Closure of critical sized defects with allogenic and alloplastic bone substitutes

Early Osteogenic-Induced Adipose-Derived Stem Cells and Canine Bone Regeneration Potential Analyzed Using Biodegradable Scaffolds

The complex process of bone regeneration is influenced by factors such as inflammatory responses, tissue interactions, and progenitor cells. Currently, multiple traumas can interfere with fracture healing, causing the prolonging or failure of healing. In these cases, bone grafting is the most effective treatment. However, there are several drawbacks, such as morbidity at the donor site and availability of suitable materials. Advantages have been provided in this field by a variety of stem cell types. Adipose-derived stem cells (ASCs) show promise. In the radiological examination of this study, it was confirmed that the C/S group showed faster regeneration than the other groups, and Micro-CT also showed that the degree of bone formation in the defect area was highest in the C/S group. Compared to the control group, the change in cortical bone area in the defect area decreased in the sham group (0.874), while it slightly increased in the C/S group (1.027). An increase in relative vascularity indicates a decrease in overall bone density, but a weak depression filled with fibrous tissue was observed outside the compact bone. It was confirmed that newly formed cortical bone showed a slight difference in bone density compared to surrounding normal bone tissue due to increased distribution of cortical bone. In this study, we investigated the effect of bone regeneration by ADMSCs measured by radiation and pathological effects. These data can ultimately be applied to humans with important clinical applications in various bone diseases, regenerative, and early stages of formative differentiation.

A novel pilot animal model for bone augmentation using osseous shell technique for preclinical in vivo studies

OBJECTIVES

Bone grafting is commonly used to reconstruct skeletal defects in the craniofacial region. Several bone augmentation models have been developed to evaluate bone formation using novel bone substitute materials. The aim of this study was to evaluate a surgical animal model for establishing a three-dimensional (3D) grafting environment in the animal's mandibular ramus for bone augmentation using the osseous shell technique, as in humans.

MATERIALS AND METHODS

Osteological survey of New Zealand white (NZW) rabbit skull (Oryctolagus cuniculus): Initial osteological and imaging surveys were performed on a postmortem skull for a feasibility assessment of the surgical procedure. Postmortem pilot surgery and cone beam computed tomography imaging: a 3D osseous defect was created in the mandibular ramus through a submandibular incision. The osseous shell plates were stabilized with osteosynthesis fixation screws, and defects were filled with particular bone grafting material. In vivo surgical procedure: surgeries were conducted in four 8-week-old NZW rabbits utilizing two osseous shell materials: xenogeneic human cortical plates and autogenous rabbit cortical plates. The created 3D defects were filled using xenograft and allograft bone grafting materials. The healed defects were evaluated for bone formation after 12 weeks using histological and cone beam computed tomography imaging analysis.

RESULTS

Clinical analysis 12 weeks after surgery revealed the stability of the 3D grafted bone augmentation defects using the osseous shell technique. Imaging and histological analyses confirmed the effectiveness of this model in assessing bone formation.

CONCLUSIONS

The proposed animal model is a promising model with the potential to study various bone grafting materials for augmentation in the mandibular ramus using the osseous shell technique without compromising the health of the animal. The filled defects could be analyzed for osteogenesis, quantification of bone formation, and healing potential using histomorphometric analysis, in addition to 3D morphologic evaluation using radiation imaging.

Sustained Delivery of Lactoferrin Using Poloxamer Gels for Local Bone Regeneration in a Rat Calvarial Defect Model

Lactoferrin (LF) is a multifunctional milk glycoprotein that promotes bone regeneration. Local delivery of LF at the bone defect site is a promising approach for enhancement of bone regeneration, but efficient systems for sustained local delivery are still largely missing. The aim of this study was to investigate the potential of the poloxamers for sustained delivery of LF to enhance local bone regeneration. The developed LF/poloxamer formulations were liquid at room temperature (20 °C) transforming to a sustained releasing gel depot at body temperature (37 °C). In vitro release studies demonstrated an initial burst release (~50%), followed by slower release of LF for up to 72 h. Poloxamer, with and without LF, increased osteoblast viability at 72 h (p < 0.05) compared to control, and the immune response from THP-1 cells was mild when compared to the suture material. In rat calvarial defects, the LF/poloxamer group had lower bone volume than the controls (p = 0.0435). No difference was observed in tissue mineral density and lower bone defect coverage scores (p = 0.0267) at 12 weeks after surgery. In conclusion, LF/poloxamer formulations support cell viability and do not induce an unfavourable immune response; however, LF delivery via the current formulation of LF200/poloxamer gel did not demonstrate enhanced bone regeneration and was not compatible with the rat calvarial defect model.

Regenerating Craniofacial Dental Defects With Calcium Phosphate Cement Scaffolds: Current Status and Innovative Scope Review

The management and treatment of dental and craniofacial injuries have continued to evolve throughout the last several decades. Limitations with autograft, allograft, and synthetics created the need for more advanced approaches in tissue engineering. Calcium phosphate cements (CPC) are frequently used to repair bone defects. Since their discovery in the 1980s, extensive research has been conducted to improve their properties, and emerging evidence supports their increased application in bone tissue engineering. This review focuses on the up-to-date performance of calcium phosphate cement (CPC) scaffolds and upcoming promising dental and craniofacial bone regeneration strategies. First, we summarized the barriers encountered in CPC scaffold development. Second, we compiled the most up to date in vitro and in vivo literature. Then, we conducted a systematic search of scientific articles in MEDLINE and EMBASE to screen the related studies. Lastly, we revealed the current developments to effectively design CPC scaffolds and track the enhanced viability and therapeutic efficacy to overcome the current limitations and upcoming perspectives. Finally, we presented a timely and opportune review article focusing on the significant potential of CPC scaffolds for dental and craniofacial bone regeneration, which will be discussed thoroughly. CPC offers multiple capabilities that may be considered toward the oral defects, expecting a future outlook in nanotechnology design and performance.

Management of patients receiving novel antithrombotic treatment in endodontic practice: Review and clinical recommendations

Cardiovascular diseases are a major component of non-communicable diseases and death, with thrombosis constituting the most common underlying pathosis of the three major cardiovascular disorders: ischaemic heart disease (acute coronary syndrome), stroke and venous thromboembolism (VTE). The introduction of direct oral anticoagulants (DOACs) in recent years has necessitated a more complex approach to periprocedural and perioperative anticoagulation management and the need for revised management strategies and protocols. Currently, patients taking classic oral anticoagulants are advised to stop taking the drugs and have their INR values checked 72 h prior to dental surgery (e.g., apical surgery, tooth extraction, and periodontal surgery) and checked again 24 h prior to the procedure to ensure it is within the therapeutic range. However, the current incorporation of these novel DOACs in routine medical practice requires changes in the way patients are managed preoperatively in dentistry, and specifically in endodontic surgery. The methodology applied in this review included searching for relevant articles in the PubMed database using keywords listed in the Entree Terms databases. Articles published on human blood clotting mechanism, antithrombotic drugs, as well as treatment guidelines and recommendations for dentistry were retrieved. In addition, textbooks and guidelines that may not have surfaced in the online search were searched manually. The aim of this paper was to review the mechanisms of action of classic and novel antithrombotic medications and their impact on endodontic treatment and the management of local haemostasis in endodontics.

Management of Root Fenestration Using Buccal Decortication and Guided Tissue Regeneration: A Case Report and 3-dimensional Analysis

The management of patients with apical fenestration and clinical symptoms has always been limited to apical root resection and placement of the root tip within the bony crypt. This result would often present resolution of clinical symptoms based on a few case studies. In this case report, we present a case in which apical resection alone did not resolve the patient's discomfort; on the contrary, it resulted in further bone loss and persistence of clinical symptoms. A corrective surgery was performed with the use of guided bone regeneration in conjunction with decortication of the cortical plate to induce bleeding. The patient symptoms resolved within a few weeks after the surgery, and the follow-up scan showed apical root coverage. Three-dimensional analysis was performed to compare the bony changes between the 2 surgeries and showed a significant amount of bone gain of around 200 mm³ and a 2-mm linear bone gain opposite the distobuccal root. The case presents a conservative approach to manage root fenestration of the buccal plate without further compromising the root apex.

Short time guided bone regeneration using beta-tricalcium phosphate with and without fibronectin - An experimental study in rats

Background

 The aim of this histomorphometric study was to assess the bone regeneration potential of beta-tricalcium phosphate with fibronectin (β-TCP-Fn) in critical-sized defects (CSDs) in rats calvarial, to know whether Fn improves the new bone formation in a short time scope.

Material and Methods

 CSDs were created in 30 Sprague Dawley rats, and divided into four groups (2 or 6 weeks of healing) and type of filling (β-TCP-Fn, β-TCP, empty control). Variables studied were augmented area (AA), gained tissue (GT), mineralized/non mineralized bone matrix (MBM/NMT) and bone substitute (BS).

Results

60 samples at 2 and six weeks were evaluated. AA was higher for treatment groups comparing to controls (p < 0.001) and significant decrease in BS area in the β-TCP-Fn group from 2 to 6 weeks (p = 0.031). GT was higher in the β-TCP-Fn group than in the controls expressed in % (p = 0.028) and in mm2 (p = 0.011), specially at two weeks (p=0.056).

Conclusions

 Both β-TCP biomaterials are effective as compared with bone defects left empty in maintaining the volume. GT in defects regeneration filed with β-TCP-Fn are significantly better in short healing time when comparing with controls but not for β-TCP used alone in rats calvarial CSDs.

Key words:Bone regeneration, biomaterials, experimental design, histology.

Osteogenic Potential of Bovine Bone Graft in Combination with Laser Photobiomodulation: An Ex Vivo Demonstrative Study in Wistar Rats by Cross-Linked Studies Based on Synchrotron Microtomography and Histology

BACKGROUND

Alveolar bone defects are usually the main concern when planning implant treatments for the appropriate oral rehabilitation of patients. To improve local conditions and achieve implant treatments, there are several methods used for increasing bone volume, among which one of the most successful, versatile, and effective is considered to be guided bone regeneration. The aim of this demonstrative study was to propose an innovative analysis protocol for the evaluation of the effect of photobiomodulation on the bone regeneration process, using rat calvarial defects of 5 mm in diameter, filled with xenograft, covered with collagen membrane, and then exposed to laser radiation.

METHODS

The animals were sacrificed at different points in time (i.e., after 14, 21, and 30 days). Samples of identical dimensions were harvested in order to compare the results obtained after different periods of healing. The analysis was performed by cross-linking the information obtained using histology and high-resolution synchrotron-based tomography on the same samples. A comparison was made with both the negative control (NC) group (with a bone defect which was left for spontaneous healing), and the positive control (PC) group (in which the bone defects were filled with xenografts and collagen membrane without receiving laser treatment).

RESULTS

We demonstrated that using photobiomodulation provides a better healing effect than when receiving only the support of the biomaterial. This effect has been evident for short times treatments, i.e., during the first 14 days after surgery.

CONCLUSION

The proposed analysis protocol was effective in detecting the presence of higher quantities of bone volumes under remodeling after photobiomodulation with respect to the exclusive bone regeneration guided by the xenograft.

Interleukin-10 Does Not Augment Osseous Regeneration in the Scarred Calvarial Defect Achieved with Low-Dose Biopatterned BMP2

BACKGROUND

Large calvarial defects represent a major reconstructive challenge, as they do not heal spontaneously. Infection causes inflammation and scarring, further reducing the healing capacity of the calvaria. Bone morphogenetic protein-2 (BMP2) has been shown to stimulate osteogenesis but has significant side effects in high doses. BMP2 has not been tested in combination with antiinflammatory cytokines such as interleukin-10.

METHODS

Sixteen New Zealand White rabbits underwent 15 × 15-mm flap calvarectomies. The flap was incubated in Staphylococcus aureus and replaced, and infection and scarring were allowed to develop. The flap was subsequently removed and the wound débrided. A 15 × 15-mm square of acellular dermal matrix biopatterned with low-dose BMP2, interleukin-10, or a combination was implanted. Computed tomographic scans were taken over 42 days. Rabbits were then killed and histology was performed.

RESULTS

Defects treated with BMP2 showed significantly (p < 0.05) greater osseous regeneration than untreated controls. Interleukin-10 did not significantly augment the healing achieved with BMP2, and interleukin-10 alone did not significantly increase healing compared with controls. Histology showed evidence of bone formation in defects treated with BMP2. Untreated controls and defects treated with interleukin-10 alone showed only fibrous tissue in the defect site.

CONCLUSIONS

Low-dose BMP2 delivered directly to the scarred calvarial defect augments bony healing. Interleukin-10 at the dose applied did not significantly augment healing alone or in combination with BMP2. Healing had not finished at 42 days and analysis at later time points or the use of higher doses of BMP2 may yield greater healing.

Bone repair scaffold coated with bone morphogenetic protein-2 for bone regeneration in murine calvarial defect model: Systematic review and quality evaluation

To systematically assess the effects of hydroxyapatite bone repair scaffold coated with bone morphogenetic protein-2 on murine calvarial defect models and to determine the quality of studies according to the Animal Research Reporting in In Vivo Experiments guidelines. Internet search was performed in duplicate using PubMed, MEDLINE, Ovid and Embase databases (without restrictions on publication date). The Animal Research Reporting in In Vivo Experiments guidelines were used to evaluate the quality of selected studies. Following screening, 12 studies were eligible for the review. Studies with average quality coefficients predominated (66.67%), followed by poor (25%) and excellent (8.33%) quality coefficients. Minimum quality scores were assigned to the Animal Research Reporting in In Vivo Experiments guideline items: housing and husbandry (9), allocation (11), outcomes (12), interpretation (18) and generalizability (19). Sprague–Dawley rats were the most frequently used (50%) species, and most studies had a sample size of more than 30 (58.33%). A defect dimension of 5 mm was the most common (33.33%). The biological hydroxyapatite composite scaffold was common (50%), and the bioactive factors were bone morphogenetic protein-2 (50%) and recombinant human bone morphogenetic protein-2 (50%). Histomorphometric results showed that bone morphogenetic protein-2 enhanced the capacity to regenerate bone considerably. In addition, scaffolds with bone morphogenetic protein-2 resulted in a significant increase in the blood vessel in the new bone. The findings suggested that data on animal experiments of hydroxyapatite scaffold coated with bone morphogenetic protein-2 in murine calvarial defect models lack homogeneity. Animal experiment should follow the Animal Research Reporting in In Vivo Experiments guidelines to promote the high quality, integrity and reproducibility. This systematic review suggested that bone morphogenetic protein-2 enhanced the capacity to regenerate bone and the angiogenesis in the new bone.

Guided bone regeneration using beta-tricalcium phosphate with and without fibronectin-An experimental study in rats

OBJECTIVE

This histomorphometric study compared bone regeneration potential of beta-tricalcium phosphate with fibronectin (β-TCP-Fn) in critical-sized calvarial defects (CSDs) in rats to assess whether fibronectin (Fn) improved new bone formation.

MATERIAL AND METHODS

Critical-sized calvarial defects were created in 30 adult male Sprague Dawley rats, which were divided into four groups according to the time of euthanasia (6 or 8 weeks of healing) and type of filling (β-TCP-Fn/6 weeks, β-TCP/6 weeks, β-TCP-Fn/8 weeks and β-TCP/8 weeks). The primary variables related to new bone formation were augmented area (AA) and gained tissue (GT; sum of mineralized bone matrix [MBM] and bone substitute [BS]). Secondary variables were the diameter of the defect, MBM, non-mineralized tissue (NMT) and BS.

RESULTS

A total of 29 rats and 58 histological samples were evaluated, 28 (48.3%) samples obtained at 6 weeks and 30 (51.7%) at 8 weeks, homogeneously distributed between right and left sides. Thirteen (22.4%) were treated with β-TCP-Fn, 16 (27.6%) with β-TCP and 29 (50%) were controls. At 8 weeks, histomorphometric analysis showed significant differences in AA using β-TCP and β-TCP-Fn versus controls (p = 0.001 and p = 0.005, respectively). Bone turnover expressed as % within the target area was slightly higher but not statistically significant in the β-TCP-Fn than in β-TCP (MBM) at 6 weeks versus 8 weeks (p = 0.067 and p = 0.335, respectively). Finally, the total GT area in mm² was higher using β-TCP-Fn as compared to β-TCP (p = 0.044).

CONCLUSIONS

β-TCP-Fn was slightly but non-significantly more effective than β-TCP without Fn for improving the volume of regenerated bone in CSDs of rats, possibly allowing a more efficient bone remodelling process. This effect however should continue being investigated.

Repair of bone defects in rat radii with a composite of allogeneic adipose-derived stem cells and heterogeneous deproteinized bone

Background

In the bone tissue engineering domain, seed cells, scaffold and cell-scaffold composites are three focuses. In this study, the feasibility of using allogeneic adipose-derived stem cells(ADSCs) combined with heterogeneous deproteinized bone (HDB) to repair segmental radial defects was investigated by observing the repair of the defect area.

Methods

ADSCs were cultured in vitro, purified, antigen-detected and osteogenic differentiation potency-measured; then, the ADSCs of the third generation were seeded into HDB to prepare an ADSCs-HDB composite partly with osteogenesis induced cells. Sixty Wistar rats were randomly divided into four groups with 15 in each group. A bone defect (4 mm in length) was created at the left radius in each rat. Two kinds of ADSCs-HDB composites were implanted in the ADSCs osteogenesis group or ADSCs group; HDB was implanted in the negative control group; nothing was filled in the blank control group. The bone defect repair was evaluated by gross observation, molybdenum target X-ray examination and histological analyses after surgery.

Results

Gross observation: the bone defect area was completely filled and difficult to recognize in the ADSCs osteogenesis group. The connection of the ADSCs group was strong, but the implants were clearly identifiable. The joints of the negative control group were slightly thick but the connection was unstable. In the blank control group, kermesinus tissue was between the two ends and bones were not connected after 8 weeks. Molybdenum target X-ray examinations: In the ADSCs osteogenesis group, evident bridges in the graft were observed in the defects in the fourth week; the defects were filled with new bone completely and a marrow cavity appeared at 8 weeks. In the ADSCs group, there were some callus formations, but the radial defect was still obvious at 8 weeks. In the negative control group, fracture lines were clear. In the blank control group, no osseous bridges were observed, which resulted in bone nonunion eventually in 8 weeks. There were significant differences in the callus density between experimental groups and the blank control group at 4 and 8 weeks (P < 0.01). Histological measures showed that the rate and quality of the new bone formation and remodelling was significantly different between the experimental and control groups.

Conclusions

A composite of ADSCs-HDB has a strong osteogenic ability. It can repair segmental bone defects well and is promising to serve as grafting material in bone tissue engineering.

Bone regeneration using composite non-demineralized xenogenic dentin with beta-tricalcium phosphate in experimental alveolar cleft repair in a rabbit model

Background

Alveolar cleft repair is performed via bone grafting procedure to restore the dental arch continuity. A suitable bone substitute materials should possess osteoinductive and osteoconductive properties, to promote new bone formation, along with a slowly resorbable scaffold that is subsequently replaced with functionally viable bone. Calcium phosphate biomaterials have long proved their efficacy as bone replacement materials. Dentin in several forms has also demonstrated its possibility to be used as bone graft replacement material in several studies. The purpose of this study was to evaluate bone regeneration pattern and quantify bone formation after grafting pre-established experimental alveolar clefts defects model in rabbits using composite xenogenic dentin and β-TCP in comparison to β-TCP alone.

Methods

Unilateral alveolar cleft defects were created in 16 New Zealand rabbits according to previously described methodology. Alveolar clefts were allowed 8 weeks healing period. 8 defects were filled with β-TCP, whereas 8 defects filled with composite xenogenic dentin with β-TCP. Bone regeneration of the healed defects was compared at the 8 weeks after intervention. Quantification of bone formation was analyzed using micro-computed tomography (µCT) and histomorphometric analysis.

Results

µCT and histomorphometric analysis revealed that defects filled with composite dentin/β-TCP showed statistically higher bone volume fraction, bone mineral density and percentage residual graft volume when compared to β-TCP alone. An improved surgical handling of the composite dentin/β-TCP graft was also noted.

Conclusions

Composite xenogenic dentin/β-TCP putty expresses enhanced bone regeneration compared to β-TCP alone in the reconstruction of rabbit alveolar clefts defects.

Biological Evaluation of Flexible Polyurethane/Poly l-Lactic Acid Composite Scaffold as a Potential Filler for Bone Regeneration

Degradable bone graft substitute for large-volume bone defects is a continuously developing field in orthopedics. With the advance in biomaterial in past decades, a wide range of new materials has been investigated for their potential in this application. When compared to common biopolymers within the field such as PLA or PCL, elastomers such as polyurethane offer some unique advantages in terms of flexibility. In cases of bone defect treatments, a flexible soft filler can help to establish an intimate contact with surrounding bones to provide a stable bone-material interface for cell proliferation and ingrowth of tissue. In this study, a porous filler based on segmented polyurethane incorporated with poly l-lactic acid was synthesized by a phase inverse salt leaching method. The filler was put through in vitro and in vivo tests to evaluate its potential in acting as a bone graft substitute for critical-sized bone defects. In vitro results indicated there was a major improvement in biological response, including cell attachment, proliferation and alkaline phosphatase expression for osteoblast-like cells when seeded on the composite material compared to unmodified polyurethane. In vivo evaluation on a critical-sized defect model of New Zealand White (NZW) rabbit indicated there was bone ingrowth along the defect area with the introduction of the new filler. A tight interface formed between bone and filler, with osteogenic cells proliferating on the surface. The result suggested polyurethane/poly l-lactic acid composite is a material with the potential to act as a bone graft substitute for orthopedics application.

* Tissue Engineering Strategies to Improve Osteogenesis in the Juvenile Swine Alveolar Cleft Model

Alveolar (gumline) clefts are the most common congenital bone defect in humans, affecting 1 in 700 live births. Treatment to repair these bony defects relies on autologous, cancellous bone transfer from the iliac crest. This harvest requires a second surgical site with increased surgical time associated with potential complications, while providing only limited cancellous bone. Improvements in treatment protocols that avoid these limitations would be beneficial to patients with clefts and other craniofacial bone defects. There have been steady advances in tissue-engineered (TE) solutions for long-bone defects and adult patients, but advances for the pediatric craniofacial skeleton have been slower to emerge. This study utilizes a previously established juvenile swine model with a surgically created, critical size alveolar defect to test the efficacy of umbilical cord (UC) mesenchymal stem cells (MSCs) treatments on nano-microfiber scaffolds. At 1 month after implanting our TE construct, mineralized tissue in the surgical gap was quantified through computed tomography (CT), and histology, and excised tissue was subjected to mechanical testing. Both undifferentiated and predifferentiated (toward an osteogenic lineage) UC MSCs generated bone within the cleft on a scale comparable to iliac crest cancellous bone, as evidenced by histology and CT scans. All of the pigs treated with scaffold/stem cell combinations had mineralized tissue within the defect, although without filling the entire defect. Several of the experimental animals exhibited poor and/or asymmetric maxillary growth 1 month after the initial surgery, especially if the surgical defect was located on the smaller side of an already asymmetric pig. Our results demonstrate that tissue engineering approaches using UC MSCs are a promising alternative for repair of the alveolar cleft. Data in the pig model demonstrate that implanted scaffolds are at least as good as the current gold standard treatment based on harvesting cancellous bone from the iliac crest, regardless of whether the cells seeded on the scaffold are precommitted to an osteogenic fate.

Effect of serum-derived albumin scaffold and canine adipose tissue-derived mesenchymal stem cells on osteogenesis in canine segmental bone defect model

Composite biological and synthetic grafts with progenitor cells offer an alternative approach to auto- or allografts for fracture repair. This study was conducted to evaluate osteogenesis of autologous serum-derived albumin (ASA) scaffolds seeded with canine adipose tissue-derived mesenchymal stem cells (Ad-MSCs) in a canine segmental bone defect model. ASA scaffold was prepared with canine serum using cross-linking and freeze-drying procedures. Beta-tricalcium phosphate (β-TCP) was mixed at the cross-linking stage. Ad-MSCs were seeded into the scaffold and incubated for one day before implantation. After 16 weeks, the grafts were harvested for histological analysis. The dogs were divided into five groups: control, ASA scaffolds with and without Ad-MSCs, and ASA scaffolds including β-TCP with and without Ad-MSCs. ASA scaffolds with Ad-MSCs had a significantly larger area of increased opacity at the proximal and distal host cortex-implant interfaces in radiographs 16 weeks after implantation compared to the groups with β-TCP (p < 0.05). Histomorphometric analysis showed that ASA scaffolds with Ad-MSCs had significantly greater new bone formation than other groups (p < 0.05). These results suggest that Ad-MSCs seeded into ASA scaffolds enhanced osteogenesis in the bone defect model, but that β-TCP in the ASA scaffold might prevent penetration of the cells required for bone healing.

Effect of platelet-rich plasma combined with demineralised bone matrix on bone healing in rabbit ulnar defects

INTRODUCTION

This study evaluates the effect of autologous platelet-rich plasma (PRP) combined with xenogeneic demineralised bone matrix (DBM) on bone healing of critical-size ulnar defects (2-2.5 times the ulnar diameter) in New Zealand White rabbits.

METHODS

Critical-size defects were created unilaterally in the ulna of 36 rabbits, while keeping the contralateral limb intact. They were divided into three groups. In Group A, the defect was filled with autologous PRP and in Group B, with autologous PRP combined with DBM; in Group C, the defect remained empty. The rabbits were euthanised 12 weeks postoperatively. Radiological, biomechanical and histological assessments were carried out and statistical analysis of the results was performed.

RESULTS

Group B had significantly higher radiological and histological scores than Groups A and C. Defects in Group B showed significant new bone formation, whereas there was minimal or no new bone formation in Groups A and C. Only specimens in Group B showed macroscopic bone union. Biomechanical evaluation of the treated and intact contralateral limbs in Group B showed significant differences.

CONCLUSION

In this study, statistically significant enhancement of bone healing was found in critical-size defects treated with PRP and DBM, as shown by radiological findings, gross assessment, and biomechanical and histopathological results. Defects in the two other groups remained unbridged. Therefore, PRP was effective only when it was used in combination with a bone graft.

Repair of critical size defects using bioactive glass seeded with adipose-derived mesenchymal stem cells

Bioactive glass has been demonstrated as a biocompatible bone substitute. However bone healing process can be prolonged due to late resorption of the material. Adipose derived stem cells (ASC) have osteogenic differentiation potential and hence can be a cell source for bone regeneration. The aim of this study was to test whether combination of bioactive glass with ASCs would enhance bone regeneration. Following creation of critical sized defects on the calvaria of 32 Wistar rats, the animals were randomly divided into four groups: Group C (control): Defects were left untreated; Group G: Defects were covered with autologous bone graft; Group BG: Defects were filled with bioactive glass; Group BG/ASC: Defects were filled with bioactive glass seeded with ASCs. The defect size was significantly greater in Group C compared to all other groups. Bone density was significantly lower in Group C compared to Group G and Group BG/ASC. Bone regeneration score of Group C was significantly lower than other groups. Group BG/ASC demonstrated lamellar bone and havers canal formation. The results of this study demonstrated that bioactive glass implanted with ASC is a biocompatible construct stimulating radiologically and histologically evident bone regeneration similar to autologous bone grafting. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1002-1008, 2017.

Comparison of the osteogenic potential of OsteoSelect demineralized bone matrix putty to NovaBone calcium-phosphosilicate synthetic putty in a cranial defect model

The purpose of this study was to compare the osteogenic potential of a synthetic and a demineralized bone matrix (DBM) putty using a cranial defect model in New Zealand white rabbits. Paired, bilateral critical-size defects (10 mm) were prepared in the frontal bones of 12 rabbits and filled with either OsteoSelect DBM Putty or NovaBone calcium-phosphosilicate putty. At days 43 and 91, 6 rabbits were killed and examined via semiquantitative histology and quantitative histomorphometry. Defects filled with the DBM putty were histologically associated with less inflammation and fibrous tissue in the defect and more new bone than the synthetic counterpart at both time points. Histomorphometric analysis revealed that the defects filled with DBM putty were associated with significantly more bone formation at day 43 (70.7% vs 40.7%, P = 0.043) and at day 91 (70.4% vs 39.9%, P = 0.0044). The amount of residual implant was similar for both test groups at each time point.

Safety and efficacy of recombinant human bone morphogenetic protein 2 on cranial defect closure in the pediatric population

BACKGROUND

Traditional reconstructive options for cranial defects include autogenous bone graft, bone substitutes, and synthetic materials. The established standard for repairing cranial defects is autogenous bone. However, young children do not have abundant donor sites for bone harvest, which leads to challenges in closing calvarial defects. Synthetic materials are not ideal alternatives because they require subsequent retrieval and are prone to infection. Their long-term effects on growth of the skull are also not well studied. Bone morphogenetic protein 2 (BMP-2), are shown to positively affect closure of cranial defects in animal models. We present a study comparing the efficacy and safety of closure of cranial defect with bone graft augmented with recombinant human BMP-2 (rhBMP-2) and compared with a series of patients treated with bone graft alone.

METHODS

This study is a retrospective multicenter evaluation of 36 patients spanning 5 years. Twenty-one patients undergoing cranial defect closure augmented with rhBMP-2 were compared with 15 patients who underwent cranial defect closure using cranial bone shavings alone. We measured preoperative and postoperative defect size on volumetric computed tomographic scan reconstructions to compare defect sizes.

RESULTS

The rhBMP-2 group had slightly increased proportional closure compared with the control group, 86% versus 76% (P < 0.018), respectively. Two patients in the rhBMP-2 group had postoperative fusion of a suture that was known to be patent at the time of cranial defect closure. No instances of brain edema, herniation, airway compromise, or other adverse effects directly attributable to rhBMP-2 were observed.

CONCLUSIONS

Bone morphogenetic protein 2 may increase the amplitude and uptake of cranial bone grafts in cranial defect closure. This study shows that defect sizes of up to 16 cm can be reliably closed using this technique. Postoperative fusion of uninvolved sutures in 2 patients indicates that rhBMP-2 may have unreported adverse effects; consideration of this finding should be weighed against the benefit of improved closure of calvarial defects.

Scintigraphic and histopathologic evaluation of combined bone grafts

OBJECTIVES

We aimed to assess various bone grafts on bone formation using bone scintigraphy and histology, especially the first study that evaluated the demineralized bone matrix (DBM) + tricalcium phosphate (TCP) + hyaluronic acid (HA) combination.

MATERIALS AND METHODS

A total of 44 pieces in groups of autogenous bone graft, TCP, DBM, DBM + TCP combination, and DBM + TCP + HA combination were applied to parietal bones of 24 New Zealand rabbits. Bone scintigraphies of the rabbits were performed at 2, 6, and 12 weeks. The uptake ratios were compared for the different types of grafts. In addition, in 2, 6, and 12 weeks, the graft areas were taken from the sacrificed rabbits and examined histologically.

RESULTS

In the 2-week evaluation, DBM + TCP combination and DBM + TCP + HA combination had more osteoblastic activity accumulation than the TCP and DBM groups. These findings supported that the DBM + TCP combination group showed new bone formation earlier in the histopathological evaluation. The DBM + TCP + HA combination had more uptake than the TCP and DBM groups on bone scintigraphy at 2 weeks, and this uptake ratio decreased in the following weeks. It was thought that the increased uptake in DBM + TCP + HA combination at 2 weeks was due to severe inflammation seen in the histopathological evaluation.

CONCLUSION

The DBM + TCP + HA combination should not be used for graft repair, although it was thought to be a good combination in the early weeks.

Evaluation of the effect of a gamma irradiated DBM-pluronic F127 composite on bone regeneration in Wistar rat

Demineralized bone matrix (DBM) is widely used for bone regeneration. Since DBM is prepared in powder form its handling properties are not optimal and limit the clinical use of this material. Various synthetic and biological carriers have been used to enhance the DBM handling. In this study we evaluated the effect of gamma irradiation on the physical-chemical properties of Pluronic and on bone morphogenetic proteins (BMPs) amount in DBM samples. In vivo studies were carried out to investigate the effect on bone regeneration of a gamma irradiated DBM-Pluronic F127 (DBM-PF127) composite implanted in the femur of rats. Gamma irradiation effects (25 kGy) on physical-chemical properties of Pluronic F127 were investigated by rheological and infrared analysis. The BMP-2/BMP-7 amount after DBM irradiation was evaluated by ELISA. Bone regeneration capacity of DBM-PF127 containing 40% (w/w) of DBM was investigated in transcortical holes created in the femoral diaphysis of Wistar rat. Bone porosity, repaired bone volume and tissue organization were evaluated at 15, 30 and 90 days by Micro-CT and histological analysis. The results showed that gamma irradiation did not induce significant modification on physical-chemical properties of Pluronic, while a decrease in BMP-2/BMP-7 amount was evidenced in sterilized DBM. Micro-CT and histological evaluation at day 15 post-implantation revealed an interconnected trabeculae network in medullar cavity and cellular infiltration and vascularization of DBM-PF127 residue. In contrast a large rate of not connected trabeculae was observed in Pluronic filled and unfilled defects. At 30 and 90 days the DBM-PF127 samples shown comparable results in term of density and thickness of the new formed tissue respect to unfilled defect. In conclusion a gamma irradiated DBM-PF127 composite, although it may have undergone a significant decrease in the concentration of BMPs, was able to maintains bone regeneration capability.

Healing of rabbit calvarial critical-sized defects using autogenous bone grafts and fibrin glue

PURPOSE

This study aimed to evaluate ossification of cranial bone defects comparing the healing of a single piece of autogenous calvarial bone representing a bone flap as in cranioplasty compared to particulated bone slurry with and without fibrin glue to represent bone collected during cranioplasty. These defect-filling materials were then compared to empty control cranial defects.

METHODS

Ten White New Zealand adult male rabbits had bilateral critical-sized calvarial defects which were left either unfilled as control defects or filled with a single full-thickness piece of autogenous bone, particulated bone, or particulated bone combined with fibrin glue. The defects were left to heal for 6 weeks postoperatively before termination. CT scans of the calvarial specimens were performed. Histomorphometric assessment of hematoxylin-eosin- and Masson trichrome-stained specimens was used to analyze the proportion of new bone and fibrous tissue in the calvarial defects.

RESULTS

There was a statistically significant difference in both bone and soft tissue present in all the autogenous bone-grafted defect sites compared to the empty negative control defects. These findings were supported by CT scan findings. While fibrin glue combined with the particulated bone seemed to delay ossification, the healing was more complete compared to empty control non-grafted defects.

CONCLUSIONS

Autogenous bone grafts in various forms such as solid bone flaps or particulated bone treated with fibrin glue were associated with bone healing which was superior to the empty control defects.

Development of a novel calcium phosphate cement composed mainly of calcium sodium phosphate with high osteoconductivity

Two novel calcium phosphate cements (CPC) have been developed using calcium sodium phosphate (CSP) as the main ingredient. The first of these cements, labeled CAC, contained CSP, α-tricalcium phosphate (TCP), and anhydrous citric acid, whereas the second, labeled CABC, contained CSP, α-TCP, β-TCP, and anhydrous citric acid. Biopex(®)-R (PENTAX, Tokyo, Japan), which is a commercially available CPC (Com-CPC), and OSferion(®) (Olympus Terumo Biomaterials Corp., Tokyo, Japan), which is a commercially available porous β-TCP, were used as reference controls for analysis. In vitro analysis showed that CABC set in 5.7 ± 0.3 min at 22 °C and had a compressive strength of 86.0 ± 9.7 MPa after 5 days. Furthermore, this material had a compressive strength of 26.7 ± 3.7 MPa after 2 h in physiologic saline. CAC showed a statistically significantly lower compressive strength in the presence of physiologic saline and statistically significantly longer setting times than those of CABC. CABC and CAC exhibited apatite-forming abilities in simulated body fluid that were faster than that of Com-CPC. Samples of the materials were implanted into the femoral condyles of rabbits for in vivo analysis, and subsequent histological examinations revealed that CABC exhibited superior osteoconductivity and equivalent bioresorbability compared with Com-CPC, as well as superior osteoconductivity and bioresorbability compared with CAC. CABC could therefore be used as an alternative bone substitute material.

Critical size defects for bone regeneration experiments in rabbit calvariae: systematic review and quality evaluation using ARRIVE guidelines

OBJECTIVES

To perform a systematic review of studies that report the healing of critical size defects (CSDs) in rabbit calvaria and to determine the quality of the studies according to ARRIVE guidelines.

MATERIALS AND METHODS

An Internet search was made in duplicate between December 2011 and August 2013 using MEDLINE, PubMed and Google Scholar (without restrictions on date of publication) for rabbit studies reporting the healing of CSD in the calvaria. Animal Research Reporting in Vivo Experiment (ARRIVE) guidelines (a list of 20 aspects to score and to ensure comparison between different experimental studies in animals) were used to evaluate the quality of the selected works.

RESULTS

Twenty-five manuscripts were evaluated. Case-control studies predominated (92.59%). Animal age was not stated in 70.37% of the studies; weight was not reported in 29.62%; most animals weighed 3.5 kg (26.31%). A CSD dimension of 15 mm was common (51.61%), generally located centrally (51.85%), followed by bilateral locations (48.14%). Circular (66.66%), rectangular (14.81%), square (14.81%) and ovoid (1.48%) geometries were used. Histomorphometric data showed incomplete healing in all CSDs and higher percentages of healing in smaller defects (<10 mm). The longer the healing time allowed, the more bone healing took place, for both smaller and larger defects (>15 mm). Minimum quality grades were assigned to ARRIVE items study design (6), experimental animals (8), housing and husbandry (9), sample size (10), allocation (11), statistics (13), results-baseline data (14), numbers analyzed (15), adverse events (17) and funding (20).

CONCLUSIONS

Data on CSDs in rabbit calvariae lack homogeneity. Smaller defects can be considered critical depending on the time of sacrifice. When new diagnostic technologies are used in addition to histomorphometry, these should be applied with caution to facilitate future comparison with other research. The ARRIVE guidelines should be followed in any animal research protocol to improve the homogeneity, comparison and reproducibility between studies.

Biologic response of local hemostatic agents used in endodontic microsurgery

Appropriate use of local hemostatic agent is one of the important factors on the prognosis of endodontic microsurgery. However, most investigations to date focus on the hemostatic efficacy of the agents, whereas their biologic characteristics have not received enough attention. The purpose of this paper was to review the biologic response of local hemostatic agents, and to provide clinical guidelines on their use during endodontic microsurgery. Electronic database (PUBMED) was screened to search related studies from 1980 to 2013, and 8 clinical studies and 18 animal studies were identified. Among the materials used in these studies, most widely-investigated and used materials, epinephrine, ferric sulfate (FS) and calcium sulfate (CS), were thoroughly discussed. Influence of these materials on local tissue and systemic condition, such as inflammatory and foreign body reaction, local ischemia, dyspigmentation, delayed or enhanced bone and soft tissue healing, and potential cardiovascular complications were assessed. Additionally, biological property of their carrier materials, cotton pellet and absorbable collagen, were also discussed. Clinicians should be aware of the biologic properties of local hemostatic agents and their carrier materials, and should pay attention to the potential complications when using them in endodontic microsurgery.

A novel oxysterol promotes bone regeneration in rabbit cranial bone defects

Bone morphogenetic proteins (BMPs) have played a central role in the development of regenerative therapies for bone reconstruction. However, the high cost and side-effect profile of BMPs limits their broad application. Oxysterols, naturally occurring products of cholesterol oxidation, are promising osteogenic agents alternative to BMPs. The osteogenic capacity of these non-toxic and relatively inexpensive molecules has been documented in rodent models. We studied the impact of Oxy49, a novel oxysterol analogue, on the osteogenic differentiation of rabbit bone marrow stromal cells (BMSCs). Moreover, we evaluated the capacity for in vivo bone regeneration with Oxy49 in rabbit cranial bone defects. We found that rabbit BMSCs treated with Oxy49 demonstrated differentiation along osteogenic pathways, and that complete bone regeneration occurred when cranial defects were treated with Oxy49. Collectively, these results demonstrate that Oxy49 has the ability to induce osteogenic differentiation in rabbit BMSCs with an efficacy comparable to that of BMP-2 and to promote significant bone regeneration in cranial defects. Oxysterols may be a viable novel agent in bone tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Low-level laser therapy promotes the osteogenic potential of adipose-derived mesenchymal stem cells seeded on an acellular dermal matrix

This study investigates the feasibility of using an adipose-derived mesenchymal stem cell (ASC)-seeded acellular dermal matrix (ADM) along with low-level laser therapy (LLLT) to repair bone defect in athymic nude mice. Critical-sized calvarial defects were treated either with ADM, ADM/LLLT, ADM/ASCs, or ADM/ASCs/LLLT. In micro-computed tomography scans, the ADM/ASCs and the ADM/ASCs/LLLT groups showed remarkable bone formation after 14 days. Additionally, bone regeneration in the ADM/ASCs/LLLT group was obvious at 28 days, but in the ADM/ASCs group at 56 days. Bone mineral density and bone tissue volume in the ADM/ASCs/LLLT group significantly increased after 7 days, but in the ADM/ASCs group after 14 days. Histological analysis revealed that the defects were repaired in the ADM/ASCs and the ADM/ASCs/LLLT group, while the defects in the ADM and the ADM/LLLT groups exhibited few bone islands at 28 and 56 days. The successful seeding of ASCs onto ADM was confirmed, and LLLT enhanced the proliferation and the survival of ASCs at 14 days. Our results indicate that ASC-seeded grafts promote bone regeneration, and the application of LLLT on ASC-seeded ADM results in rapid bone formation. The implantation of an ASC-seeded ADM combined with LLLT may be used effectively for bone regeneration.

Effects of demineralized bone matrix on tendon-bone healing in an intra-articular rodent model

BACKGROUND

Techniques to improve and accelerate tendon-bone healing could be advantageous in anterior cruciate ligament (ACL) reconstruction. Effects of demineralized bone matrix (DBM) on intra-articular tendon-bone healing have not been examined.

HYPOTHESIS

Demineralized bone matrix has the potential to convey osteoinductive growth proteins to the site of healing at the tendon-bone interface. We hypothesized that the presence of DBM will result in more bone formation and hasten tendon-bone healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fifty-six female athymic rnu/rnu (nude) rats were used. Rats were randomly allocated into 2 groups (control or treatment). The control group underwent an ACL reconstruction, while the treatment group had human DBM implanted in the tendon graft and bone tunnel before reconstruction. Rats were sacrificed at 2 (n = 8), 4 (n = 24), and 6 (n = 24) weeks for histological, and immunohistochemical (t = 2, 4, and 6 weeks), and biomechanical testing and micro-computed tomography (t = 4 and 6 weeks) end points.

RESULTS

Our findings suggest that in the presence of DBM, tendon-bone healing is augmented by increased woven bone formation and enhanced bone remodeling as indicated by histology and micro-computed tomography. This ultimately resulted in a statistically significant increase in peak load to failure of the tendon-bone interface at 4 weeks (DBM group: 5.96 ± 1.36 N; control group: 2.86 ± 0.7 N) and 6 weeks (DBM group: 9.13 ± 0.97 N; control group: 5.81 ± 1.1 N).

CONCLUSION

Demineralized bone matrix at the tendon-bone interface promotes healing between the tendon and bone in a rodent ACL model.

CLINICAL RELEVANCE

Introduction of osteoinductive DBM at the tendon-bone interface during ACL reconstructive surgery may improve short-term outcomes.

Placenta- versus bone-marrow-derived mesenchymal cells for the repair of segmental bone defects in a rabbit model

Tissue-engineered bones (TEBs) constructed with bone-marrow-derived mesenchymal stem cells (BMSCs) seeded on biomaterial scaffolds have achieved good results for bone defect repair in both animal experiments and clinical trials. This has been limited, however, by the source and quantity of BMSCs. We here explored TEBs constructed by placenta-derived mesenchymal stem cells (PMSCs) and compared their effect for the repair of critical-sized segmental osteoperiosteal defects with TEBs constructed with BMSCs. PMSCs were isolated from rabbit placenta by gradient centrifugation and in vitro monolayer culturing, and BMSCs were isolated from the hindlimb bone marrow of newborn rabbit. Primary cultured PMSCs and BMSCs were uniformly in a spindle shape. Immunocytochemistry indicated that both types of cells are positive for CD44 and CD105, and negative for CD34 and CD40L, confirming that they are mesenchymal stem cells. BrdU-labeled PMSCs and BMSCs were respectively co-cultured with bio-derived bone materials to construct TEBs in vitro. Critical-sized segmental osteoperiosteal defects of radii were created in 24 rabbits by surgery. The defects were repaired with TEBs constructed with PMSCs and BMSCs. The results showed that TEBs constructed by both PMSCs and BMSCs could repair the osteoperiosteal defects in a 'multipoint' manner. Measurement of radiography, histology, immunohistochemistry, alkaline phosphatase activity, osteocalcin assaying and biomechanical properties have found no significant difference between the two groups at 2, 4, 8 and 12 weeks after the transplantation (P > 0.05). Taken together, our results indicate that PMSCs have similar biological characteristics and osteogenic capacity to BMSCs and can be used as a new source of seeding cells for TEBs.

Cell survival and proliferation after encapsulation in a chemically modified Pluronic(R) F127 hydrogel

Pluronic® F127 is a biocompatible, injectable, and thermoresponsive polymer with promising biomedical applications. In this study, a chemically modified form, i.e., Pluronic ALA-L with tailored degradation rate, was tested as an encapsulation vehicle for osteoblastic cells. UV cross-linking of the modified polymer results in a stable hydrogel with a slower degradation rate. Toxicological screening showed no adverse effects of the modified Pluronic ALA-L on the cell viability. Moreover, high viability of embedded cells in the cross-linked Pluronic ALA-L was observed with life/death fluorescent staining during a 7-day-culture period. Cells were also cultured on macroporous, cross-linked gelatin microbeads, called CultiSpher-S® carriers, and encapsulated into the modified cross-linked hydrogel. Also, in this situation, good cell proliferation and migration could be observed in vitro. Preliminary in vivo tests have shown the formation of new bone starting from the injected pre-loaded CultiSpher-S® carriers.

Preparation and properties of calcium phosphate cements incorporated gelatin microspheres and calcium sulfate dihydrate as controlled local drug delivery system

To develop high macroporous and degradable bone cements which can be used as the substitute of bone repairing and drug carriers, cross-linked gelatin microspheres (GMs) and calcium sulfate dihydrate (CSD) powder were incorporated into calcium phosphate bone cement (CPC) to induce macropores, adjust drug release and control setting time of α-TCP-liquid mixtures after degradation of GMs and dissolution of CSD. In this study, CSD was introduced into CPC/10GMs composites to offset the prolonged setting time caused by the incorporation of GMs, and gentamicin sulphate (GS) was chosen as the model drug entrapped within the GMs. The effects of CSD amount on the cement properties, drug release ability and final macroporosity after GMs degradation were studied in comparison with CPC/GMs cements. The resulting cements presented reduced setting time and increased compressive strength as the content of CSD below 5 wt%. Sustained release of GS was obtained on at least 21 days, and release rates were found to be chiefly controlled by the GMs degradation rate. After 4 weeks of degradation study, the resulting composite cements appeared macroporous, degradable and suitable compressive strength, suggesting that they have potential as controlled local drug delivery system and for cancellous bone applications.

Calcium phosphate bone cement: a possible alternative to autologous bone graft. A radiological and biomechanical comparison in rat tibial bone

BACKGROUND

Donor site morbidity is a problem after autologous bone transplantation. An injectable CaP bone cement indicates properties similar to bone.

MATERIALS AND METHODS

Double osteotomies on rat tibias were performed. The intercalated segments were avascular (10), vascular (10), or avascular with Norian SRS(®) CaP bone cement replacing cancellous bone (10). Controls were non-operated contralateral tibias (15). All osteotomies were stabilised with an intra-medullary nail. After 8 weeks, all rats were killed. The harvested tibias were compared using X-ray, DEXA scanning, microCT scans and a biomechanical torsional test.

RESULTS

No difference in healing processes or biomechanical results has been found between the avascular bone graft, vascular bone graft and CaP bone cement groups.

CONCLUSION

The injectable CaP bone cement confirms its similarities to bone, implying that it can be used as an adjunct to secure bone fragments and as a possible alternative to autologous bone transplantation in clinical practice.

Complications of hydroxyapatite bone cement in secondary pediatric craniofacial reconstruction

Hydroxyapatite cement has become a popular alternative to bone grafts in reconstructing the calvarium. Although animal studies have shown promising results with use of hydroxyapatite, human clinical studies have shown mixed results including significant rates of infection. This is a retrospective chart review during a 7-year period (1997-2003) of 20 patients who underwent secondary forehead cranioplasty with hydroxyapatite cement (Norian Craniofacial Reconstruction System). Basic demographics including age, sex, and diagnosis were identified. Characteristics of the defects were recorded including size, location, and depth (full versus partial thickness). The volume of hydroxyapatite and any adjunctive procedures were identified. The postoperative course was analyzed for length of follow-up and the presence of infections.Twenty patients were identified in which Norian had been used and 3 patients were lost to follow-up. Secondary forehead asymmetry was the most common presentation. The mean volume of hydroxyapatite used was 24.4 mL. All patients had initially acceptable aesthetic results. Of the 17 patients, 10 (59%) ultimately had infectious complications. Infection occurred on a mean of 17.3 months after surgery (range, 4 mo to 4 y), and the mean amount of hydroxyapatite used was 32.5 mL (infections) versus 14.3 mL (no infections). Of the 10 patients with complications, 9 required surgical debridement and subsequent delayed reconstruction. Although hydroxyapatite cement can yield excellent aesthetic results, its use in secondary reconstruction has yielded unacceptably high infection rates leading to discontinuation of its use in this patient population.

Bone substitutes in the Netherlands - a systematic literature review

Autologous bone grafting is currently considered as the gold standard to restore bone defects. However, clinical benefit is not guaranteed and there is an associated 8-39% complication rate. This has resulted in the development of alternative (synthetic) bone substitutes. The aim of this systematic literature review was to provide a comprehensive overview of literature data of bone substitutes registered in the Netherlands for use in trauma and orthopedic surgery. Brand names of selected products were used as search terms in three available databases: Embase, PubMed and Cochrane. Manuscripts written in English, German or Dutch that reported on structural, biological or biomechanical properties of the pure product or on its use in trauma and orthopedic surgery were included. The primary search resulted in 475 manuscripts from PubMed, 653 from Embase and 10 from Cochrane. Of these, 218 met the final inclusion criteria. Of each product, structural, biological and biomechanical characteristics as well as their clinical indications in trauma and orthopedic surgery are provided. All included products possess osteoconductive properties but differ in resorption time and biomechanical properties. They have been used for a wide range of clinical applications; however, the overall level of clinical evidence is low. The requirements of an optimal bone substitute are related to the size and location of the defect. Calcium phosphate grafts have been used for most trauma and orthopedic surgery procedures. Calcium sulphates were mainly used to restore bone defects after tumour resection surgery but offer minimal structural support. Bioactive glass remains a potential alternative; however, its use has only been studied to a limited extent.

Osteogenic activity of β-tricalcium phosphate in a hydroxyl sulphate matrix and demineralized bone matrix: a histological study in rabbit mandible

Currently, in oral and maxillofacial surgery, there is a clinical need for efficient bone grafting materials, and various efforts are being made to improve materials used as bone substitutes to facilitate faster and denser bone regeneration. The purpose of this study was to evaluate in vivo the osteogenic potential of synthetic β-tricalcium phosphate in a hydroxyl sulphate matrix (β-TCP/HS) and human demineralized bone matrix (DBM) putty. Sixteen New Zealand White rabbits were used. In each animal, two bone defects (8 mm length × 3 mm width × 3 mm depth) were created in the left and right regions of the mandible, respectively. The defect on one side, chosen randomly, was filled with β-TCP/HS (group A) or DBM putty (group B), while the defect on the opposite side was left unfilled in order to serve as a control site. Two animals in each group were sacrificed at the end of the 1st, 3rd, 5th and 6th week after surgery, respectively, and the osteotomy sites were processed for histological evaluation. Our findings confirmed that β-TCP/HS and human DBM putty possess osteogenic activity and can support new bone formation, although at a slower rate than the spontaneous healing response, in rabbit mandibular osseous defects.

Surface modification of PCL-TCP scaffolds in rabbit calvaria defects: Evaluation of scaffold degradation profile, biomechanical properties and bone healing patterns

Traditionally, polycaprolactone (PCL) based scaffolds tend to degrade at a slow rate. Pretreatment of polycaprolactone-20% tricalcium phosphate (PCL-TCP) scaffolds under alkaline conditions can be utilized to increase the degradation rate and improve mechanical properties. Three groups of PCL-TCP scaffolds with varying pretreatment exposures with sodium hydroxide (NaOH) were studied in a rabbit calvaria defect model and analyzed at 2, 4, 8, 12, and 24 weeks. (Group A: Untreated, Group B: 3 M NaOH/ 48 h and Group C: 3 M NaOH/96 h). Micro-CT analysis demonstrated that scaffolds with increased surface roughness (Groups B and C) showed a greater impact on the overall volume loss during the early healing period between 2 and 8 weeks as compared to the untreated group. In addition, greater bone formation was detected in NaOH treated scaffolds as compared to the untreated group throughout the experiment. Scaffolds with increased surface roughness generally reported higher push out test and compressive strength values from 4 to 8 weeks of early healing. Interestingly, the mechanical properties displayed a decline in values from 12 weeks onwards in the modified groups suggesting a favorable breakdown or weakening of PCL-TCP scaffolds tailored for replacement by new bone formation.

Cranial bone defects: current and future strategies

Bony defects in the craniomaxillofacial skeleton remain a major and challenging health concern. Surgeons have been trying for centuries to restore functionality and aesthetic appearance using autografts, allografts, and even xenografts without entirely satisfactory results. As a result, physicians, scientists, and engineers have been trying for the past few decades to develop new techniques to improve bone growth and bone healing. In this review, the authors summarize the advantages and limitations of current animal models; describe current materials used as scaffolds, cell-based, and protein-based therapies; and lastly highlight areas for future investigation. The purpose of this review is to highlight the major scaffold-, cell-, and protein-based preclinical tools that are currently being developed to repair cranial defects.