Evaluation of the mechanical properties of whitening trays before and after usage

Background and objectives. The mechanical properties of whitening trays are essential for ensuring patient comfort, treatment efficacy, and long-term durability. These include flexibility, resistance to fracture, and structural stability during repeated use. This study aimed to evaluate the mechanical properties of thermoformed whitening trays under different exposure conditions: immersion in artificial saliva with macrogols, a bleaching solution and a control setting. Materials and methods. Twenty-one vacuum-formed trays were divided into three groups (n=7). After 35 hours of storage in sealed containers under the respective conditions, trays were subjected to compression testing using the Instron 3366 Universal Testing Machine. Parameters analyzed included compressive load at break and compressive extension. Statistical analysis included the Shapiro-Wilk test for normality and the Kruskal-Wallis test for group comparisons. Results. While no statistically significant differences were observed, trays exposed to the bleaching solution showed greater variability and a trend toward reduced compressive extension and fracture resistance compared to the control group. Conclusions. Within the limitations of this in vitro study, bleaching solutions may alter the mechanical properties of whitening trays. Further research is recommended to assess clinical implications over time.