engleski

Femtosecond Laser for Cavity Preparation: Temperature Measurement

Objectives Ultra-short laser pulses have the potential for ablation of various materials without thermal damage and with high precision which makes them very convenient tool in many applications. The main advantages of material structuring by ultra-short pulses are localized energy deposition, well-defined ablation thresholds and limited heat diffusion into material. Precise drilling, sufficient material removal rate (mm3 /s) and low temperature rise in tooth pulp (less than 5 K) are main prerequisite to using femtosecond laser (fs) in cavity preparation. Most of the studies so far dealt with evaluating ablation efficiency in dentin and enamel and very few with heat transfer to tooth tissue. Methods The fs pulses used in this study were generated in a Ti: Saphire amplifier with pulse length of 120 fs at 800 nm and with 1 kHz pulse repetition. The laser light is directed through a microscopic objective onto the tooth sample which were mounted on computer controlled XY translation stage. The tooth samples were prepared by diamond blade saw and thermocouple of small diameter was inserted where the pulp used to be. Simultaneously with rectangular scanning of the sample the temperature was monitored at 10 times per second rate. Results Several rectangular holes in dentin and enamel were drilled using different scanning speeds and laser intensities in order to measure temperature rise and find optimal parameters for practical use of fs laser in restorative dentistry. Temperature inside pulp chamber depended on different laser intensities and ranged between 1, 5 – 3, 7 °C. Conclusions Fully three-dimensional heat conduction model with associated boundary conditions by employing finite element analysis was developed in this study. Fourier’s heat conduction equations were used with thermophysical constants from literature. Ultra-short laser pulses can be safely used for cavity preparation.

Femtosecond Laser, Cavity preparation

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