Comparative In-Vitro Investigations On The Cutting Quality Of The Co2 Laser And The Diode Pumped Er:Yag Laser

The CO2 laser has proved its worth in daily clinical use for soft tissue surgery because of the good cutting quality. Now DPSS Er:YAG laser systems are available, which promise a better cutting efficiency and minor thermal damages. Goal of this study was the comparison of both laser systems for soft tissue cutting.Firstly, an experimental set-up was realized with a clinical CO2 laser system with micromanipulator and focusing unit. The Er:YAG laser system was an experimental set-up (DPM40, Pantec Biosolutions AG) with focusing unit in order to achieve the same spot diameter (500 mu m). For both, a computer-controlled translation stage with sample holder was used to move the sample (mucosa of fresh porcine tongues) with a defined velocity while irradiation by various laser parameters. Additionally, for the Er:YAG laser system, the influence of the laser power, cutting velocity, and pulse repetition rate on to the cut depth and thermal damage was examined. While irradiation the tissue effects were recorded by a video camera, adapted on a surgical microscope. After irradiation, the samples were analyzed by light microscopy. Also, histological sections were prepared and microscopically analyzed.The Er:YAG laser shows higher cutting depth (about 1 mm (Er:YAG) compared to 500 mu m (CO2) at 7.7 W and 5 mm/s) and less coagulation damage (about 70 mu m compared to 120 mu m). Both the cutting depth and thermal damage zone can be adjusted in a wide range by varying the irradiation parameters.In conclusion, these experiments demonstrate significant advantages of the diode pumped Er:YAG laser system for soft tissue cutting compared to the CO2 laser, in particular it is more efficient and causes minor thermal damage.