Influence of Implant Length on the Accuracy of Implant Placement in Sleeveless Guided Surgery: A Clinical Digital Superimposition Study

Background and aim Computer-guided implant surgery has improved implant placement accuracy by enabling precise transfer of the virtual plan to the surgical site. However, several factors may influence this accuracy, including surgical workflow, guide design, and implant-related variables. Among these, the effect of implant length remains insufficiently investigated. Therefore, this study aimed to evaluate the influence of implant length on the accuracy of implant placement using a sleeveless guided surgery protocol. Materials and methods Fifteen patients receiving implant-supported rehabilitation were included, with a total of 49 implants placed using a sleeveless guided surgery workflow (R2Gate SA, Megagen, Daegu, South Korea). Preoperative planning combined cone-beam CT and intraoral scan data. Placement accuracy was evaluated by digital superimposition of the planned and postoperative implant positions using scan body registration. Angular (°), coronal (mm), and apical (mm) deviations were measured. Implant length was analyzed as a continuous predictor using linear mixed-effects models, with patient as a random intercept. Results Increasing implant length was significantly associated with reduced angular deviation (β = -0.552° per 1 mm; 95% CI: -0.941 to -0.163; p = 0.0066) and reduced apical deviation (β = -0.108 mm per 1 mm; 95% CI: -0.205 to -0.011; p = 0.0305). In contrast, the association between implant length and coronal deviation did not reach statistical significance (β = -0.055 mm per 1 mm; 95% CI: -0.116 to 0.005; p = 0.0732). Conclusions Within the limitations of this study, implant length appeared to influence the accuracy of implant placement using sleeveless guided surgery. Longer implants were associated with reduced angular and apical deviations, suggesting improved placement accuracy. Further studies with larger samples are needed to confirm these findings and to better understand the role of implant-related factors in guided implant surgery accuracy.