Mechanical failures of dental implants and supported prostheses: A systematic review

PURPOSE: Though, mechanical dental implant and supported prosthesis failures are considered significant, a comprehensive evaluation is lacking. A systematic review analyzing different aspects related to such failures was therefore done. METHODS: - Electronic search was carried out in PubMed/MEDLINE and Cochrane Library for articles published between 1981 and 2021. Articles were selected using predefined criteria. Data extraction was based on mechanical complications associated with dental implants, prosthetic implant failures, survival rate of implants, mechanical failure of implants placed in the maxilla and mandible, and mechanical complications associated with implant supported over dentures. Quality of included studies was assessed. Meta-analysis for heterogenicity testing, publication bias and implant failure assessment was conducted using MedCalc® Statistical Software version 19.7. RESULTS: - Eighteen retrospective and prospective studies were included following PRISMA guidelines. Mechanical complications were more in the initial 9 years but reduced later. Abutment screw loosening was one of the more common mechanical complications (16.21%). Maxillary implant failure was greater compared to mandibular implant failure with an odds ratio of 4.66 (95% CI -3.21- 6.75). Failure of implant supported overdentures due to mechanical complications were 3% in the fixed effect, and 2.9% in the random effect model (P < 0.05). The overall prevalence of mechanical failure was between 5.6% and 7.7% (P < 0.05) CONCLUSION: Mechanical failures of implant and supported prosthesis have similar prevalence to biological and esthetic failures, and therefore need to be given due credence. Identifying specific factors contributing to such failures can help reduce incidence.