Acid resistance and structural changes of human dental enamel treated with Er:YAG laser.
OBJECTIVE
The purpose of this study was to evaluate the acid resistance and structural changes in the enamel surface of permanent teeth after subablative Er:YAG laser irradiation in vitro.


BACKGROUND
Er:YAG irradiation laser is expected to enhance acid resistance and to produce morphological changes on the enamel surface.


METHODS
One hundred twenty samples of human enamel were divided into four groups (n = 30): Group I was the control (no laser irradiation), and Groups II, III, and IV were irradiated with Er:YAG laser at 100 mJ (12.7 J/cm(2)), 100 mJ (7.5 J/cm(2)), and 150 mJ (11 J/cm(2)), respectively, at 10 Hz and with water spray. The samples were placed in an acid solution, and the released calcium was quantified by atomic absorption spectrometry. The weight percentages of calcium, phosphorus, oxygen, and chlorine on the enamel surface were determined by energy dispersive X-ray spectroscopy. The morphological changes were observed by scanning electron microscopy. One-way ANOVA and Kruskal-Wallis tests were performed (p <or= 0.05) to distinguish significant differences among groups.


RESULTS
The weight percentage of calcium in the samples obtained from EDS and the amount of calcium in the solution did not show any significant difference. All irradiated samples showed morphological changes on the enamel surface compared to the control group.


CONCLUSIONS
The results of this study suggest that acid resistance of enamel due to subablative Er:YAG laser irradiation on the samples did not increase as expected. Morphological microscopic changes included craters and cracks on the irradiated zones.
Center of Research and Advanced Studies in Dentistry, School of Dentistry of the Autonomous University of the State of Mexico, Jesús Carranza Esq. Paseo Tollocan, Col. Universidad, C.P. 50130, Toluca, Estado de México, México.
Laura Emma
LE
Rodríguez-Vilchis
Rosalía
R
Contreras-Bulnes
Ignacio
I
Sánchez-Flores
Enrique Cuauhtémoc
EC
Samano
D000143:Acids; D002118:Calcium / Q000032:analysis; D003743:Dental Enamel / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure; D019229:Dentition, Permanent; D006801:Humans; D053844:Lasers, Solid-State; D013052:Spectrometry, X-Ray Emission
D000143:Acids; D002118:Calcium