The Effect of Low-Temperature Thermal Processing on Bovine Hydroxyapatite Bone Substitutes, toward Bone Cell Interaction and Differentiation

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.

In vitro and in vivo investigation of antibacterial silver nanoparticles functionalized bone grafting substitutes

Infection is a major concern in surgery involving grafting and should be considered thoroughly when designing biomaterials. There is considerable renewed interest in silver nanoparticles (AgNPs) owing to their ability to potentiate antibacterial properties against multiple bacterial strains. This study aimed to develop two antibacterial bone regenerative scaffolds by integrating AgNPs in bovine bone particles (BBX) (Product 1), and a light cross-linked hydrogel GelMA (Product 2). The constructs were characterized using scanning electron microscopy. Metabolic activity of osteoblasts and osteoclasts on the constructs was investigated using PrestoBlue™. Disk diffusion assay was conducted to test the antibacterial properties. The regenerative capacity of the optimized AgNP functionalized BBX and GelMA were tested in a rabbit cranial 6 mm defect model. The presence of AgNPs appears to enhance proliferation of osteoblasts compared to AgNP free controls in vitro. We established that AgNPs can be used at a 100 μg dose that inhibits bacteria, with minimal adverse effects on the bone cells. Our rabbit model revealed that both the BBX and GelMA hydrogels loaded AgNPs were biocompatible with no signs of necrosis or inflammatory response. Grafts functionalized with AgNPs can provide antibacterial protection and simultaneously act as a scaffold for attachment of bone cells.

Bone volume and height changes for lateral window sinus floor elevation using two types of deproteinized bovine bone mineral: A retrospective cohort study of 1-4 years

OBJECTIVE

To compare bone volume and height changes of two types of deproteinized bovine bone mineral (DBBM) for lateral window sinus floor elevation (LSFE) with simultaneous implant placement.

MATERIALS AND METHODS

This retrospective cohort study involved 72 patients who underwent LSFE using low-temperature sintered cancellous bone-derived DBBM (C-DBBM) or high-temperature two-step sintered epiphyseal-derived DBBM (E-DBBM). Cone-beam computed tomography (CBCT) was acquired preoperatively, immediately postoperatively, 6 months and 1-4 years post-surgery. Bone volume (BV), apical bone height (ABH), endo-sinus bone gain (ESBG), and crestal bone level (CBL) were evaluated through three-dimensional fitting and superimposition. Linear mixed models (LMM) were employed to analyze factors influencing the reduction of BV (ΔBV) and ESBG (ΔESBG).

RESULTS

The E-DBBM group showed no significant change in BV 1-4 years post-surgery, while the C-DBBM group demonstrated a significant reduction (p = .006) with volume stability of 85.86%. Bone height in the E-DBBM group increased at 6 months and subsequently decreased at 1-4 years (p = .003). In the C-DBBM group, it decreased at 6 months (p = .014), then further decreased at 1-4 years (p = .001). ΔESBG was lower in the E-DBBM group than the C-DBBM group from immediate postoperative to 1-4 years (p = .009). LMM showed graft material type was the primary factor influencing ΔBV (p = .026) and ΔESBG (p = .003).

CONCLUSIONS

Within the limitations of this study, both types of DBBM could achieve favorable clinical outcomes. E-DBBM demonstrated enhanced stability in maintaining bone volume and height.

In vivo healing of low temperature deproteinized bovine bone xenograft in a rabbit cranial model

The physicochemical properties of grafting materials affect the quality of the osteointegration, resorption rate, and the new bone (NB) formation. This study assessed the physicochemical properties and integration of a low temperature deproteinized bovine bone xenograft (BBX), referred to as optimized MoaBone® (OMB). This novel BBX was physiochemically characterized both pre and post chemical bleaching and sterilization by gamma irradiation. OMB was compared to two commercial BBX; Bio-Oss® (BO) and MoaBone® (MB) using a rabbit cranial model. Residual graft and NB were quantified using histology and micro-computed tomography. Results showed that chemical treatment and gamma irradiation had limited effect on the surface texture. A significant decrease in the collagen content was detected post chemical treatment and in the carbonate content post gamma irradiation. There was no evidence of inflammatory infiltrate, necrosis, or connective tissue encapsulation, and a significant increase of NB in all grafted sites as compared to untreated defects could be observed. However, there was no statistically significant difference between the grafted sites. We conclude that chemical treatment and terminal sterilization strongly impact the final graft's properties. OMB graft showed equivalence with BO for in vivo bone formation and potentially results in lower levels of graft retention.

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

Large oral bone defects require grafting of bone blocks rather than granules to give physically robust, biocompatible and osteoconductive regeneration. Bovine bone is widely accepted as a source of clinically appropriate xenograft material. However, the manufacturing process often results in both reduced mechanical strength and biological compatibility. The aim of this study was to assess bovine bone blocks at different sintering temperatures and measure the effects on mechanical properties and biocompatibility. Bone blocks were divided into four groups; Group 1: Control (Untreated); Group 2: Initial boil for 6 h; Group 3: Boil 6 h followed by sintering at 550 °C for 6 h; Group 4: Boil 6 h followed by sintering at 1100 °C for 6 h. Samples were assessed for their purity, crystallinity, mechanical strength, surface morphology, chemical composition, biocompatibility and clinical handling properties. Statistical analysis was performed using one-way ANOVA and post-hoc Tukey's tests for normally distributed and Friedman test for abnormally distributed quantitative data from compression tests and PrestoBlue™ metabolic activity tests. The threshold for statistical significance was set at p < 0.05. The results showed that higher temperature sintering (Group 4) removed all organic material (0.02% organic components and 0.02% residual organic components remained) and increased crystallinity (95.33%) compared to Groups 1-3. All test groups (Group 2-4) showed decreased mechanical strength (MPa: 4.21 ± 1.97, 3.07 ± 1.21, 5.14 ± 1.86, respectively) compared with raw bone (Group 1) (MPa: 23.22 ± 5.24, p <0.05), with micro-cracks seen under SEM in Groups 3 and 4. Group 4 had the highest biocompatibility (p < 0.05) with osteoblasts as compared to Group 3 at all time points in vitro. Clinical handling tests indicated that Group 4 samples could better withstand drilling and screw placement but still demonstrated brittleness compared to Group 1. Hence, bovine bone blocks sintered at 1100 °C for 6 h resulted in highly pure bone with acceptable mechanical strength and clinical handling, suggesting it is a viable option as a block grafting material.

Value-added materials recovered from waste bone biomass: technologies and applications

As the world population increases, the generation of waste bones will multiply exponentially, increasing landfill usage and posing health risks. This review aims to shed light on technologies for recovering valuable materials (e.g., alkaline earth material oxide such as CaO, hydroxyapatite, beta tri-calcium phosphate, phosphate and bone char) from waste bones, and discuss their potential applications as an adsorbent, catalyst and catalyst support, hydroxyapatite for tissue engineering, electrodes for energy storage, and phosphate source for soil remediation. Waste bone derived hydroxyapatite and bone char have found applications as a catalyst or catalyst support in organic synthesis, selective oxidation, biodiesel production, hydrocracking of heavy oil, selective hydrogenation and synthesis of bioactive compounds. With the help of this study, researchers can gather comprehensive data on studies regarding the recycling of waste bones, which will help them identify material recovery technologies and their applications in a single document. Furthermore, this work identifies areas for further research and development as well as areas for scaling-up, which will lead to reduced manufacturing costs and environmental impact. The idea behind this is to promote a sustainable environment and a circular economy concept in which waste bones are used as raw materials to produce new materials or for energy recovery.