Marginal adaptation of tooth-supported fixed restorations fabricated using digital scanning versus conventional impression techniques: An overview of systematic reviews

Statement of problem

Marginal adaptation is critical for oral health and the longevity of fixed prostheses. Conventional impression techniques frequently face challenges in accurate margin reproduction and soft tissue management. Although digital scanning offers enhanced speed, ease, and precision, whether these advantages translate into better marginal adaptation remains unproven.

Purpose

The purpose of this study was to analyze systematic reviews comparing the marginal adaptation of tooth-supported fixed restorations fabricated using digital scanning versus conventional impression making.

Material and methods

A comprehensive literature search, without language restrictions, was conducted in the PubMed, Scopus, Web of Science, EMBASE, and Google Scholar databases. The review included systematic reviews, with or without meta-analyses, evaluating primary studies on digital scanning and conventional impression making for marginal adaptation of fixed prostheses in in vivo and in vitro settings.

Results

Of the 18 selected articles, 11 included meta-analyses. Four of 10 articles in vivo and 4 of 7 articles in vitro reported better marginal adaptation with digital scanning. For zirconia, digital techniques outperformed conventional methods in 4 of 5 in vivo studies (SMDs from -0.89 to 27.2) and in all in vitro studies. For lithium disilicate and cobalt chromium restorations, no significant differences emerged. Regarding prosthesis types, 4 of 6 in vivo studies and 3 of 5 in vitro studies favored digital scanning for single-unit crowns. For partial fixed prostheses, 2 of 3 studies in both in vivo and in vitro settings supported digital superiority. No study reported that the conventional technique was better. However, most articles were rated "critically low" or "low" in quality by Assessing the Methodological Quality of Systematic Reviews (AMSTAR) 2, highlighting methodological limitations.

Conclusions

Digital scanning delivered equivalent or better marginal adaptation than conventional impression making, excelling with zirconia and for single or partial fixed prostheses. No evidence favored conventional methods, positioning digital scanning as a practical choice despite challenges like cost and saliva interference. Future studies should address methodological flaws to bolster evidence.