Correlation between the cytotoxicity of self‑etching resin cements and the degree of conversion.

Aim: The aim of this study was to evaluate the correlation between the cytotoxicity and degree of conversion (DC) of self‑etch resin cements with or without photopolymerization. Materials and Methods: Three self‑etching resin cements with or without photopolymerization were evaluated. Six test groups and one control group represented by a standardized L929‑fibroblast cell culture were formed. The DC was measured by Fourier transform infrared spectrometry and was correlated with cell culture survival. Statistical Analysis: The analysis of variance and Bonferroni–Holm tests were applied (P < 0.05). Results: The results show that, the cytotoxicity of self‑etching resin cements is directly related to the DC. With the exception of Unicem, the other cements show some level of cytotoxicity, even with photopolymerization. Conclusion: These results indicate that photopolymerization of dual cure self‑etching resin cements decrease toxic effects on cell culture. Adequate photopolymerization should be considered during cementation when using dual polymerization self‑etching resin cements.

In vitro lethal photosensitization of S. mutans using methylene blue and toluidine blue o as photosensitizers

The purpose of this in vitro study was to evaluate the antimicrobial effect of photodynamic therapy on Streptococcus mutans (ATCC 25175) suspensions, using a red laser for one minute in combination with toluidine blue O (TBO) or methylene blue (MB). Both photosensitizers were used in three concentrations (25, 10 and 5 mg/L). The activity of photosensitizers and laser irradiation were tested separately on the bacteria, as well as the irradiation of this light source in the presence of the TBO or MB. These groups were compared to a control group, in which the microorganism did not receive any treatment. The activity of both TBO and MB or laser irradiation, alone, were not able to reduce the number of S.mutans. In the groups of lethal photosensitization, a bacterial reduction of 70% for TBO and 73% for MB was observed when these photosensitizers were used at 25 mg/L and a reduction of 48% was observed for MB at 5mg/L. In other concentrations there were no significant differences in comparison to the control group. Both the TBO and the MB at 25 mg/L associated with a red laser had an excellent potential for use in PDT in lethal sensitization of S. mutans.

O objetivo deste estudo in vitro foi avaliar o efeito antimicrobiano da terapia fotodinamica em suspensoes de Streptococcus mutans (ATCC 25175), utilizando um laser vermelho durante um minuto associado a dois agentes fotossensibilizantes: azul de toluidina (TBO) ou azul de metileno (MB). Os agentes fotossensibilizantes foram utilizados em tres diferentes concentracoes (25, 10 and 5 mg/L). A atividade destes agentes e da fonte de luz foi testada separadamente sobre a suspensao bacteriana, assim como a irradiacao desta fonte de luz na presenca de TBO ou MB (terapia fotodinamica). Estes grupos foram comparados a um grupo controle, onde nenhum tratamento foi realizado. A aplicacao dos dois fotossensibilizantes (TBO ou MB) e da fonte de luz, separadamente, nao foi capaz de reduzir o numero de colonias viaveis do S. mutans. Nos grupos onde a terapia fotodinamica foi aplicada, uma reducao bacteriana de 70% foi observada para o TBO e de 73% para o MB, quando estes agentes foram utilizados na concentracao de 25 mg/L. O uso do MB a 5mg/L causou uma reducao de 48%. Para as outras concentracoes testadas nao se observou nenhuma reducao em relacao ao grupo controle. Pode-se concluir que tanto o TBO quanto o MB a 25 mg/L associados ao laser vermelho demonstraram um excelente potencial para promover a fotossensibilizacao letal do S. mutans.