FT-Raman spectroscopic characterization of enamel surfaces irradiated with Er:YAG and Nd:YAG lasers

Although dental caries is a preventable disease, it is still common and remains a public health problem. One of the potentially effective preventive measures is laser irradiation. Raman spectroscopy is a powerful technique for studying the microcrystalline structure of dental enamel. The study assessed the chemical alterations occurring in enamel irradiated with Er:YAG or Nd:YAG lasers, by means of FT-Raman spectroscopy.
Material and Fifteen freshly-extracted human molars were treated as follows: no treatment in group A (n=5); 10 seconds irradiation with Er:YAG laser at 4 mm from the tooth surface, under water and air spray, in group B (n=5); 10 seconds irradiation with Nd:YAG laser, at 1 mm from the tooth surface, with 300 µm fiber used in a sweeping motion, in group C (n=5). After treatment, specimens were analyzed by FT-Raman spectroscopy.
Analysis of the carbonate content in terms of the integrated area under the curve (1065/960cm–1) showed a statistically-significant reduction in the integrated area ratio, in both laser-irradiated groups. The integrated area of organic content (2935/960 cm-1) showed a statistically-significant reduction after laser irradiation, in both irradiated groups.
The results show that laser irradiation affects both mineral and organic matrix of dental enamel, and may thus be a suitable strategy for caries prevention; the FT-Raman technique appears appropriate to detect such compositional and structural changes.