Effect of aging and mechanical brushing on color stability and translucency of three-dimensionally printed and thermoformed aligners of different thicknesses.

Objectives: The aim of this study was to evaluate the effect of aging and mechanical brushing on the color stability and translucency of three-dimensionally (3D) printed and thermoformed transparent aligners (clear aligners [CAs]) of different thicknesses.

Materials and methods: Three types of CAs (Dentsply Sirona Essix [Group 1], Scheu-Dental Thermoforming Foils [Group 2], and 3D-printed Nexdent [Group 3]) in two thicknesses (0.75 mm and 1.0 mm) were used. Each group was divided into cleaned and noncleaned subgroups (n = 10). Samples were aged in artificial saliva and subjected to mechanical brushing. Color differences (ΔE00) and relative translucency parameter values (RTP00) were recorded at 1-week intervals over 4 weeks. Statistical analyses included generalized linear models and repeated measures analyses of variance (ANOVAs) for normally distributed parameters, and robust ANOVAs and Friedman tests for nonnormally distributed parameters (P < .05).

Results: Group 1 had the highest mean RTP00 values, while Group 3 had the lowest mean RTP00 values. Noncleaned CAs exhibited higher RTP00 values than cleaned CAs (P < .05). RTP00 values decreased significantly over time, with Group 3 showing notable differences between cleaned and noncleaned subgroups. Thinner materials (0.75 mm) displayed greater color changes than thicker ones (1 mm).

Conclusions: 3D-printed CAs demonstrated more significant color variation and less translucency in comparison to thermoformed CAs. Regular cleaning helps maintain translucency and color stability, but the choice of aligner material is crucial.