Evaluation of temporary cement to prevent bacterial contamination of the root canal after pulpectomy / Avaliação da capacidade do cemento temporário prevenir a contaminação bacteriana do canal após pulpectomia

ABSTRACT To evaluate the ability of temporary cement (TC) and gutta-percha sticks (GP) to prevent bacterial contamination of the root canal through the coronal seal after pulpectomy. Eighty artificial primary maxillary central incisors were selected and randomly divided into 2 groups: TC (n = 40) and GP (n = 40). Endodontic access, rotary instrumentation, root canal filling, and coronal sealing were performed according to group allocation. The root canal opening was seeded with S. mutans and E. faecalis. Both groups were subdivided into 5 experimental time points (24, 48, 72, 96, and 120 hours), with 8 specimens per time-point group: 5 in which both root canal filling and coronal sealing were performed (with either TC or GP) and 3 controls (coronal sealing alone, without root canal filling). All specimens were incubated in an anaerobic jar at 37°C, and bacterial contamination was assessed in a spectrophotometer. ANOVA (t-test) was used to compare contamination and the Kruskal-Wallis test to compare filling scores between the experimental groups. A significant difference was observed in sealing in the first 24 hours between GP and controls (p = 0.046). There was no significant difference in the filling pattern between canals sealed with TC versus GP. Specimens sealed with GP showed less contamination than controls in the first 24 hours. At later time points, neither GP nor TC were effective at controlling bacterial contamination; both failed to provide adequate coronal sealing.

RESUMO Avaliar a capacidade do obturador provisório (OP) e da gutapercha em bastão (GP) de prevenir a contaminação bacteriana dos condutos radiculares. Foram selecionados 80 incisivos centrais superiores decíduos artificiais que foram divididos aleatoriamente em 2 grupos: OP (n = 40) e GP (n = 40). Foi realizado acesso endodôntico, instrumentação rotatória, preenchimento do canal radicular e selamento coronário conforme os grupos. Foi feita a semeadura de S.mutans e E. faecalis na entrada do canal radicular. Ambos os grupos foram subdivididos em 5 tempos experimentais (24, 48, 72, 96 e 120 horas), com 8 espécimes por tempo experimental: 5 submetidos a preenchimento do canal radicular e selamento coronário (com OP ou GP) e 3 controles (apenas selamento coronário, sem preenchimento do canal). Todos os espécimes foram incubados em jarras de anaerobiose a 37°C e a contaminação bacteriana foi avaliada em espectrofotômetro. Utilizou-se ANOVA (teste t) para a comparação da contaminação e o teste de Kruskal-Wallis para a comparação dos escores da obturação entre os grupos experimentais. Foi observada diferença significativa no selamento nas primeiras 24 horas entre GP e controles (p = 0,046). Não houve diferença estatisticamente significativa no padrão de preenchimento entre os canais selados com OP versus GP. Os espécimes selados com GP apresentaram menor contaminação do que os controles nas primeiras 24 horas. Nos demais tempos experimentais, tanto GP quanto OP não foram eficientes no controle da contaminação bacteriana; ambos apresentaram falha no selamento coronário.

Polyacrylic Acid with Methylene Blue Dye as a Sensitizing Agent for Photodynamic Therapy to Reduce Streptococcus mutans in Dentinal Caries.

Objective: To evaluate 11.5% polyacrylic acid (PA) containing 0.3% methylene blue (MB) dye as a photosensitizer for photodynamic therapy (PDT) of carious dentin. Methods: One hundred twenty molars were selected and the dentin was exposed for cariogenic challenge, where the molars were placed in brain heart infusion medium containing a standard strain of Streptococcus mutans (ATCC). Samples were randomly divided into eight groups (n = 15): S: saline, PA, MB: MB 0.3%, PA+MB: PA containing 0.3% MB + LLL: irradiation with low-level laser, PDT (MB): MB 0.3% + laser, PDT (PA): PA + laser, and PDT (PA+MB): PA containing 0.3% MB + laser. Carious dentin was collected before and after exposure to S. mutans. All samples of carious dentin were homogenized, diluted, and seeded in mitis salivarius bacitracin medium, and the cultures were incubated at 37°C for 15 days in anaerobic jars. The Wilcoxon test was used for analysis. Results: The percent microbial reduction achieved with each treatment was as follows: PDT (MB), 53.62%; PDT (PA+MB), 50.47%; PDT (PA), 46.73%; PA, 38.51%; MB, 19.75%; PA+MB, 17.18%; LLL, 12.83%; S, 5.99%. The greatest reductions in S. mutans growth occurred with PDT (MB), PDT (PA+MB), and PDT (PA) when compared to the S group (p = 0.0002, 0.0023, and 0.0232, respectively). Conclusions: PA containing 0.3% MB can be used as a photosensitizer for PDT to reduce S. mutans burden in carious dentin.