Effect of post-curing parameters and material thickness on the color stability of 3D-printed dental resins: An in vitro study

Objective > To assess the effect of variations in post-curing temperatures and times on the colour stability of 3D-printed resins used in orthodontics and paediatric dentistry applications and the effect of material thickness on colour properties was also examined. Methods > The two different disk samples (15.00 x 1.0 mm, n = 90; 15.00 x 2.00, n = 90; diameter and height, respectively) were designed and printed from biocompatible resin with SLA technology. These samples were subjected to various post-curing temperatures and times (60 degrees C and 30 min, 60 degrees C and 90 min, 60 degrees C and 120 min, 60 degrees C and 60 min, 40 degrees C and 60 min, 80 degrees C and 60 min). The values of L, a, and b of the 3D-printed resin samples were evaluated under D65 illumination conditions in the centre of the samples using a spectrophotometer. The same researcher recorded the average values after the measurements were performed three times for each sample. Results > The results indicated significant differences in colour stability (L, a, b values) among samples subjected to different post-curing conditions. Variations in post-curing time and temperature significantly affected the colour of the resins. The study found that certain post-curing conditions could lead to acceptable colour values that are similar to natural teeth. Conclusions > The study concluded that the time and temperature of post-curing significantly affected the colour properties of 3D-printed clear resins used in orthodontic applications. It suggests that a 30-minute post-curing time can yield acceptable colour values, highlighting the importance of selecting appropriate post-curing conditions based on clinical requirements. Additionally, an increase in material thickness was found to correlate with increased yellowness in the samples. Clinical significance > The changes in post-curing temperature and time may impact colour properties. Clinicians should consider this situation when manufacturing with 3D printing.