In-vitro investigations on the hard tissue ablation quality and efficiency of the diode pumped Er:YAG laser with a new temporal pulse regime

For some time now, the diode-pumped Er:YAG laser (Pantec Biosolutions AG) has been available. Due to its high repetition rate of up to 2 kHz, it shows an excellent cutting quality and efficiency in soft tissue. Now, due to the novel special pulse regime, significantly longer effective pulse duration and higher pulse energy of up to 1.5 J is available. The aim of the present study was to evaluate the ablation quality, efficiency and thermal side effects of the new pulse regime. For this purpose, in-vitro experiments were performed on slices of teeth and pig bones with varying laser irradiation parameters. The laser beam was coupled into a sapphire fiber and the fiber end was imaged onto an 800 µm spot on the sample. The sample was shifted with a computer-aided movement unit at different speeds during irradiation. A water spray with 6 ml/min was used for moistening. After irradiation, the resulted ablation quality was recorded under the light microscope and the ablation depth and width were measured. The ablation efficiency in super pulse mode is comparable on enamel and exceeds the values in dentin for standard pulse mode. The maximum ablation efficiency on bone is 0.20 mm3/J and is on average approx. 18,2% above the values achieved in standard operation. The ablation quality and the thermal injury achieved with the novel pulse regime is comparable to the results obtained with the standard operation of the diode-pumped Er:YAG laser. Overall, the tests show that the diode-pumped Er:YAG laser with the novel pulse regime and higher effective pulse energy allows larger spot size and with this more homogeneous ablation.