Valorization of Human and Cattle Dental Waste into Functional Composite Biomaterials: A Detailed Comparative Analysis

Abstract

This study investigates the conversion of human and cattle (goat and cow) teeth into bioactive hydroxyapatite-based composites and presents a detailed comparative evaluation of these biogenic materials with laboratory-synthesised (synthetic) hydroxyapatite (HAp). In this work, hydroxyapatite was extracted from human and bovine teeth through controlled calcination and milling, while synthetic HAp was prepared using a standard wet chemical precipitation route. All materials were subsequently sintered at 900 °C and fabricated into pellets for physical and biological analysis. X-ray diffraction (XRD) analysis confirmed that all samples—synthetic and biogenic—possessed crystalline structures consistent with stoichiometric hexagonal hydroxyapatite. FTIR spectra revealed characteristic phosphate, hydroxyl, and carbonate functional groups, with biogenic samples showing slightly higher carbonate substitution. Physical characterization demonstrated comparable hardness, shrinkage behaviour, densification, and porosity among the samples, with only minor variations attributable to natural ionic substitutions present in biological apatite. SEM analysis revealed interconnected porous microstructures favourable for osteoconduction, while pore-size distribution remained consistent across all groups. A strong negative correlation between porosity and hardness (r = –0.996) affirmed the influence of pore architecture on mechanical properties. Biological evaluations validated the suitability of the materials for biomedical use. MTT cytotoxicity assays demonstrated high cell viability (>95%) for all samples, indicating excellent cytocompatibility. Haemolysis percentages remained below the ASTM threshold of 5%, confirming hemocompatibility. Simulated Body Fluid (SBF) immersion studies showed enhanced apatite formation in biogenic HAp compared to synthetic HAp, highlighting superior bioactivity due to natural trace ions and surface reactivity. The findings establish human and cattle teeth as promising, sustainable resources for producing high‑quality hydroxyapatite suitable for applications in bone regeneration, implant coatings, and other biomedical domains.