Real-Time Monitoring of the Surface Modification of Root Dentin using Photoacoustic Spectroscopy and Photothermal Radiometry

摘要

For non-invasive laser dental treatment, a real-time and non-contact monitoring technique is needed. We have investigated the extent of the surface modification of root dentin using photoacoustic spectroscopy (PAS) and pulsed-photothermal radiometry (PPTR), and have discussed the applicability of each technology to in vivo monitoring during laser treatment. Root dentins were used as specimens. The wavelength, average power density, and exposure time used were varied within the ranges λ = 9.0-10.6 μm, P_(av) = 7-28 W/cm~2, and τ= 0-10 s, respectively. The temporal behaviors of the laser-induced acoustic waves and the temperature rise were measured with an audible microphone and a radiation thermometer, respectively. The extent of the surface modification was evaluated by using information on the ablation depth and the absorption spectrum of the irradiated dentin. The morphological and chemical changes of the irradiated dentin can be made available to assist in dentinal tubule sealing and increased acid resistance for root surface caries therapy. It was found that time-resolved measurements of the acoustic waves and the temperature are useful for a real-time understanding of the extent of the morphological and chemical changes, respectively. We have demonstrated the applicability of an in vivo monitoring technique using PAS and PPTR for root surface caries therapy.