Proceedings Article | 28 February 2008
Proc. SPIE. 6856, Photons Plus Ultrasound: Imaging and Sensing 2008: The Ninth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics
KEYWORDS: Minerals, Optical amplifiers, Dental caries, Modulation, Teeth, Tissues, Luminescence, Phase shift keying, Infrared radiation, Radiometry
Photothermal radiometry (PTR) and modulated luminescence (LUM) were applied to detect and monitor the
demineralization of root and enamel surfaces of human teeth to produce caries lesions and the subsequent
remineralization of the produced lesions. The experimental set-up consisted of a semiconductor laser (659 nm, 120 mW),
a mercury-cadmium-telluride IR detector for PTR, a photodiode for LUM, and two lock-in amplifiers. A lesion was
created on a 1-mm × 4-mm rectangular window, spanning root to enamel surface, using an artificial caries lesion gel to
demineralize the tooth surface and create small carious lesions. The samples were subsequently immersed in a
remineralization solution. Each sample was examined with PTR/LUM on root and enamel before and after treatment at
times from 1 to 10 days of demineralization and 2 to 10 days of remineralization. PTR/LUM signals showed gradual and
consistent changes with treatment time. At the completion of the experiments, transverse micro-radiography (TMR)
analysis was performed to correlate the PTR/LUM signals to depth of the carious lesions and mineral losses. In this
study, TMR showed good correlation with PTR/LUM. It was also found that treatment duration did not correlate well to
any technique, PTR/LUM, or TMR, which is indicative of significant variations in demineralization - remineralization
rates among different teeth.
