Laser-induced photothermal technique used for detection of caries in human tooth

Ashraf F. El-Sherif; Yasser H. El-Sharkawy M.D.

doi:10.1117/12.759157

11 February 2008 Laser-induced photothermal technique used for detection of caries in human tooth

Ashraf F. El-Sherif, Yasser H. El-Sharkawy M.D.

Proceedings Volume 6843, Lasers in Dentistry XIV; 68430B (2008) https://doi.org/10.1117/12.759157
Event: SPIE BiOS, 2008, San Jose, California, United States

Abstract

Thermal monitoring during laser-irradiated hard tissues is fundamental to enable real time feedback control and automated adjustment of laser power to maintain a constant, predetermined tissue temperature. We present an experimental technique to produce thermal wave generated in human tooth by irradiation of a high power Q-switched Nd:YAG laser operating at 1064 nm, with variable pulse energy in the range of 50-250 mJ/pulse providing laser fluences of 0.4-2 J/cm² for the laser beam with diameter of less than 1 mm, and short pulse duration down to 100 μsec (or 0.1 ms) at FWHM. A comparison of the measured time-dependent thermal wave for normal and carious human tooth using infrared thermal detector is investigated, simultaneously we have measure the photoacoustic response of the sample using piezoelectric transducer. Calculations of the results demonstrate that the faster temperature decay is for caries one with higher thermal conductivity and thermal diffusivity than the normal one. So the normal tooth has the largest absorption coefficient causing a purely surface heating effect, but for the carious one, the heat source resulting from the relatively low absorption coefficient does not resemble surface heating, but describes a heating effect extending some distance into the irradiated material. These results are in good agreement with the simultaneous measured photoacoustic response, so we can differentiate between the normal and carious ones.

Citation Download Citation

Ashraf F. El-Sherif and Yasser H. El-Sharkawy M.D. "Laser-induced photothermal technique used for detection of caries in human tooth", Proc. SPIE 6843, Lasers in Dentistry XIV, 68430B (11 February 2008); https://doi.org/10.1117/12.759157

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