TY - JOUR
T1 - Mechanism of dye-enhanced enamel ablation by Alexandrite laser radiation
AU - Esenaliev, Rinat O.
AU - Oraevsky, Alexander A.
AU - Motamedi, Massoud
AU - Rastegar, Sohi
AU - Tittel, Frank K.
N1 - Funding Information:
This work is supported by The Whitaker Foundation and The Department of Energy Centers of
Funding Information:
This work is supported by The Whitaker Foundation and The Department of Energy Centers of Excellence Grant. The authors would like to thank Brent Bell and Erin Jennett of the University of Texas Medical Branch and David Ladd of the University of Texas Houston Health Science Center, Dental Branch for their technical assistance
Publisher Copyright:
© 1995 SPIE. All rights reserved.
PY - 1995/5/22
Y1 - 1995/5/22
N2 - Insufficient light absorption in hard dental tissues makes laser ablation in near UV, visible or near IR spectral ranges very inefficient to be employed for tooth cavity preparations. We used deposition of a liquid absorber, indocyanine green (ICG) dye, to overcome this problem. Experiments employed Alexandrite laser anticipation that future near IR diode laser technology will replace existing medical lasear. Ablation kinetics and mechanisms for both free-running and Q-switched modes of Alexandrite laser were studied with the aim to determine optimal parameters of laser irradiation and optimal volume of the dye. Four experimental parameters were monitored during each ablation event: (1) incident laser fluence, (2) temporal profile of the laser pulse, (3) temporal profile and magnitude of laser-induced stress transients, (4) temporal profile and spectrum of plasma emission. We also examined kinetics of plume by probing ablation products with CW He-Ne laser beam. Result depicted ablation process as a complex multistage phenomenon. Two distinct stages associated with the tooth ablation are revealed in the free-running mode: (1) ablation of a dye droplet from a tooth surface by the first laser micropulse of a 250-μs micropluse, (2) plasma mediated ablation of a melted layer of enamel produced by thermal explosion of the dye. Plasma jet formation was delayed 10-100 μs against the beginning of free-running pluse. Ablation stages and their efficiency are defined by laser irradiation parameters, dye concentration and its total volume. In contrast, Q-switched (nanosecond) laser ablation occurs as a one stage process, and, therefore, less efficient. In addiation, Q-switched mode irradiation induces shock waves amplitudes that are about an order of magnitude higher compared with that induced by the free-running irradiation. Experimental comparison of Q-switched and free-running modes of irradiation is evident in favor of free-running mode that produces a nice smooth crater without noticeable thermomechanical damage to surrounding tissues.
AB - Insufficient light absorption in hard dental tissues makes laser ablation in near UV, visible or near IR spectral ranges very inefficient to be employed for tooth cavity preparations. We used deposition of a liquid absorber, indocyanine green (ICG) dye, to overcome this problem. Experiments employed Alexandrite laser anticipation that future near IR diode laser technology will replace existing medical lasear. Ablation kinetics and mechanisms for both free-running and Q-switched modes of Alexandrite laser were studied with the aim to determine optimal parameters of laser irradiation and optimal volume of the dye. Four experimental parameters were monitored during each ablation event: (1) incident laser fluence, (2) temporal profile of the laser pulse, (3) temporal profile and magnitude of laser-induced stress transients, (4) temporal profile and spectrum of plasma emission. We also examined kinetics of plume by probing ablation products with CW He-Ne laser beam. Result depicted ablation process as a complex multistage phenomenon. Two distinct stages associated with the tooth ablation are revealed in the free-running mode: (1) ablation of a dye droplet from a tooth surface by the first laser micropulse of a 250-μs micropluse, (2) plasma mediated ablation of a melted layer of enamel produced by thermal explosion of the dye. Plasma jet formation was delayed 10-100 μs against the beginning of free-running pluse. Ablation stages and their efficiency are defined by laser irradiation parameters, dye concentration and its total volume. In contrast, Q-switched (nanosecond) laser ablation occurs as a one stage process, and, therefore, less efficient. In addiation, Q-switched mode irradiation induces shock waves amplitudes that are about an order of magnitude higher compared with that induced by the free-running irradiation. Experimental comparison of Q-switched and free-running modes of irradiation is evident in favor of free-running mode that produces a nice smooth crater without noticeable thermomechanical damage to surrounding tissues.
KW - Ablation efficiency
KW - Cracks
KW - Dental tissues
KW - Laser drilling
KW - Microjet system
KW - Shock waves
UR - http://www.scopus.com/inward/record.url?scp=33745332664&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33745332664&partnerID=8YFLogxK
U2 - 10.1117/12.209899
DO - 10.1117/12.209899
M3 - Conference article
AN - SCOPUS:33745332664
SN - 0277-786X
VL - 2391
SP - 327
EP - 335
JO - Proceedings of SPIE - The International Society for Optical Engineering
JF - Proceedings of SPIE - The International Society for Optical Engineering
T2 - Laser-Tissue Interaction VI 1995
Y2 - 1 February 1995 through 8 February 1995
ER -