Efeito in vitro e in vivo da terapia fotodinâmica antimicrobial sobre streptococcus mutans presentes em acessórios metálicos ortodônticos

Abstract

Demineralization and caries are often present in patients with orthodontic braces due to the increased accumulation of dental biofilm containing Streptococcus mutans, which produces acids that attack the tooth surface. The Antimicrobial Photodynamic Therapy (APDT) has been shown as an alternative in microbial inactivation in dentistry. This work, carried out both in vitro and in vivo, aims to evaluate the antimicrobial effect of APDT on Streptococcus mutans present in the dental biofilm accumulated on the metal surface of orthodontic appliances and in patients undergoing orthodontic treatment. The in vitro study evaluated the susceptibility of biofilm formed by S. mutans on the metal surface under the application of orthodontic appliances APDT induced Curcumin diluted surfactant (SDS) and blue light-emitting diode (LED). The samples were treated with the photosensitizer (PS) at a concentration of 1 g/L, 0.1% surfactant and exposed to LED light (455 ± 10 nm, 46mW/cm²), fluence of 30 J/cm². The experimental groups studied were: control group (P-L-S-); light (P-L+S-), surfactant (P-L-S+) and photosensitizer (P+L-S-) groups; surfactant-light (P-L+S+), photosensitizer-surfactant (P+L-S+) and PDT (P+L+S-) groups; and the PDT-surfactant (P+L+S+) group. Each group was named accordingly to the addiction or not of the photosensitizer (P+ or P-), surfactant (S+ or S-) and application or not of light (L+ or L-), respectively. The colonies grown on plates of brain heart infusion (BHI) were counted (CFU / mL) and the results were analyzed by ANOVA and the post hoc Tukey test (p <0.05). The results showed that in this research protocol, the group P+L+S+ was able to promote significant decrease (p<0.001) on the population of S. mutans of 99.999% compared to the control group. In the in vivo study, 24 volunteers were randomly selected in order to evaluate the clinical utility of APDT and the APDT association with the surfactant (SDS) as oral decontamination agents in orthodontic patients. The selected patients (n = 24) were randomly divided into seven groups: G1 - Negative control, G2 - Curcumin mouthwash, G3 - Curcumin mouthwash+SDS, G4 - light irradiation, G5 - APDT, G6 - APDT+SDS and G7 - Positive Control (chlorhexidine 0.12% moutwash). Saliva samples were collected from unstimulated way of each patient in three steps (S) as follows: S1 - initial condition S2 - Treatment with rinsing (water, curcumin or chlorhexidine) and S3 - After APDT. The photosensitiser used was curcumin with concentration of 1 g/L. Two types of blue LED light source emitting in 450±10nm were used in the present study: one emitting with an intensity of 33.54 mW/cm² and other with 212 mW/cm². Evaluation of microbial reduction, and survival fraction in each of the studied levels, was performed using the Kruskal-Wallis ANOVA test. Statistical analysis showed that only G6 and G7 presented results of bacterial inactivation that showed statistically significant differences (p<0.05) compared to those observed in G1. These results indicated that APDT, when combined with SDS surfactant, may be used as an adjunct agent for convenient oral decontamination promoter in vivo.