volume and an implant site free of infection were included. Thirty consecutive patients received a parallel-walled implant with conical connection. After 3 months, a full contour screw-retained ZrO₂ restoration with an ASC was fabricated and connected to the implant. Clinical and radiographic examinations were performed 1 month, 12 months, and 5 years after placement of the restoration. Implant success probability was calculated using Kaplan–Meier statistics, and confidence intervals were given over the results at 5 years. Patient-reported outcome measures (PROMs) were scored prior to treatment and at follow-up intervals. The primary outcome measure was the success of the restoration. 

Results: All patients could be evaluated after 5 years. Success probability at 5 years was 73.0% (95% CI [57.0%; 89.0%]). Implant survival was 100% and restoration survival was 97%. The encountered technical complications were easily repairable (n = 12). From loading to the 5-years follow-up, the mean marginal bone loss was 0.30 mm (SD 0.52 mm). Mean scores for plaque, calculus, peri-implant mucosa, bleeding, and pocket probing depth were low, depicting healthy peri-implant conditions. PROMs had significantly improved, and the mean overall score was 9.1 ± 0.7 (scale 1–10). 

Conclusion: Full-ZrO₂ implant-supported restorations with ASC abutments employed in this study, when applied in maxillary and mandibular posterior regions, show a 97% survival rate. However, a high incidence rate of technical complications (n = 12) was noted during the 5-year observation period.