Distal Cantilevers and Implant Dentistry

Purpose: The use of distal cantilevers in fixed implant-supported prostheses is often discussed in dental literature in relation to implant restorations. The aim of this study was to conduct a systematic review of the literature in an effort to identify factors related to the long-term success of distal cantilevers. In addition, a more traditional review was conducted to determine complications associated with this type of prosthetic design. Material and Methods: A systematic literature review was conducted of all published articles identified through a search of MEDLINE from January 1980 through June 2011 using the terms "crestal bone loss," "dental implants," "distal cantilevers," "marginal bone loss," and "periodontal disease." An initial review was conducted of titles and a second review was performed using full abstracts. Articles were thus identified to assess studies that met the inclusion criteria that described fixed complete dental prostheses utilizing distal cantilevers. In vivo studies were included for data extraction while in vitro and animal studies were used for descriptions of clinical or mechanical performance. Results: Following the method described, from an initial identification of 49 studies, a total of 14 human clinical studies were found that met the inclusion criteria and provided data associated with clinical performance. An additional 5 studies detailed in vitro research. It was noted that the majority of studies lacked specific data but, nonetheless, provided subjective and objective information regarding the use of cantilevers. The follow-up period of human studies ranged from 1 to 10 years. Weighted averages demonstrate a prosthetic survival rate of 95% during a follow-up period of 7.3 ± 2.6 years. The descriptive studies demonstrate that the most frequent complication was screw loosening, which was observed equally in virtually all studies, even if controlled torque was used to connect abutments and prostheses. Porcelain chipping and esthetic veneer fracture were described, although data associated with these occurrences were not available for systematic review. Conclusions: Based on 19 articles (including 14 human studies), it was difficult to derive data-based conclusions regarding the use of cantilever prostheses other than an approximate 95% prosthetic survival rate. Subjective and objective information from these studies demonstrated a distinct preference for the use of distal cantilever prostheses, as few risks are associated with these prostheses. Careful evaluation of the studies shows that cantilevers provide a treatment option without a high risk of complications. Keywords: complications, crestal bone loss, distal extension, implant-retained prostheses