Effects of post‐curing light intensity on the trueness, compressive strength, and resin polymerization characteristics of 3D‐printed 3‐unit fixed dental prostheses

PurposeTo investigate the effect of different post‐curing light intensities on the trueness, compressive strength, and resin polymerization of 3D‐printed 3‐unit fixed dental prostheses (FPD).Materials and MethodsA total of 60 specimens were prepared to support a 3‐unit FDP with a deep chamfer marginal design, utilizing computer‐aided design and computer‐aided manufacturing (CAD‐CAM) technology. Light‐polymerizing FDP resin with varying light intensities (105, 210, 420, and 840 mW/cm2) was employed for 10 min. Subsequently, trueness assessment, fracture load testing, scanning electron microscopy (SEM) surface examination, and Fourier‐Transform Infrared (FTIR) analysis were conducted. A one‐way analysis of variance (ANOVA) was performed to ascertain the differences between the experimental groups (p < 0.05).ResultsThe group exposed to 210 mW/cm2 showed the highest trueness (57.6 ± 2.1 µm), while the 840 mW/cm2 group had the highest deviation (79.3 ± 2.7 µm) (p < 0.001). Significant differences in fracture resistance were found between groups (p < 0.001), with mean fracture strengths of 1149.77 ± 67.81 N, 1264.92 ± 39.06 N, 1331.34 ± 53.62 N, and 1439.93 ± 34.58 N for light intensities of 105, 210, 420, and 840 mW/cm2, respectively (p < 0.001). The resin polymerization analysis shows a peak intensity surge at 3579 cm−1 for O‐H and C‐H stretching vibrations, except in samples exposed to 105 mw/cm2 light, with the lowest peak at 2890 cm−1. The performance of resin polymerization is most significant under the condition of 840 mW/cm2.ConclusionThe light intensity of 210 mW/cm2 exhibited the highest trueness, while the 840 mW/cm2 group showed the highest deviation. However, the light intensity of 840 mW/cm2 demonstrated the highest compressive strength. Furthermore, polymerization occurred at all post‐treatment light intensities except 105 mW/cm2. These findings indicate that while low‐intensity usage offers greater trueness, high‐intensity usage provides better compressive strength and polymerization. Therefore, 210 mW/cm2 could be the recommended solution for post‐curing.