Department of Endodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Iranian Center for Endodontic Research, Research Institute of Dental Sciences, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Department of Pediatrics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
J Endod. 2019 Sep;45(9):1148-1154. doi: 10.1016/j.joen.2019.06.002. Epub 2019 Jul 22.
Calcium hydroxide (CH) and nano-calcium hydroxide (NCH) as intracanal medicaments may affect the physical and chemical properties of dentin. The aim of this investigation was to evaluate the effects of CH and NCH on the microhardness and superficial chemical structure of radicular dentin.
In this in vitro trial, 80 dentin discs were randomly assigned into 2 control and 2 treatment groups (n = 20). CH and NCH pastes were used in the treatment groups. In the control groups, the samples were washed with either normal saline or 2.5% sodium hypochlorite. After 1 and 4 weeks, dentin microhardness was assessed by the Vickers test, and the phosphate/amide I ratio was evaluated by the Fourier-transform infrared spectrometry test. The data were subjected to 1-way and 2-way analyses of variance, the Tukey multiple comparison test, and the Student t test.
A significant reduction in the mean microhardness was observed in the CH group after 4 weeks, whereas the differences were not significant in the NCH and control groups. The amount of reduction induced by NCH was comparable with hypochlorite. A significant increase in the mean phosphate/amide I ratio was observed in the CH and NCH groups compared with the sodium hypochlorite and intact control groups after 1 week, which did not change significantly during the observation period.
The use of CH as an intracanal medicament for 4 weeks reduced dentin microhardness, whereas NCH did not result in any change in the microhardness value. However, a change in the superficial chemical structure was observed earlier after 1 week and in both the CH and NCH groups.
氢氧化钙（CH）和纳米氢氧化钙（NCH）作为根管内药物可能会影响牙本质的物理和化学性质。本研究旨在评估 CH 和 NCH 对根管牙本质的显微硬度和表面化学结构的影响。
在这项体外试验中，将 80 个牙本质片随机分为 2 个对照组和 2 个治疗组（n = 20）。治疗组使用 CH 和 NCH 糊剂。对照组中，样本分别用生理盐水或 2.5%次氯酸钠冲洗。1 周和 4 周后，用维氏硬度试验评估牙本质显微硬度，用傅里叶变换红外光谱试验评估磷酸盐/酰胺 I 比。数据采用单因素和双因素方差分析、Tukey 多重比较检验和 Student t 检验。
4 周后，CH 组的平均显微硬度显著降低，而 NCH 组和对照组的差异不显著。NCH 引起的减少量与次氯酸钠相当。与次氯酸钠和完整对照组相比，CH 和 NCH 组在 1 周后观察到平均磷酸盐/酰胺 I 比显著增加，但在观察期间没有显著变化。
CH 作为根管内药物使用 4 周会降低牙本质的显微硬度，而 NCH 不会导致显微硬度值发生任何变化。然而，在 1 周后，表面化学结构发生了更早的变化，并且在 CH 和 NCH 组中均观察到了这种变化。
