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 × 1.0 mm, 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 (60 ̊C and 30 min, 60 ̊C and 90 min, 60 ̊C and 120 min, 60 ̊C and 60 min, 40 ̊C and 60 min, 80 ̊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.

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.