Digital Impression and Conventional Impressions in Fixed Partial Denture-A Systematic Review

Abstract

Clinicians use CAD-CAM systems to obtain a digital scan of the oral tissues followed by chairside fabrication, to transmit the digital scan to the laboratory for prosthesis fabrication , or to digitally scan a stone model fabricated from a conventional impression followed by laboratory fabrication . Potential advantages of using CAD-CAM technology over conventional methods include speed , ease of use , and the quality of restoration.The aim of this systematic review was to analyse critically marginal and internal fit of the crowns fabricated by conventional impression technique and CAD CAM systems.For identification of studies included or considered for this review , detailed search strategies were developed for the database searched . The search methodology applied was a combination of MESH terms and suitable key words . The MEDLINE search used the combination of  controlled vocabulary as well as free text terms . The key words employed in this search were broadly classified into four categories describing population , intervention , outcome and the type of study. Key words within each group were combined using Boolean operator OR and the searches of individual groups were combined using Boolean operator AND to retrieve articles electronically Out of the 18 studies obtained from electronic search 4 studies were excluded after examination of title and abstract and 8 were excluded after examination of core data and a total of 6 studies were reviewed .Research is lacking to draw robust conclusions about the relative benefits of Digital impressions in terms of restoration survival . The  marginal fit and internal fit analysis suggested similar performance in both techniques . The quality of evidence of interproximal contacts and occlusal contacts were very low to draw any conclusions regarding how the impression techniques compared .  With regard to the patient acceptance , the overall patients’ acceptance of digital impression techniques was significantly higher than that of conventional impression techniques.