Effect of Different Storage Conditions on the Fit of 3D-Printed Occlusal Devices Used to Treat Temporomandibular Disorders.

Statement of problem. Research-based storage guidelines for 3-dimensional (3D)-printed occlusal devices are lacking. Purpose. The purpose of this in vitro study was to investigate the dimensional stability of the internal surface of 3D-printed occlusal devices under different storage conditions. Material and methods. Maxillary and mandibular dental casts were scanned and exported to a 3D printer to fabricate 30 occlusal devices. The specimens were stored under 3 different conditions (n=10): air dried and stored under natural light (group DL), stored in a dark container with water (group W), and air dried and stored in a dark container (group D). The intaglio surfaces of the occlusal devices were scanned by a laboratory scanner at 4 time points: immediately after polymerization (t(0), control), after 1 day (t(1)), after 7 days (t(2)), and after 27 days (t(3)). The dimensional changes of the fitting surfaces between t(0) and t(1) (delta t(1)), t(0) and t(2) (delta t(2)), and t(0) and t(3) (delta t(3)) were measured by using best fit alignment in a surface analysis software program. In addition, comparisons were made between the posterior and anterior sections. Statistical analysis was completed with Kolmogorov-Smirnov, 1-way ANOVA, Friedman, Kruskal-Wallis, Mann-Whitney, and unpaired t tests. Results. The root mean square (RMS) of group DL between delta t(1) and delta t(2) (P=.002) and between delta t(1) and delta t(3) (P=.002) showed a statistically significant difference. The RMS of group W between delta t(1) and delta t(3) (P=.008) showed a statistically significant difference. When the groups were compared with each other at the different time points, the DL group showed a statistically significant difference compared with groups W and D at delta t(1). The examination of different areas of the occlusal device (right molar, incisor, and left molar sites) indicated no statistically significant differences in RMS among all groups (P >.05). Conclusions. The occlusal devices of group DL showed the least dimensional change of the fitting surface for delta t(1) in comparison with group W and D, while no statistically significant differences were found among the groups for delta t(2) and delta t(3). In terms of the different locations, no statistically significant differences were found among the 3 locations for any given group after 27 days.