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Proceedings Paper

Analysis of peripheral thermal damage during the rapid ablation of dentin and bone using a λ= 9.3-μm TEA CO2 laser
Author(s): Paul W. Bell; Kenneth Fan; Robert S. Jones; Daniel Fried
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Paper Abstract

TEA CO2 lasers tuned to the strong mineral absorption of hydroxyapatite at λ =9-μm are ideally suited for the efficient ablation of dental hard tissues if the laser-pulse duration is stretched to greater than 10-μs to avoid plasma formation. CO2 lasers are capable of operating at high repetition rates for the rapid removal of dentin and bone. 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 dentin and bone for dental restorations and implants at repetition rates as high as 400-Hz without peripheral thermal damage. A high repetition rate, 0-500-Hz, λ =9.3-μm TEA CO2 laser with pulse durations of 10-20-μs was used to make incisions in human dentin and porcine alveolar bone with a computer controlled scanning stage and water spray at varying irradiation intensities. The single pulse ablation rates were determined for incident fluence ranging from 1-150-J/cm2. Lateral incisions 2-3-mm in length were produced in the 2-mm thick sections. Following irradiation, transverse cross-sections were examined using polarized light microscopy (PLM) and Fourier transform infrared spectro-microscopy (SR-FTIR) at the Advanced Light Source at Lawrence Berkeley National Laboratory. The single-pulse ablation rates approached 40-μm per pulse for the stretched TEA laser pulses in dentin and bone. All incisions with and without water spray yielded thermal damage zones of less than 22-μm. Thermal damage zones with water spray were less than 14-μm, even at repetition rates of 400-Hz and SR-FTIR showed no spectral changes around the periphery of the incisions. CO2 laser pulses at λ =9.3-μm of 10-20-μs duration are well suited for the precise removal of dentin and bone for dental restorations and implants at high repetition rates without peripheral thermal damage.

Paper Details

Date Published: 15 February 2006
PDF: 8 pages
Proc. SPIE 6137, Lasers in Dentistry XII, 61370G (15 February 2006);
Show Author Affiliations
Paul W. Bell, Univ. of California, San Francisco (United States)
Kenneth Fan, Univ. of California, San Francisco (United States)
Robert S. Jones, Univ. of California, San Francisco (United States)
Daniel Fried, Univ. of California, San Francisco (United States)

Published in SPIE Proceedings Vol. 6137:
Lasers in Dentistry XII
Peter Rechmann D.D.S.; Daniel Fried, Editor(s)

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