Evaluation of Er:YAG Laser Interaction With Dentin and Enamel Hard Tissues

Pulsed Er:YAG lasers is an effective instrument to drill hard dental tissues. This article evaluates the effect of Er:YAG (2.94 µm) laser on both dentin and enamel hard tissues.
The current study aimed to evaluate the exact depth of ablation and effective ablation area on dental hard tissues, in different conditions and various factors of Er:YAG laser.
Patients and In this research, a total of 20 human molar teeth were irradiated by Er:YAG (2.94 µm) laser, after mounting process and sterilization.
Half of them were used as enamel samples and the rest, after removing the enamel tissue from their crowns, were used as dentin samples. The crowns of the samples were regarded as cube with all their lateral sides and were exposed by one special setting of the laser. Laser Irradiation was done in two different frequencies and all the procedure was accompanied by water cooling. The number of 100 pulses was selected as a fixed factor; therefore, 11 holes for all enamel and dentin samples were obtained. The hole images were taken by combining optical and computer methods, and then by processing them in MATLAB software, the depth of ablation and effective ablation area were calculated.
After evaluating the exact amounts of ablation depth and effective ablation area and analyzing the data, it was found that increasing energy yields in increasing the depth of ablation, which was the case for both enamel and dentine tissues. It was also found that variations in effective ablation area were insignificant for both tissues. Ablation depth and effective ablation area were more tangible in dentin rather than enamel tissues. Finally, using this laser did not result in blunt and clear borders for the created holes.
Application of the Er:YAG laser for hard tissue removal and cavity preparation, compared to conventional methods, is considered as a more comfortable technique because there isn’t any contact between laser beam and teeth. Secondly there is no vibration. However, this procedure is not recommended without water cooling.