In Vitro Comparative Evaluation of the Efficacy of Antimicrobial Photodynamic Therapy, Chlorhexidine, Sodium Fluoride, and Hydrogen Peroxide for Acrylic Resin Disinfection.

Introduction: Plaque accumulation on the surface of removable orthodontic appliances could lead to dental caries, periodontitis, and fungal infections. This study evaluated the effectiveness of antimicrobial photodynamic therapy (aPDT), chlorhexidine (CHX), sodium fluoride (NaF), and hydrogen peroxide (H 2 O 2 ) for the disinfection of acrylic resin. Methods: In this in vitro experimental study, 100 acrylic resin specimens were randomly divided into five groups (n=20 each): Enterococcus faecalis , Streptococcus mutans , Streptococcus salivarius , Streptococcus sanguinis , and Lactobacillus acidophilus . Each group was immersed separately in 5 mL of microbial suspension. They were then incubated until biofilm formation on their surface. Of each microorganism, one biofilm sample in phosphate-buffered saline was considered as negative control, and other biofilm samples (n=80) were subjected to aPDT with curcumin, 0.12% CHX (positive control), 1% H 2 O 2 , and 0.2% NaF. Finally, the number of colonies was counted. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests, two-way ANOVA, and Bonferroni adjustment at a significance level of 0.05. Results: The interaction effect of the treatment modality and type of microorganism was significant on the microbial count (effect size: 0.91, P <0.05). Maximum bacterial proliferation was noted in the following combinations: NaF/ E. faecalis , H 2 O 2 / E. faecalis , and H 2 O 2 / S. salivarius . Microorganisms had no or insignificant growth and proliferation in the aPDT and CHX groups. Conclusion: The results supported the optimal antimicrobial efficacy of PDT which was comparable to that of CHX. aPDT showed superior antimicrobial efficacy to NaF and H 2 O 2 for the disinfection of acrylic resin.