The Impact of Cantilever Direction on the Clinical Outcome of Implant-Supported Fixed Dental Prostheses

Abstract

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).