The Impact of Cantilever Direction on the Clinical Outcome of Implant-Supported Fixed Dental Prostheses
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It has been shown that dental implants tend to lose bone over time, which ultimately results in soft tissue loss. Recent studies, however, suggest that the design of implant-supported prostheses may contribute to peri-implant tissue stability. Aim: To evaluate retrospectively radiographic bone loss around implants supporting cantilevered pontics with either mesial or distal direction, and to identify the technical complications that may occur with mesial/distal cantilever fixed dental prosthesis. Material and Methods: Records of 14 partially dentate patients, aged between 45-83 years (mean age 69.4), who were treated from March 2003 to March 2015, with mesial/distal cantilever implant-supported fixed dental prostheses were reviewed. For each implant, the radiographs from the time of implant loading were compared to radiographs from the last follow-up visit. There were evaluated regarding: 1- The distance from widest diameter of the abutment to the crest of the peri-implant bone. 2- The radiographic changes of marginal hard tissue height from the time of implant loading compared to the time of the last follow-up appointment. Technical complications were noted as (screw-loosening, prosthesis de-cementation and prosthesis loosening). Results: A total of 28 cantilever implant-supported fixed dental prostheses supporting 32 cantilever units were evaluated. Of these 10 (35.7%) had mesial cantilevers, while 18 (64.7%) had a distal cantilever. There was no significant difference in the distribution of the cases between males and females (7 males and 7 females). The non-smokers were 43%. And the non-recorded were 29%. All technical complications associated with implants adjacent to distal cantilever pontics (prosthesis loosening P= 0.114, prosthesis de-cementation P= 0.114 and implant abutment screw-loosening: P= 0.37). Furthermore, all technical complications occurred with cantilever arm length < 10 mm. Mesial and distal bone loss on implants adjacent to the cantilevered units was not state different if cantilever direction was mesial or distal (mesial cantilever P= 0.533, distal cantilever: P= 0.82) Conclusion: Within the limitation of this study, marginal bone loss does not seem to be influenced by the presence of mesial or distal cantilever extensions. Minor technical complications were found with a distal cantilever (prosthesis loosening, prosthesis de-cementation and implant abutment screw-loosening).