Study on Dental Treatment with YAG Laser (1st Report): Temperature of Dental Tissue Irradiated with Laser Beam
- Publisher: 精密工学会 = The Japan Society for Precision Engineering
精密工学会誌 = Journal of the Japan Society of Precision Engineering,
dental treatment | Nd:YAG laser | temperature measurement | two-color pyrometer | finite element method | decayed tooth
mesheuropmc: stomatognathic diseases | stomatognathic system
The flash temperature of a dental hard tissue irradiated with pulsed Nd:YAG laser is measured using a two-color pyrometer with an optical fiber. This pyrometer consists of a chalcogenide optical fiber and a laminated infrared detector. The influence of the laser power on the temperature of the dental tissue is investigated, and the relationship between the laser power and the removal volume of the dental tissue is obtained. In order to examine the thermal damage on the dental tissue, hardness and bending strength of the tissue are measured after being heated electrically at various temperatures. FEM thermal analysis is conducted to estimate the temperature distribution in a teeth and to discuss the influence of heat flux on the dental pulp. The results obtained are as follows. The appearance of the tissue begins to change at about 150°C and its hardness decreases with the increase of temperature. Its bending strength starts to decrease at about 50°C. Only the carious tissue can be removed from the cavity due to the large difference of energy absorptivity between the tissue and the carious one. It is possible to protect the dental pulp from thermal damage, because the temperature gradient in the teeth is very steep due to the small thermal conductivity of the dental tissue.