Abstract: Objective:?To study the deposition and its distribution of light energy in dental tissue under different laser input modes and establish the qualitative relationship between laser input parameters and the temperature rise distribution in dental tissue. Methods:?Based on the Pennes equation of bio-heat transfer, a heat transport model of the dental tissue irradiated by Er: YAG laser was constructed, in which the layered structure and the heat exchange between the outer surface and surrounding environment was considered. By means of the finite difference method, the time-space distribution properties of temperature rise in dental tissue under different laser input modes were numerically simulated and compared. Results:?The change of the input modes of laser energy (pulse power, pulse width, pulse number and pulse interval) has a significant effect on the temperature rise of dental tissue, and this effect decreases gradually with the increase of depth. Under the premise that the total input energy is fixed, the effect of the change of input modes is only concentrated near the irradiation surface, but has almost no effect on the temperature rise of the pulp cavity wall. In addition, the heat exchange between the outer surface and surrounding environment will inhibit the temperature rise of the dental tissue to a certain extent and accelerate its cooling process. Conclusions:?The laser input method has an important effect on the temperature rise of the dental tissue, and the heat exchange between the external surface and the environment should be considered before and after the process with the dental tissue.

Key words: Er: YAG laser, layered dental tissue, photo-thermal action, Pennes equation of bio-heat transfer, surface heat exchange