Water sorption, water solubility, degree of conversion, elastic indentation modulus, edge chipping resistance and flexural strength of 3D-printed denture base resins

Objectives: To investigate the water sorption (wsp), water solubility (wsl), degree of conversion (DC), elastic indentation modulus (EIT), edge chipping resistance (ECR) and flexural strength (FS) of 3D-printed, milled and conventionally polymerized denture base resin materials. Methods: Specimens (N = 540) were 3D-printed (NextDent Denture 3D+ (DEN), Fotodent Denture (FOT), Freeprint Denture (FRE), V-Print dentbase (VPR)), cut (Ivotion Base (IVO)) and molded (PalaXpress (PAL)) in three geometries. Wsp, wsl, DC, EIT, ECR and FS were tested initially (24 h, 37 degrees C, H20) and after additional aging (5000 thermal cycles, 5/55 degrees C). Data were analyzed with Kolmogorov-Smirnov, univariate ANOVA, Kruskal-Wallis, Mann-Whitney U test and Spearman's correlation (p < 0.05) Results: Most 3D-printed denture base resins showed higher w(sp) (25.31-37.94 mu g/mm(3)) and wsl (0.08-8.27 mu g/ mm(3)), but also higher EIT (3.11-4.09 GPa) and FS (60.81-99.57N/mm(2)) values than the control groups. DEN and VPR showed high DC (89.36-93.53%), EIT (3.77-4.09 GPa) and FS (79.65-99.57N/mm2), while FOT showed low wsp (25.31-27.35 mu g/mm3) and wsl (1.01-3.87 mu g/mm(3)) values. In all materials, the examined parameters were affected by aging. Significance: Although 3D-printed denture base resins showed promising results with regard to the observed DC and FS, only FOT and FRE surpassed the threshold values defined by the ISO norms.