| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2004: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2003: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
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.
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