Constantin von See

Publications of Constantin von See

• Surgical treatment of zygomatic bone fracture using two points fixation versus three point fixation-a randomised prospective clinical trial.

  Authors: Majeed Rana, Riaz Warraich, Salman Tahir, Asifa Iqbal, Constantin von See, Andre M Eckardt, Nils-Claudius Gellrich

  Trials. 04/2012; 13(1):36.

  ABSTRACT: BACKGROUND: The zygoma plays an important role in the facial contour for both cosmetic and functional reasons; therefore zygomatic bone injuries should be properly diagnosed and adequatelyABSTRACT: BACKGROUND: The zygoma plays an important role in the facial contour for both cosmetic and functional reasons; therefore zygomatic bone injuries should be properly diagnosed and adequately treated. Comparison of various surgical approaches and their complications can only be done objectively using outcome measurements which in turn require protocol management and long-term follow up. The preference for open reduction and internal fixation of zygomatic fractures at three points has continued to grow in response to observations of inadequate results from two point and one point fixation techniques. The objectives of this study were to compare the efficacy of zygomatic bone after treatment with ORIF using 2 point fixation and ORIF using 3 point fixation and compare the outcome of two procedures. METHODS: 100 patients were randomly divided equally into two groups. In group A, 50 patients were treated by ORIF using two point fixation by miniplates and in group B, 50 patients were treated by ORIF using three point fixation by miniplates. They were evaluated for their complications during and after surgery with their advantages and disadvantages and the difference between the two groups was observed. RESULTS: A total of 100 fractures were sustained. We found that postoperative complication like decreased malar height and vertical dystopia was more common in those patients who were treated by two point fixation than those who were treated with three point fixation. CONCLUSIONS: Based on this study open reduction and internal fixation using three point fixation by miniplates is the best available method for the treatment zygomatic bone fractures.

• Designing the ideal model for assessment of wound contamination after gunshot injuries: a comparative experimental study.

  Authors: Constantin Von See, Majeed Rana, Marcus Stoetzer, Horst Kokemueller, Martin Ruecker, Nils-Claudius Gellrich

  BMC surgery. 04/2012; 12(1):6.

  ABSTRACT: BACKGROUND: Modern high-velocity projectiles produce temporary cavities and can thus cause extensive tissue destruction along the bullet path. It is still unclear whether gelatin blocks,ABSTRACT: BACKGROUND: Modern high-velocity projectiles produce temporary cavities and can thus cause extensive tissue destruction along the bullet path. It is still unclear whether gelatin blocks, which are used as a well-accepted tissue simulant, allow the effects of projectiles to be adequately investigated and how these effects are influenced by caliber size. METHOD: Barium titanate particles were distributed throughout a test chamber for an assessment of wound contamination. We fired .22-caliber Magnum bullets first into gelatin blocks and then into porcine hind limbs placed behind the chamber. Two other types of bullets (.222-caliber bullets and 6.5x57mm cartridges) were then shot into porcine hind limbs. Permanent and temporary wound cavities as well as the spatial distribution of barium titanate particles in relation to the bullet path were evaluated radiologically. RESULTS: A comparison of the gelatin blocks and hind limbs showed significant differences (p < 0.05) in the mean results for all parameters. There were significant differences between the bullets of different calibers in the depth to which barium titanate particles penetrated the porcine hind limbs. Almost no particles, however, were found at a penetration depth of 10 cm or more. By contrast, gas cavities were detected along the entire bullet path. CONCLUSION: Gelatin is only of limited value for evaluating the path of high-velocity projectiles and the contamination of wounds by exogenous particles. There is a direct relationship between the presence of gas cavities in the tissue along the bullet path and caliber size. These cavities, however, are only mildly contaminated by exogenous particles.

• Increase in periosteal angiogenesis through heat shock conditioning.

  Authors: Majeed Rana, Constantin von See, Martin Rücker, Paul Schumann, Harald Essig, Horst Kokemüller, Daniel Lindhorst, Nils-Claudius Gellrich

  Head & face medicine. 11/2011; 7:22.

  It is widely known that stress conditioning can protect microcirculation and induce the release of vasoactive factors for a period of several hours. Little, however, is known about the long-termIt is widely known that stress conditioning can protect microcirculation and induce the release of vasoactive factors for a period of several hours. Little, however, is known about the long-term effects of stress conditioning on microcirculation, especially on the microcirculation of the periosteum of the calvaria. For this reason, we used intravital fluorescence microscopy to investigate the effects of heat shock priming on the microcirculation of the periosteum over a period of several days. Fifty-two Lewis rats were randomized into eight groups. Six groups underwent heat shock priming of the periosteum of the calvaria at 42.5°C, two of them (n = 8) for 15 minutes, two (n = 8) for 25 minutes and two (n = 8) for 35 minutes. After 24 hours, a periosteal chamber was implanted into the heads of the animals of one of each of the two groups mentioned above. Microcirculation and inflammatory responses were studied repeatedly over a period of 14 days using intravital fluorescence microscopy. The expression of heat shock protein (HSP) 70 was examined by immunohistochemistry in three further groups 24 hours after a 15-minute (n = 5), a 25-minute (n = 5) or a 35-minute (n = 5) heat shock treatment. Two groups that did not undergo priming were used as controls. One control group (n = 8) was investigated by intravital microscopy and the other (n = 5) by immunohistochemistry. During the entire observation period of 14 days, the periosteal chambers revealed physiological microcirculation of the periosteum of the calvaria without perfusion failures. A significant (p < 0.05) and continuous increase in functional capillary density was noted from day 5 to day 14 after 25-minute heat shock priming. Whereas a 15-minute exposure did not lead to an increase in functional capillary density, 35-minute priming caused a significant but reversible perfusion failure in capillaries. Non-perfused capillaries in the 35-minute treatment group were reperfused by day 10. Immunohistochemistry demonstrated an increase in cytoprotective HSP70 expression in the periosteum after a 15-minute and a 35-minute heat shock pretreatment when compared with the control group. The level of HSP70 expression that was measured in the periosteum after 25 minutes of treatment was significantly higher than the levels observed after 15 or 35 minutes of heat shock exposure. A few days after heat shock priming over an appropriate period of time, a continuous increase in functional capillary density is seen in the periosteum of the calvaria. This increase in perfusion appears to be the result of the induction of angiogenesis.

• Virtual 3D tumor marking-exact intraoperative coordinate mapping improve post-operative radiotherapy.

  Authors: Harald Essig, Majeed Rana, Andreas Meyer, André M Eckardt, Horst Kokemueller, Constantin von See, Daniel Lindhorst, Frank Tavassol, Martin Ruecker, Nils-Claudius Gellrich

  Radiation oncology (London, England). 11/2011; 6:159.

  The quality of the interdisciplinary interface in oncological treatment between surgery, pathology and radiotherapy is mainly dependent on reliable anatomical three-dimensional (3D) allocation ofThe quality of the interdisciplinary interface in oncological treatment between surgery, pathology and radiotherapy is mainly dependent on reliable anatomical three-dimensional (3D) allocation of specimen and their context sensitive interpretation which defines further treatment protocols. Computer-assisted preoperative planning (CAPP) allows for outlining macroscopical tumor size and margins. A new technique facilitates the 3D virtual marking and mapping of frozen sections and resection margins or important surgical intraoperative information. These data could be stored in DICOM format (Digital Imaging and Communication in Medicine) in terms of augmented reality and transferred to communicate patient's specific tumor information (invasion to vessels and nerves, non-resectable tumor) to oncologists, radiotherapists and pathologists.

• Reconstruction of defects of maxillary sinus wall after removal of a huge odontogenic lesion using prebended 3D titanium-mesh and CAD/CAM technique.

  Authors: Marcus Stoetzer, Majeed Rana, Constantin von See, André M Eckardt, Nils-Claudius Gellrich

  Head & face medicine. 11/2011; 7:21.

  A 63 year-old male with a huge odontogenic lesion of sinus maxillaris was treated with computer-assisted surgery. After resection of the odontogenic lesion, the sinus wall was reconstructed with aA 63 year-old male with a huge odontogenic lesion of sinus maxillaris was treated with computer-assisted surgery. After resection of the odontogenic lesion, the sinus wall was reconstructed with a prebended 3D titanium-mesh using CAD/CAM technique. This work provides a new treatment device for maxillary reconstruction via rapid prototyping procedures.

• Calvaria bone chamber--a new model for intravital assessment of osseous angiogenesis.

  Authors: Branko Sinikovic, Paul Schumann, Meike Winkler, Julian Kuestermeyer, Frank Tavassol, Constantin von See, Carlos Carvalho, Rolf Mülhaupt, Kai-Hendrik Bormann, Horst Kokemueller, Andrea Meyer-Lindenberg, Matthias W Laschke, Michael D Menger, Nils-Claudius Gellrich, Martin Rücker

  Journal of biomedical materials research. Part A. 11/2011; 99(2):151-7.

  The faith of tissue engineered bone replacing constructs depends on their early supply with oxygen and nutrients, and thus on a rapid vascularization. Although some models for direct observation ofThe faith of tissue engineered bone replacing constructs depends on their early supply with oxygen and nutrients, and thus on a rapid vascularization. Although some models for direct observation of angiogenesis are described, none of them allows the observation of new vessel formation in desmal bone. Therefore, we developed a new chamber model suitable for quantitative in vivo assessment of the vascularization of bone substitutes by intravital fluorescence microscopy. In the parietal calvaria of 32 balb/c mice a critical size defect was set. Porous 3D-poly(L-lactide-co-glycolide) (PLGA)-blocks were inserted into 16 osseous defects (groups 3 and 4) while other 16 osseous defects remained unequipped (groups 1 and 2). By placing a polyethylene membrane onto the dura mater, the angiogenesis was mainly restricted to the osseous margins (groups 2 and 4). Microvascular density, angiogenesis, and microcirculatory parameters were evaluated repetitively during 22 days. In all animals, only a mild inflammatory reaction was observed with a climax after 2 weeks. The implantation of PLGA scaffolds resulted in a vascular growth directed towards the center of the defect as demonstrated by the significantly (p < 0.05) enhanced central microvascular densitiy from day 3 to day 22 when compared with unequipped chambers. The additional application of polyethylene membrane was found to reduce significantly the microvessel density mainly in the center of both scaffolds and defects. The present calvaria bone chamber allows for the first time to assess quantitatively the angiogenesis arising from desmal bone directly in vivo. Therefore, this chronic model may support the future research in the biological adequacy of bone substitutes.

• Bisphosphonate-associated osteonecrosis of the mandible: reliable soft tissue reconstruction using a local myofascial flap.

  Authors: Juliana Lemound, Andrè Eckardt, Horst Kokemüller, Constantin von See, Pit Jacob Voss, Frank Tavassol, Martin Rücker, Majeed Rana, Nils-Claudius Gellrich

  Clinical oral investigations. 08/2011;

  For the treatment of bisphosphonate-associated osteonecrosis of the jaw (BP-associated ONJ), poor cure rates are reported. In many cases, repeated osseous exposition and infection may occur. TheFor the treatment of bisphosphonate-associated osteonecrosis of the jaw (BP-associated ONJ), poor cure rates are reported. In many cases, repeated osseous exposition and infection may occur. The currently recommended management of affected patients is antibiotic treatment and bony decortication, which is often complicated by soft tissue deficits due to chronic infection. In severe cases osteonecrosis can be managed often only by continuity resections of the mandible. For this purpose, we developed a new surgical procedure, which allows an effective closure of difficult jaw wounds in the lateral mandible. In the last 3 years, 20 patients with BP-associated osteonecrosis of the lower jaw were treated successfully with a modified defect-covering method using a myofascial flap. A mylohyoid muscle flap was detached from mylohyoid line and used to cover the bony defect. During 19 months mean follow-up, 90% of patients were asymptomatic, the oral mucosa was intact, and no exposed bone was observed. In consequence, we are able to demonstrate that a mylohyoid muscle flap provides a reliable wound closure in the lower jaw in patients treated with BPs. Although there are still no consensual therapy guidelines for patients affected by BP-associated ONJ, the results of the presented study provide evidence for an effective surgical therapy with long-term success. Covering compromised bone with well-vascularized tissue, a muscle flap, increased healing chances by enabling and supporting the necessary nutrition and defense against opportunistic infections. This therapy concept showed a good clinical outcome.

• Endoscope-assisted transoral reduction and internal fixation versus closed treatment of mandibular condylar process fractures--a prospective double-center study.

  Authors: Horst Kokemueller, Vitomir S Konstantinovic, Enno-Ludwig Barth, Sabine Goldhahn, Constantin von See, Frank Tavassol, Harald Essig, Nils-Claudius Gellrich

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 06/2011; 70(2):384-95.

  The aim of this international AO-study was to compare the functional outcome after open versus closed treatment of mandibular condylar neck fractures. A prospective comparative study with twoThe aim of this international AO-study was to compare the functional outcome after open versus closed treatment of mandibular condylar neck fractures. A prospective comparative study with two follow-ups (FU) at 8-12 weeks and 1 year was undertaken in two clinics, which exclusively privileged either surgical or conservative treatment due to different therapeutic agendas. Patients from clinic 1 (ENDO group) received endoscope-assisted transoral open reduction and internal fixation, whereas patients from clinic 2 (CONS group) were treated conservatively without surgery. Patients with unilateral condylar neck fractures showing one or more of the following conditions were included: displacement of the condyle with an inclination >30° and/or severe functional impairment such as malocclusion or open bite, with or without dislocation of the condylar fragment; severe pain upon palpation or movement, and/or vertical shortening of the ascending ramus. High or intracapsular condylar neck fractures were excluded. 75 patients (44 CONS and 31 ENDO patients) with condylar neck fractures were included in this study. The Asymmetric Helkimo Dysfunction Score (A-HDS) was slightly lower in the CONS group than in the ENDO group at the 8-12-week FU, corresponding to better function on the short-term. At the 1-year FU, however, there were slightly better values in the ENDO group. For the Clinical Dysfunction Index (Di) and the Anamnestic Dysfunction Index (Ai), CONS patients had a better outcome than ENDO patients at the 8-12 week FU, ie, a higher proportion of ENDO patients had severe symptoms due to the operative trauma. Yet these symptoms improved by one year, finishing with a significant higher proportion of symptom-free patients in the ENDO group. In addition, these patients had better values for the Index for Occlusion and Articulation Disturbance (Oi) at both FU examinations, ie, the proportion of patients without any occlusal disturbances was significantly higher in the ENDO group. On average, the duration of postoperative maxillo-mandibular fixation (MMF) was 3 times longer for the CONS group than for the ENDO group (33 vs. 11 days). Both treatment options may yield acceptable results for displaced condylar neck fractures. Especially in patients with severe malocclusion directly after trauma, however, endoscope-assisted transoral open reduction and fixation seems to be the appropriate treatment for prevention of occlusal disturbances during FU.

• Comparably accelerated vascularization by preincorporation of aortic fragments and mesenchymal stem cells in implanted tissue engineering constructs.

  Authors: Paul Schumann, Constantin von See, Andreas Kampmann, Daniel Lindhorst, Frank Tavassol, Horst Kokemüller, Kai-Hendrik Bormann, Nils-Claudius Gellrich, Martin Rücker

  Journal of biomedical materials research. Part A. 04/2011; 97(4):383-94.

  The demanding need for tissue replacement resulted in manifold approaches for the construction of different tissues. One common problem which hampers the clinical usage of tissue engineeringThe demanding need for tissue replacement resulted in manifold approaches for the construction of different tissues. One common problem which hampers the clinical usage of tissue engineering constructs is a limited vascularization. In an attempt to accelerate the vascularization of tissue engineering constructs we compared the usage of bone marrow mesenchymal stem cells (bmMSCs) and fragments derived from the aorta in vivo. Tissue engineering constructs composed of PLGA scaffolds containing Matrigel (n = 8), aortic fragments embedded in Matrigel (n = 8), bmMSCs embedded in Matrigel (n = 8), and aortic fragments embedded in Matrigel combined with bmMSCs (n = 8) were implanted into dorsal skinfold chambers of balb/c mice and analyzed repetitively over 14 days. In all groups a weak inflammatory response was transiently apparent. Vascularization was significantly (p = 0.05) accelerated in bmMSC and aortic fragments containing constructs compared with Matrigel alone, demonstrated by a distinctly increased microvascular density throughout the whole experiment. The combination of bmMSCs and aortic fragments showed no additional effect compared with bmMSCs and aortic fragments alone. The accelerated vascularization and microvascular density of tissue engineering constructs triggered by bmMSCs and aortic fragments is comparable. Thus aortic fragments provide a new promising source for clinical relevant tissue engineering constructs.

• Forty sandwich osteotomies in atrophic mandibles: a retrospective study.

  Authors: Kai-Hendrik Bormann, Maria M Suarez-Cunqueiro, Constantin von See, Frank Tavassol, Jan-Philipp Dissmann, Martin Ruecker, Horst Kokemueller, Nils-Claudius Gellrich

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 02/2011; 69(6):1562-70.

  The aim of the present retrospective study was to assess the suitability of segmental mandibular sandwich osteotomy combined with an interpositional autograft to meet the dimensional requirements ofThe aim of the present retrospective study was to assess the suitability of segmental mandibular sandwich osteotomy combined with an interpositional autograft to meet the dimensional requirements of preimplant bone augmentation in cases of a severely atrophic mandible. A total of 27 consecutive patients (6 men and 21 women) were included in the present study. The amount of bone gain was calculated using digital volume tomography before surgery and 3 months after bone augmentation. The postoperative course was uneventful for 18 patients. Temporary sensory disturbances were observed in 6 patients, with complete recovery after 3 to 12 weeks. Dehiscence of soft tissue closure occurred in 3 patients. The mean vertical gain was 3.41 mm (range 0.3 to 12). The mean horizontal gain was 3.08 mm (range 0.2 to 8.5). A total of 88 implants were placed in 40 surgical sites at 12 weeks after bone reconstruction. Segmental mandibular sandwich osteotomy is a suitable augmentation procedure in the mandible for the atrophic alveolar ridge and provides adequate height and transversal bone augmentation.

• A new model for the characterization of infection risk in gunshot injuries: technology, principal consideration and clinical implementation.

  Authors: Constantin von See, Majeed Rana, Marcus Stoetzer, Conrad Wilker, Martin Rücker, Nils-Claudius Gellrich

  Head & face medicine. 01/2011; 7:18.

  The extent of wound contamination in gunshot injuries is still a topic of controversial debate. The purpose of the present study is to develop a model that illustrates the contamination of woundsThe extent of wound contamination in gunshot injuries is still a topic of controversial debate. The purpose of the present study is to develop a model that illustrates the contamination of wounds with exogenous particles along the bullet path. To simulate bacteria, radio-opaque barium titanate (3-6 μm in diameter) was atomized in a dust chamber. Full metal jacket or soft point bullets caliber .222 (n = 12, v0 = 1096 m/s) were fired through the chamber into a gelatin block directly behind it. After that, the gelatin block underwent multi-slice CT in order to analyze the permanent and temporary wound cavity. The permanent cavity caused by both types of projectiles showed deposits of barium titanate distributed over the entire bullet path. Full metal jacket bullets left only few traces of barium titanate in the temporary cavity. In contrast, the soft point bullets disintegrated completely, and barium titanate covered the entire wound cavity. Deep penetration of potential exogenous bacteria can be simulated easily and reproducibly with barium titanate particles shot into a gelatin block. Additionally, this procedure permits conclusions to be drawn about the distribution of possible contaminants and thus can yield essential findings in terms of necessary therapeutic procedures.

• Pre-operative planning for mandibular reconstruction - a full digital planning workflow resulting in a patient specific reconstruction.

  Authors: Harald Essig, Majeed Rana, Horst Kokemueller, Constantin von See, Martin Ruecker, Frank Tavassol, Nils-Claudius Gellrich

  Head & neck oncology. 01/2011; 3:45.

  Reconstruction of large mandiblular defects following ablative oncologic surgery could be done by using vascularized bone transfer or, more often, primarily with simultaneous or delayed boneReconstruction of large mandiblular defects following ablative oncologic surgery could be done by using vascularized bone transfer or, more often, primarily with simultaneous or delayed bone grafting, using load bearing reconstruction plates. Bending of these reconstruction plates is typically directed along the outer contour of the original mandible. Simultaneously or in a second operation vascularized or non-vascularized bone is fixed to the reconstruction plate. However, the prosthodontic-driven backward planning to ease bony reconstruction of the mandible in terms of dental rehabilitation using implant-retained overdentures might be an eligible solution. The purpose of this work was to develop, establish and clinically evaluate a novel 3D planning procedure for mandibular reconstruction. Three patients with tumors involving the mandible, which included squamous cell carcinoma in the floor of the mouth and keratocystic odontogenic tumor, were treated surgically by hemimandibulectomy. In primary alloplastic mandible reconstruction, shape and size of the reconstruction plate could be predefined and prebent prior to surgery. This study provides modern treatment strategies for mandibular reconstruction.

• Effects of VEGF loading on scaffold-confined vascularization.

  Authors: Daniel Lindhorst, Frank Tavassol, Constantin von See, Paul Schumann, Matthias W Laschke, Yves Harder, Kai-Hendrik Bormann, Harald Essig, Horst Kokemüller, Andreas Kampmann, André Voss, Rolf Mülhaupt, Michael D Menger, Nils-Claudius Gellrich, Martin Rücker

  Journal of biomedical materials research. Part A. 12/2010; 95(3):783-92.

  Adequate vascularization of tissue-engineered constructs remains a major challenge in bone grafting. In view of this, we loaded ß-tricalcium-phosphate (ß-TCP) and porous poly(L-lactide-co-glycolide)Adequate vascularization of tissue-engineered constructs remains a major challenge in bone grafting. In view of this, we loaded ß-tricalcium-phosphate (ß-TCP) and porous poly(L-lactide-co-glycolide) (PLGA) scaffolds via collagen coating with vascular endothelial growth factor (VEGF) and studied whether the VEGF loading improves scaffold angiogenesis and vascularization. Dorsal skinfold chambers were implanted into 48 balb/c mice, which were assigned to 6 groups (n = 8 each). Uncoated (controls), collagen-coated, and additionally VEGF-loaded PLGA and ß-TCP scaffolds were inserted into the chambers. Angiogenesis, neovascularization, and leukocyte-endothelial cell interaction were analyzed repeatedly during a 14-day observation period using intravital fluorescence microscopy. Furthermore, VEGF release from PLGA und ß-TCP scaffolds was studied by ELISA. Micromorphology was studied from histological specimens. Unloaded ß-TCP scaffolds showed an accelerated and increased angiogenic response when compared with unloaded PLGA scaffolds. In vitro, PLGA released significantly higher amounts of VEGF compared with ß-TCP at the first two days resulting in a rapid drop of the released amount at the following days up to day 7 where the VEGF release was negligible. Nonetheless, in vivo VEGF loading increased neovascularization, especially in ß-TCP scaffolds. This increased vascularization was associated with a temporary leukocytic response with pronounced leukocyte-endothelial cell interaction at days 3 and 6. Histology revealed adequate host tissue response and engraftment of both ß-TCP and PLGA scaffolds. Our study demonstrates that ß-TCP scaffolds offer more suitable conditions for vascularization than PLGA scaffolds, in particular if they are loaded with VEGF.

• Micro-computed tomography and histologic evaluation of the interface of hydrogel expander and underlying bone: influence of pressure distributors on bone resorption.

  Authors: Constantin von See, Martin Rücker, Paul Schumann, Franziska Goetz, Patrick Wefstaedt, Ingo Nolte, Nina von der Hoeh, Andrea Meyer-Lindenberg, Frank Tavassol, Nils-Claudius Gellrich

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 09/2010; 68(9):2179-84.

  Tissue expanders lead to changes in the underlying bone and can cause bone resorption. We investigated whether the insertion of mechanical devices that distribute the load on the bone can influenceTissue expanders lead to changes in the underlying bone and can cause bone resorption. We investigated whether the insertion of mechanical devices that distribute the load on the bone can influence these effects. A total of 28 Lewis rats were assigned to 1 of 4 groups. Hydrogel expanders were placed subcutaneously either directly on the calvaria, on titanium mesh, or on a titanium plate. The fourth group of rats served as the controls. The bone quality and thickness were assessed beneath, and at the periphery of, the expanders using micro-computed tomography and histologic examination. Micro-computed tomography images were obtained before and 21 days after insertion. The images revealed a significant decrease in hydroxyapatite density beneath the expanders in the group with only expanders. This decrease was reduced with the use of titanium mesh and completely prevented with the use of titanium plates. Histologic examination revealed a significant decrease in bone density and marked lacunae beneath the hydrogel expanders in the group with only expanders. In contrast, the titanium mesh decreased the size of the lacunae, and the titanium plates completely prevented both the formation of lacunae and the decrease in bone thickness. The bone resorption caused by hydrogel expanders can be diminished using titanium mesh and completely prevented by the insertion of a titanium plate.

• Bone augmentation after soft-tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration.

  Authors: Constantin von See, Nils-Claudius Gellrich, Ulrike Jachmann, Matthias W Laschke, Kai-Hendrik Bormann, Martin Rücker

  Clinical oral implants research. 03/2010; 21(8):842-7.

  The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft-tissue coverage can be achieved withoutThe success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft-tissue coverage can be achieved without tension through pre-augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model. Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically. During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion. Pre-augmentation soft-tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre-implant bone augmentation.

• Accelerated angiogenic host tissue response to poly(L-lactide-co-glycolide) scaffolds by vitalization with osteoblast-like cells.

  Authors: Frank Tavassol, Paul Schumann, Daniel Lindhorst, Branko Sinikovic, André Voss, Constantin von See, Andreas Kampmann, Kai-Hendrik Bormann, Carlos Carvalho, Rolf Mülhaupt, Yves Harder, Matthias W Laschke, Michael D Menger, Nils-Claudius Gellrich, Martin Rücker

  Tissue engineering. Part A. 02/2010; 16(7):2265-79.

  Bone substitutes should ideally promote rapid vascularization, which could be accelerated if these substitutes were vitalized by autologous cells. Although adequate engraftment of porousBone substitutes should ideally promote rapid vascularization, which could be accelerated if these substitutes were vitalized by autologous cells. Although adequate engraftment of porous poly(L-lactide-co-glycolide) (PLGA) scaffolds has been demonstrated in the past, it has not yet been investigated how vascularization is influenced by vitalization or, more precisely, by seeding PLGA scaffolds with osteoblast-like cells (OLCs). For this reason, we conducted an in vivo study to assess host angiogenic and inflammatory responses after the implantation of PLGA scaffolds vitalized with isogeneic OLCs. OLCs were seeded on collagen-coated PLGA scaffolds that were implanted into dorsal skinfold chambers in BALB/c mice (n = 8). Two further groups of animals received either collagen-coated (n = 8) or uncoated PLGA scaffolds (n = 8). Animals that received chambers without implants served as controls (n = 8). Angiogenesis, neovascularization, and leukocyte-endothelial cell interaction were analyzed for 14 days using intravital fluorescence microscopy. PLGA scaffolds with and without OLCs showed a temporary increase in leukocyte recruitment. At day 3 after implantation, a marked angiogenic host tissue response was observed in close vicinity of all scaffolds studied. At days 6 and 10, the angiogenic response was significantly higher (p < 0.05) in PLGA scaffolds vitalized with OLCs than in uncoated or collagen-coated PLGA scaffolds. The majority of OLCs, however, died within 14 days after implantation. Our study demonstrates that PLGA scaffold vitalization with OLCs accelerates the angiogenic response in the surrounding host tissue. Bone substitutes created by tissue engineering may thus be superior to nonvitalized substitutes although the seeded cells do not survive for long periods.

• Serratus Anterior Free Flap in Oral Reconstruction.

  Authors: Frank Tavassol, Martin Rücker, Enno-Ludwig Barth, Horst Kokemüller, Kai-Hendrik Bormann, Constantin von See, Nils-Claudius Gellrich

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 12/2009; 67(12):2577-2582.

  PURPOSE: Perforating oral and maxillofacial defects frequently cause severe functional disorders. Microvascular free flaps like the radial forearm flap and the latissimus dorsi flap have beenPURPOSE: Perforating oral and maxillofacial defects frequently cause severe functional disorders. Microvascular free flaps like the radial forearm flap and the latissimus dorsi flap have been described to cover those defects; however, harvest of the radial forearm flap causes remarkable donor-site morbidity, while the latissimus dorsi flap often turns out to be too bulky. Therefore we introduce the serratus anterior muscle as a versatile and reliable microvascular flap to cover defects of both the floor of the mouth and the maxilla. PATIENTS AND METHODS: Between 2003 and 2007, 10 oral defects were reconstructed using the serratus anterior flap. In 5 of the cases, the defects were located at the hard palate and maxilla, while in the other cases they were located in the floor of the mouth. RESULTS: All of the patients were able to feed orally within the first week postoperatively. Donor-site morbidity was observed to be negligible not least because of the achievement of primary tension-free wound closure. Successful reconstruction could be observed in 8 of 10 patients. CONCLUSION: Although the serratus anterior muscle flap lacks an epithelial layer, this flap is not restricted to a subcutaneous placement. Due to rapid epithelialization, the serratus anterior muscle is even suitable for perforating intraoral defects.

• Wound ballistics of injuries caused by handguns with different types of projectiles.

  Authors: Constantin von See, Alexander Stuehmer, Nils-Claudius Gellrich, Katrin S Blum, Kai-Hendrik Bormann, Martin Rücker

  Military medicine. 08/2009; 174(7):757-61.

  BACKGROUND: There are considerable differences in the shape and composition of military and civilian projectiles. MATERIALS AND METHODS: Five different projectiles with the same kinetic energy wereBACKGROUND: There are considerable differences in the shape and composition of military and civilian projectiles. MATERIALS AND METHODS: Five different projectiles with the same kinetic energy were fired into the heads of freshly sacrificed pigs (n=30) through the submental region in the occipital direction. Computed tomography (CT) and 3D face scans of the animal skulls were obtained before and after firing. The image data sets were fused and provided the basis for a quantitative analysis of destruction patterns. RESULTS: As a result of the destruction of the parietal bone at the potential exit site, there were significant volume difference between the Action 4 (6.45 +/- 3.42 ml) and the Hydra-Shok projectile (12.71 +/- 2.86 ml). The partial metal-jacketed projectile showed a minor increase in volume (4.89 +/- 1.47 ml) and a partial loss of soft projectile components. Radiology showed differences between the various projectiles in fragmentation and bone and soft-tissue destruction. CONCLUSIONS: Although the projectiles had the same kinetic energy, there were considerable differences in injury patterns between full metal-jacketed projectiles, which are the only projectiles permitted for military use under the Geneva Conventions, and the other investigated projectiles. These injuries present a major medical challenge to both first responders and surgeons.

• Forensic imaging of projectiles using cone-beam computed tomography.

  Authors: Constantin von See, Kai-Hendrik Bormann, Paul Schumann, Friedrich Goetz, Nils-Claudius Gellrich, Martin Rücker

  Forensic science international. 07/2009;

  In patients with gunshot injuries, it is easy to detect a projectile within the body due to the high-density of the object, but artefacts make it difficult to obtain information about the deformationIn patients with gunshot injuries, it is easy to detect a projectile within the body due to the high-density of the object, but artefacts make it difficult to obtain information about the deformation and the exact location of the projectile in surrounding tissues. Cone-beam computed tomography (CBCT) is a new radiological imaging modality that allows radio-opaque objects to be localised and assessed in three dimensions. The full potential of the use of CBCT in forensic medicine has not yet been explored. In this study, three different modern projectiles were fired into the heads of pig cadavers (n=6) under standardised conditions. Tissue destruction and the location of the projectiles were analysed separately using CBCT and multi-slice computed tomography (MDCT). The projectiles had the same kinetic energy but showed considerable differences in deformation behaviour. Within the study groups, tissue destruction was reproducible. CBCT is less severely affected by metallic artefacts than MDCT. Therefore CBCT is superior in visualising bone destruction in the immediate vicinity of the projectile and projectile deformation, whereas MDCT allows soft tissue to be evaluated in more detail. CBCT is an improved diagnostic tool for the evaluation of gunshot injuries. In particular, it is superior to MDCT in detecting structural hard-tissue damage in the immediate vicinity of high-density metal projectiles and in identifying the precise location of a projectile in the body.

• Microvascular response to the subperiosteal implantation of self-inflating hydrogel expanders.

  Authors: Constantin von See, Nils-Claudius Gellrich, Kai-Hendrik Bormann, Alexander Rahmann, Martin Rücker

  The International journal of oral & maxillofacial implants. 25(5):979-84.

  Excessive stretching of the overlying soft tissue often occurs during the attempt at primary closure after bone augmentation. Preliminary soft tissue expansion may prevent such perfusion disturbancesExcessive stretching of the overlying soft tissue often occurs during the attempt at primary closure after bone augmentation. Preliminary soft tissue expansion may prevent such perfusion disturbances caused by stretching. The purpose of this study was to investigate the effects of using self-inflating expanders at different rates to expand overlying soft tissue prior to the bone grafting procedure. Two different hydrogel expanders with different inflation curves were used. For the experiments, 48 Lewis rats were divided into six groups of eight animals each. In four groups, the different expanders were implanted subperiosteally on the calvarium. In two of these groups, an observation window was implanted for intravital microscopy. In the other two groups, histologic analysis of the covering skin was performed. Intravital microscopy of the unexpanded periosteum and histologic analyses of unoperated rats served as control groups. Following implantation of the expanders, intravital microscopic examinations showed that, irrespective of the expansion curve, periosteal microcirculation had stopped completely without reperfusion within 14 days. Histologic analyses of the soft tissues, however, showed a well-vascularized connective tissue layer clinging to the expander. The microvessel density measured was significantly higher above slowly inflating expanders (91.2 ± 8.8 vessels/mm²) than above rapidly inflating expanders (48.4 ± 2.7 vessels/mm²) or unoperated periosteum (60.4 ± 4.8 vessels/mm²). Subperiosteal implantation of self-inflating expanders leads to complete ischemia of the periosteum. However, replacement of the periosteum by connective tissue takes place within 14 days; as a result of subcutaneous angiogenesis, this tissue may have a significantly higher microvessel density than healthy periosteum.