Abstract
The purpose of this series of studies was to examine the effectiveness and safety of application of the Er: YAG laser to cavity preparation in pediatric dentistry. Following the first report, we examined the effects of laser irradiation on the dental hard tissue and pulp by performing two experiments using young rats. In Experiment 1, the irradiated surface was observed using scanning electron microscopy to evaluate different irradiation conditions. The upper incisors in the developmental stage with incomplete apices of male wistar rats weighing 30-50 g of 3 weeks of age were used for the experiment. Laser irradiation was performed at 50,100 or 150 mJ/pulse, and 5 rats were used for each irradiation condition (total 15 rats). In Experiment 2, the pulp tissues of rats were observed histopathologically to examine the effects of laser irradiation on the rat pulp. Using 24 rats for each irradiation condition (total 72 rats), the occlusal surface of the right lower molars was irradiated. These rats were then divided into 3 groups according to the postoperative period (immediately,7 days and 30days after irradiation), and postoperative changes in the pulp were observed.
1. Using scanning electron microscopy of the irradiation surfaces, no smear layer was not observed under any condition, which can be observed after using high speed rotary cutting instruments, and the dentinal tubules were found to be cut open.
2. Based on histopathological study, circulatory disorders such as hyperemia, hemorrhage and exudative changes, disarray in the arrangement of the odontoblasts, and absence of the pulpo-dentinal membrane were observed immediately after irradiation. At 7 days after irradiation, these changes were reduced with formation of osteodentin and proliferation of the pulp cells under all irradiation conditions. At 30 days after irradiation, there were no marked changes in the pulp tissue.
