Mechanical Complications Related to the Retention Screws of Prefabricated Metal Abutments With Different Angulations: A Retrospective Study With 916 Implants

Prosthetic complications and failures of implant-supported fixed partial dentures: A scoping review

STATEMENT OF PROBLEM

Although high survival rates of implant-supported fixed partial dentures (ISFPDs) have been reported, evidence for complications, failures, and factors that interfere with their longevity is lacking.

PURPOSE

The purpose of this scoping review was to review the literature to investigate the most common failures and complications of ISFPDs.

MATERIAL AND METHODS

This review followed the preferred reporting items for systematic reviews and meta-analyses scoping review (PRISMA ScR) guidelines, and the methodology was registered on the open science framework (osf.io/5xqkp). An electronic search was conducted in PubMed/MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science databases and nonpeer-reviewed literature for articles published from 2013 to January 2023. Studies that evaluated the clinical performance of ISFPDs with at least 1 year of follow-up and described the concepts of failure and success were included.

RESULTS

The search yielded 5695 studies. Fourteen articles were included in this review for data extraction. Veneering porcelain fracture, screw fracture, and implant loss were the most common failures reported. Technical complications mainly involved screw loosening, loss of retention, and wear of the screw-access restoration.

CONCLUSIONS

Bruxism, mismatch of the thermal expansion coefficient, unsatisfactory support of the framework, choice of cement, shape of the titanium abutments, and extended length of the cantilever were associated with the longevity of the ISFPD. Despite the high survival rate of ISFPDs, data must be carefully interpreted because of the variation in the materials used to manufacture the ISFPD and the heterogeneity of the studies in this review.

Biological and mechanical complications of angulated abutments connected to fixed dental prostheses: A systematic review with meta-analysis

OBJECTIVES

To evaluate the biological and mechanical complications of angulated abutments on full-arch and partial jaw rehabilitations with a follow-up for at least 1 year.

METHODS

Electronic search was carried out in MEDLINE, EMBASE and Web of Science. Studies published between January 2000 and January 2019 were included. The quality of the included studies was assessed. The data extraction was focused on implant loss, marginal bone loss and mechanical complications, and meta-analyses were performed for marginal bone loss, mechanical complications and implant failure.

RESULTS

Nine studies, three prospective and six retrospective cohort studies were included. They reported on 797 patients that received 4127 implants. The total number of abutments was 4079 of which 1673 were angulated, and 2406 were straight. All abutments were prefabricated. Angulated abutments were associated with increased implant failure rates (two studies; RR = 7.30; 95% CI = 2.79-19.08) and an effect that was both statistically significant (P < .001) and clinically relevant. Three studies reported differentiated data for mechanical and technical complications at 1 year of follow-up, being mostly related to the retention screw while screw fracture. Angulated abutments were associated with a statistically significant increase in MBL 1 year after insertion compared to straight abutments (three studies; MD = 0.08 mm; 95% CI = 0.01-0.14 mm; P = .02), which might be, however, clinically negligible.

CONCLUSIONS

The prosthetic complications such as screw loosening and abutment loosening were frequent. After 1 year of follow-up, implants supporting angulated abutments yielded significantly more marginal bone loss than those supporting straight abutments.