Representative images of interfaces dentin/resin. A, B and C represent experimental group with 0 wt% of filler; D, E and F represent experimental group with 2 wt% of nanostructure hydroxyapatite; and, G, H and I represent group of commercial adhesive system. Figures A, D and G show overall interface with all spectra, where the X axis represents the wave number (cm-1), the Z axis represents the measurement points and the Y axis represents the intensity (arbitrary unit). Figures B, C, E, F, H and I represent the integration of peaks intensity, where the Y axis show the intensity (arbitrary units) and the X axis show the measurement points. Figures B, E and H show the result of integration of 960 cm-1 peak intensity. Figures C, F and I show the result of integration of 1610 cm-1 peak intensity.