Abstract
The aim of this study was to investigate the thermal effects of Er : YAG Laser (250 mJ, 2 Hz, 200 pulse, and 150 mJ, 2 Hz, 200 pulse) on human deciduous enamel by using Polarizing Microscopy,SEM and Micro X-ray Diffraction. Under the both irradiated conditions, craters are formed in the lased central regions. SEM images showed that the walls of the crater were composed of many layered structures of the enamel prisms, and micro-cracks were observed around the irradiated surfaces of the crater. From observation of the Polarizing microscope, there were layers which showed different interference colors (e.g. brown, orange) around the irradiated central regions (e.g. black-brown). 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.
