Numerical modelling and experimental study of femtosecond laser ablation on dental hard tissues

Ultrashort pulsed laser processing is well known for the precise removal of target tissue with less thermal effect which may be used as a non-invasive tool for tooth preparation in dentistry. However, optimizing the laser processing conditions beforehand is imperative to avoid excessive loss of tissue, preventing necrosis and nerve damage. The present work proposes a heat conduction model to simulate the femtosecond laser ablation profile and temperature field on the dental hard tissues (enamel and dentin). The model is developed based on the finite element simulation using COMSOL Multiphysics software. The present model is validated on enamel and dentin samples by comparing with the in vitro studies. The laser-tissue interaction is simulated for the dental hard tissues of 1.00 mm thickness using 2D heat conduction model. In order to compare the simulation results, a single scan laser irradiation experiments were carried out using 800 nm, 100 fs, Ti:Sapphire femtosecond laser at the scanning speed of 10 mm/s and repetition rate of 10 kHz. The surface morphology of the irradiated samples is measured by optical profiler and SEM images. The simulation and experimental results are compared and discussed. The proposed femtosecond laser ablation model can be used to understand the real-time ablation dynamics and also, to determine the temperature field as well as the ablation profile. The simulation can be handful tool for the clinician to optimise the laser processing conditions thus it will improve the precision of the laser surgery and reduce the nerve damage during tooth preparation.