Optimizing deep bone ablation by means of a microsecond Er:YAG laser and a novel water microjet irrigation system

Lina M Beltrán Bernal; Ferda Canbaz; Antoine Droneau; Niklaus F Friederich; Philippe C Cattin; Azhar Zam

doi:10.1364/BOE.408914

Optimizing deep bone ablation by means of a microsecond Er:YAG laser and a novel water microjet irrigation system

Biomed Opt Express. 2020 Nov 19;11(12):7253-7272. doi: 10.1364/BOE.408914. eCollection 2020 Dec 1.

Authors

Lina M Beltrán Bernal^{1

2}, Ferda Canbaz¹, Antoine Droneau³, Niklaus F Friederich⁴, Philippe C Cattin⁵, Azhar Zam^{1

6}

Affiliations

¹ Biomedical Laser and Optics Group (BLOG), Department of Biomedical Engineering, University of Basel, CH-4123 Allschwil, Switzerland.
² lina.beltran@unibas.ch.
³ Grenoble INP; Grenoble Alpes University, Phelma, France.
⁴ Center of Biomechanics and Biocalorimetry (COB), Department of Biomedical Engineering, University of Basel, CH-4123 Allschwil, Switzerland.
⁵ Center for Medical Image Analysis and Navigation (CIAN), Department of Biomedical Engineering, University of Basel, CH-4123 Allschwil, Switzerland.
⁶ azhar.zam@unibas.ch.

Abstract

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.