Dental alloplastic bone substitutes currently available in Korea

A biphasic calcium phosphate/acylated methacrylate gelatin composite hydrogel promotes osteogenesis and bone repair

PURPOSE/AIM

Bone defects caused by trauma, tumors, congenital malformation, or inflammation are very common in orthopedics. In recent years, mimicking the composition and structure of natural bone tissue has become a hot topic in biomaterial research, with the aim of developing an ideal biomaterial for bone defect transplantation. Here, the feasibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel to repair bone defects was evaluated in vitro and in rats.

MATERIALS AND METHODS

The biocompatibility of a biphasic calcium phosphate (BCP)/acylated methacrylate gelatin (GelMA) composite hydrogel was evaluated by cytoskeleton staining, live/dead cell staining and cell proliferation assays. The in vitro osteogenic activities of the composite hydrogel were evaluated by alkaline phosphatase and alizarin red staining, as well as osteogenic gene expression analysis at both transcript and protein levels. The in vivo bone repair activities were evaluated using the rat skull defect model.

RESULTS

The BCP/GelMA composite hydrogel displayed excellent biocompatibility and promoted osteogenesis of bone marrow mesenchymal stem cells in vitro. In addition, the BCP/GelMA composite hydrogel markedly promoted new bone formation in the rat skull-defect model.

CONCLUSIONS

BCP/GelMA composite hydrogel may be an effective artificial material for bone tissue engineering.

A Histologic, Histomorphometric, and Immunohistochemical Evaluation of Anorganic Bovine Bone and Injectable Biphasic Calcium Phosphate in Humans: A Randomized Clinical Trial

Following trauma, chronic periapical process, or tooth extraction, a large loss of bone volume is noticed during the healing process. To facilitate the placement of dental implants, various surgical procedures are used for an optimal alveolar ridge profile, while maintaining adequate bone dimensions. The main aim of this study was to determine the healing ability (histologically and immunohistologically) of alveolar bone defects during augmentation with two different biomaterials: injectable biphasic calcium phosphate (BCP) and anorganic bovine bone (ABB). Thirty-eight subjects were randomly divided into two groups. The first group received the tested bone substitute biomaterial (BSB), i.e., BCP (maxresorb inject®), and the second group received an alternative to the gold standard, i.e., ABB (Bio-Oss®). The histopathological, histomorphometric, and immunohistochemical analyses gave comparable results for these bone substitute materials in terms of newly formed bone: (BCP: 39.91 ± 8.49%, ABB: 41.73 ± 13.99%), residual biomaterial (BCP: 28.61 ± 11.38%, ABB: 31.72 ± 15.52%), and soft tissue (BCP: 31.49 ± 11.09%, ABB: 26.54 ± 7.25%), with no significant difference found between the groups (p < 0.05, t-test), proving that BCP is equally suitable and successful for alveolar bone regeneration.

The Effect of Whitlockite as an Osteoconductive Synthetic Bone Substitute Material in Animal Bony Defect Model

This study aimed to evaluate the biomechanical properties in vitro and the bone regeneration of whitlockite (WH) compared with hydroxyapatite (HA) or β-tricalcium phosphate (β-TCP)-based material. We investigated the morphology and phase composition of the bone grafts using a scanning electron microscope and X-ray diffractometer patterns and tested the compressive strength. Four circular defects of 8 mm in diameter were created on the calvaria of twelve rabbits. One defect was left empty, and each of the other defects was filled with WH, HA, and β-TCP. At 4 and 8 weeks, the specimens were harvested to evaluate for the new bone formation and the remaining bone grafts. Regarding the biomechanical properties, the three grafts had a similar micropore size, and WH showed nanopores. The compressive strength of WH was higher than HA and β-TCP without statistical significance. The radiological and histomorphometric analyses demonstrated that the new bone formation was similar among the groups. The remaining bone graft of the WH group was greater than that of the HA and β-TCP groups at 4 weeks (p < 0.05), and the total bone area of the WH, HA, and β-TCP groups was greater than that of the other (p < 0.01). WH has excellent volumetric stability and osteoconductivity compared with HA and β-TCP.

Osteogenic Induction with Silicon Hydroxyapatite Using Modified Autologous Adipose Tissue-Derived Stromal Vascular Fraction: In Vitro and Qualitative Histomorphometric Analysis

Large bone defects requiring invasive surgical procedures have long been a problem for orthopedic surgeons. Despite the use of autologous bone grafting, satisfactory results are often not achieved due to associated limitations. Biomaterials are viable alternatives and have lately been used in association with Stromal Vascular Fraction (SVF), stem cells, and signaling factors for bone tissue engineering (BTE). The objective of the current study was to assess the biocompatibility of Silicon Hydroxyapatite (Si-HA) and to improve osteogenic potential by using autologous adipose-derived SVF with Si-HA in a rabbit bone defect model. Si-HA granules synthesized using a wet precipitation method were used. They were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and X-ray diffraction (XRD). A hemolysis assay was used to assess the hemolytic effects of Si-HA, while cell viability was assessed through Alamar Blue assay using MC3T3 mouse osteoblasts. The osteogenic potential of Si-HA both alone and with enzymatically/non-enzymatically-derived SVF (modified) was performed by implantation in a rabbit tibia model followed by histomorphometric analysis and SEM of dissected bone after six weeks. The results showed that Si-HA granules were microporous and phase pure and that the addition of Silicon did not influence Si-HA phase composition. Si-HA granules were found to be non-hemolytic on the hemolysis assay and non-toxic to MC3T3 mouse osteoblasts on the Alamar Blue assay. Six weeks following implantation Si-HA showed high biocompatibility, with increased bone formation in all groups compared to control. Histologically more mature bone was formed in the Si-HA implanted along with non-enzymatically-derived modified SVF. Bone formation was observed on and around Si-HA, reflecting osseointegration. In conclusion, Si-HA is osteoconductive and promotes osteogenesis, and its use with SVF enhances osteogenesis.

Applying extrusion-based 3D printing technique accelerates fabricating complex biphasic calcium phosphate-based scaffolds for bone tissue regeneration

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Biphasic calcium phosphates offer a chemically similar biomaterial to the natural bone, which can significantly accelerate bone formation and reconstruction.

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Robocasting is a suitable technique to produce porous scaffolds supporting cell viability, proliferation, and differentiation.

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This review discusses materials and methods utilized for BCP robocasting, considering recent advancements and existing challenges in using additives for bioink preparation.

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Commercialization and marketing approach, in-vitro and in-vivo evaluations, biologic responses, and post-processing steps are also investigated.

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Possible strategies and opportunities for the use of BCP toward injured bone regeneration along with clinical applications are discussed.

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The study proposes that BCP possesses an acceptable level of bone substituting, considering its challenges and struggles.

Background

Aim of review

Key scientific concepts of review

Enhanced Bone Regeneration in Variable-Type Biphasic Ceramic Phosphate Scaffolds Using rhBMP-2

Our aim was to investigate the bone regeneration capacity of powder-type biphasic ceramic scaffold (BCP powder), block-type BCP (BCP block), and collagen-added block-type BCP (BCP collagen) with different concentrations of recombinant human bone morphogenetic protein 2 (rhBMP-2) in an animal model. Four rabbits were assigned to each of the following groups: no graft + rhBMP-2 (0.1/0.2 mg/mL), BCP powder + rhBMP-2 (0.1/0.2 mg/mL), BCP block + rhBMP-2 (0.1/0.2 mg/mL), and BCP collagen + rhBMP-2 (0.1/0.2 mg/mL), i.e., a total of 32 rabbits. Polycarbonate tubes (Φ 7 mm × 5 mm) for supporting scaffolds were fixed into a 7 mm round border. Subsequently, 0.1 mL of rhBMP-2 solutions with different concentrations was injected into the tubes. Both radiological and histomorphometric analyses showed that osteogenesis was not enhanced by increasing the concentration of rhBMP-2 in all groups at both 3 and 6 weeks. Radiological analysis showed that bone formation was higher in the BCP collagen group than in the BCP powder and BCP block groups at both rhBMP-2 concentrations at 3 weeks. rhBMP-2 enhanced bone formation; however, as the concentration increased, bone formation could not be enhanced infinitely. Collagen-added alloplastic graft material may be useful for mediating rapid bone formation in initial stages.

Synthetic Injectable Biomaterials for Alveolar Bone Regeneration in Animal and Human Studies

After tooth extraction, the alveolar ridge undergoes dimensional changes. Different bone regeneration biomaterials are used to reduce bone loss. The aim of this article was to systematically review the literature on the effect of injectable synthetic biomaterials and their advantages and disadvantages for new bone formation in the maxilla and mandible in animals and humans. A literature search was conducted in November 2020 via MEDLINE PubMed, Cochrane, and Embase. Of the 501 records screened, abstract analysis was performed on 49 articles, resulting in 21 studies that met the inclusion criteria. Animal studies have shown heterogeneity in terms of animal models, follow-up time, composition of the injectable biomaterial, and different outcome variables such as bone–implant contact, newly formed bone, and peri-implant bone density. Heterogeneity has also been demonstrated by human studies. The following outcomes were observed: newly formed bone, connective tissue, residual injectable bone graft substitute, radiographic density, residual bone height, and different follow-up periods. Further studies, especially in humans, based on the histological and biomechanical properties of the injectable delivery form, are needed to draw more concrete conclusions that will contribute to a better understanding of the benefits of this type of biomaterials and their role in bone regeneration.

Collagenated Porcine Heterologous Bone Grafts: Histomorphometric Evaluation of Bone Formation Using Different Physical Forms in a Rabbit Cancellous Bone Model

Collagenated porcine-derived bone graft materials exhibit osteoconductive properties and the development of different formulations intends to enhance bone regeneration. This study aims to evaluate bone healing in a rabbit cancellous bone defect in response to grafting with different physicochemical forms of heterologous porcine bone. Twenty-six adult male New Zealand White rabbits received two critical size femoral bone defects per animal (n = 52), each randomly assigned to one of the five tested materials (Apatos, Gen-Os, mp3, Putty, and Gel 40). Animals were sacrificed at 15- and 30-days post-surgery. Qualitative and quantitative (new bone, particle and connective tissue percentages) histological analyses were performed. Histomorphometry showed statistically significant differences in all evaluated parameters between mp3 and both Putty and Gel 40 groups, regardless of the timepoint (p < 0.05). Moreover, statistical differences were observed between Apatos and both Putty (p = 0.014) and Gel 40 (p = 0.007) groups, at 30 days, in regard to particle percentage. Within each group, regarding new bone formation, mp3 showed significant differences (p = 0.028) between 15 (40.93 ± 3.49%) and 30 (52.49 ± 11.04%) days. Additionally, intragroup analysis concerning the percentage of particles revealed a significant reduction in particle occupied area from 15 to 30 days in mp3 and Gen-Os groups (p = 0.009). All mp3, Gen-Os and Apatos exhibited promising results in terms of new bone formation, thus presenting suitable alternatives to be used in bone regeneration.

Alloplastic Bone Substitutes for Periodontal and Bone Regeneration in Dentistry: Current Status and Prospects

Various bone graft products are commercially available worldwide. However, there is no clear consensus regarding the appropriate bone graft products in different clinical situations. This review is intended to summarize bone graft products, especially alloplastic bone substitutes that are available in multiple countries. It also provides dental clinicians with detailed and accurate information concerning these products. Furthermore, it discusses the prospects of alloplastic bone substitutes based on an analysis of the current market status, as well as a comparison of trends among countries. In this review, we focus on alloplastic bone substitutes approved in the United States, Japan, and Korea for use in periodontal and bone regeneration. According to the Food and Drug Administration database, 87 alloplastic bone graft products have been approved in the United States since 1996. According to the Pharmaceuticals and Medical Devices Agency database, 10 alloplastic bone graft products have been approved in Japan since 2004. According to the Ministry of Health and Welfare database, 36 alloplastic bone graft products have been approved in Korea since 1980. The approved products are mainly hydroxyapatite, β-tricalcium phosphate, and biphasic calcium phosphate. The formulations of the products differed among countries. The development of new alloplastic bone products has been remarkable. In the near future, alloplastic bone substitutes with safety and standardized quality may be the first choice instead of autologous bone; they may offer new osteoconductive and osteoinductive products with easier handling form and an adequate resorption rate, which can be used with growth factors and/or cell transplantation. Careful selection of alloplastic bone graft products is necessary to achieve predictable outcomes according to each clinical situation.

Extraction socket preservation

Extraction socket preservation (ESP) is widely performed after tooth extraction for future implant placement. For successful outcome of implants after extractions, clinicians should be acquainted with the principles and indications of ESP. It is recommended that ESP be actively implemented in cases of esthetic areas, severe bone defects, and delayed implant placement. Dental implant placement is recommended at least 4 months after ESP.

Sinus membrane elevation and implant placement

Sinus Schneiderian membrane elevation surgery is widely performed for dental implant placement in the maxillary posterior region. With regard to sinus elevation surgery, various complications can occur and lead to implant failure. For successful implants in the maxillary posterior region, the clinician must be well acquainted with sinus anatomy and pathology, a variety of bone graft materials, the principles of sinus elevation surgery, and prevention and management of complications.