(A) Comparative infrared absorption spectra of all four protein extracts. All the spectra were baseline corrected and normalized. (B–E) Curve fitting of the amide I band of incisor (B) canine (C) premolar (D) and molar (E) protein extracts. Protein secondary structure content should read as α: alpha helix, β: beta sheets, L: loops, T: turns, R: Random, β’: Extended B sheets, U: Unstructured, A: Amino acid side chains. Each spectrum was baseline corrected and normalized to the equal band amplitudes.