Clinical and cone beam radiographic evaluation of different designs of hybrid implant abutment-crowns

Abstract Background Dental implant therapy is reliable for replacing missing teeth, but single-implant restorations face higher biomechanical challenges. This study explores how abutment design influences peri-implant tissue health and marginal bone levels, testing the null hypothesis that restoration design does not affect peri-implant hard and soft tissue responses over time. Patients and methods A total of 30 patients, aged 25–55 years and medically free, were selected based on strict inclusion and exclusion criteria. Each patient received an implant with zirconia restorations milled on titanium inserts. Participants were randomly assigned to two treatment groups: group 1: Hybrid abutment-crown (one-piece design) and group 2: Hybrid abutment with a separate crown (two-piece design). Probing depth (PD) was clinically assessed at baseline (48 h postprosthesis placement), 6, and 12 months. Radiographic assessments were conducted using cone beam computed tomography to evaluate vertical facial bone loss. Results Regarding marginal bone loss (MBL), significant differences were observed between the two groups ( P < 0.001). Regarding PD, the results showed a significant difference in PD across the follow-up periods ( P < 0.001) but no significant difference between the two designs ( P = 0.166). However, a significant interaction was found between design and follow-up periods ( P < 0.001). Conclusion The study demonstrated that restoration design significantly impacts MBL and PD over time. MBL was significantly higher in the one-piece design compared to the two-piece design, suggesting that the hybrid-abutment design of the two-piece system provides better force dissipation and stress distribution.