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.

The two different disk samples (15.00×1.0mm, n=90; 15.00×2.00, 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 (60̊C and 30min, 60̊C and 90min, 60̊C and 120min, 60̊C and 60min, 40̊C and 60min, 80̊C and 60min). 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.

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.

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.

The changes in post-curing temperature and time may impact colour properties. Clinicians should consider this situation when manufacturing with 3D printing.