Pilot Ex Vivo Study of Laser-Induced Breakdown Spectroscopy to Detect Bone Dehydration: An Approach for Irrigation Feedback in Laserosteotomy

A successful laserosteotome should cut the bone without inducing thermal damage to the surrounding tissue, otherwise the healing process will be prolonged. To avoid such thermal damage, laserosteotomes typically employ an irrigation system with a pre-defined flow rate of cooling water. If this pre-defined flow rate is insufficient, for any reason, the laser beam will induce thermal damage by first dehydrating and then carbonizing the tissue. On the other hand, a too high water flow rate will result in lower ablation rates since the laser beam first needs to ablate the extra water before cutting bone, especially with lasers that water has a high absorption peak in their wavelengths, like Er:YAG and CO2. While a feedback mechanism detecting carbonization has been demonstrated in literature already, it would be desirable to detect possible dehydration at an earlier stage (underirrigation) where the tissue damage is still negligible. This pilot study evaluates the applicability of laser-induced breakdown spectroscopy (LIBS) to detect bone dehydration already at its onset. The results confirmed a good accuracy of over 89 % (cross-validated) in classifying normal and dehydrated bone.