Durability of 3D Orthodontic Models: Effects of Time and Storage

Objectives: This study aims to evaluate the long-term stability of 3D printed orthodontic models by comparing them to their initial 3D printed state. The study also investigates the effects of various storage conditions such as temperature and light exposure on the models' stability over time.
Methods: A standardized dental model of the mandibular arch was 3D printed using Draft Resin V2™ (FormLabs, Somerville, MA) and measured post-printing (T0) with an E3 scanner (3Shape, Copenhagen, Denmark). Models were randomly split into groups for storage at high (55°C), ambient (22±2°C), or low (4°C) temperatures, under either dark or light conditions for each temperature group, for 1 month (T1) and 3 months (T2). They were scanned at each time point, and the scans were superimposed on the original STL file to identify discrepancies in dimensions according to best-fit.
Results: The estimated marginal means from the mixed effect linear models, after Benjamini-Hochberg adjustment demonstrated that models stored in dark exhibited significant differences between T0-T1and T1-T2 for low temperature (1.08x and 0.921x respectively; p<0.05); and between T0-T1and T0-T2 in ambient temperature group (1.19x and 1.13x respectively; p<0.05). For the high-temperature group significant differences were observed in T0-T1, T0-T2, and T1-T2 group (0.87x, 0.80x, 0.91x respectively; p<0.05). Models stored exposed to light, low temperature group had no significant contrasts among the timepoints, whereas ambient temperature exhibited significant changes in all three timepoints (1.18x, 1.33x, 1.14x respectively; p<0.05), and high temperature group exhibited significant changes for all timepoints (0.85x, 0.94x, 1.10x respectively; p<0.05).
Conclusions: The stability of 3D printed orthodontic models is significantly affected by storage conditions. Regardless of exposure to dark or light environments, 3D printed dental models exhibited greater dimensional changes at ambient and high temperatures. These findings emphasize the need to standardize temperature conditions for the long term storage of dental models.