Periodontal repair following implantation of beta-tricalcium phosphate with different pore structures in class III furcation defects in dogs

Recent Advances in Scaffolds for Guided Bone Regeneration

The rehabilitation of alveolar bone defects of moderate to severe size is often challenging. Currently, the therapeutic approaches used include, among others, the guided bone regeneration technique combined with various bone grafts. Although these techniques are widely applied, several limitations and complications have been reported such as morbidity, suboptimal graft/membrane resorption rate, low structural integrity, and dimensional stability. Thus, the development of biomimetic scaffolds with tailor-made characteristics that can modulate cell and tissue interaction may be a promising tool. This article presents a critical consideration in scaffold's design and development while also providing information on various fabrication methods of these nanosystems. Their utilization as delivery systems will also be mentioned.

Immuno-histologic and histomorphometric evaluation of Angelica sinensis adjunctive to ß-tricalcium phosphate in critical-sized class II furcation defects in dogs

OBJECTIVE

The study evaluates the effectiveness of Angelica sinensis (As) adjunctive to Beta-tricalcium phosphate (β-TCP) bone graft in the management of induced critical sized class II furcation defects in dogs.

MATERIAL AND METHOD

A randomized study design was conducted on the third and fourth premolars of six dogs. A total of twenty-four defects were surgically created. After reflecting a mucoperiosteal flap, twelve defects were filled with As granules mixed with β-TCP (Experimental group) while the other twelve defects were filled with β-TCP only (Control group) and both were covered by collagen membrane. At the fourth and eighth weeks, jaw segments were dissected and processed for immune-histological examination and histomorphometry analysis.

RESULTS

At four and eight weeks after treatment, experimental group showed a statistically significant increase in the height of newly formed interradicular bone (p = 0.001 and p = 0.0001 respectively), its surface area (p = 0.002 and p = 0.02 respectively), and the thickness of its trabeculae (p = 0.0001 and p = 0.001 respectively), when compared to control group. Moreover. alkaline phosphatase immunoreaction showed higher intensity in the osteoblast cells of experimental group compared to control group.

CONCLUSION

As enhances periodontal regeneration and bone-formation when used in the management of furcation defects.

Histologic and histomorphometric evaluation of Aloe vera adjunctive to β-tricalcium phosphate in class II furcation defects in dogs

Aloe vera has antimicrobial activity and enhances the osseointegration process, thus it may have the potential in treating periodontal defects. This study aimed to evaluate the effect of Aloe vera as an adjunction to Beta-tricalcium phosphate (β-TCP) bone graft in Grade II furcation defects. A randomized study was conducted on six healthy mongrel dogs' premolars. A total of twenty-four Grade II furcation critical-sized defects were surgically created after reflecting a full-thickness flap, twelve defects were filled with β-TCP while the other twelve defects were filled with Aloe vera mixed with β-TCP and both covered by collagen membrane. Animals were euthanized at the end of the fourth and eighth week and defects were analyzed histologically and histomorphometrically. Histologically, Aloe vera mixed with β-TCP resulted in more bone formation and new PDL fibers compared to β-TCP alone. After 2 and 4 weeks, the experimental group had significantly higher newly formed interradicular bone height (p < 0.0001, and p < 0.0001, respectively), bone thickness (p < 0.0001, and p < 0.0001, respectively), and percentage of the surface area (p = 0.009, and p = 0.023, respectively). Aloe vera gel adjunctive to β-TCP is an effective bioactive agent that enhances periodontal tissue regeneration and bone formation in critically sized defects.

Characterization of a cotton-wool like composite bone graft material

Bone graft materials are applied in patients to augment bone defects and enable the insertion of an implant in its ideal position. However, the currently available augmentation materials do not meet the requirements of being completely resorbed and replaced by new bone within 3 to 6 months. A novel electrospun cotton-wool like material (Bonewool^®, Zurich Biomaterials LLC, Zurich, Switzerland) consisting of biodegradable poly(lactic-co-glycolic) acid (PLGA) fibers with incorporated amorphous ß-tricalcium phosphate (ß-TCP) nanoparticles has been compared to a frequently used bovine derived hydroxyapatite (Bio-Oss^®, Geistlich Pharma, Wolhusen, Switzerland) in vitro. The material composition was determined and the degradation behavior (calcium release and pH in different solutions) as well as bioactivity has been measured. Degradation behavior of PLGA/ß-TCP was generally more progressive than for Bio-Oss^®, indicating that this material is potentially completely resorbable. Graphical abstract.

3D gel-printed porous magnesium scaffold coated with dibasic calcium phosphate dihydrate for bone repair in vivo

Background

/Objective: The treatment of bone defect has always been a difficult problem in orthopedic clinic. The search for alternative biodegradable implants is a hot topic. The development of biodegradable magnesium scaffolds for the treatment of bone defects has long been a goal of the public.

Methods

In this study, we proposed a porous magnesium scaffold prepared by 3D gel printing and surface modification with an additional calcium phosphate coating and use of its strength, degradability and slow degradation rate in a bone graft substitute material. The porous magnesium granular scaffold was prepared by 3D gel printing technology and modified by DCPD (Dibasic Calcium Phosphate Dihydrate) coating. The biocompatibility, degradation rate, and osteogenic ability of the scaffold were evaluated in vitro and in vivo.

Results

The biocompatibility, in vivo degradation and bone defect healing response of the implants were investigated. Porous magnesium scaffolds were successfully prepared, and the strength of sintered scaffolds reached 5.38 ​MPa. The degradation rates of scaffolds were significantly reduced after coating with DCPD. The cell compatibility evaluation showed that DCPD-coated Mg scaffold was suitable for cell proliferation. In vivo biosafety monitoring showed that scaffold implantation did not cause an increase in Mg ion concentration in vivo, and no toxic damage was detected in the liver or kidney. Micro-CT and pathological results showed that a large amount of new bone was formed at 6 weeks. At 12 weeks, approximately 52% of the scaffold volume remained. At 24 weeks, osteogenesis, which was stimulated by some residual scaffold, still can be observed. In summary, this study suggests that 3D gel-printed DCPD-coated porous magnesium scaffolds have great potential as bone graft alternatives.

Conclusion

In summary, this study suggests that 3D gel-printed DCPD-coated porous magnesium scaffolds have great potential as bone graft alternatives.

The Translational potential of this article

The translational potential of this article is to make use of the advantages of 3D gel printing technology with higher efficiency and lower cost compared with SLM and SLS technologies, and use pure magnesium powder as raw material to prepare degradable porous magnesium metal scaffolds, opening up a new technical route for the preparation of degradable porous magnesium scaffolds which are made for bone defect regeneration in the future.

Novel multimodal MRI and MicroCT imaging approach to quantify angiogenesis and 3D vascular architecture of biomaterials

Quantitative assessment of functional perfusion capacity and vessel architecture is critical when validating biomaterials for regenerative medicine purposes and requires high-tech analytical methods. Here, combining two clinically relevant imaging techniques, (magnetic resonance imaging; MRI and microcomputed tomography; MicroCT) and using the chorioallantoic membrane (CAM) assay, we present and validate a novel functional and morphological three-dimensional (3D) analysis strategy to study neovascularization in biomaterials relevant for bone regeneration. Using our new pump-assisted approach, the two scaffolds, Optimaix (laminar structure mimicking entities of the diaphysis) and DegraPol (highly porous resembling spongy bone), were shown to directly affect the architecture of the ingrowing neovasculature. Perfusion capacity (MRI) and total vessel volume (MicroCT) strongly correlated for both biomaterials, suggesting that our approach allows for a comprehensive evaluation of the vascularization pattern and efficiency of biomaterials. Being compliant with the 3R-principles (replacement, reduction and refinement), the well-established and easy-to-handle CAM model offers many advantages such as low costs, immune-incompetence and short experimental times with high-grade read-outs when compared to conventional animal models. Therefore, combined with our imaging-guided approach it represents a powerful tool to study angiogenesis in biomaterials.

Immunohistopathologic evaluation of Drynaria fortunei rhizome extract in the management of Class II furcation defects in a canine model

BACKGROUND

Management of furcation defects is still a challenging subject in periodontal therapy. Drynaria fortunei (Df) is a common type of traditional Chinese herb in the area of orthopedics and traumatology. In vitro and tissue engineering studies have shown that Df induces osteoblastic proliferation and promotes the differentiation of human periodontal ligament cells. This study investigated the management of Class II furcation defects in dogs using guided tissue regeneration (GTR) and Df granules mixed with β-tricalcium phosphate (β- TCP) alloplast.

METHODS

Sixteen Class II critical-sized furcation defects were surgically created in four mongrel dogs: Eight defects were treated with GTR and Df granules mixed with (β-TCP) alloplast served as the experimental group, while the other eight were managed with GTR and alloplast, served as control. Dogs were sacrificed at 4 and 8 weeks and the premolars were processed for the evaluation of treatment outcome including; osteoblastic count (OC), cementum layer thickness (CLT), percentage of collagen in bone matrix (CBM), and alkaline phosphatase (ALP) immunoreaction.

RESULTS

Experimental group treated with Df showed a significant increase (P < 0.001) in the values of OC, CLT, CBM, and ALP immunoreactivity when compared with control at 4 and 8 weeks after treatment.

CONCLUSION

Drynaria fortunei demonstrated increased regeneration and bone formation when used in the treatment of furcation defects in a canine model.

A novel two-step sintering for nano-hydroxyapatite scaffolds for bone tissue engineering

In this study, nano-hydroxyapatite scaffolds with high mechanical strength and an interconnected porous structure were prepared using NTSS for the first time. The first step was performed using a laser characterized by the rapid heating to skip the surface diffusion and to obtain the driving force for grain boundary diffusion. Additionally, the interconnected porous structure was achieved by SLS. The second step consisted of isothermal heating in a furnace at a lower temperature (T₂) than that of the laser beam to further increase the density and to suppress grain growth by exploiting the difference in kinetics between grain-boundary diffusion and grain-boundary migration. The results indicated that the mechanical properties first increased and then decreased as T₂ was increased from 1050 to 1250°C. The optimal fracture toughness, compressive strength and stiffness were 1.69 MPam^1/2, 18.68 MPa and 245.79 MPa, respectively. At the optimal point, the T₂ was 1100°C, the grain size was 60 nm and the relative density was 97.6%. The decrease in mechanical properties was due to the growth of grains and the decomposition of HAP. The cytocompatibility test results indicated that cells adhered and spread well on the scaffolds. A bone-like apatite layer formed, indicating good bioactivity.

Key role of the expression of bone morphogenetic proteins in increasing the osteogenic activity of osteoblast-like cells exposed to shock waves and seeded on bioactive glass-ceramic scaffolds for bone tissue engineering

In this work, the role of shock wave-induced increase of bone morphogenetic proteins in modulating the osteogenic properties of osteoblast-like cells seeded on a bioactive scaffold was investigated using gremlin as a bone morphogenetic protein antagonist. Bone-like glass-ceramic scaffolds, based on a silicate experimental bioactive glass developed at the Politecnico di Torino, were produced by the sponge replication method and used as porous substrates for cell culture. Human MG-63 cells, exposed to shock waves and seeded on the scaffolds, were treated with gremlin every two days and analysed after 20 days for the expression of osteoblast differentiation markers. Shock waves have been shown to induce osteogenic activity mediated by increased expression of alkaline phosphatase, osteocalcin, type I collagen, BMP-4 and BMP-7. Cells exposed to shock waves plus gremlin showed increased growth in comparison with cells treated with shock waves alone and, conversely, mRNA contents of alkaline phosphatase and osteocalcin were significantly lower. Therefore, the shock wave-mediated increased expression of bone morphogenetic protein in MG-63 cells seeded on the scaffolds is essential in improving osteogenic activity; blocking bone morphogenetic protein via gremlin completely prevents the increase of alkaline phosphatase and osteocalcin. The results confirmed that the combination of glass-ceramic scaffolds and shock waves exposure could be used to significantly improve osteogenesis opening new perspectives for bone regenerative medicine.

Calcium orthophosphates in dentistry

Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.