Accurate determination of the optical properties of dental enamel is important for modeling the energy redistribution of laser radiation incident on the tissue. The high absorption coefficients of dental enamel in the mid-IR preclude the use of conventional transmission methods for the determination of optical properties, therefore non- conventional methods must be used. Enamel was irradiated with 9.3 micrometers , 9.6 micrometers , 10.3 micrometers , and 10.6 micrometers light from a CO₂ laser with a pulse duration of approximately 100 microsecond(s) . Samples were irradiated with fluences up to 2 J/cm². These fluences produce temperature excursions below the melting point for the tissue. Surface temperatures were monitored using time resolved radiometric measurements with 1 microsecond(s) temporal resolution. A 1D heat conduction model was used to estimate the temperature increase in enamel. By varying the absorption coefficient, the model temperature versus time profile was fitted to the experimental profile. The absorption coefficients of enamel were found to fall well below values in the literature determined using angular-resolved reflectance measurements at the same wavelengths. The new absorption coefficients were used in our heat conduction model to determine temperature excursions below the surface of the tooth. This study is a vital step in determining the optimum laser parameters for caries preventive treatments.

Date Published: 15 May 1997
PDF: 8 pages
Proc. SPIE 2973, Lasers in Dentistry III, (15 May 1997); doi: 10.1117/12.273596

Published in SPIE Proceedings Vol. 2973:
Lasers in Dentistry III
Harvey A. Wigdor D.D.S.; John D. B. Featherstone; Peter Rechmann D.D.S., Editor(s)