The Temperature Changes in the Pulp Chamber During Cavity Preparation with the Er:YAG Laser Using a Very Short Pulse

Objective: The aim of this study was to examine the temperature changes in the pulp chamber during cavity preparation with the Er:YAG laser (2940 nm) with a very short pulse (VSP). Materials and Methods: Nine groups of 10 intact molars each were used. One root of each sample was amputated and a thermocouple was inserted into the chamber. Class V cavity preparation in enamel was performed, and then preparation was performed in dentine. The enamel was lased with 400, 360, and 320 mJ in contact mode using a VSP with a duration of 100 mu sec. The diameter of the fiber tip was 950 mu m. Frequencies of 10, 12, and 15 Hz were used, and the total time of irradiation was 10 sec. The dentine was irradiated with 340, 280, and 200 mJ at 10, 8, and 5 Hz for 7 sec. Cooling was done with a water spray (73 psi and 50 mL/min). The differences were tested by MANOVA and the Bonferroni post hoc test. Results: The highest rise in temperature in the pulp was achieved after enamel irradiation with 400 mJ and 15 Hz (1.99 +/- 0.28 degrees C), and the lowest was after irradiation with 320 mJ and 10 Hz (0.70 +/- 0.18 degrees C). In dentine the highest temperature increase was achieved with 340 mJ and 10 Hz (1.37 +/- 0.42 degrees C), and the lowest was with 200 mJ and 5 Hz (0.43 +/- 0.18 degrees C). Two-way analysis of both enamel and dentine showed that the influence of energy on temperature increase was stronger than that of frequency. Conclusion: Cavity preparation with an Er:YAG laser using VSP mode in vitro did not cause significant increases in temperature in the pulp chamber of human molars.