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Q: Quantenoptik

Q 30: Poster: Laser in Medicine

Q 30.2: Poster

Friday, April 6, 2001, 12:30–15:00, AT2

Hard Tissue Ablation with a free running and Q-switched Erbium YAG and a CO₂ laser: a comparative study — •Rene Franzen¹, Joerg Meister^1,2, Maren Stanislawski¹, Thomas Mitra^1,3, Michail Ivanenko³, and Peter Hering^1,3 — ¹Institute for Lasermedicine - University of Duesseldorf — ²Department of Conservative Dentistry, Periodontology and Preventive Dentistry of the RWTH Aachen — ³Center for Advanced European Studies and Research (CAESAR)

Er:YAG and CO₂ lasers are competitors in the field of hard tissue ablation. The use of an Erbium laser (2.94 microns, pulse length 100-200 µs free running and 250 ns Q-switched) shows smaller areas of thermal damages than super-pulsed CO₂ lasers (9.6 microns and 250 ns pulse length). Similar results have been achieved with a Q-switched CO₂ laser (9.6 microns, 250 ns). In this poster, ablation experiments for both laser system are presented. Using a water spray which operates at rates of 3 to 10 ml per minute to prevent carbonization during laser irradiation, different parameters are compared. Among these the energy density shows a minimum at 9 J/cm² for the CO₂ laser and a broad minimum in the range of 10 to 70 J/cm² for the Er:YAG laser. Furthermore, the Er:YAG laser shows a lower specific ablation energy of 15 J/mm³ compared with 55 J/mm³ for the CO₂ laser. In addition, cut shape, cut depth, surface properties, and cut velocity will be discussed based on SEM-pictures. Areas of thermal and mechanical damage (destruction of cell nucleuses) are examined with histological images.