Longitudinal Clinical Outcomes of Tissue-Level Dental Implants in a Periodontal Practice: A Retrospective Study

Objectives: This study aimed to evaluate the 28-year cumulative success and survival rates of tissue-level implants placed by a periodontist in Taiwan. Materials and Methods: In this retrospective cohort study, 685 tissue-level implants placed in 199 patients between 1996 and 2024 were analyzed. A success was defined as the absence of probing depth (PD) ≥ 5 mm nor implant loss—while survival referred to the presence and clinical function of the implant. Kaplan–Meier analysis was used to estimate cumulative rates at both implant and patient levels. Potential risk factors, including patient demographics, smoking status, implant characteristics, periodontal status, and frequency of maintenance visits, were examined using Cox proportional hazards regression models. Results: At 28 years, the cumulative success rates were 71.00% at the implant level and 38.02% at the patient level, while the survival rates were 92.58% and 81.38%, respectively. Multivariable regression analysis identified male and severe periodontitis as significant predictors of peri-implant disease or implant loss. In contrast, more frequent maintenance visits were protective. Treatment outcomes for peri-implantitis were variable and difficult to predict. Conclusions: Tissue-level implants demonstrated favorable long-term clinical performance in a Taiwanese population, with success and survival rates comparable to those reported in Western cohorts. These findings underscore the importance of periodontal health and regular maintenance care in sustaining implant longevity.