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Proceedings Paper

Mass spectrometric analysis of evolved CO2 during 9.6-um CO2 irradiation of dental enamel
Author(s): John Xie; Daniel Fried
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Paper Abstract

Carbon dioxide laser irradiation induces chemical changes in dental hard tissues including, dehydration, decomposition, disproportionation, and vaporization. Such changes can lead to either an increase or decrease in susceptibility to acid dissolution and adversely affect the bond strength to restorative materials. The objective of this study was to measure the evolved molecular species produced during laser irradiation. Samples of bovine enamel were irradiated by a 9.6 micrometers TEA CO2 laser in a vacuum chamber connected to a quadruple mass spectrometer. At irradiation intensities above 0.37 J/cm2 an increase in evolved CO2 and H2O were detected indicative of thermal decomposition of the mineral phase. The respective ion yields changed markedly with increasing number of laser pulses suggesting that the decomposition was complete after less than ten laser pulses at irradiation intensities from 0.4 to 0.8 J/cm2. Above irradiation intensities of 1.0 J/cm2 there is continual emission after 50 laser pulses indicative of vaporization and material removal. At higher ablative fluence, higher mass species were detected due to the ejection of hydroxyapatite. This study demonstrates that mass spectroscopy can be used to directly probe laser induced physical and chemical changes in dental hard tissue during laser ablation.

Paper Details

Date Published: 3 June 2002
PDF: 5 pages
Proc. SPIE 4610, Lasers in Dentistry VIII, (3 June 2002); doi: 10.1117/12.469325
Show Author Affiliations
John Xie, Univ. of California/San Francisco (United States)
Daniel Fried, Univ. of California/San Francisco (United States)

Published in SPIE Proceedings Vol. 4610:
Lasers in Dentistry VIII
Peter Rechmann D.D.S.; Daniel Fried; Thomas Hennig, Editor(s)

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