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Evaluation of Crystalline Changes and Resistance to Demineralization of the Surface of Human Dental Enamel Treated With Er:Yag Laser and Fluoride Using X-Ray Diffraction Analysis and Vickers Microhardness Publisher



Behroozibakhsh M1, 2 ; Shahabi S1, 3 ; Ghavamilahiji M1, 2 ; Sadeghian S4 ; Nazari NSF5
Authors
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Authors Affiliations
  1. 1. Department of Dental Biomaterials, School of Dentistry, Tehran University of Medical Sciences, Ghods Street, Enghelab, Tehran, 14176-14411, Iran
  2. 2. Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran, Iran
  3. 3. Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, 14176-14411, Iran
  4. 4. School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran
  5. 5. Sharif University of Technology Central Lab, Tehran, Iran

Source: Laser Physics Published:2018


Abstract

This study aimed to investigate the changes in crystalline structure and resistance to demineralization of human dental surface enamel treated with erbium-doped yttrium aluminium garnet laser (Er:YAG) laser and fluoride. The enamel surfaces were divided into four groups according to the treatment process including, (L): irradiated with Er:YAG; (F): treated with acidulated phosphate fluoride gel (LF): Pre-irradiated surfaces with Er:YAG subjected to acidulated phosphate fluoride gel and (FL): laser irradiation was performed on the fluoridated enamel surface. Before and after the treatment procedure, the samples were evaluated using X-ray diffraction, scanning electron microscope (SEM) and the Vickers microhardness test. The surface microhardness values also were measured after a pH-cycling regime and acid challenge. The a-axis of all lased groups was contracted after treatment procedure. Measurement of the area under the peaks showed the highest crysallinity in the FL group. The hardness values of all laser treated samples significantly reduced after treatment procedure compared to the F group (p ≤ 0.001). The morphological observations showed remarkable changes on the lased enamel surfaces including cracks, craters and exposed prisms. These findings suggest, irradiation of the Er:YAG laser accompanying with fluoride application can induce some beneficial crystalline changes regarding the acid-resistance properties of enamel, however, the craters and cracks produced by laser irradiation can promote enamel demineralization and consequently the positive effects of the Er:YAG laser will be eliminated. © 2018 Astro Ltd.