Comparison of Low and High Temperature Sintering for Processing of Bovine Bone as Block Grafts for Oral Use: A Biological and Mechanical In Vitro Study

Purified bone xenografts: A novel and efficient animal bone substitute derived from an optimized supercritical CO2 treatment

Bone xenografts represent a promising alternative to autologous or allograft transplants, yet antigenicity in animal-derived tissues remains a major limitation to their clinical use. To provide any risk of contamination or allogenic rejection, the Supercrit® process was developed to treat allogeneic human bone combining a supercritical CO2 treatment followed by a chemical treatment using high quantities of different solvents. The aim of this study was to produce a xenogeneic bone substitute thanks to the development of a new one-step supercritical process, 'Goxcrit', and to test it in vivo. This new process reduces the use of solvents by injecting them under pressure into the supercritical CO2 flow, while maintaining the cleaning quality of the bone matrix and better preserving its inner structure, essential for its future bone integration. Porcine derived bone samples were treated using Goxcrit or Supercrit®, and compared with human bone treated with Supercrit®, the commercialized bone allograft. In vitro analyses demonstrated the absence of cytotoxicity and of the alpha-gal epitope mainly responsible for cross-species immunogenicity. Additionally, in vivo experiments revealed improved bone formation in rats critical calvarial defects (BV/TV and von Kossa analyses) implanted with Goxcrit samples, with bone remodeling (TRAP/ALP stains), compared to those treated with Supercrit®. These results can be attributed to the less aggressive chemical process of the Goxcrit, which preserves the bone's inner structure critical for remodeling. Our study highlighted the interest of using a porcine bone source treated with the Goxcrit process to meet the growing demand for reliable and effective bone substitutes.

Supercritical CO2 With Enzymatic Posttreatment Enhances Mechanical and Biological Properties of Cancellous Bovine Bone Block Grafts

Bone loss resulting in large bony defects presents a significant challenge for surgeons. In cases requiring reconstruction, bone "block" grafts that have the key attributes of both physical robustness and biocompatibility are required to facilitate bone healing and regeneration. Current technologies employed for the development of block grafts often result in constructs with suboptimal strength and integration. This study aimed to develop a bovine-derived bone block graft using the process of supercritical fluid (SCF) extraction to maintain mechanical strength and biocompatibility. Bone blocks were prepared from the condyles of bovine femurs. After optimization, the blocks were divided into six groups; Group 1: Raw bone, Group 2: SCF-CO2, Groups 3: SCF-CO2-H2O2, and Group 4: SCF-CO2-H2O2 + Pepsin. Characterization of the constructs included analysis of organic material (thermogravimetric analysis, TGA), crystallinity using x-ray diffraction (XRD), surface topography with scanning electron microscopy (SEM), and chemical composition using Fourier-transform infrared (FTIR) spectroscopy. Mechanical strength was assessed using compression testing, and clinically relevant handling was investigated with a bench-top drill test. Biological testing was carried out in vitro using human bone marrow-derived mesenchymal stem cells (hBMSCs). The SCF-treated bone blocks showed promising results with enhanced mechanical strength (raw bone [mean = 23.01 8.9 MPa], SCF-CO2-H2O2 [mean = 48.9 ± 11.6 MPa], p < 0.0001) reduced organic content (raw bone = 17.6%, SCF-CO2-H2O2 + Pepsin = 12.4%), and significantly higher hBMSCs' metabolic activity on the SCF-CO2 and SCF-CO2 + H2O2 compared to Bio-Oss at 24, 48, 72, and 96 h (p < 0.05). SEM photomicrographs showed reduced debris in trabecular structures with open pores after SCF-CO2 treatment, especially in SCF-CO2-H2O2 + Pepsin blocks. Moreover, the bench-top clinical handling test demonstrated the ease of block fixation with surgical screws. Overall, the SCF-CO2 and posttreatments of bovine block grafts showed potential for clinical application.

Novel Approaches for the Treatment of Maxillofacial Defects

Maxillofacial defects, located in a region characterized by a complex interplay of soft and hard tissues, along with a sophisticated capillary and neural network, have long posed significant challenges in both clinical practice and research [...].

Recombinant bone matrix maintains the graft space, induces vascularized bone regeneration and preserves canine tooth extraction socket structure

AIM

Recombinant bone matrix (RBM) is a newly conceived and engineered porous bone graft granule of average size 600 μm composed of purified recombinant collagen peptide. We sought to examine the behaviour with time of RBM that was grafted in the canine tooth extraction socket.

MATERIALS AND METHODS

The canine tooth extraction socket of the hemisectioned mandibular third premolar distal root was grafted with RBM granules, whereas the opposite side extraction socket served as non-grafted control. The mandibular samples were harvested at 1, 3 and 6 months of healing and subjected to micro-CT imaging and decalcified paraffin-embedded histology. Separately, the effect of RBM was compared with that of deproteinized cancellous bovine bone (DCBB) and bovine atelocollagen plug (BACP) in the canine tooth extraction model at 3 months of healing.

RESULTS

RBM maintained the grafted space in the socket and the gingival connective tissue until new bone was formed within its porous space. The regenerated bone was highly vascularized and continued to mature, while RBM was completely bioresorbed by 6 months. The buccal and lingual alveolar ridge heights of the RBM-grafted extraction socket was better preserved than those of non-grafted control sockets. The degree of socket preservation by RBM was equivalent to that by DCBB, although their healing mechanisms were different.

CONCLUSIONS

This study demonstrated that RBM induced controlled active bone regeneration and preserved the extraction socket structure in a canine model. Bioresorbable RBM engineered without animal or human source materials presents a novel bone graft category with robust bone regenerative property.