Real-Time Monitoring of the Surface Modification of Root Dentin Using MIR-FEL-Induced Acoustic Waves

Abstract

For a non-invasive laser 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 have discussed the applicability of PAS technique to in vivo monitoring during laser treatment. Temporal behaviors of laser-induced acoustic waves were measured with an audible microphone. The extent of the surface modification, such as morphological and chemical changes, was evaluated by using information on the ablation depth and absorption spectrum of the irradiated dentins. The morphological and chemical changes of the irradiated dentin are respectively available for caries removal and increased acid resistance for root surface caries therapy. From the observations, it was found that time-resolved measurement of acoustic waves leads to a real-time understanding on the extent of the morphological change of the irradiated dentin. We have demonstrated the applicability of an in vivo monitoring technique involving PAS for root surface caries therapy.