Horst Kokemüller

Five-year retrospective study of mandibular fractures in Freiburg, Germany: incidence, etiology, treatment, and complications

PURPOSE To evaluate current trends in maxillofacial trauma, a retrospective review of mandibular fractures at a German university hospital was carried out. PATIENTS AND METHODS In this retrospective study, records of 444 patients with mandibular fractures between 2000 and 2005 at the Department of Oral and Maxillofacial Surgery, University Hospital of Freiburg, Germany, were reviewed. A total of 444 patients presented with 696 mandibular fractures. RESULTS Three hundred twenty-nine (74%) of the fractures occurred in male and 115 (26%) in female patients (2.9:1). One hundred forty-two fractures (32%) resulted from road traffic accidents, 126 from fights (28%), and 116 from falls (26%). Forty-four fractures were caused by sport accidents (10%) and 16 by pathologic fractures (4%). The mandibular condyle area was the most common fracture site, with 291 fractures (42%), followed by 144 fractures of the symphyseal and parasymphyseal area (21%) and 141 angle fractures (20%). Combined fractures were found in nearly half of the cases. Five hundred seventy-nine (83%) of patients with mandibular fractures were treated by surgical intervention, 117 (17%) of patients conservatively. Regarding the surgical treatment, 561 (65%) miniplates, 247 (29%) locking plates, and 51 (6%) lag screws were used. Complications, such as postoperative infections, abscesses, and osteomyelitis appeared in 66 (9%) cases. CONCLUSION We concluded that osteosynthesis of mandibular fractures by miniplates and locking plates are both reliable.

Reconstruction of mandibular defects - clinical retrospective research over a 10-year period -

BackroundFunctional and cosmetic defects in the maxillofacial region are caused by various ailments and these defects are addressed according to their need. Simplicity of procedure, intact facial function and esthetic outcome with the least possible donor site morbidity are the minimum requirements of a good reconstruction. Oro-mandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes with the use of autogenous bone grafts. Reconstruction of trauma- or mandibular oncologic defects with bony free flaps is considered the gold standard. However the the optimal reconstruction of mandibular defects is still controversial in regards to reconstructive options which include the donor site selection and the timing of surgery. The purpose of this study was to determine the outcome of different osseous reconstruction options using autogenous bone grafts for mandibular reconstructions.MethodsThis study was carried out on 178 patients with mandibular bone defects. They were reconstructed with autogenous bone grafts from different donor sites. At post operative visits they were evaluated for functional and cosmetic results.ResultsThe success rate found in this study was around 90%. Only 7.6% of the cases showed poor results regarding facial contours and mouth opening. All other patients were satisfied with their cosmesis and mouth opening at the recipient sites was in the normal range during last follow-up visits. Donor sites were primarily closed in all cases and there was no hypertrophic scar.ConclusionBased on this study, autogenous bone grafts are a reliable treatment modality for the reconstruction of mandibular bone defects with predictable aesthetic and functional outcomes. As the free vascularized fibular flap has the least resorption and failure rate, it should be the first choice for most cases of mandiblular reconstruction.

RECURRENT AMELOBLASTOMA FOLLOWING OSSEOUS RECONSTRUCTION--A REVIEW OF TWENTY YEARS

BACKGROUND The adequate therapy of ameloblastoma may require a compromise between the least destructive treatment possible of a benign tumour and a sufficiently radical method to prevent recurrences. Frequently recurrences appear after 10 years or longer, therefore regular follow-up visits even after more than 5 years are recommended. The primary reconstruction of bones and/or soft tissues, which is likely to be performed especially for benign processes is threatened by recurrences. METHODS A retrospective analysis of our patient group during the past 20 years has shown that a differentiated pretherapeutic securing of the histology as well as a radical surgical policy are the most important criteria, influencing the likelihood of recurrences. Three representative case histories are described below. RESULTS The rate of cumulative relapses with regard to various observation time amounted to 17% after 5 years and 19% after 10 years, respectively. CONCLUSION Ameloblastomas carry a certain risk of developing local recurrences depending on histology and the type of surgical treatment. Long-term follow-up should be arranged.

Effects of VEGF loading on scaffold-confined vascularization

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.

Sandwich osteotomy for vertical and transversal augmentation of the posterior mandible

The aim of this study is to describe the treatment outcome after alveolar ridge augmentation in the atrophic posterior mandible by segmental sandwich osteotomy combined with an interpositional autograft prior to placement of endosseous implants. Thirteen consecutive patients (five males, mean age 48 years, and eight females, mean age 61 years) were included in this study. The postoperative course was uneventful in six patients. Sensory disturbances in the mental nerve were found in five patients, all of them with hypoaesthesia. None of these patients complained of permanent sensory disturbances. Vertical gain ranged from 2.0 to 7.8mm (mean value 4.61mm). Horizontal gain ranged from 2.0 to 6.3 (mean value 3.42mm). A total of 41 implants were placed in 22 surgical sites, 12 weeks after bone reconstruction. In conclusion, segmental mandibular sandwich osteotomy is recommended to meet the dimensional requirements of preimplant bone augmentation in atrophic posterior mandible.

En bloc prefabrication of vascularized bioartificial bone grafts in sheep and complete workflow for custom-made transplants

The aim of this pilot study was to determine, in a new experimental model, whether complex bioartificial monoblocs of relevant size and stability can be prefabricated in a defined three-dimensional design, in which the latissimus dorsi muscle serves as a natural bioreactor and the thoracodorsal vessel tree is prepared for axial construct perfusion. Eighteen sheep were included in the study, with six animals in each of three experimental groups. Vitalization of the β-tricalcium phosphate-based constructs was performed by direct application of unmodified osteogenic material from the iliac crest (group A), in vivo application of nucleated cell concentrate (NCC) from bone marrow aspirate (group B), and in vitro cultivation of bone marrow stromal cells (BMSC) in a perfusion bioreactor system (group C). The contours of the constructs were designed digitally and transferred onto the bioartificial bone grafts using a titanium cage, which was bent over a stereolithographic model of the defined subvolume intraoperatively. At the end of the prefabrication process, only the axial vascularized constructs of group A demonstrated vital bone formation with considerable stability. In groups B and C, the applied techniques were not able to induce ectopic bone formation. The presented computer-assisted workflow allows the prefabrication of custom-made bioartificial transplants.

Additive effect of mesenchymal stem cells and VEGF to vascularization of PLGA scaffolds

Bone marrow derived mesenchymal stem cells (bmMSCs) are widely used for the generation of tissue engineering constructs, since they can differentiate into different cell types occurring in bone tissues. Until now their use for the generation of tissue engineering constructs is limited. All cells inside a tissue engineering construct die within a short period of time after implantation of the construct because vascularization and establishment of connections to the recipient circulatory system is a time consuming process. We therefore compared the influences of bmMSC, VEGF and a combination of both on the early processes of vascularization, utilizing the mice skinfold chamber model and intravital fluorescence microscopy. Tissue engineering constructs based on collagen coated Poly d,l-lactide-co-glycolide (PLGA) scaffolds, were either functionalized by coating with vascular endothelial growth factor (VEGF) or vitalized with bmMSC. PLGA without cells and growth factor was used as the control group. Functionalized and vitalized tissue engineering constructs showed an accelerated growth of microvessels compared to controls. Only marginal differences in vascular growth were detected between VEGF containing and bmMSC containing constructs. Constructs containing VEGF and bmMSC showed a further enhanced microvascular growth at day 14. We conclude that bmMSCs are well suited for bone tissue engineering applications, since they are a valuable source of angiogenic growth factors and are able to differentiate into the tissue specific cell types of interest. The dynamic process of vascularization triggered by growth factor producing cells can be amplified and stabilized with the addition of accessory growth factors, leading to a persisting angiogenesis, but strategies are needed that enhance the resistance of bmMSC to hypoxia and increase survival of these cells until the tissue engineering construct has build up a functional vascular system.

Elongated coronoid process: CT-based quantitative analysis of the coronoid process and review of literature

Impingement of the enlarged coronoid processes against the medial surfaces of the zygomatic arches and posterior surfaces of the body of the zygomatic bones results in mechanical restriction of the mouth opening. The authors introduce a helpful tool for easy assessment and estimatation of the length of the coronoid process, measured on the CT scans of 40 patients (20 adults, 20 adolescents) and report a case of a 13-year-old boy suffering from restricted mouth opening caused by bilateral hyperplasia of the coronoid process. The CT based analysis resulted in a mean length of the coronoid process of 13.02mm in adults and 12.43mm in adolescents. The 13-year-old boy had a length of nearly 2cm. For comparison, a coronoid/condyle ratio was developed. This ratio showed a value of 0.78 for all patients compared with a value of about 2.0 for the boy. The literature review revealed comparable results to the reported case. Most of the patients were adolescent, male and presented a median history of 2 years until correct diagnosis.

Accelerating the early angiogenesis of tissue engineering constructs in vivo by the use of stem cells cultured in matrigel

In tissue engineering research, generating constructs with an adequate extent of clinical applications remains a major challenge. In this context, rapid blood vessel ingrowth in the transplanted tissue engineering constructs is the key factor for successful incorporation. To accelerate the microvascular development in engineered tissues, we preincubated osteoblast-like cells as well as mesenchymal stem cells or a combination of both cell types in Matrigel-filled PLGA scaffolds before transplantation into the dorsal skinfold chambers of balb/c mice. By the use of preincubated mesenchymal stem cells, a significantly accelerated angiogenesis was achieved. Compared with previous studies that showed a decisive increase of vascularization on day 6 after the implantation, we were able to halve this period and achieve explicitly denser microvascular networks 3 days after transplantation of the tissue engineering constructs. Thereby, the inflammatory host tissue response was acceptable and low, comparable with former investigations. A co-incubation of osteoblast-like cells and stem cells showed no additive effect on the density of the newly formed microvascular network. Preincubation of mesenchymal stem cells in Matrigel is a promising approach to develop rapid microvascular growth into tissue engineering constructs. After the implantation into the host organism, scaffolds comprising stem cells generate microvascular capillary-like structures exceptionally fast. Thereby, transplanted stem cells likely differentiate into vessel-associated cells. For this reason, preincubation of mesenchymal stem cells in nutrient solutions supporting different steps of angiogenesis provides a technique to promote the routine use of tissue engineering in the clinic.

Reconstruction of oral mucosal defects using the nasolabial flap: clinical experience with 22 patients

BackgroundVarious surgical options are available for reconstruction of intraoral soft tissue defects. For smaller defects of the oral mucosa in different anatomic locations of the oral cavity the nasolabial flap is a very useful and simple alternative to other pedicled flaps and free flaps.MethodsThe results of reconstruction of oral mucosal defects or facial skin defects using 29 nasolabial flaps in 22 patients were reviewed retrospectively.ResultsThe patient group consisted of 16 patients (70%) with squamous cell carcinoma of the oral cavity, 2 patients (10%) with cystic lesions of the maxilla, 3 patients (15%) with osteonecrosis of the jaw, and 1 patient with an oral metastasis of a lung carcinoma. Healing was uneventful in 93%, partial or complete flap loss was observed in 7%.ConclusionsThe nasolabial flap is a valuable alternative for reconstruction of smaller defects of the oral cavity in particular in older and medically compromised patients.