Objective To study the effects of the cold-light bleaching technique on crystals and microstructure of the dental enamel. Methods The human premolars extracted for orthodontic reasons were treated by a standard cold-light bleaching procedure. After the treatment, all samples were detected by high resolution micro-area X-ray diffractometer, Fourier transform infrared spectroscope and scanning electron microscope. Results After the permanent teeth were treated with cold-light bleaching technique, the enamels′ crystal dimension, crystallinity decreased and irregular surfaces and shallow disk pits appeared. Conclusion The cold-light bleaching technique could lead to the changes of crystals and microstructure in the surface layer of dental enamel.
