Colour stability of 3D-printed resin orthodontic brackets

Objective: To evaluate the colour stability of polymeric resins that could be used to 3D-print orthodontic brackets. Design: In vitro, laboratory study Materials and Methods: Disc-shaped specimens were fabricated via 3D printing using three resins: Dental LT; Dental SG; and Clear. Five conditions were evaluated for each resin (n 10 per treatment per resin) to assess its correspond- ing effect on colour and translucency: immersion in (1) red wine, (2) coffee, (3) tea and (4) distilled water (control), and (5) exposure to accelerated aging. Colour and translucency measurements were made before and after exposure using a spectrophotometer. Mean colour differences (Delta E-00) and changes in translucency parameter (Delta TP00) were calculated for each sample using the CIEDE2000 colour difference formula. Results: Statistically significant effects of the resin material, the treatment condition and interactions effects of material and condition were observed for Delta E-00 and Delta TP00 (P < 0.001). The most pronounced changes in colour (Delta E-00) were a result of the staining effects of wine on all three resins, ranging from 14.5 +/- 0.6 to 20.8 +/- 1.2. Dental LT, Dental SG and Clear resins all showed changes in colour when exposed to certain staining agents. Dental SG and Clear resins exhibited changes in colour with aging, while the colour of Dental LT resin remained stable with aging. Conclusions: The colour changes of the resins investigated does not support their use in 3D-printed aesthetic bracket applications.