Randomized Controlled Clinical Trial of All-Ceramic Single Tooth Implant Reconstructions Using Modified Zirconia Abutments: Radiographic and Prosthetic Results at 1 Year of Loading

Purpose: This study aims to test whether or not veneering of the submucosal part of zirconia abutments with pink dental ceramic affects radiographic and technical outcomes of implant-supported single crowns (ISSC). Materials and Methods: Single tooth implants were randomly restored with either pink-veneered zirconia abutments (test; n = 10) or non-veneered zirconia abutments (control group; n = 10) and all-ceramic crowns. At baseline (crown insertion), and 6-and 12-month radiographic and technical evaluations were performed including standardized x-rays and modified United States Public Health Service criteria (technical). Survival and complication rates were assessed for implants and restorations. Robust linear mixed model analysis was performed to investigate the effect of group and time-point on radiographic outcomes. Results: At 1 year, the survival rate for implants was 100% and 95% for ISSC. Most of the implants were placed subcrestally. Therefore, mean marginal bone levels decreased in both groups between implant insertion and baseline (p < .05), but then remained stable up to 1 year (test: 0.15 mm +/- 0.42 mm; control 0.23 mm +/- 0.63 mm) (p > .005). At 6 months, one minor chipping occurred in the test group. At 1 year, three crowns (control) exhibited occlusal roughness. In addition, one abutment fracture occurred (test). The differences between test and control group were not statistically significantly different for any of the evaluated outcome measures (p > .05). Conclusions: Veneering of the submucosal part of zirconia abutments did not affect biological and technical outcomes of ISSCs. Technical complications of the reconstructions, however, were frequent, resulting in a rate of 75% of the crowns being complication free.