engleski

Temperature rise in human tooth upon drilling by femtosecond pulses

Thanks to increased availability of ultrashort lasers pulses (ps and fs) there are numerous studies dealing with ultrashort laser interaction with hard dental tissue which could lead to replacement of mechanical drills. In our research we employed fs pulses generated in a Ti:Saphire amplifier with pulse length of 120 fs at 800 nm and with 1 kHz pulse repetition to form cavity in a tooth sample. Simultaneously with formation of cavity we measured the temperature with thermocouple at the place where the dental pulp was and numerically modelled the heat transfer in order to assess safe parameters for future employment of fs laser for hard dental tissue preparation. Compared to previous work, we used lower repetition rates and slower scanning speeds. We used finite element analysis to develop fully three-dimensional heat conduction model with associated boundary conditions. Values of the thermophysical properties are taken from literature. Fourier’s heat conduction equations were used. We modeled the incident heat flux from the laser as a moving spatially distributed volumetric heat source where we used the known value for the optical penetration depth in dentine and Beer-Lambert law to model incident heat flux in the direction normal to the incident top surface. The conditions for safe operating are found and can be checked by altering dimensions, powers, and scanning speeds in our model. This work can contribute to assessment of the use of fs lasers in restorative dentistry

ultrashort pulses ; laser ablation ; dental applications

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