Mechanism of dye-enhanced enamel ablation by Alexandrite laser radiation

Rinat O. Esenaliev, Alexander A. Oraevsky, Massoud Motamedi, Sohi Rastegar, Frank K. Tittel

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)327-335
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - May 22 1995
EventLaser-Tissue Interaction VI 1995 - San Jose, United States
Duration: Feb 1 1995Feb 8 1995


  • Ablation efficiency
  • Cracks
  • Dental tissues
  • Laser drilling
  • Microjet system
  • Shock waves

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Mechanism of dye-enhanced enamel ablation by Alexandrite laser radiation'. Together they form a unique fingerprint.

Cite this