The first application of laser technology to dentistry was for the removal of caries. However, reports of laser application on improvement of dental surface were emerged, much attention has been focused on the laser’s potential to enhance enamel’s hardness and resistance to acid. Most of the previous reports concentrated on the photo issue interaction. Few research has pursued the photochemical phenomenon occurred during laser irradiation on biological tissues. In order to find a creative method to remineralize the dissociating enamel and exposed coronal of dentine, the authors developed a novel procedure during laser irradiation. Slice of sound molar and artificial HAp pellet were irradiated separately, with CO₂ laser under different laser parameters. Tow series of samples covered with saturation calcium ion solution were irradiated separately. To investigate the crystal morphology, XRD pattern were surveyed. The comparison of each cases show that the chemical coating affected the ablation process evidently though distinct XRD results were observed. After CO₂ laser irradiation, the (002) reflection was increased significantly that indicates the crystal growth in c-axis.