Assessment of Tooth Structure Using Laser Based Ultrasonics
Dental health care and research workers require a means of imaging the structures within teeth in vivo. For example, there is a need to image the margins of a restoration for the detection of poor bonding or voids between the restorative material and the dentin. With conventional x-ray techniques, it is difficult to detect cracks and to visualize interfaces between hard media. This is due to the x-ray providing only a 2 dimensional projection of the internal structure (i.e. a silhouette). In addition, a high resolution imaging modality is needed to detect tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated which can help the tooth to re-mineralize itself. Currently employed x-ray imaging is incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration with a synthetic material. Other clinical applications include the visualization of periodontal defects, the localization of intraosseous lesions, and determining the degree of osseointegration between a dental implant and the surrounding bone.
The Johns Hopkins University Applied Physics Laboratory has developed a means of assessing the internal structure of the tooth based upon use of high frequency, highly localized ultrasound generated by a laser pulse. Optical interferometric detection of ultrasound, a complementary technique with a very small detection footprint, has also been researched. Initial results using laser-based ultrasound for assessment of dental structures have been completed. Ultrasonic measurements showed that high-frequency ultrasound were clearly able to resolve the interfaces between the different layers. Measurements were also taken on a human bicuspid with an amalgam restoration. Interfaces within the human bicuspid were clearly visible.
Patent Status: U.S. patent(s) 7285091 issued. International patents issued.
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