Performance and Risk Assessment of One Step Implant Therapy with Severely Atrophic Posterior Maxillae: A Preliminary Report

Abstract

Background: The purpose of this retrospective study was to assess the efficacy of and risk factors associated with performing a one-step, non-submerged, open window surgical technique that allows simultaneous implant placement in sites with ≤ 5 mm of residual bone. Materials and methods: Clinical data were obtained from Periodontic Department at Buddist Tzu Chi General Hospital, Taipei. The dataset included all consecutively placed implants in the maxillary sinus using an open window technique. Remaining bone height at implant sites was classified into A (4 ~ 5 mm), and B (＜ 4 mm). In total, 34 patients and 41 sinuses received 70 two-piece implants to support both multiple and single tooth reconstruction. Healing abutments were simultaneously inserted at the time of fixture placement. The generalized estimating equation method for univariable and multivariable analysis was performed to assess possible risk factors associated with marginal bone loss and implant failure. Results: Among the patients, 77% (54) of the implant sites were class B and 23% were class A. No implant had marginal bone loss that was ＞ 2 mm. One implant was lost and was restored successfully. The overall implant survival and success rates over 5 years were 98.4% and 97.1% respectively. Univariable analysis indicated that implants with a wide diameter (p=0.045), implants where a perforation of the sinus membrane occurs (p=0.058), and implants in patients who smoked (p=0.015) seemed to be associated with early bone loss. Multivariable analyses showed that smoking (p=0.028) and 5 mm wide implants (p ＜ 0.05) were more likely to show early bone loss. Conclusions: The present clinical study shows that with careful case selection single-stage implant placement in maxillary sinus using an open window technique is predictable. Smoking, sinus perforation, and wide implants are more likely to show early bone loss. Further long-term evaluation with a larger sample is needed.