Evaluation of photopolymer resins for dental prosthetics fabricated via the stereolithography process at different polymerization temperatures—Part I: Conversion rate and mechanical properties

Abstract

Improvement in the mechanical properties of 3-dimensional (3D) printed dental prostheses is necessary to prevent wear caused by an antagonist or fracture. However, how different printing temperatures affect their mechanical properties is unclear. The purpose of this in vitro study was to evaluate the mechanical properties of 3D printed parts fabricated at different printing temperatures. Photopolymer specimens were fabricated at 3 different temperatures (room temperature, 50°C, and 70°C) using a stereolithography 3D printer. After rinsing to remove the residual monomer, the specimens were divided into 2 groups: with or without postprocessing. The viscosity of the photopolymerization resin was measured while the temperature was increased. Furthermore, the double-bond conversion (DBC) of the printed part was evaluated (n=3). Mechanical properties were investigated via dynamic mechanical analysis (n=1) and tensile testing (n=5). Statistical comparisons were performed via 1-way analysis of variance, followed by the Tukey honestly significant difference test (α=.05). The DBC rates of the green condition group increased from 66.67% to 86.33% with increasing temperature. In addition, these specimens exhibited improved mechanical properties and reduced residual monomer levels. Specimens fabricated at a temperature of 70°C exhibited mechanical properties suitable for clinical application.