Clinical and Radiographic Outcomes of Sloped-Shoulder Implants in the Posterior Mandible: A Retrospective Study

Background/Objectives: This retrospective study aimed to evaluate the survival and marginal bone loss (MBL) of sloped-shoulder implants placed in the posterior mandible, and to explore the influence of both patient- and implant-related factors. Materials and Methods: All patients treated with sloped-shoulder-profile implants (Astra Tech Implant System, Dentsply Sirona, Bensheim, Germany) in the posterior mandible between 2012 and 2023 at two private clinics were included. Implant survival was analyzed with Kaplan-Meier estimates. MBL was measured from prosthesis delivery (baseline radiograph) to the most recent available radiograph. Outcomes were compared across thresholds of 0, 0.5, and 1.5 mm, which were considered radiographic success criteria. According to the 2017 World Workshop, peri-implantitis was not diagnosed solely based on MBL. Associations with potential risk factors (periodontitis, bruxism, and smoking) were explored. The study was approved by a local ethics committee (PI 106/2023); informed consent was waived due to the retrospective design and anonymization of data. Results: A total of 43 patients with 48 implants were included, with a mean follow-up of 40.1 months. The cumulative survival rate was 93.7%, with all failures occurring before 24 months. Mean MBL at the mesial and distal aspects was 0.27 mm and 0.39 mm, respectively. In 82.2% of implants, MBL remained ≤0.5 mm at a mean follow-up of 44.2 months. No statistically significant associations were found between risk factors such as periodontitis, bruxism, or smoking and implant outcomes. Conclusions: Sloped-shoulder implants in the posterior mandible showed high survival and stable marginal bone levels over the medium term. Their design may simplify treatment in oblique ridges, potentially reducing the need for GBR procedures.