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Proceedings Paper

Investigations of the damage mechanisms during ultrashort pulse laser ablation of dental tissue
Author(s): Matthias Domke; Sebastian Wick; Maike Laible; Stephan Rapp; Julia Kuznetsova; Christian Homann; Heinz P. Huber; Ronald Sroka
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Paper Abstract

Several investigations of dental tissue ablation with ultrashort pulsed lasers suggest that these lasers enable precise and selective material removal and reduce the formation of micro cracks and thermal effects, when compared to ns-pulses. In this study, two damage mechanisms are presented occurring during ablation of dentin using a laser emitting pulses of a duration of 380 fs at a wavelength of 1040 nm. First, it was found that nano cracks appear around the craters after single fs-pulse ablation. These cracks are directed to the crater and cross the dentinal tubules. Transient investigation of the single fs-pulse ablation process by pump-probe microscopy suggest that the driving mechanism could be a pressure wave that is released after stress confinement. Second, squared ablation holes were created by moving the laser focus at scan speeds between 0.5 mm/s and 2.0 m/s and fluences up to 14 J/cm2. It was found that deep cracks appear at the edges of the squared holes, if the scan speed is about 0.5 m/s. The fluence has only a minor impact on the crack formation. The crack propagation was investigated in the depth using x-ray micro tomography and optical coherence tomography. It was found that these cracks appear in the depth down to the dental pulp. These findings suggest that fast scanning of the laser beam is the key for damage free processing using ultrashort pulse lasers. Then, ablation rates of about 2.5 - 3.5 mm3/min/W can be achieved in dentine with pulse durations of 380 fs.

Paper Details

Date Published: 15 July 2015
PDF: 7 pages
Proc. SPIE 9542, Medical Laser Applications and Laser-Tissue Interactions VII, 95420Q (15 July 2015); doi: 10.1117/12.2184039
Show Author Affiliations
Matthias Domke, Vorarlberg Univ. of Applied Sciences (Austria)
Sebastian Wick, Munich Univ. of Applied Sciences (Germany)
Maike Laible, Klinikum der Univ. München (Germany)
Stephan Rapp, Munich Univ. of Applied Sciences (Germany)
Friedrich-Alexander-Univ. Erlangen-Nürnberg (Germany)
Julia Kuznetsova, Klinikum der Univ. München (Germany)
Christian Homann, Klinikum der Univ. München (Germany)
Heinz P. Huber, Munich Univ. of Applied Science (Germany)
Ronald Sroka, Munich Univ. of Applied Sciences (Germany)

Published in SPIE Proceedings Vol. 9542:
Medical Laser Applications and Laser-Tissue Interactions VII
Lothar D. Lilge; Ronald Sroka, Editor(s)

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