De-Deus G, Paciornik S, Mauricio M H P
Department of Endodontics, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Int Endod J. 2006 May;39(5):401-7. doi: 10.1111/j.1365-2591.2006.01094.x.
To evaluate the effect of citric acid, ethylenediaminetetraacetic acid (EDTA) and ethylenediaminetetraacetic acid plus Cetavlon (EDTAC) solutions on the microhardness of human root canal dentine.
Sixteen maxillary human canines were sectioned transversely at the cemento-enamel junction and the crowns were discarded. Subsequently, each root was embedded in an epoxy resin cylinder and their middle third sectioned horizontally into 4 mm thick slices. The samples were randomly divided into three groups according to the chelating agent employed, as follows (n = 6): group 1: EDTA 17%, group 2: EDTAC 17% and group 3: citric acid 10%. Dentine microhardness was then measured with a load of 50 g for 15 s. At the beginning of the experiment, reference microhardness values were obtained for samples without any etching (t = 0 min). The same samples were then exposed to 50 microL of the chelator solution for 1, 3 and 5 min. The Student's t-test (P < 0.05) was used to compare results for different times for each chelator and different chelators for each time.
Microhardness decreased with increasing time of application of chelating solutions. There were no significant (P > 0.05) differences between initial microhardness for the three groups as well as after 1 min of application of the substances. After 3 min, EDTA produced a significantly greater reduction in microhardness. However, there was no significant difference between EDTA and EDTAC after 5 min. Citric acid caused significantly less reduction in microhardness.
Overall, citric acid was least effective in reducing dentine hardness whilst EDTA had the strongest effect.
评估柠檬酸、乙二胺四乙酸（EDTA）以及乙二胺四乙酸加西他氯铵（EDTAC）溶液对人根管牙本质显微硬度的影响。
将16颗上颌人犬齿在牙骨质 - 釉质界处横向切开，弃去牙冠。随后，将每颗牙根嵌入环氧树脂圆柱体中，并将牙根中部的三分之一水平切成4毫米厚的薄片。根据所使用的螯合剂，将样本随机分为三组，如下（n = 6）：第1组：17% 的EDTA，第2组：17% 的EDTAC，第3组：10% 的柠檬酸。然后用50克的载荷持续15秒测量牙本质显微硬度。在实验开始时，获取未进行任何酸蚀处理的样本的参考显微硬度值（t = 0分钟）。然后将相同的样本暴露于50微升螯合剂溶液中1、3和5分钟。采用Student's t检验（P < 0.05）比较每种螯合剂在不同时间以及每种时间下不同螯合剂的结果。
随着螯合剂溶液应用时间的增加，显微硬度降低。三组的初始显微硬度以及在应用这些物质1分钟后均无显著（P > 0.05）差异。3分钟后，EDTA使显微硬度显著降低。然而，5分钟后EDTA和EDTAC之间无显著差异。柠檬酸导致的显微硬度降低显著较少。
总体而言，柠檬酸在降低牙本质硬度方面效果最差，而EDTA效果最强。
