Antibacterial, cytotoxic, and mechanical characteristics of a novel chitosan-modified orthodontic primer: An in-vitro study

Aim: Enamel demineralization around orthodontic brackets due to the formation of cariogenic biofilms can be prevented by modifying the adhesive/primers with certain antimicrobials. The aim of this study was to evaluate the antimicrobial, cytotoxic, and mechanical properties of a novel chitosan-modified (CH) orthodontic primer and compare it with a control primer. Materials and Methods: This in-vitro study involved two groups (Group A: CH-modified primer and Group B: control primer). Antibacterial properties against Streptococcus mutans were evaluated using the agar well-diffusion technique to measure the zone of inhibition, and minimum inhibitory concentration (MIC) was evaluated using the two-fold diffusion technique. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) fibroblast assay was done to evaluate the cytotoxicity. After bonding brackets on extracted natural teeth the shear bond strength (SBS), contact angle (CA), and adhesive remnant index (ARI) were evaluated for both groups. Statistical analysis was done using SPSS software and the independent t-test and Mann–Whitney test were performed. Results: The CH primer when compared to the control primer had higher zone of inhibition values and lower MIC value. MTT fibroblast assay showed that the cell viability percent shown by the CH primer was more in comparison to the control primer. Statistically nonsignificant differences were found between the two primers for SBS (P > 0.05), CA (P > 0.05), and ARI (P > 0.05). Conclusion: The CH primer showed higher antibacterial activity against S. mutans at a lower inhibitory concentration, with less cytotoxicity with no effect on the SBS, CA, and ARI scores.