Objective: The aim of this study was the evaluation of two different photosensitizers activated by red light emitted by light-emitting diodes (LEDs) in the decontamination of carious bovine dentin. Materials and Methods: Fifteen bovine incisors were used to obtain dentin samples which were immersed in brain-heart infusion culture medium supplemented with 1% glucose, 2% sucrose, and 1% young primary culture of Lactobacillus acidophilus 10 8 CFU/mL and Streptococcus mutans 10 8 CFU/mL for caries induction. Three different concentrations of the Photogem solution, a hematoporphyrin derivative (1, 2, and 3 mg/mL) and two different concentrations of toluidine blue O (TBO), a basic dye (0.025 and 0.1 mg/mL) were used. To activate the photosensitizers two different light exposure times were used: 60 sec and 120 sec, corresponding respectively to the doses of 24 J/cm 2 and 48 J/cm 2 . Results: After counting the numbers of CFU per milligram of carious dentin, we observed that the use of LED energy in association with Photogem or TBO was effective for bacterial reduction in carious dentin, and that the greatest effect on S. mutans and L. acidophilus was obtained with TBO at 0.1 mg/mL and a dose of 48 J/cm 2 . It was also observed that the overall toxicity of TBO was higher than that of Photogem, and that the phototoxicity of TBO was higher than that of Photogem. Conclusion: Based on our data we propose a mathematical model for the photodynamic effect when different photosensitizer concentrations and light doses are used.

The aim of the study was to microbiologically analyze the root canal space prepared for prosthetic intracanal posts. Thus, a 2% chlorhexidine solution was used after the intraradicular preparation of ten teeth with endodontic treatment performed for prosthetic purposes and pulp vitality history. Two collections were performed for microbiological analysis: one before the use of the studied solution, showing positive microbiological culture in all cases; and another, after application for 3 minutes of 2% chlorhexidine solution. The results showed the effectiveness of the solution in nine of ten cases, presenting negative results in microbial culture.