Placement of a distal implant to convert a mandibular removable Kennedy class I to an implant-supported partial removable Class III dental prosthesis: A systematic review

Statement of problem. A number of authors have reported the placement of a distal implant associated with a partial removable dental prosthesis (PRDP) to make this rehabilitation more stable. This strategy may represent an option for resolving the problem of the intrusive movements of the PRDP and for reducing treatment costs. Purpose. The purpose of this systematic review was to evaluate the current evidence about the placement of a distal implant associated with a mandibular PRDP to improve patient satisfaction and the clinical performance of the abutment tooth and distal implant. Material and methods. Two independent prosthetic specialist reviewers conducted this systematic review. The search was performed using selected clinical studies with PRDP associated with distal implants published in English up to May 2014 from the PubMed and Cochrane Library databases. A data extraction form was developed to collect general information: authors, title, year of publication, aim of study, level of evidence, number of participants, number of implants used, implant system, implant length and diameter, abutment type, masticatory performance, patient satisfaction, implant mean bone loss, abutment tooth mean bone loss, prosthetic complications, follow-up period, and implant survival rate. The quality of the selected studies and the risk of bias were also reported. Results. The initial electronic search identified 231 studies, and the manual process identified 15 studies (total of 246 studies). After the title and abstract reading and the removal of duplicates, the full texts of 43 studies were obtained. The articles that did not meet the inclusion criteria were excluded (28 studies), and the data from 15 studies were extracted. Seven were retrospective studies, 1 a crossover pilot study, 2 case series, 2 paired clinical studies, and 3 case reports, demonstrating that a high number of the selected studies were of low methodological quality. Nevertheless, the high survival rates for PRDP associated with dental implants have been described. Conclusions. The use of a PRDP associated with dental implants to convert a Kennedy class I to class III dental prosthesis benefits patients by improving their satisfaction and masticatory abilities without decreasing implant survival rates. Considering the abutment tooth survival rate, clinical studies with comparable methodology are still lacking to define protocols regarding the use of distal implants associated with PRDP. Long-term, prospective clinical trials are still needed to understand which implant abutments increase abutment tooth survival rate.