Dimensional accuracy and degree of conversion of a novel self-polymerized acrylic resin modified with chlorhexidine-halloysite nanotubes: An in vitro controlled study.

Objectives: The integration of chlorhexidine-loaded halloysite nanotubes (CHX/HNTs) into acrylic-based orthodontic devices is a promising preventive measure to mitigate microbial proliferation under removable orthodontic appliances. The study was aimed at evaluating the physical properties of acrylic resin, particularly the degree of conversion (DC) and dimensional accuracy, after the integration of a novel CHX/HNT antimicrobial nanomaterial. Methods: Fifty rectangular acrylic polymethyl methacrylate specimens were prepared with varying concentrations of CHX-HNTs. The degree of conversion was assessed using Fourier transform infrared spectroscopy. Dimensional accuracy was measured with digital caliper, which was used to assess the acrylic indentation dimensions before and after water immersion at multiple time points. Statistical comparisons were performed using one-way ANOVA, Tukey's tests, and Bonferroni testing following repeated measures ANOVA. Results: All experimental groups showed a significantly lower DC than the control group (P ≤ 0.05). No statistically significant differences in the mean dimensions of the control and modified acrylic resins were found at all concentrations of integrated CHX-HNT nanofillers before immersion in water. After water immersion, the control samples, compared with the CHX/HNT nanocomposite samples, showed statistically significant dimensional expansional differences (P ≤ 0.05) directly proportional to the immersion duration. Conclusions: Incorporation of CHX/HNT nanofillers negatively affected the DC but enhanced the dimensional stability of PMMA acrylic resin for as long as 60 days.