Development of an ultrasonic device to detect early demineralized lesions and establishment of clinical criteria for these diagnoses

龋齿发病的特点是牙齿表面出现白斑或染色。然而，估计这些病变的龋活动是困难的，因为我们没有工具来识别哪些病变是脱矿，阻止或再矿化。为了检测牙齿表面受牙釉质和牙根蛀牙影响的初始变化，我们开发了一种采用超声波传感器技术的无创、无损牙齿探测器。该超声传感器检测系统由用于传感的振荡压电元件、用于获取齿面频率特性的压电检测元件和用于将传感器定位在齿面上的轻量化臂组成。在知情同意的情况下收集拔牙，用乳酸- cmc凝胶（6%,pH 4.5）制备脱矿牙釉质标本。超声传感器被加载在这些牙齿表面并扫描以绘制频率特性图。在共振法中，表面特性用振荡的频移来表示。所研制的超声传感器的检测元件在临床上足够小。通过对四组牙釉质标本的测量，发现牙釉质龋的早期病变明显表现为低频率振荡，且振荡呈脱矿时间依赖性。通过对10颗拔牙表面的扫描，该检测系统能够区分牙釉质和牙根上的声音或龋齿病变、牙石沉积、染色、牙釉质表面的白斑和裂纹。然而，在探索具有重叠病变的复杂表面时，需要额外的信息。我们的新感官探索者采用超声共振方法被发现是一个强大的工具，估计初步变化和发展程度的龋。

The onset of dental caries is characterized by white-spots or staining on tooth surfaces. However, estimation of caries activities of these lesions is difficult because we have no tool for recognition which lesion is demineralizing, arresting or re-mineralizing. For detection of the initial changes of the tooth surface affected by dental caries on the enamel and root, we developed a noninvasive, nondestructive dental explorer employing ultrasonic sensor technology. The ultrasonic sensor detection system consists of an oscillating piezoelectric element for sensing, a piezoelectric detective element to obtain frequency characteristics of the tooth surface, and a lightweight arm for positioning the sensor on the tooth surface. Extracted teeth were collected with informed consent and demineralized enamel specimens were prepared with lactate-CMC gel (6%, pH 4.5). The ultrasonic sensor was loaded on these tooth surfaces and scanned for drawing a map of the frequency characteristics. The surface characteristics were represented by the frequency shifts of oscillation in the resonance method. The detecting element of the developed ultrasonic sensor was sufficiently small in the clinic. By measurements using four sets of enamel specimens, early lesions of enamel caries were dearly represented by low frequency shifts of oscillation in a demineralized time-dependent manner. By scanning surfaces of ten extracted teeth, this detection system was able to distinguish sound or caries lesions on the enamel and roots, calculus depositions, staining, white spots and cracks on the enamel surface. However, additional information was need when exploring complex surfaces with overlapping lesions. Our new sensory explorer employing the ultrasonic resonance method was found to be a powerful tool for estimating initial change and degree of progression of dental caries.