Influence of antimicrobial photodynamic therapy in carious lesion. Randomized split-mouth clinical trial in primary molars

Background. The literature presents many studies regarding photodynamic antimicrobial therapy (aPDT). However, the great variety of protocols to be used can directly influence its effectiveness in reducing micro-organisms. The aim of this randomized split-mouth clinical study was to evaluate the effect of aPDT in the reduction of Streptococcus mutans and their effect on restorations performed. Methods: Twenty children between 6 and 8 years old with active caries and dentin cavitation, located on the occlusal surface of homologous primary molars were included. The selective removal of carious tissue was performed in both molars, than one was subsequently restored and the other received aPDT treatment on the affected dentin with low intensity laser (InGaAIP) associated to 0.005% methylene blue photosensitizer before restoration. Dentin collections were performed only in the tooth submitted to aPDT in three moments: before and after selective caries removal and after application of aPDT. The restorations were analyzed after polishing and after 6 months using United States Public Health Service (USPHS) method. Data were analyzed using ANOVA with repeated measures and Bonferroni post-hoc test with a significance level of 5%. Results: There was a significant reduction on the amount of microorganisms after selective caries removal (p = 0.04) and also after the application of aPDT (p = 0.01). The reduction of S. mutans CFU was of 76.4% after caries removal, but associated with aPDT was 92.6%. After 6 months of clinical evaluation, no difference between groups was found for retention, marginal adaptation, color, marginal discoloration, and secondary caries. Conclusions: aPDT can be used as an additional treatment against cariogenic microorganisms after selective caries removal without compromising composite resin restorations.