Figure 2. Illustration of the method used to obtain dentin discs and the approach used to perform both microhardness and FTIR measurement on the same sample. (a) Dentin discs were cross-sectioned from caries free third molars; (b) The deep pulpal side of each dentin disc was subsequently ground and polished; (c) Half side of each treated dentin surface was used for microhardness measurement and the other half was used for FTIR measurement. FTIR, Fourier transform infrared spectrophotometer.