Optical Impression Accuracy of Preparations for Fixed Prosthodontics: A Systematic Review

Introduction: This systematic review aimed to evaluate the accuracy of different optical impressions of tooth preparations. Methods: An electronic search in PubMed, Web of Science, Scopus, Medline Complete, and ScienceDirect was performed to identify articles comparing the accuracy of different optical impressions (OI) published up to the 1st of March 2022. The inclusion criteria enclosed the accuracy of optical impressions acquired for tooth-supported fixed prosthodontics. Exclusion criteria were defined as studies focused on orthodontic impressions and implant-supported restorations. This review was registered to Prospero; CRD42021287758. Results: Eleven included studies had in vitro design and a low risk of bias. Considering scanned objects, 5 studies evaluated the accuracy based on a single preparation, 2 studies evaluated the accuracy of OIs based on fixed partial denture (FPD) restoration, 3 studies included both single preparation and preparations to receive FPD restorations, and 1 article included a full arch scan. Mean values of the trueness and precision of OI systems varied according to methodological differences. Conclusions: Optical impression has certain advantages. However, stating a particular optical impression system as the most accurate or superior to conventional impression is not feasible because of the heterogeneity of the accuracy results presented in this systematic review.