[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.

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.

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.

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.

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.

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.

Factors affecting survival and usefulness of implants placed in vascularized free composite grafts used in post-head and neck cancer reconstruction.

BACKGROUND: Bone-containing vascularized grafts have been used successfully to reconstruct post-cancer surgical defects. Dental implants can be placed in these bone-containing grafts to allow implant-supported prosthodontic reconstruction of these patients. PURPOSE: The aim of this study was to evaluate the survival of dental implants used in the rehabilitation of subjects treated with bone-containing vascularized grafts to compare usability of implants placed at the time of reconstruction and after healing. MATERIALS AND METHODS: A cross-sectional study was undertaken to examine survival rates of implants placed in vascularized bone-containing grafts either immediately at the time of surgical reconstruction or after 3 months healing. Other factors such as graft type, whether radiation therapy was given, and implant type were recorded. RESULTS: A total of 41 patients had 145 implants placed in 47 vascularized bone-containing flaps. Increased failure rate of implants was seen in immediately placed implants. There was also a significant increase in the number of osseointegrated implants that were prosthodontically unusable or sub-optimally placed in the immediate placement group. Radiation therapy was associated with a significant increase in failure rate. Modern implant surfaces appeared to perform better than machined/turned surfaces. Graft donor site did not influence implant survival. CONCLUSION: This study demonstrated the difficulties encountered with immediate placement of dental implants at the time of post-cancer reconstructive surgery.

Long-term results of endosteal implants following radical oral cancer surgery with and without adjuvant radiation therapy.

PURPOSE: The aim of this study was to analyze the long-term survival of implants and implant-retained prostheses in patients after ablative surgery of oral cancer with or without adjunctive radiation therapy. MATERIALS AND METHODS: Between 1997 and 2008, 66 patients who had undergone ablative tumor surgery in the oral cavity were treated with dental implants (n = 262). Thirty-four patients received radiation therapy in daily fractions of 2 Gy administered on 18 to 30 days. Implants were inserted in the maxilla (49; 18.7%) or mandible (213; 81.3%), in non-irradiated residual (65; 24.8%) or grafted bone (44; 16.8%) and in irradiated residual (15.6%) or grafted bone (39; 14.9%). Seventeen fixed protheses and 53 removable dentures (34 bar attachments, 9 telescopic and 10 ball retained dentures) were inserted. RESULTS: Mean follow-up after implant insertion was 47.99 (±34.31) months (range 12-140 months). The overall 1-, 5-, and 10-year survival rates of all implants were 96.6%, 96.6%, and 86.9%, respectively. Fourteen implants were lost in nine patients (5.3% of all implants); eight implants were primary losses, and five secondary losses because of an operation of tumor recurrence. There was no significantly lower implant survival for implants inserted into irradiated bone (p = .302), bone and/or soft-tissue grafts (p = .436), and maxilla or mandible (p = .563). All prosthetic restorations in patients without tumor recurrence could be maintained during the observation period. CONCLUSIONS: Implant survival is not significantly influenced by radiation therapy, grafts (bone and/or soft tissue), or location (maxilla or mandible). However, implants placed in irradiated bone exhibit a higher failure rate during the healing period than those placed in non-irradiated bone. No superstructure was particularly favorable. Osseointegrated implants can be used successfully in patients with prior history of ablative surgery with and without additional radiation therapy.

The eligibility of the free fibula graft for masticatory rehabilitation using monocortical implants insertion--a morphologic and biomechanical study.

The use of the vascularized fibula graft has already been established for reconstruction of the mandible following ablative surgery. In order to reconstruct the vertical height of the alveolar process and improve implant position as well as angulation, some therapeutic options are available, including primary use of the fibula as a double-barrel graft and vertical distraction as well as later augmentation with avascular bone grafts. We analyzed the anatomic and morphologic features in 40 fibula bones of 20 cadavers and provided the mean cortical thickness of different transplant sites. Furthermore, we investigated the primary implant stability of dental implants inserted monocortically in harvested fibula segments using established biomechanical methods as well as Periotest(®). The minimal bone height of the clinically relevant segments of the fibula transplant measured 9.06 ± 0.45 mm, which was assessed in the most distal part. In contrast, a maximal total bone height of 15.46 ± 0.78 was observed in the middle segment of the fibula bone. We assessed sufficient primary stability in all inserted implants as well as a reliable relative micro-movement of the implants in the fibula bone. Fibula graft as a single-barrel graft alone may provide through monocortical implant insertion a further refinement of the method to fit complex requirements and shorten prolonged therapeutic procedures. Monocortical implant insertion in the fibula graft would simplify oral rehabilitation after ablative surgery of the jaw and reduce costs as well as therapy period.