Hard tissue ablation with a free running Er : YAG and a Q-switched CO2 laser: a comparative study

The Er:YAG and the CO2 laser are competitors in the field of hard tissue ab lation. The use of Er:YAG lasers (2.93 mum, pulse length tau (L) of 100 to 200 mus) show smaller areas of thermal defects then "superpulsed" CO2 laser s with pulse lengths of approximately 100 mus. Only the development of a Q- switched CO2 laser (9.6 mum, tau (L) = 250 ns) allowed for similar results. In this paper new results for the Er:YAG and the Q-switched CO2 laser unde r the influence of water spray will be presented, Several parameters are of special interest for these investigations: the specific ablation energy, w hich shows a minimum for the CO2 laser at an energy density of 9 J/cm(2) an d a broad shallow minimum in the range of 10 to 70 J/cm(2) for the Er:YAG l aser, and comparison of the cut-shape and depth. Surface effects and cuttin g velocity are discussed based on SEM pictures.