Influence of tooth preparation design on margin discrepancy and internal gap in digitally fabricated fixed complete coverage zirconia prostheses: A systematic review of in vitro studies

Statement of problem

A systematic review of the effect of tooth preparation design on margin discrepancy and internal gap in digitally fabricated fixed complete coverage zirconia prostheses is lacking.

Purpose

The purpose of this systematic review was to evaluate the effect of tooth preparation design on margin discrepancy and internal gap in digitally fabricated fixed complete coverage zirconia prostheses.

Material and methods

Electronic databases (Ovid, Medline/Embase, PubMed, Scopus, Web of Science, and Google Scholar) and manual searches were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to identify relevant studies evaluating the effect of different tooth preparation designs (finish lines, taper, and occlusal reduction) on the marginal discrepancy and internal adaptation of fixed complete coverage zirconia prosthesis fabricated by using a completely digital workflow.

Results

The electronic search identified 130 articles, of which 27 in vitro studies were included for both qualitative and quantitative analyses. Of these, 17 studies examined the finish lines, 1 on occlusal reduction, 9 on taper, 1 on both occlusal reduction and finish line, and only 2 investigated fixed partial dentures, while the majority focused exclusively on single crowns.

Conclusions

The selected articles generally reported clinically acceptable marginal fit and internal adaptation, whereas the results of marginal fit favored the rounded shoulder finish line and internal adaptation favored the chamfer finish line. A planar occlusal reduction with a chamfer finishing line provided better marginal fit. Taper had positive effects on marginal fit and internal adaptation.