Marginal and internal adaptation of single crowns and fixed dental prostheses by using digital and conventional workflows: A systematic review and meta-analysis

Statement of problem: Digital and conventional options for definitive impressions and for the fabrication of fixed dental prostheses (FDPs) have been compared in previous studies. However, a comprehensive review with concluding data that determined which method provided the minimal internal and marginal adaptation is lacking.

Purpose: The purpose of this systematic review and meta-analysis of in vivo and in vitro studies was to compare the marginal and internal adaptation of complete-coverage single-unit crowns and multiunit FDPs resulting from digital and conventional impression and fabrication methods.

Material and methods: The review protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Cochrane Trials, Scopus, and Open Grey databases were used to identify relevant articles. Based on fixed prostheses impression and fabrication methods, groups from each study were categorized into 4 groups: conventional impression and fabrication (CC), conventional impression and digital fabrication (CD), digital scanning and conventional fabrication (DC), and digital scanning and fabrication (DD). The risk of bias was assessed by using the Cochrane Collaboration tool for clinical trials and the modified Methodological Index for Non-Randomized Studies (MINORS) for in vitro studies. Heterogeneity was evaluated among studies, and meta-analysis was performed with random-effect models (α=.05). Subgroup analysis was conducted when possible.

Results: Eight clinical trials and 21 in vitro studies were eligible for analysis. There was no significant difference between the CD and DD clinical groups for marginal adaptation (P=.149); However, the DD group had significantly less internal discrepancy than the CD group (P=.009). The in vitro studies found no significant difference in marginal adaptation among the CC-CD, CC-DC, and CC-DD pairs (P=.437, P=.387, P=.587), but in the comparison CD versus DD group, a significantly better marginal adaptation was observed for the DD group (P=.001). All the compared in vitro groups were similar in terms of internal adaptation.

Conclusions: Impression and fabrication techniques may affect the accuracy of fit of complete-coverage fixed restorations. A completely digital workflow yielded restorations with comparable or better marginal adaptation than the other methods.