[Examination of influence of microstructure of grafts on TiO2 base on the process of bone tissue forming]. / Badanie wplywu mikrostruktury wszczepów na osnowie TiO2 na proces formowania sie tkanki kostnej.

AIM OF THE STUDY: Evaluation of the influence of the introduced structure modification in porous ceramic grafts on TiO2 base on overgrowing with bone tissue, in examinations with use of scanning microscopy and X-rays was the subject of the examinations. MATERIAL AND METHOD: New ceramic materials based on TiO2 with high values of mechanical resistance, large sintering degree and biocompatibility in in vitro conditions were prepared. Those properties cause that they are worth interest as potential osteosubstitutive materials. Two kinds of grafts were created from ceramics based on TiO2: with compact and porous structure. The introduced structure modification - macroporosity - had the purpose to give osteoconductive properties to the grafts, to evoke processes favorable for bone tissue forming. In examinations of the local reaction of bone tissue after implantation of the formed porous grafts, degree of their osteointegration, the essential issue is the evaluation of the settling of the inner spaces with supporting tissues. Samples of the tested compact and porous materials in the form of cylinders were implanted in femoral bones of rabbits for a period till 6 months. The surfaces of grafts and the degree of their settling with supporting tissues were evaluated in cross-sections of the implants with light and scanning microscopic methods and they were confirmed in X-ray tests. RESULTS: Analysis of the obtained data showed that, the surface of solid ceramic on TiO2 base was covered mainly with increasing with a time of observation quantities of extracellular substance and lamellas of bone. The macrporous structure of porous ceramic on TiO2 base enabled settling of the inner spaces of graft with supporting tissue cells, partly in the 1st month, more intensively in the 3rd and it was not completed in the 6th month after implantation. CONCLUSIONS: Porous grafts in the form of ceramic foam on TiO2 base showed osteoconductive properties, though process of colonization after 6th month observation was not completed and the condition of the cells inside of the implant was reduced.

[Aseptic bone flap osteonecrosis following cranioplasty after decompressive cranietomy]. / Aseptische Osteonekrose einer Kranioplastie nach dekompressiver Kraniektomie.

This case report discusses a case of aseptic osteonecrosis in a cranioplasty bone flap after decompressive craniectomy, which is a known, but rare complication after autologous cranioplasty. We suggest that the pathophysiology of cranial bone flap necrosis may have a similar pathophysiology to free flap necrosis/failure. The key suggested problem causing the osteonecrosis is vessel thrombosis within the smaller vessels of the bone flap due to the prothrombotic effects of the factors released during drilling of the bone flap. Suspicious local findings like wound dehiscence or fluid leakage should lead to a head computed tomography in order to discuss a prophylactic artificial second cranioplasty if necessary.

Prefabrication of vascularized bone allograft in a recipient rat using a flow-through vascular pedicle, bone morphogenetic protein, and bisphosphonate.

We attempted to prefabricate vascularized bone allografts by implanting flow-through vascular bundles from recipient rats into transplanted bone allografts. We also applied bone morphogenetic protein (BMP) and bisphosphonate into the bone allograft to accelerate bone formation and inhibit bone resorption in the transplanted bone. After prefabrication, bone formation and resorption in the vascularized bone allograft were evaluated radiographically and histologically. We also attempted to transfer the prefabricated vascularized bone allograft onto the femur of recipient rats, and bone union between was subsequently assessed. Bone formation in the transplanted allograft was significantly stimulated with addition of BMP. However, bone resorption was also stimulated by BMP; this stimulated bone resorption caused by BMP was effectively inhibited with addition of bisphosphonate. The bone union rate between transplanted bone allografts and recipient femora was also stimulated by BMP. Bisphosphonate slightly delayed bone union but effectively protected the grafted bone from bone resorption caused by BMP. Our results suggest that prefabrication of vascularized bone allografts can be achieved in the recipient rat by implanting a flow-through vascular bundle from the recipient into the transplanted bone allograft. Combination treatment with BMP and bisphosphonate allows development of an ideal vascularized bone allograft.

Is there a therapeutic role for cranioplasty?

Cranioplasty is often undertaken as a joint neurosurgical and maxillofacial procedure. The principal aims remain to improve cosmesis and to protect the underlying brain. We report two cases of cranioplasty with subsequent improvement in neurological function and discuss the possible therapeutic role of cranioplasty.

Alveolar distraction osteogenesis for dental implant rehabilitation following fibular reconstruction: a case series.

OBJECTIVE: Alveolar distraction osteogenesis (ADO), a novel bone augmentation technique, is gaining acceptance in restoring the vertical bone discrepancy between the transplanted graft and the residual alveolar bone after mandibular reconstruction. This case series presents the outcomes of ADO in fibula-reconstructed mandibles rehabilitated with dental implants, with an emphasis on clinical indications, surgical protocol, clinical outcomes, histologic evidence, and complications. MATERIALS AND METHODS: Five patients underwent fibula distraction procedures after undergoing mandibular reconstruction with a vascularized fibula bone graft. The indication for the application of ADO was for the correction of the vertical discrepancy between the top of the reconstructed fibula and the adjacent alveolar crest to achieve adequate vertical bone height before implant placement. RESULTS: The mean vertical bone height achieved was 13.58 mm. Twenty-two dental implants were placed in 5 patients. All patients were rehabilitated with implant-supported prostheses. Bone biopsies showed the distracted area was filled with newly formed, bony trabeculae between the transported fibula and the basal segments. The most common complication was transient infection around the distractor rod. CONCLUSIONS: ADO can be performed on fibula-reconstructed mandibles to achieve the restoration of alveolar height, which then can be rehabilitated with dental implant-supported prostheses. The procedure has a minor risk of infection associated with the distractor rod, which does not compromise the bone regeneration from distraction. Patients with mandibles reconstructed with fibulas can attain dental implant rehabilitation with ADO, achieving good esthetic and occlusal outcomes.

Prefabricated iliac crest transplant.

PURPOSE: Our aim was to augment the extremely atrophic mandibular alveolar crest with a pedicled transplant as the best option for a satisfactory preprosthetic outcome. MATERIALS AND METHODS: After computed tomography of the mandible, a model was milled for 6 patients. The iliac crest transplant with its vascular pedicle was harvested and, after preliminary preparation, fixed to the model. The transplant was then placed in the axilla. After 3 months, the graft was removed and fixed to the mandible. RESULTS: The prefabricated transplant fit exactly in all 6 patients. The length of the pedicle and coverage with the newly developed alveolar mucous membrane were satisfactory. The grafts allowed prosthetic reconstruction with good functional outcomes. No bone loss was observed during 7 years of follow-up. Additionally, indocyanine green angiography showed good perfusion in 4 patients after 6 months. CONCLUSIONS: The results suggest that carefully prefabricated pedicled transplants can augment an atrophied mandibular alveolar crest.

A comparison of tissue-engineered bone from adipose-derived stem cell with autogenous bone repair in maxillary alveolar cleft model in dogs.

This study was designed to compare bone regeneration of tissue-engineered bone from adipose-derived stem cell and autogenous bone graft in a canine maxillary alveolar cleft model. In this prospective clinical trial, mesenchymal stem cells (MSCs) were isolated from subcutaneous canine adipose tissue. Undifferentiated cells were incubated with a 3mm×3mm×3mm hydroxyapatite/beta-tricalcium phosphate scaffold, in specific osteogenic medium for 21 days. Four mongrel dogs were prepared by removal of two of the three incisors bilaterally and a 15mm defect in bone was created from crest to nasal floor. After healing, repair was followed by a tissue engineered bone graft from adipose-derived stem cells on one side and corticocancellous tibial auto graft on the other side. Bone regeneration was evaluated by histomorphometry on days 15 and 60 after implantation. The data were analysed with descriptive and t test methods (α=0.05). Bone formation on the autograft sides was higher than on the stem cell sides at 15 and 60 days, 45% and 96% versus 5% and 70%, respectively. Differences between the two groups at 15 and 60 days were significant (p=0.004 and 0.001, respectively). Although autograft is still the gold standard for bone regeneration, tissue engineered bone may provide an acceptable alternative.

Effect of guided bone regeneration with or without pericardium bioabsorbable membrane on bone formation.

OBJECTIVE: The purpose of this study was to evaluate bone formation after using allogeneic bone alone or with a membrane. STUDY DESIGN: Bone graft was performed using the allograft Tutoplast, mineralized cancellous bone allograft, and pericardium in calvarial defects of 60 rats. Rats were divided in 3 groups: control group (no bone graft), group 1 (bone graft without membrane), and group 2 (bone graft with membrane). RESULTS: The most new bone formation occurred in group 2. After 6 weeks, group 2 showed infiltration of inflammatory cells, and inflammatory cells were still observed after 12 weeks. The membrane remained even after 12 weeks, and the membrane facilitated bone regeneration by blocking connective tissue. CONCLUSIONS: The membrane facilitated new bone formation by inhibiting connective tissue invasion.

Prefabrication of vascularized bone grafts using a combination of bone marrow mesenchymal stem cells and vascular bundles with ß-tricalcium phosphate ceramics.

OBJECTIVE: Large bone defects are often treated with autologous vascularized bone grafts. These operations may be associated with donor site morbidities and a limited volume of harvested bone. To overcome such issues, we prefabricated vascularized bone grafts using a combination of bone marrow mesenchymal stem cells (BMSCs) and vascular bundles in a ß-tricalcium phosphate ceramic (ß-TCP). STUDY DESIGN: We used 15 New Zealand White rabbits as our experimental animals. Single photon-emission computed tomography and histologic analyses were used to evaluate angiogenesis and new bone formation of the bone grafts. RESULTS: The results showed that axial vessels not only promoted angiogenesis of the bone grafts, but also enhanced new bone formation. CONCLUSION: These findings suggested that the insertion of blood vessels into tissue-engineered bone grafts was an effective strategy for enhancing angiogenesis and bone formation and had potential significance for clinical applications.

A comparative evaluation of the systemic and local alendronate treatment in synthetic bone graft: a histologic and histomorphometric study in a rat calvarial defect model.

OBJECTIVE: The purpose of this study was to compare the relative efficacy of systemic and local alendronate treatment of synthetic bone graft in a rat calvarial defect model. STUDY DESIGN: Forty Wistar rats were divided into 4 groups: experimental animals received alendronate systemically or locally combined with micro-macroporous biphasic calcium phosphate (MBCP) graft material. In the control group, the defect was left empty. On each animal, a 5-mm standardized bone defect was created with a standard trephine bur in calvarium. All animals were killed after 8 weeks. The number of osteoclasts, osteoclast morphology, resorption lacunae, osteoblastic activity, and lamellar bone formation were histopathologically evaluated and the newly formed bone area was analyzed histomorphometrically. RESULTS: Eight weeks after surgery, the number of osteoclasts and the resorption lacunae in the MBCP group using systemic alendronate therapy was significantly higher than those of the other groups (P < .05). Osteoblast number in the MBCP group using systemic alendronate treatment was significantly increased (P < .05). No significant difference was found among all MBCP groups using local or systemic alendronate treatments with regard to new bone formation (P > .05). CONCLUSIONS: Within the limits of the study, alendronate, when administered systemically or locally, did not increase bone regeneration with MBCP graft in the rat calvarial defect model.

Periosteal expansion before local bone reconstruction using a new technique for measuring soft tissue profile stability: a clinical study.

PURPOSE: To evaluate the outcome of intraoral soft tissue expansion by measuring the profile change using objective 3D metering equipment and to evaluate localized bone grafting after soft tissue expansion with regard to gain of bone and complications. MATERIALS AND METHODS: Using a prospective study design, we asked patients with an osseous and soft tissue defect on the buccal aspect of the alveolar process to participate in this study. In 10 patients (experimental group) a self-inflatable soft tissue expander was placed under the periosteum. After 2 weeks, the expander was removed and a particulated onlay bone graft was placed in the expanded area, protected by a titanium mesh covered with a collagen membrane. Ten patients (reference group) were treated with a mandibular ramus bone block graft. The soft tissue profile was registered before each surgical procedure. The vertical and lateral dimensions of the bone grafts were noted at the grafting procedure and at the implant installation. P < .05 was considered significant. RESULTS: The mean soft tissue profile change was 2.9 ± 1.1 mm after soft tissue expansion and 2.3 ± 2.1 mm at implant placement in the experimental group compared with 1.5 ± 1.4 mm at implant placement in the reference group (P = .065). Two patients had minor perforations of the soft tissue expander. In the experimental group, the mean lateral bone augmentation after soft tissue expansion was 4.5 ± 1.3 mm, and after healing, it decreased to 3.9 ± 1.4 mm (P = .063). The mean vertical augmentation was 4.1 ± 1.7 mm and had decreased at implant placement to 3.0 ± 1.4 mm (P = .041). In the reference group, the mean lateral augmentation was 3.8 ± 0.8 mm, and after healing, it reduced to 2.7 ± 0.8 mm (P = .024). The mean vertical augmentation was 2.9 ± 0.9 mm, and after healing of the bone graft at implant placement, it was reduced to 1.6 ± 0.8 mm (P = .01). When smokers were excluded, there was significantly less resorption of the bone grafts in both lateral (P = .049) and vertical (P = .012) dimensions in the experimental group compared with the reference group. CONCLUSION: Hydrogel expansion of the periosteum is an applicable method to achieve a surplus of soft tissue to cover bone grafts. More refinements to the technique may be required to minimize complications, especially in smoking patients.

Five-year results of implants inserted into freeze-dried block allografts.

PURPOSE: The purpose of this study was to evaluate the outcome after 5 years of allografts as bone growth material and success of implants inserted in fresh-frozen allograft bone. MATERIALS AND METHODS: A total of 20 patients were operated and 41 onlay block freeze-dried allografts (calvarial and iliac crest) were inserted for bone augmentation. A total of 64 dental implants were performed in a two-stage procedure. Four patients had total edentulism and 16 had partial edentulism. RESULTS: A total of 41 onlay block allografts were used to augment atrophic maxillae and mandibles in 20 patients. In five cases, there were horizontal and vertical augmentations. Exposure of bone allograft occurred in three cases during the first 6 weeks; all of them located in the posterior area. There were no postoperative effects in any of the cases. Fracture was observed in one case, the remaining bone was adequate to place the implants. Sixty-two dental implants were placed at second stage surgery. There was no loss of implants. CONCLUSIONS: The use of fresh-frozen allogenic bone blocks can be considered as being reliable for reconstruction of maxillomandibular defects.

Biological response to porcine xenograft implants: an experimental study in rabbits.

PURPOSE: The aim of this study was to evaluate the effect of a new porcine biomaterial and collagen paste in 20 New Zealand rabbits. MATERIALS AND METHODS: Forty implants using a porcine xenograft made up of 80% corticocancellous collagenated bone particles of ≤300 µm in size were placed in the proximal metaphyseal area of both tibiae. Four periods of time were formed: 1h, 5, 8, and 15 months. After implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 µm and stained using hematoxylin-eosin, Masson's trichromic, and Gordon-Switt reticulin stains. RESULTS: These results confirmed the biocompatibility of this porcine biomaterial-collagen paste; only a few, occasional macrophages and scattered lymphocytes were observed. No fibrosis was observed between the implants and the bone. Moreover, the material was osteoconductive acting as a "scaffold" for bone cells, and there was a progressive increase in bone growth in and around the implants. CONCLUSION: This new porcine biomaterial-collagen paste seemed to be biocompatible, bioresorbable, and osteoconductive.

Growth factor-mediated combination therapy to treat large local human alveolar ridge defects.

The purpose of this case report is to demonstrate the effectiveness of a matrix consisting of recombinant human platelet-derived growth factor BB (rhPDGF-BB)-hydrated cancellous allogenic block graft in the reconstruction of large local human alveolar ridge defects. The results suggest improved bone regeneration when combining rhPDGF-BB with the allogenic block graft. The clinical and histologic evidence of new bone formation as well as bone remodeling supports the clinical potency of this growth factor-mediated therapy.

Bone graft healing in alveolar osteoplasty in patients with unilateral lip, alveolar process, and palate clefts.

Secondary osteoplasty by means of autogenic spongy bone grafting is the most common procedure used in the reconstruction of the continuity of the maxillary alveolar process. The aim of the study was to analyze retrospectively the effect of certain factors on the course of the bone graft healing process in patients with unilateral complete clefts of the lip, alveolar process, and palate. The investigations involved 62 children aged 8 to 14 years (mean age, 11 years) with unilateral complete cleft of the lip, alveolar process, and palate operated on at the Clinic of Plastic Surgery in Polanica Zdrój from November 2007 to April 2009. All the procedures consisted in the reconstruction of the maxillary alveolar process by means of autogenic spongy bone grafting from the iliac bone. The analysis was performed on the basis of computed tomography scans presenting maxillary alveolar processes in the horizontal cross-sectional planes performed on the second or third postoperative day and after 6 months. They were used as the basis for the measurement of the volume and density (condensation) of the bone graft, the surface of its adhesion to the maxillary alveolar bone, and the volume and density of the healed bone. The following correlation coefficients were determined: between the adhesion surface of the bone to the alveolar bone and the volume of the healed bone, between the adhesion surface of the bone to the alveolar bone and the density of the healed bone, and between the density of the graft and the volume of the healed bone. Increasing the surface of the graft adhesion to the bone ridges of the alveolar cleft contributes to increased volume of the healed bone and slows down the increase in its density (on 6-month follow-up). Crushing of the bone graft increases its resorption and reduces volume of the healed bone.

Impact of portable duplex ultrasonography in head and neck reconstruction.

We have reviewed the use of portable duplex ultrasonography (PDU) in 12 patients who underwent soft tissue/bone head and neck reconstruction, aiming to determine its role in the design and management of such complex cases. According to our data, there were modifications either of the surgical plan or of patient's management, based on PDU findings, in 9 (75%) of 12 patients. The use of ultrasound directed to subtle modifications in 3 patients (25%) but to significant changes of the surgical plan in the other 3 patients (25%). Also, the use of duplex ultrasound impacted significantly the postoperative management in 4 patients (33.33%). Thus, significant impact of PDU in patient's treatment was recorded in 58.33% of cases. Portable ultrasound represents generally available method for preoperative, intraoperative, and postoperative diagnosis and decision making in free tissue transfer, hence could replace in the future the unidirectional Doppler in the hands of head and neck surgeons.

Autogenous bone graft: basic science and clinical implications.

No single biomaterial is optimum for every craniomaxillofacial application. Instead, surgeons should consider the advantages and disadvantages of each alternative in a given clinical situation, and select the material with lowest overall cost and morbidity, and the highest likelihood of success. Autogenous bone is still considered the gold standard for most applications; it becomes vascularized and osseointegrates with surrounding bone, thus minimizing the risk of infection, dislodgement, or break-down. Limitations include added operative time for graft harvest, donor site morbidity, graft resorption, molding challenges, and limited availability, especially in the pediatric population. Numerous alternatives to bone graft have become available to address these limitations; unfortunately, most of these products are expensive, do not osseointegrate, and have unpredictable biologic activity. Understanding the physiologic behavior of autogenous bone graft can help clarify the indications for its use and provide a conceptual framework for achieving the best possible outcome when this alternative is chosen.

Platelet-rich plasma promotes angiogenesis of prefabricated vascularized bone graft.

PURPOSE: The objective was to assess the impact of platelet-rich plasma (PRP) on angiogenesis and bone formation of tissue-engineered bone in the prefabricated stage. MATERIALS AND METHODS: Both thighs of New Zealand white rabbits were used as prefabricated vascularized bone grafts using a combination of bone mesenchymal stem cells and vascular bundles in a titanium cage filled with ß-tricalcium phosphate ceramic. PRP was applied in the test group, and the same procedure was performed in the control group without the application of PRP. After 4, 8, and 12 weeks, delayed static bone scanning with technetium-99m methylene diphosphonate was performed before sacrifice, and the tissue-engineered bone samples were collected for immunohistochemical analysis using a monoclonal antibody against CD31 and histologic analysis. RESULTS: The results showed superior angiogenesis in the PRP group compared with the control group at each time point as determined by bone scintigraphy and immunohistochemical examinations. The results of histologic analysis also showed that there was more bone formation in the PRP group than in the control group at each time point. CONCLUSIONS: The application of autologous PRP was an effective strategy for increasing angiogenesis and bone formation in tissue-engineered bone and had potential significance for clinical applications.

Intraoperative cooling of iliac bone graft: an experimental evaluation of cell viability.

PURPOSE: A cancellous iliac bone graft is used to treat alveolar clefts. A few hours can exist between graft harvest and placement into the alveolar defect. The purpose of this study was to determine whether intraoperative cooling of bone optimizes viability and to evaluate cellular preservation of cooled graft over time. PATIENTS AND METHODS: Twelve cancellous iliac bone graft specimens were obtained prospectively from consecutive patients undergoing alveolar cleft repair. Each sample was collected during graft procurement and divided into 3 groups: group 1 (immediate analysis), group 2 (analysis after 2 hours at room temperature), and group 3 (analysis after 2 hours on ice). To generate a viability curve, iliac bone specimens were stored on ice and assayed immediately and hourly for 8 hours. Resazurin, an oxidation-reduction indicator of metabolically active cells, was used to assess cellular viability (normalized relative fluorescence units). RESULTS: Group 1 (n = 7,370) had more active cells than did group 2 (n = 4,104) or group 3 (n = 5,005; P = .03). Group 3 had greater viability than group 2 (P = .03). Cellular preservation of the cooled graft was 100% at the immediate analysis, 98.4% ± 13.9% at 1 hour, 91.8% ± 9.8% at 2 hours, 83.1% ± 31.8% at 3 hours, 71.8% ± 27.2% at 4 hours, 71.4% ± 16.9% at 5 hours, 69.9% ± 19.0% at 6 hours, 70.0% ± 22.5% at 7 hours, and 66.7% ± 13.3% at 8 hours. CONCLUSIONS: Storing iliac bone graft on ice rather than at room temperature optimizes cellular viability, with cooled bone demonstrating 22.0% more active cells after 2 hours. Cellular loss of cooled graft plateaued after 4 hours. Clinically, the iliac graft should be maintained on ice until placed into the alveolar cleft.