Effect of different storage conditions on the fit of 3D-printed occlusal devices used to treat temporomandibular disorders

Abstract

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 (t₀, control), after 1 day (t₁), after 7 days (t₂), and after 27 days (t₃). The dimensional changes of the fitting surfaces between t₀ and t₁ (Δt₁), t₀ and t₂ (Δt₂), and t₀ and t₃ (Δt₃) 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 Δt₁ and Δt₂ (P=.002) and between Δt₁ and Δt₃ (P=.002) showed a statistically significant difference. The RMS of group W between Δt₁ and Δt₃ (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 Δt₁. 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 Δt₁ in comparison with group W and D, while no statistically significant differences were found among the groups for Δt₂ and Δt₃. In terms of the different locations, no statistically significant differences were found among the 3 locations for any given group after 27 days.