Abstract
Changes in microstructure induced by laser irradiation on demineralized dental enamel were examined by means of a combination of transmission electron microscopy (TEM) and selected area electron diffraction (SAED) techniques. Specimens for TEM and SAED examinations were prepared by ion-beam thinning. Dyes were not employed in the present study. Therefore, contrasts observed in TEM images were correlated directly with crystal structure found in SAED patterns. The surface layer of lased enamel was melted to a depth of approximately 0.5μm. The melted surface layer was solidified by crystallization. Amorphous regions were not found in the present study. But after laser irradiation was made at 134J/cm2, the crystal structure consisted of hydroxyapatite only. No calcium compounds such as α-TCP and/or β-TCP were detected in the SAED patterns.
