Comparison Between Altered Cast Impression and Conventional Single-Impression Techniques for Distal Extension Removable Dental Prostheses: A Systematic Review

Abstract

PURPOSE: To systematically review the available literature and determine the potential benefits of altered cast impression technique over conventional single-impression techniques for the fabrication of distal extension removable dental prostheses. MATERIALS AND METHODS: The indexed English literature published up to April 30, 2018, was systematically searched for studies comparing altered cast impression technique to conventional single-impression techniques for the fabrication of distal extension removable dental prostheses using guidelines recommended by Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA). The databases searched were PubMed, the Cochrane Library, and MEDLINE (OVID). Two reviewers independently screened and shortlisted the relevant studies based on predefined inclusion and exclusion criteria. RESULTS: Seven studies were included in this review; all were in vivo studies. All seven studies reported that cast removable partial dentures fabricated with altered cast impression technique displayed less vertical movement of denture bases compared to those fabricated using conventional impression techniques. Two of these studies reported that this difference in vertical movement was clinically insignificant, while the other five studies reported a statistically significant difference in vertical movement but were uncertain regarding clinical significance. CONCLUSION: The results of this literature review indicate that the altered cast impression technique did not offer significant advantages over conventional single-impression techniques. The lack of convincing data to predict superiority of the altered cast impression technique for distal extension removable dental prosthesis impressions emphasizes the need for more scientific research with larger sample sizes and longer performance reviews of removable dental prostheses.