Allogenic Bone Graft in Dentistry: A Review of Current Trends and Developments

Biomimetic Fabrication and Osteogenic Effects of E7BMP-2 Peptide Coassembly Microspheres Based α-Tricalcium Phosphate with Silk Fibroin

The repair and reconstruction of bone defects remain a challenge in orthopedics. Inadequate mechanical qualities, poor biocompatibility, and insufficient osteoconductivity are some of the issues facing current bone healing materials. Better materials that can replicate the composition and functionality of natural bone, promote quick and full healing, and reduce the likelihood of rejection and infection are desperately needed. Bone tissue engineering, combining biomaterial scaffolds and pro-osteogenic drugs, provides support in the repair and regeneration of bone defects. The development of an effective scaffold for bone defect repair is an urgent clinical need. The present study investigates the feasibility of using microspheres based on α-tricalcium phosphate and fibroin as an osteoconductive matrix and a carrier for controlled local delivery of the E7BMP-2 peptide, in which the E7 domain confers a calcium chelation property, while the BMP-2 mimicking peptide induces bone formation. We prepared α-tricalcium phosphate/silk fibroin (α-TCP/SF) microspheres through a high voltage electric field based on the protocol of α-TCP/SF bone cement slurry. This α-TCP/SF microspheres-based system was designed for delivery vehicles of the modified BMP-2 peptide by the E7 domain to realize sustainable and steady release of the peptide. In vitro cell tests and the experimental model of cranial bone defects in rats were used to investigate the pro-osteogenic benefits. The results demonstrated that the E7BMP-2 peptide-bound microspheres functioned as a sustained release system for the peptide and enhanced osteogenic differentiation of bone marrow mesenchymal stem cells in rat calvarial defects. Additionally, toxicity studies showed that microspheres have good biocompatibility and safety. Thus, these E7BMP-2 peptide-bound α-TCP/SF microspheres provide a promising therapeutic strategy for the treatment of bone defects.

Guided Tissue Regeneration of Periodontal Infrabony Defects with Frozen Radiation-Sterilized Allogenic Bone Graft Versus Deproteinized Bovine Bone Mineral: 5-Year Outcomes of RCT

The aim of this study was to compare the efficacy of the guided tissue regeneration (GTR) of periodontal infrabony defects using the frozen radiation-sterilized allogenic bone graft (FRSABG) versus deproteinized bovine bone mineral (DBBM) 5 years after treatment. The association between patients' compliance and periodontitis recurrence with 5-year outcomes was also evaluated. Thirty infrabony defects in 15 stage III/IV periodontitis patients were randomly allocated to the FRSBAG group (tests) or the DBBM group (controls). Between 1 and 5 years, one patient was lost to follow-up and one tooth was extracted due to root fracture. No tooth was extracted for periodontal reasons. Consequently, 13 teeth in test sites and 14 teeth in control sites were available for the 5-year analysis. The clinical attachment level gain (CAL-G, primary outcome), probing pocket depth (PPD), radiographic defect depth (DD), and linear defect fill (LDF) were examined at baseline and 5 years post-surgically. Both groups showed statistically significant improvements in all evaluated clinical and radiographic parameters at 5 years, with insignificant intergroup differences. CAL-Gs were 4.46 ± 2.07 mm in the FRSBAG group, and 3.86 ± 1.88 mm in the DBBM group (p = 0.5442). In six (43%) patients, we observed periodontitis recurrence, among whom two (33.33%) participated regularly in supportive periodontal care (SPC) and the other four (66.7%) did not take part in SPC. A regression analysis revealed that periodontitis recurrence was a significant predictor of CAL loss and DD increase. FRSBAG and DBBM were both equally effective 5 years after the GTR of infrabony defects. Within the limitations of the present study, its outcomes advocate that both grafts may be considered as a viable option based on patient preferences and clinical considerations.

Development of fully-resorption replacement paste-like organic/inorganic artificial bones compatible with bone remodeling cycles

Calcium-phosphate cement (CPC), commonly used as a bone graft substitute, sets as hydroxyapatite (HAp) and remains in the body for extended periods. To enhance bioresorbabability, we developed a chelate-setting tricalcium β-phosphate (β-TCP) cement using inositol phosphate (IP6) surface modification. By incorporating poly(lactic-co-glycolic acid) (PLGA) particles as a pore-forming agent and calcium sulfate hemihydrate (CSH) to this CPC, we created an organic/inorganic hybrid cement combining bioresorbability with favorable material properties. In this study, varying amounts of PLGA particles were added alongside CSH, and the resulting cement's properties, cytotoxicity, and in vivo response large animals (pigs) were assessed. The cement exhibited a compressive strength of ∼ 30 MPa and set within 15 min, making it suitable for clinical use. Cytotoxicity tests using Transwell® demonstrated cell growth in all cement specimens. In a pig tibia model, the amount of PLGA particle of 5 mass%, 10 mass%, and 20 mass% were tested to optimize material resorption and bone formation, compared with commercial HAp-based CPCs. Histological evaluations showed that higher amount of PLGA particles (10 mass% and 20 mass%) led to increased material resorption but impaired bone formation. The cement containing 5 mass% PLGA particles achieved the best balance, promoting the highest rate of bone formation. Thus, 5 mass% PLGA is the optimal amount for balancing resorption and bone regeneration in β-TCP cement. This formulation is expected to serve as a fully absorbable hybrid paste-type artificial bone supporting bone remodeling cycles.

The Role of Formononetin in Osteoblast Function and Mineralization Potential with Deproteinized Bovine Bone Material

OBJECTIVES

Dental bone formation involves various cellular and molecular mechanisms, and phytoestrogens such as formononetin (FORM) are promising because of their estrogenic, anti-inflammatory, and antioxidant effects. This study investigated the effect of FORM on osteoblast proliferation, differentiation, and mineralization in combination with spongiosa granulates (BO) in vitro.

MATERIALS AND METHODS

Human fetal osteoblast cells (hFOB1.19) were treated with increasing concentrations of FORM (1, 10, and 100 µg/mL), BO, or their combination. Cell proliferation was assessed using a MTT assay. Alkaline phosphatase (ALP) activity, intracellular Ca2+, and Pi levels were measured using ELISA. Vascular endothelial growth factor (VEGF) and osteocalcin expression levels were analyzed by western blotting.

RESULTS

Cell proliferation increased with FORM, with or without BO, after 6 days (p < 0.001). FORM and BO had a synergistic effect on ALP activity (p < 0.001). Intracellular Ca2+ and Pi levels were highest in the BO-FORM group, suggesting superior mineralization (p < 0.05). VEGF and osteocalcin expression was significantly upregulated with FORM, alone and with BO (p < 0.05), indicating improved angiogenesis and bone maturation over 9 days.

CONCLUSIONS

FORM enhances osteoblast proliferation, differentiation, and mineralization potential, particularly in BO spongiosa granulates. These data support the in vitro potential of formononetin-phytoestrogen in promoting osteoblast differentiation and mineralization potential with BO. These findings suggest that FORM, combined with BO, could improve bone augmentation in clinical applications such as maxillofacial surgery. FORM shows valuable potential for clinical applications, such as maxillofacial surgery, by promoting faster and more effective healing.

Saddle Nose Deformity Reconstruction with a Allograft Bone

OBJECTIVE

Providing lasting cosmetic and functional results for patients with saddle nose deformity with allograft.

METHODS

This report describes experience with using a of freeze-dried allograft bone allograft in 58 patients who underwent dorsal augmentation over 5-year period (2018-2023). Thirty-eight patients had saddle-shaped deformity of the nose, and 16 patients had post-traumatic cases with saddle nose deformities. All patients underwent a clinical examination using computed tomography. Before surgery using a 3D model, the graft was contoured according to the shape of the nasal defect. The grafts were installed using a closed approach and were placed under the periosteum of the bone. Using lateral photographs, anthropometric measurements of the nose were taken before and after surgery to assess aesthetic outcome after surgery. To assess the results of aesthetic rhinoplasty (UQ), the Portuguese version of the Utrecht Questionnaire was used, which contains a visual analogue scale (VAS) on a 5-point Likert scale.

RESULTS

A total of 56 patients were satisfied with the results of the surgical procedure. No complications or major graft resorption was observed. An analysis comparing preoperative and 1-year follow-up data using 3D scanning showed a significant increase in dorsal height without dorsal expansion. After rhinoplasty, the mean visual analog scale (VAS) aesthetic score improved significant from 2.3 preoperatively, 3 months postoperatively 8.4, and 8.9 1 year postoperatively.

CONCLUSION

The use of freeze-dried allograft bone is a useful method of dorsal augmentation in rhinoplasty without donor site complications.

LEVEL OF EVIDENCE II

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A Case of Simultaneous Sinus Augmentation and Oroantral Fistula Closure for Implant Preparation

An oroantral communication may form in the upper molar region after tooth extraction. The patient is a 59-year-old female, who is a nonsmoker. At the initial visit, teeth #14, #15, and #17 were missing. After tooth #16 was extracted due to apical periodontitis, a bone defect with a diameter of approximately 4 mm was observed, leading to the formation of an oroantral fistula (OAF). Another window was created in the lateral wall adjacent to the superior part of the bone defect at the fistula site to achieve closure of the OAF through bone formation and simultaneously perform sinus floor elevation (lateral approach) for implant placement. Through this lateral window, instruments were inserted into the maxillary sinus towards the bone defect at the fistula site. During this process, the remaining bone between the lateral window and the bone defect at the fistula site was carefully removed with instruments, connecting the two bone defects to facilitate manipulation of the instruments. The Schneiderian membrane was elevated without enlarging the tear. Six months after these surgeries, a cone beam computerized tomography (CBCT) scan confirmed the closure of the fistula with hard tissue and the elevation of the sinus floor. Subsequently, three implants were placed, and prosthetic treatment was completed. Follow-up data is provided, including periapical X-ray and CBCT images taken 2 years and 3 months after surgery (1 year and 3 months after the placement of the final prosthetic structure). The progress so far has been favorable.

Adipose-derived stem cell exosomal miR-21-5p enhances angiogenesis in endothelial progenitor cells to promote bone repair via the NOTCH1/DLL4/VEGFA signaling pathway

BACKGROUND

Angiogenesis is essential for repairing critical-sized bone defects. Although adipose-derived stem cell (ADSC)-derived exosomes have been shown to enhance the angiogenesis of endothelial progenitor cells (EPCs), the underlying mechanisms remain unclear. This study aims to explore the effects and mechanisms of ADSC-derived exosomes in enhancing bone repair by promoting EPC angiogenesis.

METHODS

Transmission electron microscopy, nanoparticle tracking analysis, and Dil reagent kit were employed to identify ADSC-derived exosomes and their internalization by EPCs. Micro-CT analysis, H&E staining, and Masson staining were used to assess bone mineral density (BMD), bone volume fraction (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N), as well as the pathological changes and fibrosis at defect sites. Cell viability, migration, invasion, and tube formation of EPCs were evaluated using CCK-8, wound healing, Transwell, and tube formation assays. Immunohistochemical staining, RT-PCR, and Western blotting were utilized to measure the gene and protein expression of markers such as CD31, VEGFA, OCN, RUNX2, NOTCH1, and DLL4. Gene sequencing and bioinformatics analyses were conducted to identify the most highly expressed miRNA in exosomes, while miRDB and dual-luciferase reporter assays were used to explore the interaction between miR-21-5p and NOTCH1.

RESULTS

The ADSC-derived exosomes, averaging 126 nm in diameter, were internalized by EPCs. In vivo, these exosomes promoted new bone formation, increased BMD, BV/TV, Tb.Th, and Tb.N, reduced pathological damage to cranial defect tissues, enhanced vascular and bone tissue regeneration, and upregulated OCN and RUNX2 expression. In vitro, ADSC-derived exosomes enhanced EPC viability, migration, invasion, and tube formation. Both in vivo and in vitro experiments demonstrated that ADSC-derived exosomes upregulated CD31 and VEGFA expression. miR-21-5p, the most highly expressed miRNA in ADSC-derived exosomes, was found to target NOTCH1. Overexpression of miR-21-5p in these exosomes facilitated EPC migration, tube formation, and VEGFA expression while downregulating NOTCH1 and DLL4 expression. Inhibition of miR-21-5p produced opposite effects on EPCs.

CONCLUSIONS

These findings indicate that miR-21-5p in ADSC-derived exosomes promotes angiogenesis in EPCs to accelerate bone repair by targeting the NOTCH1/DLL4/VEGFA signaling pathway, offering a potential therapeutic strategy for bone defect treatment.

Comparative Analysis of Heavy Metal Content in Impacted Third Molars from Industrial and Non-Industrial Areas and Its Effect on the Isolation, Culture, and Proliferation of Dental Stem Cells (DSCs)

Background: This study investigates the impact of environmental pollution on the quality and viability of dental stem cells (DSCs) from impacted third molars. By comparing DSCs from patients in industrial areas with high air pollution and those from non-industrial regions, the research assesses the adverse effects of heavy metals on stem cell proliferation. Methods: Impacted lower third molars were collected from 28 patients-10 from industrial and 18 from non-industrial areas. Patients were divided into two age groups: 18-27 years and 28-38 years old. Dental pulp was extracted under sterile conditions, and DSCs were isolated and cultured. Heavy metal concentrations in dental tissues were measured using atomic absorption/emission spectrometry. Results: The study found significantly higher concentrations of copper and lead in the dental tissues of patients in industrial areas. Cell viability was lower in samples from these areas, with a statistically significant difference in average doubling time and the number of cells obtained after the first passage. There was no significant impact of gender on heavy metal content, except for higher iron levels in men. Conclusions: Exposure to industrial pollutants negatively affects the viability and proliferation of DSCs, but there are no differences in differentiation in the osteogenic medium regarding cell mineralization. These studies highlight the importance of environmental factors for oral health, suggesting that residents of polluted areas may face greater difficulties in dental and regenerative treatments. Further research is needed to develop strategies to mitigate the effects and improve clinical outcomes for affected populations.

Hierarchical Biomaterial Scaffolds for Periodontal Tissue Engineering: Recent Progress and Current Challenges

The periodontium is a complex hierarchical structure composed of alveolar bone, periodontal ligament, cementum, and gingiva. Periodontitis is an inflammatory disease that damages and destroys the periodontal tissues supporting the tooth. Periodontal therapies aim to regenerate the lost tissues, yet current treatments lack the integration of multiple structural/biochemical instructive cues to induce a coordinated regeneration, which leads to limited clinical outcomes. Hierarchical biomaterial scaffolds offer the opportunity to recreate the organization and architecture of the periodontium with distinct compartments, providing structural biomimicry that facilitates periodontal regeneration. Various scaffolds have been fabricated and tested preclinically, showing positive regenerative results. This review provides an overview of the recent research on hierarchical scaffolds for periodontal tissue engineering (TE). First, the hierarchical structure of the periodontium is described, covering the limitations of the current treatments used for periodontal regeneration and presenting alternative therapeutic strategies, including scaffolds and biochemical factors. Recent research regarding hierarchical scaffolds is highlighted and discussed, in particular, the scaffold composition, fabrication methods, and results from in vitro/in vivo studies are summarized. Finally, current challenges associated with the application of hierarchical scaffolds for periodontal TE are debated and future research directions are proposed.

In vivo study on osteogenic efficiency of nHA/ gel porous scaffold with nacre water-soluble matrix

BACKGROUND/PURPOSE

Nano-hydroxyapatite (nHA)/ gel porous scaffolds loaded with WSM carriers are promising bone replacement materials that can improve osseointegration ability. This investigation aimed to evaluate the osteoinductive activity by implanting the composition of nano-hydroxyapatite (nHA)/ Gel porous scaffolds as a carrier of WSM via an animal model.

MATERIALS AND METHODS

WSM was extracted and nHA was added to the matrix to construct porous composite scaffolds. The dose-effect curve of WSM concentration and alkaline phosphatase (ALP) activity was made by culturing rat osteoblasts and examining the absorbance. Three different materials were implanted into critical size defects (CSD) in the skulls of rats, which were further divided into four groups: WSM nHA /Gel group, n-WSM nHA /Gel group, HA powder group, and control group.

RESULTS

WSM (150 μg/mL-250μg/mL) effectively improved the activity of ALP in rat osteoblasts. All rats in each group had normal healing. WSM-loaded nHA /Gel group showed better performance on newly-formed bone tissue of rat skull and back at 4th week and 8th week, respectively. At the 4th week, the network of woven bone formed in the WSM-loaded nHA/Gel scaffold material. At 8th week, the reticular trabecular bone in the WSM-loaded scaffold material became dense lamellar bone, and the defect was mature lamellar bone. In the subcutaneous implantation experiment, WSM-loaded nHA/Gel scaffold material showed a better performance of heterotopic ossification than the pure nHA/Gel scaffold material.

CONCLUSION

WSM promotes osteoblast differentiation and bone mineralization. The results confirm that the nHA/ Gel Porous Scaffold with Nacre Water-Soluble Matrix has a significant bone promoting effect and can be used as a choice for tissue engineering to repair bone defects.