RESUMEN
The microsecond Er:YAG pulsed laser with a wavelength of λ = 2.94 µm has been widely used in the medical field, particularly for ablating dental tissues. Since bone and dental tissues have similar compositions, consisting of mineralized and rigid structures, the Er:YAG laser represents a promising tool for laserosteotomy applications. In this study, we explored the use of the Er:YAG laser for deep bone ablation, in an attempt to optimize its performance and identify its limitations. Tissue irrigation and the laser settings were optimized independently. We propose an automated irrigation feedback system capable of recognizing the temperature of the tissue and delivering water accordingly. The irrigation system used consists of a thin 50 µm diameter water jet. The water jet was able to penetrate deep into the crater during ablation, with a laminar flow length of 15 cm, ensuring the irrigation of deeper layers unreachable by conventional spray systems. Once the irrigation was optimized, ablation was considered independently of the irrigation water. In this way, we could better understand and adjust the laser parameters to suit our needs. We obtained line cuts as deep as 21 mm without causing any visible thermal damage to the surrounding tissue. The automated experimental setup proposed here has the potential to support deeper and faster ablation in laserosteotomy applications.
RESUMEN
A novel real-time and non-destructive method for differentiating soft from hard tissue in laser osteotomy has been introduced and tested in a closed-loop fashion. Two laser beams were combined: a low energy frequency-doubled nanosecond Nd:YAG for detecting the type of tissue, and a high energy microsecond Er:YAG for ablating bone. The working principle is based on adjusting the energy of the Nd:YAG laser until it is low enough to create a microplasma in the hard tissue only (different energies are required to create plasma in different tissue types). Analyzing the light emitted from the generated microplasma enables real-time feedback to a shutter that prevents the Er:YAG laser from ablating the soft tissue.