INFLUENCE OF DIFFERENT IMPLANT ABUTMENT CONNECTION DESIGNS ON ABUTMENT SCREW LOOSENING IN DENTAL IMPLANT SYSTEMS – A SYSTEMATIC REVIEW.

Abstract

Background: Dental implants have provided an alternative method of prosthetic rehabilitation with high long-term success rates. However, mechanical or biological complications may occur with implants amongst which loosening of the screw is very common. Loosening of the screw might cause misfit of implant‒abutment interface and may occur due to preload loss subsequent to inadequate  initial torque, distortion of the screw, wear of the screw, overloading, and micro-movements because of functional loading. The implant-abutment connection design like internal hex, external hex and morse taper may affect the screw stability. The effect of various implant-abutment connections on the stability of abutment screw has been discussed in this systematic review. Aim: The aim of this review is to assess and compare effect of different abutment connections on loosening of the screw. Data Sources: An online search was made for the articles using Google Scholar and PubMed. Study Eligibility Criteria: Articles published in English language or those articles that have a detailed summary in English language were included. Articles published between 1st January 2000 and 30th September 2018 were selected. Scientific research papers, Randomized controlled trials were included with data on the effect of various implant abutment connections on the loosening of the screw. Results: Out of 449 articles that were identified through electronic database searching. 19 articles were selected. These articles were screened for duplicates and 7 articles were obtained after eliminating the duplicates. None were excluded after screening of the duplicate articles. This review provides an understanding of effect of various abutment connections on loosening of the screw. Limitations: Few articles do not give concrete conclusions due to smaller sample sizes, differences inter-study sample population, variety of groups compared. Conclusions: Out of all studies that were evaluated few stated that internal hex connection design had least screw loosening compared to external hex and morse taper while the other studies were inconclusive. Keywords: Dental Implant, Implant-Abutment Connection, Screw Loosening