Kolosowski Kamil P, Sodhi Rana N S, Kishen Anil, Basrani Bettina R
Discipline of Endodontics, Faculty of Dentistry, University of Toronto, Toronto, Canada.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada.
J Endod. 2014 Dec;40(12):2036-40. doi: 10.1016/j.joen.2014.08.017. Epub 2014 Oct 8.
Interaction of sodium hypochlorite (NaOCl) mixed with chlorhexidine (CHX) produces a brown precipitate containing para-chloroaniline (PCA). When QMiX is mixed with NaOCl, no precipitate forms, but color change occurs. The aim of this study was to qualitatively assess the formation of precipitate and PCA on the surface and in the tubules of dentin irrigated with NaOCl, followed either by EDTA, NaOCl, and CHX or by saline and QMiX by using time-of-flight secondary ion mass spectrometry (TOF-SIMS).
Dentin blocks were obtained from human maxillary molars, embedded in resin, and cross-sectioned to expose dentin. Specimens in group 1 were immersed in 2.5% NaOCl, followed by 17% EDTA, 2.5% NaOCl, and 2% CHX. Specimens in group 2 were immersed in 2.5% NaOCl, followed by saline and QMiX. The dentin surfaces were subjected to TOF-SIMS spectra analysis. Longitudinal sections of dentin blocks were then exposed and subjected to TOF-SIMS analysis. All samples and analysis were performed in triplicate for confirmation.
TOF-SIMS analysis of group 1 revealed an irregular precipitate, containing PCA and CHX breakdown products, on the dentin surfaces, occluding and extending into the tubules. In TOF-SIMS analysis of group 2, no precipitates, including PCA, were detected on the dentin surface or in the tubules.
Within the limitations of this study, precipitate containing PCA was formed in the tubules of dentin irrigated with NaOCl followed by CHX. No precipitates or PCA were detected in the tubules of dentin irrigated with NaOCl followed by saline and QMiX.
次氯酸钠（NaOCl）与洗必泰（CHX）混合会产生一种含有对氯苯胺（PCA）的棕色沉淀。当QMiX与NaOCl混合时，不会形成沉淀，但会发生颜色变化。本研究的目的是通过飞行时间二次离子质谱（TOF-SIMS）定性评估用NaOCl冲洗后，再用乙二胺四乙酸（EDTA）、NaOCl和CHX或生理盐水和QMiX冲洗的牙本质表面和小管中沉淀及PCA的形成情况。
从人类上颌磨牙获取牙本质块，嵌入树脂中并进行横截面切片以暴露牙本质。第1组的标本先浸入2.5%的NaOCl中，接着依次浸入17%的EDTA、2.5%的NaOCl和2%的CHX中。第2组的标本先浸入2.5%的NaOCl中，接着依次浸入生理盐水和QMiX中。对牙本质表面进行TOF-SIMS光谱分析。然后暴露牙本质块的纵截面并进行TOF-SIMS分析。所有样本和分析均重复进行三次以作验证。
第1组的TOF-SIMS分析显示，牙本质表面有不规则沉淀，含有PCA和CHX分解产物，堵塞并延伸至小管。第2组的TOF-SIMS分析未在牙本质表面或小管中检测到包括PCA在内的任何沉淀。
在本研究的局限性范围内，用NaOCl冲洗后再用CHX冲洗的牙本质小管中形成了含PCA的沉淀。在用NaOCl冲洗后再用生理盐水和QMiX冲洗的牙本质小管中未检测到沉淀或PCA。
