Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, 5 Lower Kent Ridge Road, 119074 Singapore, Singapore.
J Dent. 2010 Feb;38(2):138-48. doi: 10.1016/j.jdent.2009.09.013. Epub 2009 Oct 2.
The purpose of this study was two-fold: (1) to monitor bacterial biofilm formation and bacteria-induced demineralization of dentine in situ by using electrochemical impedance spectrum (EIS); (2) to examine the relationship between EIS findings and changes in the chemical composition and ultrastructure of dentine during bacteria-induced demineralization.
In this study, dentine demineralization was induced by Streptococcusmutans (ATCC 25175) in the presence of sucrose in culture medium and was monitored using two EIS measurement systems (Type A with a working electrode and Type B without a working electrode). Scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) were employed to examine the morphology, element contents and crystallinity of hydroxyapatite (HAP) on the dentine surface. Transverse microradiography (TMR) was used to characterize the lesion depth and degree of mineral loss during demineralization.
The resistance of the bulk dentine (R(d)) and the apparent resistance of dentine (R(a)) measured from the Type A and Type B EIS systems, respectively, decreased gradually with demineralization. The resistance of the biofilm formed on dentine surface was determined by fitting the EIS data with equivalent circuits. The presence of biofilm slightly increased R(a) of dentine before demineralization. However, the electrochemical behavior of biofilm did not affect the decreasing impedance of dentine with demineralization. The SEM, EDX, XRD and TMR results demonstrated that the surface and bulk dentine gradually became more porous due to the loss of minerals during demineralization, which in turn resulted in the decrease in R(d) and R(a) values obtained from EIS systems.
This investigation highlighted EIS as a potential technique to monitor biofilm formation and bacterial-induced demineralization in situ.
本研究旨在双重目的：（1）通过电化学阻抗谱（EIS）监测细菌生物膜形成和细菌诱导牙本质脱矿；（2）研究 EIS 结果与细菌诱导牙本质脱矿过程中牙本质化学成分和超微结构变化之间的关系。
本研究中，在培养基中含有蔗糖的条件下，用变异链球菌（ATCC 25175）诱导牙本质脱矿，并使用两种 EIS 测量系统（带工作电极的 A 型和不带工作电极的 B 型）进行监测。扫描电子显微镜（SEM）、场发射扫描电子显微镜（FESEM）、能量色散 X 射线（EDX）和 X 射线衍射（XRD）用于检查牙本质表面羟基磷灰石（HAP）的形态、元素含量和结晶度。横向显微放射照相术（TMR）用于表征脱矿过程中的病变深度和矿物质损失程度。
分别从 A 型和 B 型 EIS 系统测量的牙本质体电阻（R(d)）和牙本质表观电阻（R(a)）随脱矿逐渐降低。用等效电路拟合 EIS 数据确定牙本质表面生物膜的电阻。生物膜的存在在脱矿前略微增加了牙本质的 R(a)。然而，生物膜的电化学行为并不影响牙本质脱矿时阻抗的降低。SEM、EDX、XRD 和 TMR 结果表明，由于脱矿过程中矿物质的损失，表面和牙本质体逐渐变得更加多孔，从而导致从 EIS 系统获得的 R(d)和 R(a)值降低。
本研究强调了 EIS 作为一种潜在技术，可用于监测原位生物膜形成和细菌诱导的脱矿。
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