Abstract
The aim of this study was to investigate the thermal effects of Nd : YAG Laser (8 W, 2 sec, 5 W, 2 sec) on human deciduous enamel by using Polarizing Microscopy, SEM and Micro X-ray Diffraction. The lased central regions showed a milky white circle. From observation of the Polarizing microscope, there were several layers which showed different interference colors around the central regions and these altered regions extended diffusely to the enamel-dentine junction. Based on analysis of the altered regions using the Micro X-ray diffraction, it was found that the enamel crystals [HAP : Ca10(PO4)6(OH)2] were altered as follows ; at the irradiated central regions, high temperature phases such as α -Ca3(PO4)2 and semi-high temperature phases such as β -Ca3(PO4)2 and α -, β -, γ -Ca2P2O7 were identified. In the surrounding layers, there were gradual changes from the high temperature phases to the semi-high temperature phases, and to the normal HAP.
