Evaluation of the Effect of Post-Curing Times on the Optical and Mechanical Properties and the Chemical Structure of Different 3D-Printed and Conventional Temporary Crown Materials.

Purpose: To evaluate the effect of post-printing treatment conditions, including curing time, on the optical and mechanical properties of temporary crown (TC) materials.

Materials and methods: A total of 108 specimens of TC materials (PowerResins Temp, PioNext Temporary Restoration Resin) and conventional polymethyl methacrylate (PMMA) were produced. The 3D-printed specimens were post cured for different time durations (0, 15, 30, and 45 minutes) (n = 11). During the evaluation of optical properties, color measurement and translucency measurement were performed, while surface hardness and flexural strength were tested mechanically. For structural characterization, analyses were carried out using Fourier transform infrared and Raman spectroscopy (FTIR) and scanning electron microscopy. Data were analyzed with ANOVA (P = .05).

Results: The highest color change was observed in the PioNext Temporary Restoration Resin cured for 15 minutes (11.81 ± 0.95), while the lowest was in the noncured PowerResins Temp group (1.93 ± 0.38; P < .001). Hardness and flexural strength increased significantly with curing duration (P < .001). FTIR analysis revealed optimal polymerization at 30 minutes, suggesting this duration offers a clinically favorable balance of mechanical, optical, and chemical properties.

Conclusions: Both post-curing times and different production techniques affected the microstructural, optical, and mechanical properties of the tested samples. Although longer curing time improved the mechanical properties of the materials, chemical analysis showed that 45 minutes of curing negatively affected the polymerization. Moreover, curing for 30 minutes had a positive effect on the mechanical properties without changing the chemical structure of the samples.