Comparative Raman–FTIR Assessment of Crystallinity and Carbonate Substitution in Bioapatite‐Based Graft Materials

ABSTRACT

We investigated the physicochemical characteristics of commercially available bone graft substitutes of bovine, human, and natural hydroxyapatite origin, aiming to evaluate whether compositional differences detectable by vibrational spectroscopy may influence their suitability for bone regeneration. Raman and Fourier transform infrared (FTIR) spectroscopy techniques were employed to examine the vibrational signatures of phosphate and carbonate groups in the mineral phase, focusing on spectral descriptors associated with crystallinity, carbonate substitution, and lattice ordering. Carbonate‐to‐phosphate ratios derived from both Raman and FTIR spectra were used for a comparative assessment of the mineral composition of the different graft types. All materials exhibited characteristic phosphate and carbonate bands consistent with hydroxyapatite as the dominant mineral phase. Minor variations were observed in band positions/widths and carbonate‐related features, indicating subtle differences in structural order that can be attributed to specific manufacturing processes in the synthesis. However, the carbonate‐to‐phosphate ratios showed limited variability, and only minor changes in carbonate‐related spectral parameters were observed among bovine, human, and natural hydroxyapatite grafts. This study provides a methodological reference for carbonate substitution and crystallinity analysis, clarifying structural trends across commercial bioapatite grafts and supporting future research in this field. Even though the observed compositional differences are small, this study confirms that commercial grafts share a highly similar mineral framework, indicating a broad physicochemical similarity among the evaluated graft materials.