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Results for “Bone Demineralization Technique”

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At least 19 recordsLinked to original sources

PubMed1996

Expression of extracellular matrix macromolecules around demineralized freeze-dried bone allografts.

In the present study histochemical techniques were used to identify specific macromolecular components of the extracellular matrix associated with the tissue reaction to demineralized freeze-dried bone allografts (DFDBA) placed under barrier membranes for ridge augmentation. Small biopsies were obtained from tissues underneath the membranes at various times after placement of the DFDBA and processed for routine immunohistochemistry. Sections were stained with antibodies to osteocalcin, collagen type I, collagen type III, decorin, and biglycan. Non-immune serum, irrelevant antibodies, and omission of the primary antibodies served as negative controls. Histologic examination of the biopsies revealed allograft particles surrounded by well-formed fibrous connective tissue with little or no evidence of new bone formation. Vital autogenous bone fragments were present in the peripheral portions of the biopsies and served as positive controls for comparative purposes with the DFDBA particles. Only 7 out of the 20 biopsies studied were found to have any signs of bone formation around the DFDBA particles and in these such bone formation was irregular and inconsistent around the DFDBA particles. Around the periphery of the allograft particles, osteocalcin, collagen type I, collagen type III, decorin, and biglycan all showed relatively strong staining. Osteocalcin staining was also noted within the vital bone matrix but not in the surrounding fibrous connective tissue. Decorin, biglycan, collagen type I, and collagen type III were also found within the vital bone matrix. None of these antibodies stained the DFDBA particles. The unremarkable osteogenic response of the tissues to the DFDBA particles after healing periods of up to 12 months raises questions as to the predictability of these agents in inducing new bone.

Adult↗

PubMed1995

[The experimental morphological bases for using a microsurgical technic and demineralized bone in the restorative surgery of hollow organs and blood vessels].

By means of experimental material from 339 animals it was shown that microsurgical technique provides primary recovery of the wounds of the hollow organs, their anastomoses and blood vessels: demineralized bone is found to be a suitable material easily adapting in implantation. The use of microsurgical methods and technique and demineralized osseus matrix for nonosseous plastics is a perspective direction in improvement of the results of reconstructive and restorative operations on hollow organ and blood vessels.

Abdomen↗

PubMed1998

Ultrasound characterization of bone demineralization.

Quantitative ultrasound (QUS) assessment of bone may permit an assessment of bone properties currently not available by bone densitometry techniques. To explore the effects of the quantity of bone mineral on acoustic parameters, we carried out an in vitro study of the impact of demineralization on attenuation of ultrasound in trabecular bone. Ten fresh cubes of trabecular bone obtained from bovine distal femurs were progressively demineralized using formic acid solution. The progression of demineralization was controlled by monitoring the specimen bone mineral density (BMD) using dual x-ray absorptiometry (DXA). At five stages of demineralization-0% (baseline), 25%, 50%, 75%, and 100% (all mineral removed)-the US properties of the specimens were assessed (Walker Sonix UBA 575+). The US parameters investigated were broadband ultrasound attenuation (BUA) and ultrasound attenuation in bone (UAB). Both DXA and QUS measurements were made along the three orthogonal axes of each cube. Our results demonstrated significant variability in both BUA and UAB along the three principle axes of the cubes whereas BMD did not differ in the different directions. A strong but nonlinear correlation was found between BMD and US attenuation. A reduction in BMD to 50% of the baseline values resulted in BUA (UAB) reduction to 25% and 19%, respectively. A random effect model analysis supported a multiplicative relationship between BMD and the US parameters. US attenuation is a sensitive indicator of bone mineral changes with nonlinear dependence on bone mineral loss. Bone collagen structure reinforced by hydroxyapatite crystal accounts for fundamental US characteristics. Ultrasound attenuation associated with trabecular orientation is basically dominated by the mineral spread in a collagen framework.

Absorptiometry, Photon↗

PubMed1996

Use of demineralized bone implants in orbital and craniofacial reconstruction and a review of the literature.

A retrospective study and review of the literature was performed on the use of demineralized bone implants for the correction of orbital and craniofacial defects. Demineralized bone implants heal by endochondral osteogenesis, inducing a transformation of local cells, as well as by osteoconduction, similar to autogenous grafts. They induce the chemotaxis and transformation of mesenchymal cells into chondroblasts, followed by ossification. They also act as a scaffold, with bone resorption taking place simultaneous with bone formation. This study reviewed 21 patients and 31 orbits, in which demineralized bone was used for orbitocranial reconstruction for congenital deformities (nine patients), after surgery for orbital fractures (seven patients: four floor, three roof), and orbital tumors (five patients). The surgical technique is described, and the results are discussed. The follow-up period averaged 15 months (6 months to 33 months). The overall resorption rate of the demineralized bone implants was estimated based on follow-up radiologic studies (facial films, computed tomography scans, and magnetic resonance imaging scans), as well as clinical examinations. All patients had a satisfactory to excellent result. The demineralized bone and Grafton (Osteotech, Shrewsbury, NJ, U.S.A.) was obtained from the Musculoskeletal Transplant Foundation of Holmdel, New Jersey, and it was all processed and reconstituted in a standard manner with Alloprep System. Surgical complications were cerebrospinal fluid leaks (one patient) with infection, transient chemosis, enophthalmos, and hypophthalmos. There were no complications related to demineralized bone alone. Properly prepared demineralized bone is a safe material for orbital reconstruction that eliminates the need for a second operative site to harvest a bone graft.

Adult↗

PubMed1997

A clinical evaluation of guided tissue regeneration with a bioabsorbable matrix membrane combined with an allograft bone graft. A series of case reports.

THE PURPOSE OF THIS STUDY was to evaluate the clinical effectiveness of a surgical technique in treating periodontal defects. The technique combined tetracycline treatment of a root planed root, grafting of the osseous defect with a demineralized freeze-dried bone allograft combined with tetracycline and the placement of a bioabsorbable matrix membrane, made of polylactic acid softened with citric acid ester. Thirty defects were treated in 27 patients. Statistically significant changes, as a result of the surgical procedure, were observed in marginal recession (mean: 0.5 mm), probing depth reductions (mean: 5.7 mm), and attachment level gain (mean: 5.2 mm). No statistically significant difference existed between the results in the furcation and non-furcation groups. The defects with probing depths > or = 10 mm had a greater mean probing depth reduction (7.4 mm) and mean attachment level improvement (7.2 mm) than the defects with < 10 mm probing depths (probing depth reduction 4.5 mm and attachment level gain 3.9 mm). The proposed surgical procedure seemed to be an effective method to treat periodontal defects.

Adult↗

PubMed1997

[The effect of calcium content in bovine cancellous bone as carrier on expression of tumor necrosis factor-alpha gene in mice].

We investigated the expression of tumor necrosis factor-alpha (TNF alpha) gene in the area of implanted calf cancellous bone with different calcium content and the influence of calcium salts on local cellular immunity. The particles of mineralized and partially demineralized bone were implanted in the mouse's muscle pouch, and removed 3, 5, 10 and 20 days after implantation of the bone particles. The specimens were processed for determining the expression of mRNA encoding TNF alpha, which was performed by a nonradioactive in situ hybridization technique. The expression of TNF alpha mRNA was markedly higher in the mineralized bone group than in the partially demineralized bone group (P < 0.01). The positive rate of TNF alpha gene expression was highest by 10 days after implantation. There was a strong hybridization signal localization to the cytoplasm of morphologically identifiable monocytes and multinucleated giant cells. Similar activity was detected in the cytoplasm or nuclei of mesenchymal cells, fibroblasts as well as striated muscle fibers. This finding suggests that the calcium content in calf cancellous bone possesses a significantly stimulative effect on TNF alpha mRNA expression, and calcium salts may be of importance for the modulation of local cellular immunity.

Animals↗

PubMedDate not supplied

Anterior lumbar interbody fusion with titanium mesh cages, coralline hydroxyapatite, and demineralized bone matrix as part of a circumferential fusion.

BACKGROUND CONTEXT: Anterior lumbar interbody fusion (ALIF) has become one of the primary choices for eliminating motion between vertebral segments in patients with severe discogenic pain and other lumbar pathologies. Autograft is the gold standard for spinal fusion. However, multiple authors have reported complication and morbidity rates associated with iliac crest harvesting to be as high as 25%. Drawbacks to the use of allograft in the anterior column include slower incorporation rates, the possibility for disease transmission, increasing cost resulting from stringent processing and unavailability on a worldwide basis resulting from religious and economic concerns. PURPOSE: To determine the clinical and arthrodesis efficacy of coralline hydroxyapatite as an osteoconductive bone graft substitute in the anterior lumbar spine using a titanium mesh cage. STUDY DESIGN: A series of 50 patients returning for long-term prospective follow-up, implanted with titanium mesh cages filled with coralline hydroxyapatite and demineralized bone matrix for ALIF as part of a circumferential fusion. PATIENT SAMPLE: Long-term clinical and radiographic follow-up were examined for the first 50 patients undergoing this technique by one surgeon. OUTCOME MEASURES: Pain was measured with a visual analog scale and function was measured with the Oswestry Disability Index. METHODS: All 50 patients underwent successful ALIF with titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix, as well as an autologous posterolateral fusion with rigid posterior instrumentation. Patients filled out follow-up questionnaires and appropriate radiographs were taken. RESULTS: A solid fusion rate of 96% was achieved. Mean pain decrease was 60% overall. A total of 70% of all patients either returned to work or to full home activities at a mean of 8 months after surgery. Ninety percent felt the surgery was successful. CONCLUSIONS: The combination of titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix is effective for anterior interbody fusion of the lumbar spine when used as part of a rigidly instrumented circumferential fusion.

Adult↗

PubMed1999

Characterization of matrix-induced osteogenesis in rat calvarial bone defects: I. Differences in the cellular response to demineralized bone matrix implanted in calvarial defects and in subcutaneous sites.

The cellular and biochemical sequences of osteogenesis induced by implanting demineralized bone matrix (DBM) in rat cranial defects and in subcutaneous sites have been studied by histological, histochemical, and biochemical techniques from days 2 to 28 after implantation. In subcutaneous sites, allogenic DBM induced cartilage cells and matrix for approximately the first 10 days which were subsequently resorbed and replaced by bone with little evidence for the classical endochondral sequence of ossification. In sharp contrast, the first cells that differentiated from the mesenchymal stem cells in the cranial defects were alkaline phosphatase (ALP) positively stained osteoblasts that appeared 3 days after implantation followed by synthesis of bone matrix which calcified shortly thereafter. A few clusters of cartilage cells were observed beginning at days 6-7 which were spatially distinct from the new bone and later resorbed. By day 28 the tissue induced in both the subcutaneous and cranial sites consisted almost solely of bone; however, the total amount of new bone in the subcutaneous implants was significantly less than the mass of bone formed in the calvarial defects. Bovine DBM induced bone formation in rat cranial defects to a very much lesser extent than allogenic DBM. A few cartilage cells were induced by bovine DBM in subcutaneous sites and rapidly resorbed and not replaced with bone. These results clearly indicate that the cellular sequence induced by allogenic and xenogenic DBM and the repair tissues synthesized are distinctly different in the cranial defects from those induced in the subcutaneous sites.

Alkaline Phosphatase↗

PubMed1997

Utilization of type I collagen gel, demineralized bone matrix, and bone morphogenetic protein-2 to enhance autologous bone lumbar spinal fusion.

Autologous bone grafts are currently considered "gold standard" material for achieving long-term spinal arthrodesis. The present study was performed to determine whether demineralized bone matrix (DBM), type I collagen gels, or bone morphogenetic protein-2 (BMP-2) can improve autologous bone spinal fusions. Using a unilateral decompression-contralateral fusion technique in dogs, each of these materials was added to an autologous bone graft. Volumetric analysis, histological analysis, and biomechanical testing were performed to assess the effectiveness of each material. The DBM had an inhibitory effect on solid bone fusion of the spine, whereas the type I collagen gels improved the bony interface between the graft and the host spine. The BMP-2 strongly enhanced the amount of bone deposition at the fusion site and increased the number of intervertebral levels that were solidly fused. This study strongly supports the use of BMP-2 as an additive to autologous bone grafts in spine stabilization.

Animals↗

PubMed1996

Transforming growth factor-beta 1 in a guanidine-extracted demineralized bone matrix carrier rapidly closes a rabbit critical calvarial defect.

Transforming growth factor beta 1 (TGF-beta 1) is a polyfunctional regulatory cytokine that has been shown to have roles in extracellular matrix interactions, soft tissue healing, and osteogenesis. Twenty-five microL of recombinant human TGF-beta 1 was added to guanidine-extracted demineralized bone matrix carrier and the implants were used to fill a 14-mm osteoperiosteal critical calvarial defect in New Zealand white rabbit model. The defects were allowed to heal over 4 weeks and the degree of new bone formation was assess by radiodensitometry and undecalcified bone histomorphometry techniques. Implants with TGF-beta 1 showed complete bridging of the gap with new bone in all cases, while the controls showed fibrous tissue repair of the gap with little or no new bone formation. These results demonstrate the ability of TGF-beta 1 to induce new bone in a brief time period in an inactive carrier.

Animals↗

PubMed2003

Healing of large defects treated with calcium sulfate pellets containing demineralized bone matrix particles.

Calcium sulfate (OsteoSet, Wright Medical Technology, Inc, Arlington, Tenn) and calcium sulfate/demineralized bone matrix (DBM) pellets (OsteoSet DBM, Wright Medical Technology, Inc) have been evaluated preclinically in a bilateral medullary defect model of a canine humerus. In this model, both short (6 week) and long (26 week) time points have been evaluated. An analysis of bone response to the pellets was conducted using radiological, histological, mechanical, and quantification techniques. The calcium sulfate/DBM pellets exhibited more rapid trabecular bone remodeling as demonstrated by the absence of the ringlet bone structure typically seen with calcium sulfate pellets. We concluded that calcium sulfate and calcium sulfate/DBM pellets are both effective bone graft substitutes.

Animals↗

PubMed1996

Morphological changes of autoclaved autogenic bone implantation and autoclaved autogenic bone supplemented with allogenic demineralized bone matrix in rat parietal bone.

The healing process of resected, autoclaved (121 degrees C, 20 minutes) and re-implanted bone in the rat parietal bone was compared with that of autoclaved bone that was supplemented with allogenic bone matrix (AAA-bone), using a scanning electron microscope and a light microscope. In the implant without AAA-bone, bone union and replacement of the autoclaved bone was seen at 2 weeks after implantation. There was no evidence of any inflammatory reaction around the autoclaved bone. The implant was gradually replaced by the new bone. In the implant with AAA-bone, the new bone formation around the implanted bone was more abundant than that of the implant without AAA-bone. An inflammatory reaction was also observed after 1 week. The replacement of the implant with AAA-bone was inferior to the nonsupplemented group. The reason for the poor replacement was the disturbance of the blood supply in the implant by abundant new bone formation. In these results, the autoclaved bone re-implantation was an excellent bone substitute with osteoconductive ability and biocompatibility. The implantation with AAA-bone was good for the new bone formation, but the position and the technique of supplement with AAA-bone have to be more deeply investigated.

Animals↗

PubMed2001

Demineralized bone matrix as an alternative for mastoid obliteration and posterior canal wall reconstruction: results in an animal model.

HYPOTHESIS: This study was conducted to evaluate the use of Grafton human demineralized bone matrix as a graft material for mastoid cavity obliteration and canal wall reconstruction in an animal model. BACKGROUND: Canal wall down procedures in the treatment of cholesteatoma may result in a problematic mastoid cavity. Elimination of the mastoid cavity by obliteration or canal wall reconstruction can prevent or correct this problem. Many techniques and implant materials have been used for this application, yet no single material has proven to be ideal. METHODS: Athymic rats received tympanic bulla obliteration and lateral bulla wall reconstruction utilizing the Grafton Putty and Flex formulations, respectively. Wound healing was monitored twice a week. Auditory brainstem evoked responses were obtained 8 weeks after implantation. Nine weeks after implantation, the animals were killed, and histologic sections were prepared. A histologic bone formation score (range 0-4) was determined for each implant. RESULTS: Wound healing occurred without complication. Auditory brainstem response thresholds (average 23.5) fell within the normal range for all ears tested. The average histologic bone formation score for all implants was 3.7. The average scores for obliteration implants and wall reconstruction implants were 3.5 and 3.9, respectively. All wall reconstruction implants underwent partial or total collapse into the bulla. CONCLUSIONS: The high level of bone formation obtained by the use of Grafton implants in this study makes this material a promising resource for use in mastoid obliteration. The use of the material for canal wall reconstruction will likely require a sturdier preparation to prevent collapse into the mastoid cavity.

Animals↗

PubMed1997

Improved method for examination of microvascular structures in bone tissue.

Scanning electron microscopy of methylmethacrylate vascular corrosion casts was used for the morphologic examination of the microvascular system in bone. The methylmethacrylate used for vascular casting was prepared by prepolymerization with ultraviolet light. To approximate the viscosity of blood in the microcirculation, where the hematocrit of blood is lower than in the rest of the circulation, a viscosity between that of plasma and full blood was chosen for the casting material. Neither the ultraviolet prepolymerization of methylmethacrylate nor the choice of a viscosity this low has been used in microcorrosion casting in bone before. Further preparation of the tissue followed 2 directions: (1) complete maceration and decalcification of the specimens, thereby exposing all the vascular structures for detailed examination. By this procedure, it was possible to show detailed and sharp impressions of the vascular bed, and to show, for the first time, the vascular loop from a cutting cone; and (2) maceration without decalcification of the specimens, which is suitable for examination of relations between the microvascular system and the bone tissue. This technique enables studies of the role of the vascular system in bone remodeling and of the involvement of vascular structures in bone disorders. This improved technique for examination of microvascular structures in bone enables detailed studies of the vascular system and its relation to active remodeling sites in bone.

Animals↗

PubMedDate not supplied

[Bone grafts in orthopedic surgery].

In orthopedic surgery the demand for the use of bone grafts increases daily because of the increasing quantity and complexity of surgical procedures. At present, the gold standard is the autologous bone graft but the failure rate, morbidity of the donor site and limited availability have stimulated a proliferation for finding materials that work as bone graft substitutes. In order to have good success, we must know the different properties of these choices and the environment where the graft is going to be used. As bone graft substitutes and growth factors become clinical realities, a new gold standard will be defined. Tissue engineering and gene therapy techniques have the objective to create an optimum bone graft substitute with a combination of substances with properties of osteconduction, osteogenesis and osteoinduction.

Animals↗

PubMed2002

Effects of collagen unwinding and cleavage on the mechanical integrity of the collagen network in bone.

The objective of this study was to investigate how molecular level changes in the collagen network affect its mechanical integrity. Our hypothesis is that the cleavage and unwinding of triple helices of collagen molecules significantly reduce the mechanical integrity of the collagen network in bone, whereas collagen crosslinks play a major role in sustaining the structural integrity of the collagen network. To test this hypothesis, the collagen molecular structure was altered in demineralized human cadaveric bone samples in the following two ways: heat induced unwinding and pancreas elastase induced cleavage of collagen molecules. Along with control specimens, the treated specimens were mechanically tested in tension to determine their strength, elastic modulus, toughness, and strain to failure. Also, the percentage of denatured collagen molecules and amounts of two major collagen crosslinks (hydroxylysylpyridinoline and lysylpyridinoline) were determined using high-performance liquid chromatography techniques. It was found that unwinding of collagen molecules may cause more reduction in stiffness (E) but less strain to failure (ef) than cleavage. Both collagen denaturation types cause similar changes in the strength (ss) and work to fracture (Wf) of the collagen network with no significant changes in hydroxylysylpyridinoline and lysylpyridinoline crosslinks. The results of this study indicate that the integrity of collagen molecules significantly affect the mechanical properties of the collagen network in bone, and that collagen crosslinks may play an important role in maintaining the mechanical integrity of the collagen network after collagen denaturation occurs.

Adult↗

PubMedDate not supplied

Demineralized bone matrix-induced ectopic bone formation in rats: in vivo study with follow-up by magnetic resonance imaging, magnetic resonance angiography, and dual-energy X-ray absorptiometry.

The aim of this study was to further explore the use of magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and dual-energy X-ray absorptiometry (DEXA) to assess bone formation and blood circulation in a pedicled bone graft substitute. In 14 Wistar rats, initially 10 weeks old, heterogeneous demineralized femur bone matrix implants were wrapped in pedicled adductor thigh muscle flaps. One rat died after surgery. Subsequently, bone formation and maintenance of blood vessel functionality were evaluated in six rats 6 weeks postimplantation by means of in vivo MRI/MRA and postmortem histomorphometry. The other seven rats were left for 12 weeks, whereafter bone formation was evaluated by in vivo DEXA and postmortem histomorphometry. The results demonstrated that after 6 weeks bone formation was present in four of six animals, quantified as 42 (+/-35)% and 25 (+/-19)% by means of MRI and histomorphometry, respectively. MRA was able to show patency of the pedicles of these four rats only, which suggests that the lack of blood supply in the other two rats is the cause of the failure to form bone. In the 12-week group, histology showed increased bone formation without signs of osteolysis, which was quantified histomorphometrically to be as high as 48 (+/-15)%. DEXA failed to show bone formation. It is concluded that in vivo MRI proved to be a reliable method for monitoring ectopic bone formation in a rat model, whereas in vivo DEXA was unable to detect the implants. Furthermore, in vivo MRA proved to be a useful technique for studying the circulation of muscle flaps in this animal model.

Absorptiometry, Photon↗

PubMed2004

Histologic evaluation of demineralized freeze-dried bone allografts in barrier membrane covered periodontal fenestration wounds and ectopic sites in dogs.

BACKGROUND/AIM: The aim of this study was to investigate healing responses to demineralized freeze-dried bone powder allografts in standardized periodontal fenestration defects, compared with subcutaneous wounds in a dog model. METHODS: Circular periodontal fenestration defects were created buccally at all four canines in 14 mongrel dogs. Each site received one of the following underneath a barrier membrane: (a) ethylene oxide (EO)-sterilized demineralized freeze-dried bone allografts (DFDBA), (b) heat-treated DFDBA, (c) non-sterilized DFDBA and (d) ungrafted control. Twelve of the 14 dogs had three subcutaneous chest wall pouches created and one of the three DFDBA materials placed in each. The animals were necropsied at 4 weeks. Histologic sections were prepared through the center of the fenestration sites in an apico-coronal direction. Quantitative analysis using computer-assisted imaging technique was performed. Subcutaneous implants were evaluated histologically and quantified for associated inflammatory cell infiltrate. RESULTS: Fenestration defects healed by partial osseous fill and cementum regeneration with formation of a periodontal ligament. The graft particles generally appeared isolated from the site of osteogenesis and covered by cementum-like substance. Graft particles incorporated into newly formed bone at a distance from the root surface was the exception. No statistically significant differences in new bone formation were observed between treatment groups within animals, but significant inter-animal variation was found (p<0.01). Quantities of retained graft particles were limited, and without cellular resorption. A bone augmentation effect was associated with the barrier in the majority of sites. No bone formation was evident at the subcutaneous sites where graft particles displayed distinctly modified surface zones and multinucleated giant cell resorption. Significantly more inflammatory infiltrate was associated with EO-sterilized grafts compared with heat-treated grafts (p=0.05). CONCLUSION: Implantation of DFDBA neither enhanced osseous healing in periodontal fenestration defects, nor resulted in ectopic bone induction. DFDBA particles implanted in either periodontal fenestration or subcutaneous wounds evoked distinctly different healing responses.

Alveolar Bone Loss↗