Antibacterial effectiveness in vitro of different formulations of calcium hydroxide paste

ABSTRACT Objective: To evaluate the antibacterial activity of four formulations of calcium hydroxide paste against microorganisms commonly found in infected root canals. Methods: To evaluate antibacterial activity through the agar diffusion method, pastes of calcium hydroxide were made from its pro-analysis form, diffused into four separate vehicles: distilled water, camphorated p-monochlorophenol, propylene glycol and Otosporin®, testing the antimicrobial activity of these on strains of Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis. After the incubation period, the presence or otherwise of inhibition zones were observed and their sizes in three stages: 24h, 48h and 72h. With this data, the median between the four dishes was obtained and the consequent value was submitted to Kruskal-Wallis nonparametric statistical analysis, with post-tests of Mann-Whitney and Bonferroni correction, at a significance level of 5%. Results: Only pastes with camphorated p-monochlorophenol and Otosporin vehicles caused the formation of significant inhibition zones, with medians of 8.0 mm. Against the strains of Enterococcus faecalis, only pastes with the camphorated p-monochlorophenol vehicle resulted in the formation of significant inhibition zones, with a median of 3.0 mm. Conclusion : Otosporin and CMCP vehicles provide greater antimicrobial potential to calcium hydroxide against the studied bacteria. However, only the Ca(OH)2 and CMCP combination was effective against all the strains, and can thus be regarded as the paste formulation with the greatest antimicrobial effectiveness in this study.摘要 目的：评估四种配方的氢氧化钙糊剂（calcium hydroxide paste）对感染根管常见致病菌的抗菌活性。方法：采用琼脂扩散法（agar diffusion method）评估抗菌活性：以分析纯级氢氧化钙制备糊剂，分别以蒸馏水、樟脑对一氯苯酚（camphorated p-monochlorophenol）、丙二醇及Otosporin®作为载体配制四组糊剂，测试其对金黄色葡萄球菌（Staphylococcus aureus）、枯草芽孢杆菌（Bacillus subtilis）及粪肠球菌（Enterococcus faecalis）的抗菌活性。孵育结束后，观察抑菌圈的有无，并于24h、48h、72h三个时间点测量其直径。以每组4个培养皿的直径中位数作为统计数据，采用克鲁斯卡尔-沃利斯（Kruskal-Wallis）非参数统计分析，辅以曼-惠特尼（Mann-Whitney）事后检验及邦费罗尼校正（Bonferroni correction），显著性水平设为5%。结果：仅以樟脑对一氯苯酚及Otosporin®为载体的糊剂可形成显著抑菌圈，中位数为8.0mm。针对粪肠球菌，仅以樟脑对一氯苯酚为载体的糊剂可形成显著抑菌圈，中位数为3.0mm。结论：Otosporin®与樟脑对一氯苯酚载体可提升氢氧化钙对受试菌株的抗菌潜能。但仅氢氧化钙与樟脑对一氯苯酚的组合可对所有受试菌株产生有效抑制，为本研究中抗菌效果最优的糊剂配方。