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Journal of Biomedical Optics

Rapid and conservative ablation and modification of enamel, dentin, and alveolar bone using a high repetition rate transverse excited atmospheric pressure CO2 laser operating at λ=9.3 μm
Author(s): Kenneth Fan; Paul W. Bell; Daniel Fried
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Paper Abstract

Transverse excited atmospheric pressure (TEA) CO2 lasers tuned to the strong mineral absorption of hydroxyapatite near λ=9 μm are well suited for the efficient ablation of dental hard tissues if the laser pulse is stretched to greater than 5 to 10 μs to avoid plasma shielding phenomena. Such CO2 lasers are capable of operating at high repetition rates for the rapid removal of dental hard tissues. The purpose of this study was to test the hypothesis that stretched λ=9.3-μm TEA CO2 laser pulses can produce lateral incisions in enamel, dentin, and alveolar bone for dental restorations and implants at repetition rates as high as 400 Hz without peripheral thermal damage. The single pulse ablation rates through enamel, dentin, and bone were determined for incident fluence ranging from (1 to 160 J/cm2) for laser pulses from 5 to 18 μs in duration. Lateral incisions were produced in hard tissue samples using a computer-controlled scanning stage and water spray, and the crater morphology and chemical composition were measured using optical microscopy and high-resolution synchrotron radiation infrared spectromicroscopy. The residual energy remaining in tooth samples was measured to be 30 to 40% for enamel and 20 to 30% for dentin without water cooling, under optimum irradiation intensities, significantly lower than for longer CO2 laser pulses. The transmission through 2-m length 300-, 500-, 750-, and 1000-µm silica hollow waveguides was measured and 80% transmission was achieved with 40 mJ per pulse. These results suggest that high repetition rate TEA CO2 laser systems operating at λ=9.3 μm with pulse durations of 10 to 20 μs are well suited for dental applications.

Paper Details

Date Published: 1 November 2006
PDF: 11 pages
J. Biomed. Opt. 11(6) 064008 doi: 10.1117/1.2401151
Published in: Journal of Biomedical Optics Volume 11, Issue 6
Show Author Affiliations
Kenneth Fan, Univ. of California/San Francisco (United States)
Paul W. Bell, Univ. of California/San Francisco (United States)
Daniel Fried, Univ. of California/San Francisco (United States)

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