Effects of storage and toothbrush simulation on color, gloss, and roughness of CAD/CAM, hand-cast, thermoforming, and 3D-printed splint materials

Objectives The aim was to investigate color, gloss, or roughness of splint materials after storage in liquids and toothbrush simulation. Materials and methods A total of 58 x 8 (n =10 per material and group) specimens were fabricated (hand-cast, thermoforming, CAD/CAM-milled, 3D-printed materials); stored in air, water, coffee, red wine, and cleaning tablets; and investigated after fabrication, 24 h, two-, and four-week storage or toothbrushing. Color values (L*, a*, b*; ISO 11664-4:2008; CM3500d, Konica-Minolta), gloss (ISO 2813:2014), and roughness values were determined (3D laser-scanning-microscope, KJ 3D, Keyence) before and after simulation or storage. Statistics: Levene-test, one-way ANOVA, Bonferroni post hoc test, between-subjects effects, Pearson correlation (alpha = 0.05). Results Color, gloss, and roughness altered due to contact with staining solutions/toothbrush simulation. Highest impact on color, gloss, and roughness presented the material followed by storage time (Delta E material (eta 2 = 0.239/p < 0.001), storage time (eta 2 = 0.179/p < 0.001); gloss (eta 2 = 0.751/p < 0.001) (eta 2 = 0.401/p < 0.001); Ra/Rz (eta 2 >= 0.801/p < 0.001) (eta 2 >= 0.416/p <0.001)). Correlations were found between Rz and Ra (Pearson 0.887/p <= 0.001) or Rz and Delta E (0.517/p <= 0.001) or Ra and Delta E (0.460/p <= 0.001). Conclusions Storage and toothbrushing were accompanied by a change in color, gloss, and roughness. Almost all materials showed visible discoloration after 4 weeks of storage. Gloss values decreased as storage time increased. The initial roughness and polishability were better with harder materials.

Automated summary

The study investigated the color, gloss, and roughness changes of splint materials after storage in liquids and toothbrush simulation. The results showed that contact with staining solutions/toothbrush simulation altered the color, gloss, and roughness. The material and storage time had the most significant impact on these changes. Storage and toothbrushing resulted in visible discoloration and decreased gloss values of the splint materials.