Modification of xenogenic bone substitute materials--effects on the early healing cascade in vitro

A comparative analysis of particulate bovine bone substitutes for oral regeneration: a narrative review

PURPOSE

Particulate bovine bone substitutes (BS) are commonly used in oral regeneration. However, more literature is needed focusing on comparative analyses among various particulate bovine BS. This study evaluates pre-clinical and clinical data of different particulate bovine BS in oral regeneration.

METHODS

A narrative review was conducted by screening the PubMed database Included in the review were pre-clinical and clinical studies until 2024 comparing a minimum of two distinct particulate bovine BS. In addition to examining general data concerning manufacturing and treatment processes, biological safety, physical and chemical characteristics, and graft resorption, particular emphasis was placed on assessing pre-clinical and clinical data related to ridge preservation, sinus floor elevation, peri-implant defects, and various forms of alveolar ridge augmentation utilizing particulate bovine BS.

RESULTS

Various treatment temperatures ranging from 300 to 1,250 °C and the employment of chemical cleaning steps were identified for the manufacturing process of particulate bovine BS deemed to possess biosecurity. A notable heterogeneity was observed in the physical and chemical characteristics of particulate bovine BS, with minimal or negligible graft resorption. Variations were evident in particle and pore sizes and the porosity of particulate bovine BS. Pre-clinical assessments noted a marginal inclination towards favorable outcomes for particulate bovine BS subjected to higher treatment temperatures. However, clinical data are insufficient. No distinctions were observed regarding ridge preservation, while slight advantages were noted for high-temperature treated particulate bovine BS in sinus floor elevation.

CONCLUSIONS

Subtle variances in both pre-clinical and clinical outcomes were observed in across various particulate bovine BS. Due to inadequate data, numerous considerations related to diverse particulate bovine BS, including peri-implant defects, must be more conclusive. Additional clinical studies are imperative to address these knowledge gaps effectively.

Hyaluronic Acid with Bone Substitutes Enhance Angiogenesis In Vivo

Introduction: The effective induction of angiogenesis is directly related to the success of bone-substitute materials (BSM) for maxillofacial osseous regeneration. Therefore, the addition of pro-angiogenic properties to a commercially available bovine bone-substitute material in combination with hyaluronic acid (BSM+) was compared to the same bone-substitute material without hyaluronic acid (BSM) in an in-vivo model. Materials and Methods: BSM+ and BSM were incubated for six days on the chorioallantoic membrane (CAM) of fertilized chicken eggs. Microscopically, the number of vessels and branching points, the vessel area and vessel length were evaluated. Subsequently, the total vessel area and brightness integration were assessed after immunohistochemical staining (H&E, alphaSMA). Results: In the BSM+ group, a significantly higher number of vessels (p < 0.001), branching points (p = 0.001), total vessel area (p < 0.001) as well as vessel length (p = 0.001) were found in comparison to the BSM group without hyaluronic acid. Immunohistochemically, a significantly increased total vessel area (p < 0.001 for H&E, p = 0.037 for alphaSMA) and brightness integration (p = 0.047) for BSM+ in comparison to the native material were seen. Conclusions: The combination of a xenogenic bone-substitute material with hyaluronic acid significantly induced angiogenesis in vivo. This might lead to a faster integration and an improved healing in clinical situations.

Does Platelet-Rich Fibrin Enhance the Early Angiogenetic Potential of Different Bone Substitute Materials? An In Vitro and In Vivo Analysis

The impaired angiogenic potential of bone substitute materials (BSMs) may limit regenerative processes. Therefore, changes in the angiogenetic properties of different BSMs in combination with platelet-rich fibrin (PRF) in comparison to PRF alone, as well as to native BSMs, were analyzed in vitro and in vivo to evaluate possible clinical application. In vitro, four BSMs of different origins (allogeneic, alloplastic, and xenogeneic) were biofunctionalized with PRF and compared to PRF in terms of platelet interaction and growth factor release (vascular endothelial growth factor (VEGF), tissue growth factor ß (TGFß) and platelet-derived growth factor (PDGF)) after 15 min. To visualize initial cell–cell interactions, SEM was performed. In vivo, all BSMs (±PRF) were analyzed after 24 h for new-formed vessels using a chorioallantoic membrane (CAM) assay. Especially for alloplastic BSMs, the addition of PRF led to a significant consumption of platelets (p = 0.05). PDGF expression significantly decreased in comparison to PRF alone (all BSMs: p < 0.013). SEM showed the close spatial relation of each BSM and PRF. In vivo, PRF had a significant positive pro-angiogenic influence in combination with alloplastic (p = 0.007) and xenogeneic materials (p = 0.015) in comparison to the native BSMs. For bio-activated xenogeneic BSMs, the branching points were also significantly increased (p = 0.005). Finally, vessel formation was increased for BSMs and PRF in comparison to the native control (allogeneic: p = 0.046; alloplastic: p = 0.046; and xenogeneic: p = 0.050). An early enhancement of angiogenetic properties was demonstrated when combining BSMs with PRF in vitro and led to upregulated vessel formation in vivo. Thus, the use of BSMs in combination with PRF may trigger bony regeneration in clinical approaches.

A collagen membrane influences bone turnover marker in vivo after bone augmentation with xenogenic bone

Background

The aim was to compare early biochemical and histological osseous healing of chronic mandibular defects regenerated with bovine bone substitute with and without collagen membrane in vivo.

Methods

Eight weeks after formation of a lateral full-thickness perforating bone defect in the mandible of 40 rabbits, bovine bone substitute with (“+”;n = 20) and without (“-”;n = 20) collagen membrane was applied. Blood and bone was collected 24, 72 h, 7, 14 and 21 days after surgery. Total acid phosphatase, bone acid phosphatase, total alkaline phosphatase and bone alkaline phosphatase activities were compared between groups. Formation of new bone was quantified histologically for all time points.

Results

Twenty-four hours after surgery, bone alkaline phosphatase was significantly elevated in “+” group when compared to “-” (p=0.012). After 72 hours, all bone turnover markers except for total acid phosphatase (p=0.078) where significantly elevated in “+” (all p < 0.05). Fourteen days after surgery, the significant highest values for all bone turnover markers were detected in “-” (all p < 0.05). A significant difference in favor of group “-” could also be detected after 3 weeks in terms of both acid phosphatases (p < 0.05). In histology, no significant differences could be detected.

Conclusion

Bone regeneration with bovine bone substitute material and collagen membrane shows a significantly earlier bone remodeling activity but does not seem to influence formation of new bone in histological samples.

Influence of Different Rehydration Protocols on Biomechanical Properties of Allogeneic Cortical Bone Plates: A Combined in-vitro/in-vivo Study

Introduction: Allogeneic cortical bone plates (CP) are used for alveolar ridge augmentation. Since CP are freeze-dried and dehydrated during processing, the breaking strength (BS) and the flexibility (FX) are reduced, resulting in a relevant risk for plate fractures during insertion. The aim of this study was to evaluate the influence of rehydration time on the biomechanical properties (BS & FX) of CP in-vitro and in vivo.Material and Methods: 40 CP were randomly divided into four experimental groups. (A) untreated control (n = 10), rehydration for 10 (B), 30 (C) and 60 (D) minutes in 0.9% saline solution (n = 10 each). BS [Newton, N] and FX [mm] (force till fracture and distance of deflection to the breaking point) were analyzed. Besides, architectural features of all CP groups were visualized and examined by scanning electron microscopy (SEM). In addition, the frequency of CP fractures of rehydrated- vs. non-rehydrated CP was retrospectively analyzed in 6 patients.Results: Compared to the control group, significantly increased BS and FX were demonstrated after 10, 30 and 60 minutes of rehydration (p each ≤ 0.035). After a rehydration time of 10 minutes, no additional increase of BS and FX was seen when compared to30 and 60 minutes (p each = 1.0). SEM scans demonstrated that the CP fracture characteristics were influenced by the different rehydration protocols. The frequency of CP fractures was reduced in patients by CP rehydration.Conclusion: The biomechanical properties of CP can be significantly improved by 10 min of rehydration, resulting in an increased BS and FX, that might be clinically relevant.

Combination of an allogenic and a xenogenic bone substitute material with injectable platelet-rich fibrin - A comparative in vitro study

The aim of the in vitro study was a comparison of an allogenic (ABSM) and a xenogenic bone substitute material (XBSM) with and without injectable platelet-rich fibrin (ABSM-i-PRF & XBSM-i-PRF) on cell characteristics of human osteoblasts (HOB). Here, ABSM and XBSM (+ i-PRF = test; - i-PRF = control) were incubated with HOB for 3, 7 and 10 days. HOB viability, migration, proliferation and differentiation (RT-PCR on alkaline phosphatase (AP), bone morphogenetic protein 2 (BMP-2) and osteonectin (OCN)) were measured and compared between groups. At day 3, an increased viability, migration and proliferation was seen for ABSM-i-PRF. For viability and proliferation (days 7 and 10) and for migration (day 10), ABSM-i-PRF/XBSM-i-PRF showed higher values compared to ABSM/XBSM with maximum values for ABSM-i-PRF and minimum values for XBSM. At days 3 and 7, the highest expression of AP was detected in ABSM-i-PRF/XBSM-i-PRF when compared to ABSM/XBSM, whereas at day 10, AP expression levels were elevated in ABSM-i-PRF/ABSM. The highest BMP-2 expression was seen in ABSM-i-PRF whereas OCN expression showed higher levels in ABSM-i-PRF/XBSM-i-PRF at days 3 and 7 with lowest expression for ABSM. Later on, elevated OC levels were detected for ABSM-i-PRF only. In conclusion, i-PRF in combination with ABSM enhances HOB activity when compared to XBSM-i-PRF or untreated BSM in vitro. Therefore, addition of i-PRF to ABSM and - to a lower extent - to XBSM may influence osteoblast activity in vivo.

Guided Bone Regeneration Using Collagen Scaffolds, Growth Factors, and Periodontal Ligament Stem Cells for Treatment of Peri-Implant Bone Defects In Vivo

Introduction

The aim of the study was an evaluation of different approaches for guided bone regeneration (GBR) of peri-implant defects in an in vivo animal model.

Materials and Methods

In minipigs (n = 15), peri-implant defects around calcium phosphate- (CaP-; n = 46) coated implants were created and randomly filled with (1) blank, (2) collagen/hydroxylapatite/β-tricalcium phosphate scaffold (CHT), (3) CHT + growth factor cocktail (GFC), (4) jellyfish collagen matrix, (5) jellyfish collagen matrix + GFC, (6) collagen powder, and (7) collagen powder + periodontal ligament stem cells (PDLSC). Additional collagen membranes were used for coverage of the defects. After 120 days of healing, bone growth was evaluated histologically (bone to implant contact (BIC;%)), vertical bone apposition (VBA; mm), and new bone height (NBH; %).

Results

In all groups, new bone formation was seen. Though, when compared to the blank group, no significant differences were detected for all parameters. BIC and NBH in the group with collagen matrix as well as the group with the collagen matrix + GFC were significantly less when compared to the collagen powder group (all: p < 0.003).

Conclusion

GBR procedures, in combination with CaP-coated implants, will lead to an enhancement of peri-implant bone growth. There was no additional significant enhancement of osseous regeneration when using GFC or PDLSC.