Mass spectrometric analysis of evolved CO2 during 9.6-um CO2 irradiation of dental enamel

John Xie; Daniel Fried

doi:10.1117/12.469325

3 June 2002 Mass spectrometric analysis of evolved CO₂ during 9.6-μm CO₂ irradiation of dental enamel

John Xie, Daniel Fried

Proceedings Volume 4610, Lasers in Dentistry VIII; (2002) https://doi.org/10.1117/12.469325
Event: International Symposium on Biomedical Optics, 2002, San Jose, CA, United States

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.

Citation Download Citation

John Xie and Daniel Fried "Mass spectrometric analysis of evolved CO₂ during 9.6-μm CO₂ irradiation of dental enamel", Proc. SPIE 4610, Lasers in Dentistry VIII, (3 June 2002); https://doi.org/10.1117/12.469325

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