Marginal Bone Loss Compared in Internal and External Implant Connections: Retrospective Clinical Study at 6-Years Follow-Up.

The aim of this study was to assess and compare the marginal bone loss between two different categories of implants (Winsix, Biosafin, Ancona, Italy) having the same diameter and belonging to the Torque Type® (TT®) line, in the internal hexagon version (TTi, Group A) and in the external hexagon configuration (TTx, Group B). Patients with one or more straight implants (insertion parallel to the occlusal plane) in the molar and premolar regions in association with tooth extraction at least 4 months prior to implant insertion, who have a fixture diameter of 3.8 mm, who followed up for at least 6 years, and whose radiographic records were available were enrolled in this study. Depending on implant connections (externally or internally), the sample was divided into groups A and B. For externally connected implants (66), the marginal resorption was 1.1 ± 0.17 mm. The subgroup of single and bridge implants showed no statistically significant differences with a marginal bone resorption of 1.07 ± 0.15 mm and 1.1 ± 0.17 mm, respectively. Internally connected implants (69) showed an overall marginal resorption of 0.91 ± 0.17 mm, while the subgroup of single and bridge implants showed resorption of 0.90 ± 0.19 mm and 0.90 ± 0.17 mm, respectively, with no statistically significant differences. According to the obtained results, internally connected implants showed less marginal bone resorption than externally connected implants.