Theoretical investigation of opto-thermal transfer in human dentine irradiated by Nd：YAG laser

The major concern during laser irradiation of teeth is the high potential of tissue overheating resulting high temperatures that can spread in toward the dentin,causing irreversible damage to cells presented in the pulp chamber and leading to cell death,so the related laser irradiation parameters should be controlled strictly.The thermal diffusion model in dentin is built and the distribution of temperature field at the surface and subsurface region of dentin irradiated by Nd:YAG laser with different parameters is simulated numerically using Crank-Nicolson finite differential method.Calculation results show that the final temperature at the surface of dentin and at the pulp chamber wall depends on the pulse duration,interval and numbers.Laser irradiation by dividing total energy into several laser pulses leads to lower temperature at the dentin surface,while the reverse situation occurs at pulp region,the higher temperature is achieved with increasing pulse numbers.The related opto-thermal mechanism is discussed and it is put forward that controlling the energy of the single laser pulse is the optimum measure for opto-thermal ablation of dentin.