Do color stability and translucency differ between 3D printed and milled resin-based fixed dental restorations? A systematic review and meta-analysis

STATEMENT OF PROBLEM: Whether additive manufactured (AM) and subtractive manufactured (SM) resin-based restorations differ in optical properties after aging and staining is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate whether AM and SM resin-based dental restoration materials differ in color change (ΔE), translucency (TP), and translucency change (ΔTP). MATERIAL AND METHODS: A systematic search was conducted in the PubMed, Embase, Scopus, Web of Science, and Cochrane Library databases up to January 2025. Eligible studies were English-language, peer-reviewed in vitro investigations comparing AM and SM resin-based fixed dental restorations for ΔE, TP, or ΔTP. Nonresin and noncomparative studies were excluded. Outcomes were synthesized as weighted mean differences (WMDs) using random-effects meta-analysis. Between-study heterogeneity was assessed using Cochrane Q and I² statistics and explored through subgroup and random-effects meta-regression analyses (α=.05). Publication bias was evaluated using funnel plots, Begg and Egger tests, and nonparametric trim-and-fill analysis. Risk of bias was assessed using the Quality Assessment Tool for In Vitro Studies (QUIN). RESULTS: Of 8169 records screened, 37 studies were included. AM resin-based materials showed greater ΔE compared with SM materials (WMD=1.40; 95% CI: 1.33 to 1.46; P99%). Evidence regarding TP differences between AM and SM materials was inconclusive because of high heterogeneity (I²>99%). ΔTP was greater in AM materials (WMD=-0.29; 95% CI: -0.43 to -0.15; P