Lithium disilicate, full coverage crowns: what is the effect of using conventional impressions compared to digital impression with respect to the internal fit of the restoration? A systematic review

Digital dentistry provides an alternative to fabrication of crowns. This systematic review focuses on the accuracy of the mean internal space of lithium disilicate crowns when comparing intraoral scanning to conventional impressions.

Ovid Medline, Cochrane and PUBMED were searched and the review protocol followed the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42023379908) and guided by The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Cohen Kappa coefficient confirmed the agreement of data. The revised Cochrane Risk of Bias tool was utilised to evaluate randomised controlled trials The Methodological Index for non-randomised controlled trials.

Of the six in vivo studies, three concluded that digital techniques improved the internal fit over their conventional counterparts. Two found that there was no significant difference and one indicated that digital technique resulted in an inferior internal fit. Of the eight in vitro studies, two concluded digital techniques to be superior, two found digital techniques to be inferior and four found no significant difference.

Significant heterogeneity between studies limits the potential any systematic review of the internal fit of dental crowns when comparing conventional and optical impressions. This systematic review indicates digital methodology is comparable to that of conventional impressions.