ISSN (print):1855-9913 | ISSN (web): 1855-9921
Investigation of the Existence of an Electromagnetically Induced Mechanical Cutting Mechanism with Er:YAG Lasers
M. Lukac, T. Suhovrsnik, C. Filipic
Erbium lasers are well suited for the thermal cutting of hard dental tissues due to the very high absorption of their wavelengths in water, which is an important constituent of hard dental tissue. The thermal cutting mechanism is based on the absorption of laser light within the water contained in the target. There has been an additional cutting mechanism proposed, which is not based on a thermal cutting process but on an external water-spray's "electromagnetically induced mechanical cutting" of the target surface. In order to detect this mechanism, Erbium laser energy in combination with a water spray was directed to various non-porous targets with no internal water content, which were transparent to the Er:YAG laser wavelength. In the absence of thermal cutting, any observed cutting of the tested targets would demonstrate the possible presence of disruptive forces caused by an electromagnetically-induced cutting mechanism. No evidence of the cutting effect was observed on a broad range of non-porous, optically transparent targets under a wide range of laser pulse durations, pulse energies and water spray conditions. Similarly, measurements of the Er:YAG laser cutting efficacy on hard dental tissues, cementum and enamel demonstrated the highest cutting speed in the absence of water spray, i.e., in the absence of any interaction of the water fluid particles with the optical energy. This proves that the Er:YAG cutting of hard dental tissues is based on the heating up of interstitially trapped water within the hard dental tissue, and not on electromagnetically induced mechanical cutting caused by the interaction of optical laser energy with atomized water particles in the volume above the tissue surface.
Key words: Er:YAG laser, ablation, absorption, hardness, water.
Article: J. LA&HA, Vol. 2015, OnlineFirst. Received: August 21, 2015; Accepted: October 27, 2015