Chemical and morphological analysis of the human dental enamel treated with argon laser during orthodontic bonding

Introduction: The main utilities of the argon laser in orthodontics are the high speed curing process in orthodontic bonding and the caries resistance promotion of the tooth enamel. Objective: To evaluate the chemical and morphological changes in the tooth enamel treated with the argon laser in the orthodontic bonding parameters. Methods: Fifteen sound human first premolars, removed for orthodontic reason, were selected and sectioned across the long axis in two equal segments. One section of each tooth was treated and the other remained untreated. A total of thirty samples was analyzed, creating the laser (n =15) and the control groups (n =15). The treatment was done with 250 mW argon laser beam for 5 seconds, with energy density of 8 J/cm2. Results: The X-ray analysis demonstrated two different phases in both groups, the apatite and the monetite phases. The reduction of the monetite phase was significant following laser treatment, suggesting higher crystallinity. The EDS analysis showed an increase in the calcium-phosphorus ratio in the laser group, linked with the decrease of the monetite phase. The surface morphology was smoother after the laser exposure. Conclusion: The results of high crystallinity and superficial enamel smoothness in the laser group are suggestive of the caries resistance increase of the tooth enamel. Abstract