Comparative characteristics of the xenogenic synthetic biomimetic composite and spongy bone tissue for the goals of osteoplasty in dentistry

Background ― The structural and morphological features in the natural and synthetic biomimetic composites should be defined and compared to determine the optimal artificial material for osteoplastic tasks. Methods ― The sample of osteoplastic material of the xenogenic group representing the treated bone blocks of cattle, sample of a spongy bone tissue of a human lower jaw and a sample of biomimetic carbonate-substituted calcium hydroxyapatite synthesized with the use of birds’ egg-shells were studied using X-ray diffraction (XRD) and Fourier Transmission Infrared spectroscopy (FTIR) for the structure, phase and molecular composition analysis, X-ray spectral microanalysis (XMA) was applied for chemical element composition, optical and scanning electron microscopy (SEM) were used for a surface features analysis of the materials with a porous structure. Results ― The analysis of the xenogenic material as well as the bone tissue sample by XRD and FTIR reveal that the samples are comprised of a single crystalline phase, i.e. a carbonate-substituted calcium hydroxyapatite (CHAP) with distortions in the crystalline structure. The calculations of the hydroxyapatite crystallites size in the samples of the bone tissue and the xenogenic materials by the XRD data are 35.2±1.5 nm and 11.1±0.6 nm respectively. A different content of the amide and carboxyl groups in the bone tissue and in the osteoplastic material were found using IR-spectroscopy in the 1,800-1,200 cm -1 indicates the presence of protein structures in the latter which are different in the molecular structure from those presented in the native human bone tissue. The redistribution of the vibration modes in the spectral ranges 3000-2800 and 800-500 cm -1 also confirm this suggestion. Scanning electron microscopy demonstrated that xenogenic materials possess the morphology and a system of conjugated pores similar to those of the human bone tissue. At the micrometer level the pores that are present in the xenograft coincide in their size with those in the native bone matrix (3-6 m). Optical microscopy investigations shows that in the osteoplastic xenogenic materials at the macrolevel there are no pores with the size of 0.25-1.5 mm, which are observed in the samples of the native bone tissue. Conclusion ― Based on the results of comparison of the structural, molecular and morphological properties of the studied samples, it is possible to conclude that the samples of the osteoplastic materials do not completely correspond to the spongy human bone tissue, which imposes certain constraints on their practical applications. Comparison of the structure, phase and molecular composition as well as the morphology of the samples of native porous bone tissue and xenogenic materials allowed us to identify the principal differences between the two materials as well as to design the requirements and guidelines for manufacturers on extra processing of a xenogenic material for eliminating the factors affecting the quality of implantation and resorption of a biomimetic composite: macroporosity, crystallinity and molecular composition.