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Proceedings Paper

Nanomechanical properties of dentin treated with a CO2 laser for potential caries inhibition
Author(s): Stefan Habelitz; Daniel Fried; Charles Q. Le; John D. Featherstone
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Paper Abstract

The effect of pulsed CO2-laser treatments on the microstructure and nanomechanical properties was studied using atomic force microscopy and nanoindentation. The microstructure and roughness of dentin specimens treated by a 9.3 μm CO2 laser at fluences of 0.5; 0.75; 1.0; and 1.5 J/cm2 were evaluated and the elastic modulus and hardness before and after a nine days demin/remin application for laser treatments at 0.75 and 1.5 J/cm2 were determined. The hypothesis that CO2-laser-treatments reduce or inhibit the demineralization process was tested. Surface cracks were observed at fluences of 0.75 J/cm2 and higher. Surface roughness increased strongly after laser irradiation and was about 10 times higher at maximum fluence. Mechanical properties profiles from the laser treated surface to sound dentin showed increased modulus and hardness values at dentin surfaces treated, indicating removal of organic phases and reinforcement of the tissue by increased mineral content. Mechanical properties decreased after demin/remin application in all groups and the hardened surface layer disappeared for samples treated at 0.75 J/cm2. While increased properties were still observed in the laser affected surface zone for treatments at 1.5 J/cm2, demineralization was severe underneath these layers as indicated by a sharp drop in properties. The depth of demineralization was slightly decreased in the laser-treated group compared to the untreated controls. We conclude that CO2-laser treatments produce dentin surfaces with increased nanomechanical properties. These surface layers do not, however, provide protection against demineralization due to surface cracking and possible delamination. Moreover, the surface cracks induced by the laser-irradiation raise concerns about a clinical potential for caries inhibition in dentin.

Paper Details

Date Published: 27 February 2008
PDF: 7 pages
Proc. SPIE 6843, Lasers in Dentistry XIV, 684306 (27 February 2008); doi: 10.1117/12.778796
Show Author Affiliations
Stefan Habelitz, Univ. of California/San Francisco (United States)
Daniel Fried, Univ. of California/San Francisco (United States)
Charles Q. Le, Univ. of California/San Francisco (United States)
John D. Featherstone, Univ. of California/San Francisco (United States)

Published in SPIE Proceedings Vol. 6843:
Lasers in Dentistry XIV
Peter Rechmann; Daniel Fried, Editor(s)

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