Conical Versus Internal Hex Implant–Abutment Connections: A Randomized Controlled CBCT (Cone Beam Computed Tomography) -Based Evaluation of Peri-Implant Crestal Bone Loss

Background Preservation of peri-implant crestal bone is a critical determinant of long-term implant success. The implant–abutment connection plays an important role in maintaining peri-implant tissue stability by influencing force distribution, micromovement, and microleakage at the implant interface. Conical connections have been proposed to provide superior mechanical stability and enhanced crestal bone preservation compared with internal hex connections.

Aim To evaluate and compare peri-implant crestal bone loss around implants with conical and internal hex implant–abutment connections using cone-beam computed tomography (CBCT).

Materials and Methods This prospective randomized controlled clinical trial included 20 systemically healthy patients requiring replacement of a single missing posterior tooth. Participants were randomly allocated into two groups (n=10 each). Group A received implants with a conical connection (S-Fix®), while Group B received implants with an internal hex connection (i-Fix®). Clinical and radiographic evaluations were performed at baseline and after 9 months. Crestal bone loss was assessed using CBCT, with the implant–abutment junction serving as the reference point. Data were analyzed using paired and unpaired t-tests, with statistical significance set at p ≤ 0.05.

Results All implants demonstrated successful osseointegration, resulting in a survival rate of 100% at 9 months. Mean crestal bone loss in the conical connection group was 0.86 ± 0.09 mm, whereas the internal hex connection group exhibited a mean crestal bone loss of 0.93 ± 0.08 mm. Although the conical connection group showed lower crestal bone loss, intergroup comparison revealed no statistically significant difference (p = 0.071).

Conclusion Within the limitations of the present study, both conical and internal hex implant–abutment connections demonstrated favorable clinical and radiographic outcomes. Implants with conical connections exhibited a trend toward reduced crestal bone loss; however, the difference was not statistically significant. Further long-term studies with larger sample sizes are required to validate these findings.