Development of Micro pH Sensor for Diagnosis of Dental Caries Activity

使用pH成像显微镜对提取的龋齿和完整牙本质的pH值进行了直观和定量的研究(Kitasako等人，2002年)。龋齿牙本质的pH分布低于完整牙本质。此外，在活动性牙本质龋损中，pH降低和矿物质丢失之间存在显著的相关性(Hiraishi等人，2003年)。Nakajima等人。(2004)也报道了钙、磷、镁等矿物质在患龋牙本质粘接界面上的分布与正常牙本质不同。然而，pH成像传感器体积太大，不能直接评价口腔内龋齿的pH值。较小的版本将允许在体内对口腔内的龋损进行pH成像表征。最近，一种使用离子敏感场效应晶体管(ISFET)的微型pH传感器已经被开发出来，以克服玻璃和锑电极的问题(Murakami等人，2005年)。20颗拔除的龋齿随机分为活动性龋病组和缓解期龋病组。用三种方法测量龋损牙本质表面的pH值：用微pH传感器直接测量表面pH值；用pH成像显微镜或微pH传感器测量切开的牙齿。在所有技术中，活动性和阻滞性龋性牙本质的最低pH值(5.3~6.5)均小于完整牙本质(6.8~7.4)。与pH成像显微镜和微型pH传感器测得的相同pH点的pH数据进行比较，结果显示高度一致(p=0.890)。在所有技术中，活动性和阻滞性牙本质龋之间的pH值有统计学意义的差异。由于这种微型pH传感器可以评估每颗牙齿上的龋齿活动，因此它可能有可能帮助评估龋损，然后使用最小干预的概念进行后续的临床治疗。

The pH values of extracted carious and intact dentin have been investigated visually and quantitatively using a pH-imaging microscope (Kitasako et al., 2002). The pH distribution of carious dentin was shown to be lower than that of intact dentin. In addition, there was a significant correlation between a decrease in pH and mineral loss in active dentinal caries lesions (Hiraishi et al.2003). Nakajima et al. (2004) also reported the distributions of the minerals, Ca, P, and Mg, at the adhesive interface to caries-affected dentin were different from normal dentin. However, the pH-imaging sensor is too large for evaluating the pH of caries in the oral cavity directly. A smaller version would allow in vivo pH-imaging characterization of caries lesions in the oral cavity. Recently, a micro-pH sensor using an Ion Sensitive Field Effect Transistor (ISFET) has been developed to overcome the problem of the glass and antimony electrodes (Murakami et al., 2005). Twenty extracted carious teeth were divided into two groups, active or arrested caries. The surface pH values of carious dentin were measured using three methods : surface pH directly measured using the micro-pH sensor ; sectioned teeth using a pH-Imaging microscope or the micro-pH sensor. For all techniques, the lowest pH values of the active and arrested carious dentin (5.3-6.5) were less than those of intact dentin (6.8-7.4). Comparison of pH data from pH-Imaging microscope or micro-pH sensor, which measured the same pH point, a high agreement (p=0.890) was confirmed. For all techniques, there was a statistically significant differences of pH values between active and arrested dentinal caries. Because this micro-pH sensor can evaluate caries activity on each tooth, it might have the potential to aid in assessment of caries lesions and then the subsequent type of clinical management using the concepts of Minimal Intervention.