Evaluating the biomechanical properties of 3D-milled and 3D-printed restorative dental materials.

Abstract

The aim of this study was to evaluate the biaxial flexural strength (BFS) and modulus (BFM) of 3D-milled and 3D-printed restorative materials and assess their biomechanical behavior when bonded to dentin analog. Five dental material classes were tested: lithium disilicate glass-ceramic (Emax CAD), leucite-reinforced glass-ceramic (Empress CAD), polymer-infiltrated ceramic (Vita Enamic), 3D-milled resin-based composite (Lava Ultimate), and 3D-printed resin-based composite (Crown X). Disk-shaped specimens (n = 20, d = 12 mm, t = 1 mm) were fabricated. BFS and BFM were measured using biaxial flexural testing. Additional specimens were bonded to dentin analog (NEMA G10) and tested for BFS. Finite element analysis (FEA) evaluated stress distribution. Fractographic analysis used digital optical and scanning electron microscopy. Data was analyzed using one-way ANOVA and Weibull distribution (α = 0.05). Emax CAD exhibited highest mean BFS (312.71 ± 51.89 MPa) and BFM (41.30 ± 0.76 GPa), significantly superior to other materials (P < 0.05). Crown X demonstrated second-highest BFS (156.55 ± 30.88 MPa) but lowest BFM (10.77 ± 0.40 GPa). When bonded to dentin analog, BFS ranking changed: Emax CAD > Empress CAD > Enamic > Lava Ultimate > Crown X. FEA revealed materials with higher moduli retained stress within restoration, while lower modulus materials transferred stress to dentin analog. Weibull analysis showed Vita Enamic had highest Weibull modulus when bonded, indicating lowest variability, while Emax CAD showed lowest despite superior strength. 3D-milled lithium disilicate (Emax CAD) demonstrated superior mechanical properties and stress distribution. While 3D-printed composite (Crown X) showed promising strength when tested alone, performance significantly decreased when bonded to dentin analog.