Comparative Analysis of Osseointegration Outcomes of Titanium and Zirconia Implants: A Retrospective Observational Cohort Study

Introduction: Successful implant therapy depends on achieving stable and long-lasting osseointegration in the peri-implant environment. Zirconia implants have emerged as potential alternatives to titanium implants because of their favorable esthetic properties and biocompatibility. This study aimed to compare the osseointegration outcomes of titanium and zirconia posterior single-tooth implants using clinical and radiographic parameters over a 12-month follow-up period. Materials and methods: This retrospective observational cohort study included 50 posterior single-tooth implant sites retrieved from the institutional records between January 2018 and December 2024. Patients were allocated into the titanium implant (Group T, n = 25) and zirconia implant (Group Z, n = 25) groups. Clinical and radiographic parameters, including marginal bone loss (MBL), peri-implant probing depth, modified plaque index, bleeding on probing, bone density, and radiographic bone-to-implant contact, were assessed 12 months after loading. MBL was measured using calibrated digital radiographs analyzed with ImageJ software (National Institutes of Health, Bethesda, MD, USA). Statistical analysis was performed with significance set at p < 0.05. Results: Baseline demographic and implant-related variables were comparable between the groups, except for the submerged healing protocol, which was significantly more common in the titanium group than in the zirconia group (P = 0.023). The median MBL was 0.58 mm in the titanium group and 0.74 mm in the zirconia group, without a statistically significant difference (p = 0.118). Bleeding on probing was observed in four (16.0%) titanium implants and seven (28.0%) zirconia implants (p = 0.308). No statistically significant differences were observed in peri-implant probing depth, plaque index, radiographic bone density, or bone-to-implant contact (all p > 0.05). Multivariable regression analysis identified the baseline peri-implant bone density as a significant predictor of MBL (p = 0.029). Inter- and intra-examiner reliabilities demonstrated excellent agreement, with intraclass correlation coefficient (ICC) values exceeding 0.90. Conclusion: Both titanium and zirconia implants demonstrated favorable osseointegration and comparable peri-implant clinical outcomes after 12 months of functional loading. Zirconia implants may represent a clinically acceptable alternative to titanium implants in selected patients requiring metal-free rehabilitation with improved esthetic outcomes.