Department of Endodontics, Dental School, University of São Paulo, São Paulo, Brazil.
Dent Traumatol. 2010 Jun;26(3):276-80. doi: 10.1111/j.1600-9657.2010.00874.x. Epub 2010 Apr 23.
The aims of endodontic treatment in cases of apical periodontitis are to reduce as much as possible the number of microorganisms inside the root canal system and to inactivate toxins produced by them. Most of the times, these objectives are not achieved solely by chemomechanical preparation, and intracanal dressing may be necessary. In these cases, calcium hydroxide is used as a root canal dressing due to its well-known and recognized antimicrobial activity. Chlorhexidine has a wide spectrum of antimicrobial activity and its association with calcium hydroxide has been recommended in an attempt to amplify antimicrobial effects of calcium hydroxide. It is also known that dentin exerts a buffering effect under wide pH variations, and may be responsible for decreasing the antimicrobial activity of drugs inside the root canal. The objectives of this study were to assess the pH of 2% chlorhexidine gel and calcium hydroxide alone or in combination, as well as the influence of dentin on the pH of these compounds. Dentin powder was obtained from bovine teeth and added as 1.8% to the volume of the medications. All substances were individually stored in plastic flasks, in triplicate. A pH meter was used at five different moments to assess pH in viscous medium: immediately after preparation and after 24 h, and 7, 14, and 21 days. Results were analyzed by paired Student's t-test. Statistically significant differences were observed in the 2% chlorhexidine gel group alone or associated with calcium hydroxide and added of dentin powder (P < 0.05). Mean pH values indicated the influence of dentin powder because of a significant increase in pH. Calcium hydroxide with propylene glycol as the vehicle always showed high pH, demonstrating that this compound was not affected by the presence of dentin.
牙髓根尖周炎的根管治疗目的是尽可能减少根管系统内的微生物数量，并使它们产生的毒素失活。大多数情况下，这些目标仅通过化学机械预备无法实现，可能需要根管内封药。在这种情况下，由于氢氧化钙具有众所周知和公认的抗菌活性，因此将其用作根管封药。洗必泰具有广谱的抗菌活性，其与氢氧化钙联合使用已被推荐，试图增强氢氧化钙的抗菌效果。众所周知，牙本质在 pH 值广泛变化下发挥缓冲作用，并可能导致根管内药物的抗菌活性降低。本研究的目的是评估 2%洗必泰凝胶和单独的氢氧化钙以及它们的组合的 pH 值，以及牙本质对这些化合物 pH 值的影响。从牛牙中获得牙本质粉末，并按药物体积的 1.8%添加。所有物质均单独储存在塑料瓶中，一式三份。使用 pH 计在粘性介质中在五个不同时间点评估 pH 值：制备后立即以及 24 小时后，以及 7、14 和 21 天时。使用配对 Student t 检验分析结果。单独使用 2%洗必泰凝胶或与氢氧化钙联合使用并添加牙本质粉末的组中观察到统计学上的显著差异（P <0.05）。平均 pH 值表明牙本质粉末的影响，因为 pH 值显著增加。以丙二醇为载体的氢氧化钙始终表现出高 pH 值，表明该化合物不受牙本质存在的影响。
