Ultrasonic studies of unblemished and artificially demineralized enamel in extracted human teeth: a new method for detecting early caries

• Published in: Journal of dentistry Vol. 16; no. 5; pp. 201 - 209
• Main Authors: Ng, S.Y., Ferguson, M.W.J., Payne, P.A., Slater, P.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.1988
• Subjects: Densitometry; Dental caries; Dental Caries - diagnosis; Dental Enamel - anatomy & histology; Dentistry; Diagnosis; Humans; Ultrasonography - instrumentation; Ultrasonography - methods; Ultrasound; Dental caries; Ultrasound; Diagnosis
• ISSN: 0300-5712; 1879-176X
• DOI: 10.1016/0300-5712(88)90070-X

Ultrasonic imaging of unblemished and artificially demineralized enamel in extracted human teeth was investigated using ultrasound of 18 MHz centre frequency. Double-blind experiments were performed on extracted permanent teeth which had two small ‘window’ areas on their labial enamel surfaces demineralized in 6 per cent hydroxyethylcellulose gel for 1, 3 or 7 days, to produce lesions analogous to early dental caries. The degree of demineralization was determined from densitometry of contact microradiographs of sections of the cervical half of each specimen. The incisal halves were separately scanned by the ultrasound pulse-echo technique to obtain blind and independent acoustic information on the degree of demineralization. Artificial enamel lesions with less than 57 per cent mineral content (where intact enamel = 100 per cent on microradiographs) in the body of the lesion can be differentiated acoustically from intact enamel on the basis of relative amplitude changes of the enamel surface echo and the amelodentinal junction (ADJ) echo. An apparent correlation exists between the mineral content of the body of the lesion and the relative echo amplitude changes, and is explained by changes in specific acoustic impedance. It is hypothesized that the profile of the carious lesion may be deduced from time-of-flight graphs of the enamel surface echo and the ADJ echo.