The aim of this study was to investigate the impact of emodin nanoparticles (n-Emo) on the flexural strength of acrylic resin used in orthodontics.

A total of 24 acrylic resin discs were prepared according to ISO:20795-1 and divided into four groups (n=6): 0% n-Emo, 0.5% n-Emo, 1% n-Emo, and 2% n-Emo. The flexural strength of each group was measured using the Universal Testing Machine. One-way analysis of variance (ANOVA) and Tukey tests were used to analyse the data.

The highest flexural strength values were observed in the groups containing 0% and 0.5% concentrations of n-Emo, while the lowest mean flexural strength was recorded in the group containing 2% concentration of n-Emo. There were significant difference in flexural strength values between the groups containing 0% with those containing 1% and 2% concentrations (P=0.045, P=0.011, respectively), as well as between those containing 0.5% and 2% concentrations of n-Emo (P=0.041).

The results of the study showed that the incorporation of n-Emo had a negative impact on the flexural strength of the acrylic resin utilized in orthodontics. Nonetheless, the mean flexural strength values of all groups fell within the normal range, implying that the addition of n-Emo did not jeopardize the mechanical properties of the acrylic resin. It is therefore conceivable that the use of n-Emo as an antimicrobial agent in acrylic resin could be a promising approach to reducing enamel demineralisation and dental caries, while preserving its mechanical properties.

This study was approved by the ethics committee of the Tehran University of Medical Sciences (1401-2-398-54892).