Can digital scans replace conventional impressions for complete denture fabrication? A scoping review

With the advent of digital technologies, a shift has taken place from conventional impressions (CIs) to digital scans (DSs). However, DSs of completely edentulous arches remain challenging.

The purpose of this scoping review was to explore the literature aiming to answer the question of whether DSs can entirely replace CIs for complete denture fabrication.

The review followed the recommendations of the preferred reporting items for systematic review and meta-analysis extension for scoping review statement (PRISMA-ScR). An electronic search was conducted in MEDLINE/PubMed, Scopus, Web of Science, and Cochrane library. The search strategy used a combination of terms for "completely edentulous arches" and "digital scans." Any study from 2010 to 2024 was considered and included if in English. Those on complete arch implant impressions were excluded. The null hypothesis was that DSs would be equivalent with CIs.

The initial search retrieved 1980 articles. After deleting duplicates and applying the inclusion criteria, 26 articles were included. Nine were clinical cross-over studies, 8 were studies that introduced methods to enhance the accuracy of DSs of edentulous arches, and 9 were in vitro studies that compared the accuracy of DSs made by different scanners. The methods introduced somewhat improved the stitching process. However, the difficulty in acquiring data of the functional morphology of mobile tissues remained a challenge, especially for mandibular arches. Intraoral scanner (IOS)-related factors (such as scanning technology, scanned area, scanned arch, and scan strategy) seemed to affect the accuracy of DSs.

The main challenges in recording edentulous arches digitally included the lack of anatomic indicators, difficulty in capturing vestibular tissues, and IOS-related factors. Currently, reliable evidence that DSs could entirely replace CIs in complete denture wearers is lacking.