103 - Dimensional Stability of BioFlx Crowns After Sterilization

Purpose: Recently hybrid resin pediatric crowns were introduced that are flexible and esthetic (NuSmile BioFlx). The purpose of this study was to investigate whether sterilization can affect the dimensions of these flexible crowns.

Methods: Two groups (n=10) of flexible crowns for lower second primary molars were tested. One group was subjected to heat sterilization via autoclave and the other to cold sterilization via Sporox II sterilizing solution. The circumference of the intaglio surface at the cervical margin was measured at baseline and after 1, 2, and 10 rounds of sterilization under an optical microscope using image analysis software. The data was analyzed using a 2-way analysis of variance (ANOVA) for the effect of sterilization method (hot or cold) and the effect of subsequent sterilization cycles at a 0.05 significance level.

Results: Significant changes in circumference were found after the first round of sterilization. Method of sterilization had a significant effect (p < 0.001), whereas repeated sterilization had no effect (p=0.245) on the circumference. Pairwise comparisons showed a statistically significant decrease in crown circumference (crown getting smaller) after heat sterilization and a statistically significant increase (crown getting larger) after cold sterilization.

Conclusion: Flexible crowns that are sterilized after try-on are likely to change in size after their first sterilization, where hot sterilization shrunk and cold sterilization expanded the crowns. Subsequent sterilizations did not change their size anymore.