Changes in chemical composition and collagen structure of dentine tissue after erbium laser irradiation

Erbium laser radiation has a great affinity for the water molecule, which is present in quantity in biological hard tissues. The objective of this work is to identify chemical changes by infrared spectroscopy of irradiated dentine by an Er:YAG-2.94 μm laser. The irradiation was performed with fluences between 0.365 and 1.94 J/cm2. For the infrared analysis a Fourier transform infrared spectrometer was used. After the irradiation were observed: loss of water, alteration of the structure and composition of the collagen, and increase of the OH− radical. These alterations can be identified by a decrease in intensity of the water band between 2800–3800 cm−1, OH− band at 3575 cm−1 and bands ascribed to organic matrix between 2800–3400 cm−1 and 1100–1400 cm−1.