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Open AccessArticle

Bone Regeneration and Remodeling within a Unidirectional Porous Hydroxyapatite Bone Substitute at a Cortical Bone Defect Site: Histological Analysis at One and Two Years after Implantation

by Masashi Iwasashi, Toru Funayama, Arata Watanabe, Hiroshi Noguchi, Toshinori Tsukanishi, Yasushi Suetsugu, Takeshi Makihara, Naoyuki Ochiai, Masashi Yamazaki and Masataka Sakane

Materials 2015, 8(8), 4884-4894; https://doi.org/10.3390/ma8084884 - 30 Jul 2015

Cited by 24 | Viewed by 6256

Abstract

Unidirectional porous hydroxyapatite (UDPHAp) is an artificial bone substitute with a unique microstructure consisting of 100–300-µm oval pores that present the material unidirectionally. UDPHAp has a compression strength of 14 MPa and a porosity of 75%, which promotes cell migration and capillary formation [...] Read more.

Unidirectional porous hydroxyapatite (UDPHAp) is an artificial bone substitute with a unique microstructure consisting of 100–300-µm oval pores that present the material unidirectionally. UDPHAp has a compression strength of 14 MPa and a porosity of 75%, which promotes cell migration and capillary formation within the material. Despite these advantageous properties, bone remodeling and bone formation with UDPHAp remain unclear. To examine long-term remodeling and differences in bone formation based on the defect site, trapezoidal prism-shaped UDPHAp blocks were implanted into rectangular-shaped cortical bone defects in the proximal tibia of Japanese white rabbits. Histological analysis performed at 52 and 104 weeks after implantation revealed that bone and capillaries had formed within the implanted UDPHAp material. Bone formed within the UDPHAp implanted in the cortical defect of rabbit tibia and remodel up to two years. The percentage of new bone area within UDPHAp was larger in cortical lesions than that in medullary lesions. These findings suggest that UDPHAp is a promising material for the repair of non-critical-sized cortical bone defects. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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3926 KiB

Open AccessArticle

A Bone Sample Containing a Bone Graft Substitute Analyzed by Correlating Density Information Obtained by X-ray Micro Tomography with Compositional Information Obtained by Raman Microscopy

by Johann Charwat-Pessler, Maurizio Musso, Alexander Petutschnigg, Karl Entacher, Bernhard Plank, Erik Wernersson, Stefan Tangl and Peter Schuller-Götzburg

Materials 2015, 8(7), 3831-3853; https://doi.org/10.3390/ma8073831 - 25 Jun 2015

Cited by 3 | Viewed by 5835

Abstract

The ability of bone graft substitutes to promote new bone formation has been increasingly used in the medical field to repair skeletal defects or to replace missing bone in a broad range of applications in dentistry and orthopedics. A common way to assess [...] Read more.

The ability of bone graft substitutes to promote new bone formation has been increasingly used in the medical field to repair skeletal defects or to replace missing bone in a broad range of applications in dentistry and orthopedics. A common way to assess such materials is via micro computed tomography (µ-CT), through the density information content provided by the absorption of X-rays. Information on the chemical composition of a material can be obtained via Raman spectroscopy. By investigating a bone sample from miniature pigs containing the bone graft substitute Bio Oss^®, we pursued the target of assessing to what extent the density information gained by µ-CT imaging matches the chemical information content provided by Raman spectroscopic imaging. Raman images and Raman correlation maps of the investigated sample were used in order to generate a Raman based segmented image by means of an agglomerative, hierarchical cluster analysis. The resulting segments, showing chemically related areas, were subsequently compared with the µ-CT image by means of a one-way ANOVA. We found out that to a certain extent typical gray-level values (and the related histograms) in the µ-CT image can be reliably related to specific segments within the image resulting from the cluster analysis. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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952 KiB

Open AccessArticle

3D Printable Biophotopolymers for in Vivo Bone Regeneration

by Guenter Russmueller, Robert Liska, Juergen Stampfl, Christian Heller, Andreas Mautner, Karin Macfelda, Barbara Kapeller, Roman Lieber, Agnes Haider, Kathrin Mika, Christian Schopper, Christos Perisanidis, Rudolf Seemann and Doris Moser

Materials 2015, 8(6), 3685-3700; https://doi.org/10.3390/ma8063685 - 19 Jun 2015

Cited by 22 | Viewed by 6768

Abstract

The present study investigated two novel biophotopolymer classes that are chemically based on non-toxic poly (vinyl alcohol). These vinylesters and vinylcarbonates were compared to standard acrylates in vitro on MC3T3-E1 cells and in vivo in a small animal model. In vitro, both [...] Read more.

The present study investigated two novel biophotopolymer classes that are chemically based on non-toxic poly (vinyl alcohol). These vinylesters and vinylcarbonates were compared to standard acrylates in vitro on MC3T3-E1 cells and in vivo in a small animal model. In vitro, both vinylester and vinylcarbonate monomers showed about tenfold less cytotoxicity when compared to acrylates (IC₅₀: 2.922 mM and 2.392 mM vs. 0.201 mM) and at least threefold higher alkaline phosphatase activity (17.038 and 18.836 vs. 5.795, measured at [10 mM]). In vivo, polymerized 3D cellular structures were implanted into the distal femoral condyle of 16 New Zealand White Rabbits and were observed for periods from 4 to 12 weeks. New bone formation and bone to implant contact was evaluated by histomorphometry at end of observation. Vinylesters showed similar rates of new bone formation but significantly less (p = 0.002) bone to implant contact, when compared to acrylates. In contrast, the implantation of vinylcarbonate based biophotopolymers led to significantly higher rates of newly formed bone (p < 0.001) and bone to implant contact (p < 0.001). Additionally, distinct signs of polymer degradation could be observed in vinylesters and vinylcarbonates by histology. We conclude, that vinylesters and vinylcarbonates are promising new biophotopolymers, that outmatch available poly(lactic acid) and (meth)acrylate based materials. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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2758 KiB

Open AccessArticle

Graft Remodeling following Transcrestal Sinus Floor Elevation via the Gel-Pressure Technique (GPT) and Pasteous Nano-Crystalline Hydroxyapatite Bone Substitute

by Bernhard Pommer, Ewald Unger, Dieter Busenlechner, Robert Haas, Georg Mailath-Pokorny, Rudolf Fürhauser and Georg Watzek

Materials 2015, 8(6), 3210-3220; https://doi.org/10.3390/ma8063210 - 03 Jun 2015

Cited by 4 | Viewed by 5440

Abstract

Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation [...] Read more.

Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation via the Gel-Pressure Technique (GPT) and application of pasteous nano-crystalline hydroxyapatite bone substitute. A total of 25 patients with deficient alveolar ridges in the posterior maxilla (mean residual bone height: 4.7 ± 1.8 mm) were subjected to 32 flapless transcrestal sinus floor augmentations and simultaneous insertion of 40 implants. Sinus membrane elevation height averaged 11.2 ± 2.7 mm and minimal vertical graft resorption of 0.1 mm was observed after four months. Radiographic bone density averaged 460 Hounsfield units in regions adjacent to the native jawbone (1 to 7 mm distance), while reduction of bone density by −7.2%, −11.3%, −14.8%, −19.6% and −22.7% was recorded in more apical regions of 8, 9, 10, 11, and ≥12 mm distance to the original sinus floor, respectively. The results suggest that graft remodeling is completed up to a distance of 7 mm within a healing period of four months after sinus augmentation using nano-crystalline hydroxyapatite bone substitute material. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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965 KiB

Open AccessArticle

Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

by Zeeshan Sheikh, Corneliu Sima and Michael Glogauer

Materials 2015, 8(6), 2953-2993; https://doi.org/10.3390/ma8062953 - 27 May 2015

Cited by 144 | Viewed by 23252

Abstract

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used [...] Read more.

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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2262 KiB

Open AccessArticle

A Novel Porcine Graft for Regeneration of Bone Defects

by Eisner Salamanca, Wei-Fang Lee, Chin-Yi Lin, Haw-Ming Huang, Che-Tong Lin, Sheng-Wei Feng and Wei-Jen Chang

Materials 2015, 8(5), 2523-2536; https://doi.org/10.3390/ma8052523 - 12 May 2015

Cited by 12 | Viewed by 6369

Abstract

Bone regeneration procedures require alternative graft biomaterials to those for autogenous bone. Therefore, we developed a novel porcine graft using particle sizes of 250–500 μm and 500–1000 μm in rabbit calvarial bone defects and compared the graft properties with those of commercial hydroxyapatite [...] Read more.

Bone regeneration procedures require alternative graft biomaterials to those for autogenous bone. Therefore, we developed a novel porcine graft using particle sizes of 250–500 μm and 500–1000 μm in rabbit calvarial bone defects and compared the graft properties with those of commercial hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP) over eight weeks. Surgery was performed in 20 adult male New Zealand white rabbits. During a standardized surgical procedure, four calvarial critical-size defects of 5 mm diameter and 3 mm depth were prepared. The defects were filled with HA/β-TCP, 250–500 μm or 500–1000 μm porcine graft, and control defects were not filled. The animals were grouped for sacrifice at 1, 2, 4, and 8 weeks post-surgery. Subsequently, sample blocks were prepared for micro-computed tomography (micro-CT) scanning and histological sectioning. Similar bone formations were observed in all three treatment groups, although the 250–500 μm porcine graft performed slightly better. Rabbit calvarial bone tissue positively responded to porcine grafts and commercial HA/β-TCP, structural analyses showed similar crystallinity and porosity of the porcine and HA/β-TCP grafts, which facilitated bone formation through osteoconduction. These porcine grafts can be considered as graft substitutes, although further development is required for clinical applications. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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767 KiB

Open AccessArticle

Fibrin Hydrogel Based Bone Substitute Tethered with BMP-2 and BMP-2/7 Heterodimers

by Lindsay S. Karfeld-Sulzer, Barbara Siegenthaler, Chafik Ghayor and Franz E. Weber

Materials 2015, 8(3), 977-991; https://doi.org/10.3390/ma8030977 - 06 Mar 2015

Cited by 17 | Viewed by 6248

Abstract

Current clinically used delivery methods for bone morphogenetic proteins (BMPs) are collagen based and require large concentrations that can lead to dangerous side effects. Fibrin hydrogels can serve as osteoinductive bone substitute materials in non-load bearing bone defects in combination with BMPs. Two [...] Read more.

Current clinically used delivery methods for bone morphogenetic proteins (BMPs) are collagen based and require large concentrations that can lead to dangerous side effects. Fibrin hydrogels can serve as osteoinductive bone substitute materials in non-load bearing bone defects in combination with BMPs. Two strategies to even further optimize such a fibrin based system include employing more potent BMP heterodimers and engineering growth factors that can be covalently tethered to and slowly released from a fibrin matrix. Here we present an engineered BMP-2/BMP-7 heterodimer where an N-terminal transglutaminase substrate domain in the BMP-2 portion provides covalent attachment to fibrin together with a central plasmin substrate domain, a cleavage site for local release of the attached BMP-2/BMP-7 heterodimer under the influence of cell-activated plasmin. In vitro and in vivo results revealed that the engineered BMP-2/BMP-7 heterodimer induces significantly more alkaline phosphatase activity in pluripotent cells and bone formation in a rat calvarial model than the engineered BMP-2 homodimer. Therefore, the engineered BMP-2/BMP-7 heterodimer could be used to reduce the amount of BMP needed for clinical effect. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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Review

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864 KiB

Open AccessReview

Preclinical in vivo Performance of Novel Biodegradable, Electrospun Poly(lactic acid) and Poly(lactic-co-glycolic acid) Nanocomposites: A Review

by Claudia Holderegger, Patrick R. Schmidlin, Franz E. Weber and Dirk Mohn

Materials 2015, 8(8), 4912-4931; https://doi.org/10.3390/ma8084912 - 03 Aug 2015

Cited by 19 | Viewed by 6820

Abstract

Bone substitute materials have witnessed tremendous development over the past decades and autogenous bone may still be considered the gold standard for many clinicians and clinical approaches in order to rebuild and restore bone defects. However, a plethora of novel xenogenic and synthetic [...] Read more.

Bone substitute materials have witnessed tremendous development over the past decades and autogenous bone may still be considered the gold standard for many clinicians and clinical approaches in order to rebuild and restore bone defects. However, a plethora of novel xenogenic and synthetic bone substitute materials have been introduced in recent years in the field of bone regeneration. As the development of bone is actually a calcification process within a collagen fiber arrangement, the use of scaffolds in the formation of fibers may offer some advantages, along with additional handling characteristics. This review focuses on material characteristics and degradation behavior of electrospun biodegradable polyester scaffolds. Furthermore, we concentrated on the preclinical in vivo performance with regard to bone regeneration in preclinical studies. The major findings are as follows: Scaffold composition and architecture determine its biological behavior and degradation characteristics; The incorporation of inorganic substances and/or organic substances within composite scaffolds enhances new bone formation; L-poly(lactic acid) and poly(lactic-co-glycolic acid) composite scaffolds, especially when combined with basic substances like hydroxyapatite, tricalcium phosphate or demineralized bone powder, seem not to induce inflammatory tissue reactions in vivo. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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2470 KiB

Open AccessReview

Mineralized Collagen: Rationale, Current Status, and Clinical Applications

by Zhi-Ye Qiu, Yun Cui, Chun-Sheng Tao, Zi-Qiang Zhang, Pei-Fu Tang, Ke-Ya Mao, Xiu-Mei Wang and Fu-Zhai Cui

Materials 2015, 8(8), 4733-4750; https://doi.org/10.3390/ma8084733 - 24 Jul 2015

Cited by 70 | Viewed by 12430

Abstract

This paper presents a review of the rationale for the in vitro mineralization process, preparation methods, and clinical applications of mineralized collagen. The rationale for natural mineralized collagen and the related mineralization process has been investigated for decades. Based on the understanding of [...] Read more.

This paper presents a review of the rationale for the in vitro mineralization process, preparation methods, and clinical applications of mineralized collagen. The rationale for natural mineralized collagen and the related mineralization process has been investigated for decades. Based on the understanding of natural mineralized collagen and its formation process, many attempts have been made to prepare biomimetic materials that resemble natural mineralized collagen in both composition and structure. To date, a number of bone substitute materials have been developed based on the principles of mineralized collagen, and some of them have been commercialized and approved by regulatory agencies. The clinical outcomes of mineralized collagen are of significance to advance the evaluation and improvement of related medical device products. Some representative clinical cases have been reported, and there are more clinical applications and long-term follow-ups that currently being performed by many research groups. Full article

(This article belongs to the Special Issue Novel Bone Substitute Materials)

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