The Influence of Implant Design on Bone Remodeling around Surface-Modified Southern Implants®

Background: Implant survival and success have shown to be related to a number of factors. Aim: To evaluate the impact of implant design on implant survival and success, focusing on thread pitch and implant shape. Materials and Methods: Non-smoking patients treated by two experienced periodontists with standard diameter externally-hexed Southern® implant(s) inserted in healed bone were retrospectively selected. A one-stage surgical approach was used in all cases and implants had been installed for at least 6 months. Information pertaining to patient-related variables, time of loading, implant design and radiographical outcome was retrieved from patients' records. Implant success was defined according to the criteria by Albrektsson and Isidor, taking into consideration bone level, defined as the distance from the implant-abutment interface to the first bone-to-implant contact. Results: In total, 59 patients treated with one hundred eleven externally-hexed Southern Implants® met the inclusion criteria. Fifty-six straight implants with a thread pitch of 0.6mm and 55 tapered implants with a thread pitch of 1.0mm were placed. The total implant survival rate was 98.2% after a mean follow-up period of 14 months (range 6-28). The mean bone level was 1.35mm (SD 0.46, range 0.59-3.70) and the overall implant success rate was 75.7%. Age, gender, length, and time of loading were not decisive for implant neither failure nor bone loss in contradiction to implant design and thread pitch (p<.01). Tapered implants with a 1.0mm thread pitch were less successful than parallel-walled implants with a 0.6mm thread pitch. Conclusion: The Southern Implants® system shows good short-term survival rates and bone preservation. However, bone remodeling seems affected by the implant design. Whether this is due to the tapered shape of the implant or the thread pitch is unclear and needs to be elucidated in future research. © 2010 Wiley Periodicals, Inc.