Effect of the addition of Chitosan and TiO2 nanoparticles on antibacterial properties of an orthodontic composite in fixed orthodontic treatment: a randomized clinical trial study
Authors: Farzanegan Fahimeh , Shahabi Mostafa , Niazi Ahmad Ehsan , Soleimanpour Saman , Shafaee Hooman , Rangrazi Abdolrasoul 
Published: May 2021

Abstract
Due to the existing demands for methods independent of patient co-operation in preventing and overcoming the incidence of white spot lesions (WSLs) and caries in fixed orthodontic treatments, several studies have considered the modification of orthodontic composites using antimicrobial nanomaterials. In this regard, the aim of this study is to investigate the effect of the addition of chitosan nanoparticles (NPs) and TiO2 NPs on Streptococcus mutans (S. mutans) counts and the enamel mineral content in fixed orthodontic patients. A double-blind randomized clinical trial study was carried out in 24 patients (i.e., 48 upper second premolars and 48 maxillary lateral incisors) who were candidates for fixed orthodontic treatment. In the case of the control group, the bracket was bonded to the tooth with an orthodontic adhesive (Transbond XT, 3M Unitek, USA) while, in the experimental group, the bracket was bonded to the tooth with Transbond XT containing 1% chitosan NPs and 1% TiO2 NPs. For the maxillary lateral incisor and upper second premolar teeth, the S. mutans counts around the brackets were measured, through the usage of real-time PCR, at the time points of 1 day, 2 months, and 6 months after bonding the brackets to the tooth. Furthermore, the enamel mineral content measurement was also performed around the brackets at 1 day, 2 months, and 6 months after bonding the brackets to the tooth. The S. mutans counts were analyzed using Friedman and Mann–Whitney U tests. The Repeated measures ANOVA test and Independent samples T-test were also applied, in order to evaluate the mineral content. According to the results, there was a significant reduction in the S. mutans counts of experimental group at the time points of 1 day, 2 months, and 6 months in both maxillary lateral incisor and upper second premolar teeth. However, we did not observe any significant differences in the control group between the reports at 1 day, 2 months, and 6 months in both maxillary lateral incisor and upper second premolar teeth. The outcomes of this study indicate that, with regard to maxillary lateral incisor teeth, there were no significant differences between the results of the experimental group and control group at the time points of 1 day, 2 months, and 6 months. Furthermore, with respect to the upper second premolar teeth, no significant differences were observed between the two groups at 1 day and 2 months; however, S. mutans counts were significantly lower in the experimental group than in the control group at the time point of 6 months. Moreover, our gathered data confirmed the absence of any significant differences between the experimental group and control group, in terms of enamel mineral content, at the time intervals of 1 day, 2 months, and 6 months. In conclusion, the incorporation of chitosan NPs and TiO2 NPs in orthodontic composites induces an antibacterial property in the resultant adhesive to be used for fixed orthodontic treatment.