Low-fluence CO2 laser irradiation decreases enamel solubility

• Published in: Laser physics Vol. 18; no. 4; pp. 478 - 485
• Main Authors: Esteves-Oliveira, M., Apel, C., Gutknecht, N., Velloso, W. F., Cotrim, M. E. B., Eduardo, C. P., Zezell, D. M.
• Format: Journal Article
• Language: English
• Published: Moscow Nauka/Interperiodica 01.04.2008; Springer
• Subjects: Biological and medical applications; Biological and medical sciences; Biology; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); General aspects, investigation technics, apparatus; Industrial applications; Laser Methods in Chemistry; Lasers; Materials science; Medicine; Optical Devices; Optics; Photonics; Physics; Tissues, organs and organisms biophysics; Treatment of materials and its effects on microstructure and properties; 87.64.Je; 87.64.Gb; 87.15.-v; 81.40.-z; Scanning electron microscopy; Caries; Calcium; Laser assisted processing; Enamels; Dentistry; Laser irradiation; Laser beam applications; Gas lasers; Pulsed lasers; Carbon dioxide lasers
• ISSN: 1054-660X; 1555-6611
• DOI: 10.1134/S1054660X08040233

This study investigated whether subablative-pulsed CO 2 laser (10.6 μm) irradiation, using fluences lower than 1 J/cm 2 , was capable of reducing enamel acid solubility. Fifty-one samples of bovine dental enamel were divided into three groups: control group, which was not irradiated (CG); group laser A (LA) irradiated with 0.3 J/cm 2 ; and group laser B (LB) irradiated with 0.7 J/cm 2 . After irradiation, the samples were subjected to demineralization in an acetate buffer solution and were then analyzed by SEM. A finite-element model was used to calculate the temperature increase. The calcium and phosphorous content in the demineralization solution were measured with an ICP-OES. ANOVA and the t-test pairwise comparison ( p < 0.016) revealed that LB showed significantly lower mean Ca and P content values in the demineralization solution than other groups. A reduction in the enamel solubility can be obtained with pulsed CO 2 laser irradiation (0.7 J/cm 2 , 135 mJ/pulse, 74 Hz, 100 μs) without any surface photomodification and a less than 2°C temperature increase at a 3-mm depth from the surface.