Supercritical CO₂ engineered block grafts developed for bone regeneration

Bone loss is a significant challenge in dentistry and often leads to alveolar bone resorption, compromising dental outcomes. Current methods for developing block grafts often result in constructs with inadequate strength and osseointegration. This study aimed to develop a bovine-derived bone block xenograft using supercritical fluid extraction (SCF) and post-SCF treatments to optimize mechanical strength and biocompatibility. Bovine femur condyle blocks were divided into six groups; Group 1: Raw bone, Group 2: Bio-Oss®, Group 3: SCF-CO₂, Groups 4: SCF-CO₂-H₂O_2, Group 5: SCF-CO₂-H₂O₂ + Pepsin and Group 6: SCF-CO₂-H₂O₂ + Pepsin + TMSB10. Analysis included the following: chemical composition and crystallinity using FTIR, mechanical strength via compression testing, surface topography from SEM and chemical characterization using EDS. Safety and biological testing were carried out in vivo using rat subcutaneous and sheep mandibular bone onlay-grafting models. SCF-treated scaffolds showed promising results with reduced lipids, and good biocompatible in biosafety testing in rats. Group 4 and 5 blocks showed enhanced mean (±SD) mechanical strength (37.47 ± 16.91 MPa and 34.95 ± 11.89, respectively) as compared to raw bone (p < 0.05). SEM photomicrographs revealed collagen fibers with reduced debris in trabecular structures and open pores after SCF-CO₂ treatment especially in SCF-CO₂-H₂O₂. The rat and sheep models did not show any adverse immunological effects. Overall, SCF-CO₂ and post-treatments offer a novel xeno-derived block graft with very promising potential for clinical application.