FTIR and SEM analysis of CO2 laser irradiated human enamel

ObjectivesConsidering the enamel chemical structure, especially carbonate band, which has a major role in the caries prevention, the objective of the present study was to assess the chemical alterations on the enamel irradiated with CO₂ laser by means of FTIR spectroscopy and SEM analysis.DesignThe enamel surfaces were analysed on a spectrometer for acquisition of the absorption spectrum relative to the chemical composition of the control sample. The irradiation was conducted with a 10.6-μm CO₂ laser (0.55 W, 660 W/cm²). The carbonate absorption band at 1600–1291 cm^?1 as well as the water absorption band at 3793–2652 cm^?1 was measured in each sample after the irradiation. The water band was measured again 24-h after the irradiation. The band area of each chemical compound was delimited, the background was subtracted, and the area under each band was integrated. Each area was normalized by the phosphate band (1190–702 cm^?1).ResultsThere was a statistically significant decrease (p < 0.05) in the water content after irradiation (control: 0.184 ± 0.04; irradiated: 0.078 ± 0.026), which increased again after rehydration (0.145 ± 0.038). The carbonate/phosphate ratio was measured initially (0.112 ± 0.029) and its reduction after irradiation indicated the carbonate loss (0.088 ± 0.014) (p < 0.05).ConclusionThe 10.6-μm CO₂ laser irradiation diminishes the carbonate and water contents in the enamel after irradiation.