The effects of CO2 laser and Nd:YAG with and without water/air surface cooling on tooth root structure: correlation between FTIR spectroscopy and histology.
Morphologic and chemical characterization of root surfaces treated with either the CO2 laser, Nd:YAG, or Nd:YAG with water/air surface cooling (Nd:YAG-C) was completed using scanning electron microscopy (SEM) and FTIR photoacoustic spectroscopy (FTIR/PAS). Specimens for morphologic analysis consisted of 20 extracted single rooted teeth unaffected by periodontal disease. The specimens were exposed at varying energy densities to a single pass of the laser. SEM examination revealed, for all lasers, a direct correlation between increasing energy densities and depth of tissue ablation and width of tissue damage. The Nd:YAG-C required higher energy densities than either the CO2 or Nd:YAG lasers to achieve the same relative depth of tissue ablation. Regardless of energy density, and in contrast with other laser types, areas treated with the Nd:YAG-C did not exhibit collateral zones of heat damage. Specimens for spectroscopic examination consisted of 12 disks, 6 x 2 mm, cut from debrided root surfaces of extracted, unerupted human molars. The spectral results indicate a substantial reduction in the absorption bands attributable to protein and an additional band at 2015 cm-1 in specimens exposed to the Nd:YAG without water. In the presence of water/air coolant, the band at 2015 cm-1 appears only at a substanially higher energy density. The spectra of the CO2 treated specimens, with the char layer present, show a significant reduction in the protein bands and additional bands at 2015 and 2200 cm-1, that are tentatively assigned to the cyanamide and cyanate ions, respectively. These results suggest a reaction of the organic matrix and mineral with laser exposure.
University of Missouri-Kansas City School of Dentistry, Department of Oral Biology 64108, USA.
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Cobb
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McCollum
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Wieliczka
D000162:Acoustics; D003739:Dental Cementum / Q000293:injuries / Q000528:radiation effects* / Q000648:ultrastructure; D003777:Dental Prophylaxis / Q000295:instrumentation*; D006801:Humans; D007834:Lasers / Q000009:adverse effects*; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D007507:Therapeutic Irrigation; D014092:Tooth Root / Q000737:chemistry / Q000528:radiation effects* / Q000648:ultrastructure