Evaluation of flexural strength of additively manufactured resin materials compared to auto-polymerized provisional resin with and without hydrothermal aging

Additive manufacturing (AM) technologies are used to fabricate 3D-printed provisional dental restorations. The purpose of this study was to investigate the flexural strength of 3D-printed resins and compare their mechanical performance with those of conventional resins indicated for provisional restorations. This study included six different 3D-printed resin materials, namely (Nextdent (ND); Temp PRINT (TP); Optiprint temp (OT); 3Delta Etemp (DE); Saremco print | CROWNTEC (SA); MED690 (ST)), and one conventional (Protemp (PT)) (Control) provisional resin material. Specimens (N = 168) were prepared (25x2x2 mm3) following ISO 10477:2018 guidelines for temporary materials using a printer (Asiga MAX 3D). Post-processing was accomplished following each manufacturer's recommendation. While half of the specimens were tested after 24 H without aging, the other half was subjected to thermomechanical aging in a custom-made chewing simulator (1.200.000 cycles, 5 °C and 55 °C). Flexural strength of the specimens was determined using a Universal Testing Machine. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test (α = 0.05). Weibull modulus for each group was calculated based on parametric distribution analysis of censored data for maximum fracture load. No significant difference was observed in mean flexural strength (MPa) when non-aged and aged conditions were compared in the OT and PT groups (p>0.05). Groups ND, SA, TP, DE, and ST presented significant differences ranging between 12.67 and 57.39 MPa (p