The Infulence of Water Layer Thickness on Microstructure Changes of Bone Tissue Ablated with Pulse CO2 Laser: An SEM Evaluation

The objective of this study was to evaluate the influence of different thickness of water layer on microstructure changes of bone tissue irradiated by pulse CO₂ laser. Bovine shank bone was divided into four groups randomly for laser irradiation: without water layer and with a static water layer applied to target tissue surface at thickness of 0.4, 0.8 and 1.2 mm. The wavelength used in the study was 10.64 μm with pulse repetition rate of 60 Hz. The energy density was 50 J/cm² and the beam diameter of about 400 μm. The microstructure changes of ablation grooves were examined and compared with scanning electron microscope (SEM). It shows that the addition of water layer applied to target tissue surface actually mediated the interaction of laser with tissue and took an important role in microstructure changes. There was a critical thickness of water layer for a given radiant exposure to obtain regular cut profile with sharp-cut edge and smooth inner wall surface.