Max Heiland

Current trends and future perspectives of bone substitute materials - from space holders to innovative biomaterials.

An autologous bone graft is still the ideal material for the repair of craniofacial defects, but its availability is limited and harvesting can be associated with complications. Bone replacement materials as an alternative have a long history of success. With increasing technological advances the spectrum of grafting materials has broadened to allografts, xenografts, and synthetic materials, providing material specific advantages. A large number of bone-graft substitutes are available including allograft bone preparations such as demineralized bone matrix and calcium-based materials. More and more replacement materials consist of one or more components: an osteoconductive matrix, which supports the ingrowth of new bone; and osteoinductive proteins, which sustain mitogenesis of undifferentiated cells; and osteogenic cells (osteoblasts or osteoblast precursors), which are capable of forming bone in the proper environment. All substitutes can either replace autologous bone or expand an existing amount of autologous bone graft. Because an understanding of the properties of each material enables individual treatment concepts this review presents an overview of the principles of bone replacement, the types of graft materials available, and considers future perspectives. Bone substitutes are undergoing a change from a simple replacement material to an individually created composite biomaterial with osteoinductive properties to enable enhanced defect bridging.

Neuromodulation of chronic headaches: position statement from the European Headache Federation

The medical treatment of patients with chronic primary headache syndromes (chronic migraine, chronic tension-type headache, chronic cluster headache, hemicrania continua) is challenging as serious side effects frequently complicate the course of medical treatment and some patients may be even medically intractable. When a definitive lack of responsiveness to conservative treatments is ascertained and medication overuse headache is excluded, neuromodulation options can be considered in selected cases.Here, the various invasive and non-invasive approaches, such as hypothalamic deep brain stimulation, occipital nerve stimulation, stimulation of sphenopalatine ganglion, cervical spinal cord stimulation, vagus nerve stimulation, transcranial direct current stimulation, repetitive transcranial magnetic stimulation, and transcutaneous electrical nerve stimulation are extensively published although proper RCT-based evidence is limited. The European Headache Federation herewith provides a consensus statement on the clinical use of neuromodulation in headache, based on theoretical background, clinical data, and side effect of each method. This international consensus further gives recommendations for future studies on these new approaches.In spite of a growing field of stimulation devices in headaches treatment, further controlled studies to validate, strengthen and disseminate the use of neurostimulation are clearly warranted. Consequently, until these data are available any neurostimulation device should only be used in patients with medically intractable syndromes from tertiary headache centers either as part of a valid study or have shown to be effective in such controlled studies with an acceptable side effect profile.

Outcome and complications of 540 microvascular free flaps: the Hamburg experience.

The aim of this study was to retrospectively analyze surgical outcome and complications of 540 free flap procedures performed at the Department of Oral and Maxillofacial Surgery of the University Medical Center Hamburg-Eppendorf during 1987–2005. A total of 532 patients were reconstructed with 540 flaps: 32% were latissimus dorsi flaps, 23% were radial forearm flaps, 21% were iliac crest flaps, 10% were fibula flaps, 6% were jejunal flaps, and 8% were other flaps. Thrombosis of one of the vessels and hematoma were the most frequent causes of failure in microvascular free tissue transfer. A total free flap failure occurred in 34 (6.2%) and a partial flap failure in 42 (7.7%) patients. The most reliable flap in regard to survival was the radial forearm flap. The present study confirms that free flaps are extremely reliable in achieving successful reconstruction of the head and neck.

Impact of Dental Implant Surface Modifications on Osseointegration.

Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

Definition, etiology, prevention and treatment of peri-implantitis – a review

Peri-implant inflammations represent serious diseases after dental implant treatment, which affect both the surrounding hard and soft tissue. Due to prevalence rates up to 56%, peri-implantitis can lead to the loss of the implant without multilateral prevention and therapy concepts. Specific continuous check-ups with evaluation and elimination of risk factors (e.g. smoking, systemic diseases and periodontitis) are effective precautions. In addition to aspects of osseointegration, type and structure of the implant surface are of importance. For the treatment of peri-implant disease various conservative and surgical approaches are available. Mucositis and moderate forms of peri-implantitis can obviously be treated effectively using conservative methods. These include the utilization of different manual ablations, laser-supported systems as well as photodynamic therapy, which may be extended by local or systemic antibiotics. It is possible to regain osseointegration. In cases with advanced peri-implantitis surgical therapies are more effective than conservative approaches. Depending on the configuration of the defects, resective surgery can be carried out for elimination of peri-implant lesions, whereas regenerative therapies may be applicable for defect filling. The cumulative interceptive supportive therapy (CIST) protocol serves as guidance for the treatment of the peri-implantitis. The aim of this review is to provide an overview about current data and to give advices regarding diagnosis, prevention and treatment of peri-implant disease for practitioners.

Prognostic Relevance of Circulating Tumor Cells in Blood and Disseminated Tumor Cells in Bone Marrow of Patients with Squamous Cell Carcinoma of the Oral Cavity

Purpose: Current staging methods for squamous cell carcinomas (SCC) of the oral cavity (OSCC) need to be improved to predict the risk of individual patients. Because hematogenous tumor cell dissemination is a key event in tumor progression, we assessed the prognostic significance of disseminated tumor cells (DTC) in bone marrow and circulating tumor cells (CTC) in peripheral blood from patients with OSCC. Experimental Design: From 110 patients with OSCC, tumors were surgically resected (R0) without neoadjuvant therapy. The CellSearch system was used to enumerate CTCs. Bone marrow was aspirated from the iliac crest, and mononuclear cells (MNC) were enriched by Ficoll density gradient centrifugation. To detect DTCs, MNCs were immunostained with the pan-keratin antibody A45-B/B3. Results were correlated with clinicopathologic parameters and clinical outcome such as recurrence and death during follow-up time (mean 916 days). Results: Ten of 80 patients (12.5%) harbored CTCs in peripheral blood, whereas in 18 of 90 patients (20.0%) DTCs in bone marrow could be detected. Surprisingly, in only 2 patients (1.8%) CTCs and DTCs were detected simultaneously. Significant correlations could be found for CTCs and tumor size (P = 0.04), nodal status and DTCs (P = 0.02), and distant metastasis with CTCs (P = 0.004) and DTCs (P = 0.005). Univariate and multivariate analyses revealed that CTCs and DTCs were significant and independent predictors of recurrence-free survival (P < 0.001). Conclusions: Both DTCs and CTCs are independent prognostic markers in patients with OSCC, predicting relapse with higher sensitivity at various disease stages than routine staging procedures. Bone marrow might be an interesting target organ for future therapeutic interventions. Clin Cancer Res; 20(2); 425–33. ©2013 AACR.

Intraoperative Cone-Beam Computed Tomography in Oral and Maxillofacial Surgery Using a C-Arm Prototype : First Clinical Experiences After Treatment of Zygomaticomaxillary Complex Fractures

PURPOSE To describe the first clinical applications of intraoperative cone-beam computed tomography with an integrated flat-panel detector in oral and maxillofacial surgery after surgical treatment of zygomaticomaxillary complex fractures PATIENTS AND METHODS Nine cone-beam computed tomography datasets of patients with zygomaticomaxillary complex fractures were intraoperatively acquired using a mobile isocentric C-arm (PowerMobil; Siemens Medical Solutions, Erlangen, Germany), including a flat-panel detector. Datasets based on 400, 200, and 100 fluoroscopic images were performed with different tube currents (4.6 mA, 3.3 mA, 2.3 mA, 1.2 mA, and 0.5 mA) and a current tube voltage of 100 kV. Postprocessing resulted in 15 different datasets available for comparison with corresponding preoperative computed tomography datasets. Four oral and maxillofacial surgeons and 2 experienced radiologists evaluated each dataset regarding noise, transition, and the delimitation of landmarks. RESULTS All examinations were successfully performed. Reconstructed datasets showed high-resolution images of all midfacial osseous structures in near-computed tomography quality. Regarding high-contrast structures, detailed analyses of datasets acquired in this study suggest that the parameters 400 projections, 1.2 mA, and 100 kV are sufficient. In terms of soft-tissue visualization, a higher level of mA seems preferable. CONCLUSIONS The tested prototype predicts a new era in cone-beam computed tomography imaging. The integration of a flat-panel detector will overcome the limitations of current available systems. The size of the field of view is increased allowing regularly the visualization of the whole facial skeleton. Particularly in cases of open reduction of unilateral fractures, the assessment of symmetry is of clinical value.

Virtual dental surgery as a new educational tool in dental school

PURPOSE The virtual environment of the Voxel-Man simulator that was originally designed for virtual surgical procedures of the middle ear has been adapted to intraoral procedures. To assess application of the simulator to dentistry, virtual apicectomies were chosen as the pilot-test model. METHODS A group of 53 dental students provided their impressions after virtual simulation of apicectomies in the Voxel-Man simulator. RESULTS Fifty-one of the 53 students recommended the virtual simulation as an additional modality in dental education. The students indicated that the force feedback (e.g. simulation of haptic pressure), spatial 3D perception, and image resolution of the simulator were sufficient for virtual training of dental surgical procedures. CONCLUSION The feedback from dental students involved in this pilot-test has encouraged our interdisciplinary group to continue further development of the simulator with the goal of creating new training strategies in dental and medical education.

68Ga DOTA-TATE PET/CT allows tumor localization in patients with tumor-induced osteomalacia but negative 111In-octreotide SPECT/CT

Tumor-induced osteomalacia (TIO) is a paraneoplastic syndrome characterized by renal phosphate wasting, hypophosphatemia and low calcitriol levels as well as clinical symptoms like diffuse bone and muscle pain, fatigue fractures or increased fracture risk. Conventional imaging methods, however, often fail to detect the small tumors. Lately, tumor localization clearly improved by somatostatin-receptor (SSTR) imaging, such as octreotide scintigraphy or octreotide SPECT/CT. However, recent studies revealed that still a large number of tumors remained undetected by octreotide imaging. Hence, studies focused on different SSTR imaging methods such as 68Ga DOTA-NOC, 68Ga DOTA-TOC and 68Ga DOTA-TATE PET/CT with promising first results. Studies comparing different SSTR imaging methods for tumor localization in TIO are rare and thus little is known about diagnostic alternatives once a particular method failed to detect a tumor in patients with TIO. Here, we report the data of 5 consecutive patients suffering from TIO, who underwent both 111Indium-octreotide scintigraphy (111In-OCT) SPECT/CT as well as 68Ga DOTA-TATE PET/CT for tumor detection. While 111In-OCT SPECT/CT allowed tumor detection in only 1 of 5 patients, 68Ga DOTA-TATE PET/CT was able to localize the tumor in all patients. Afterwards, anatomical imaging of the region of interest was performed with CT and MRI. Thus, successful surgical resection of the tumor was achieved in all patients. Serum phosphate levels returned to normal and all patients reported relief of symptoms within weeks. Moreover, an iliac crest biopsy was obtained from every patient and revealed marked osteomalacia in all cases. Follow-up DXA revealed an increase in BMD of up to 34.5% 1-year postoperative, indicating remineralization. No recurrence was observed. In conclusion our data indicates that 68Ga DOTA-TATE PET/CT is an effective and promising diagnostic tool in the diagnosis of TIO, even in patients in whom 111In-OCT prior failed to detect a tumor.

Current concepts in pathogenesis of acute and chronic osteomyelitis.

Purpose of review The term osteomyelitis covers a wide range of inflammatory bone disorders caused by microbial invasion or due to autoinflammatory processes, but furthermore osteomyelitis also occurs at different ages and at preferred localizations in the human skeleton. This article aims to give an overview of the current literature focussing on pathognomonic aspects of osteomyelitis because of microbial invasion. Recent findings Outlining the chronological sequence of osteomyelitis originating from the invasion of microbes finally leading to destruction of bone tissue, the formation and proliferation of biofilm structures play a key role in the development of inflammatory bone disorders. The components of the biofilm on the one hand mediate an immune response leading to an increase of local cytokines and induction of osteoclastogenesis but on the other hand also directly interact with the osteoblasts. As a result, the bone-remodelling process is immensely diminished by induction of proapoptotic pathways, decreased proliferation and differentiation of osteoblasts and an additional promotion of osteoclastogenesis. Summary Although microbial invasion is responsible to be the cause for inflammatory bone disorders, except for an autoinflammatory origin, the underlying and detailed mechanisms in the pathogenesis of osteomyelitis are not yet fully understood, but represent an absolute precondition for the development of effective causal treatment strategies in the future.