Norbert R Kübler

Publications of Norbert R Kübler

• Tissue expanders for soft tissue reconstruction in the head and neck area-requirements and limitations.

  Authors: Jörg Handschel, Stefanie Schultz, Rita A Depprich, Ralf Smeets, Christoph Sproll, Michelle A Ommerborn, Christian Naujoks, Norbert R Kübler, André Zimmermann

  Clinical oral investigations. 05/2012;

  OBJECTIVES: The repair of skin defects in the head and neck region still poses a significant problem for many clinicians. Tissue expansion is described as a treatment option providing good color,OBJECTIVES: The repair of skin defects in the head and neck region still poses a significant problem for many clinicians. Tissue expansion is described as a treatment option providing good color, texture, and thickness match of the expanded skin. Unfortunately, the complication rates for tissue expansion range from 0 to 48 %. Therefore, the purpose of this study was to investigate risk factors for the use of tissue expanders in head and neck reconstructions. MATERIALS AND METHODS: Forty-nine patients with skin deficits in the head and neck area underwent tissue expansion. Sixty-two implanted expanders were analyzed regarding the various complications and the success rate. RESULTS: The success rate of treated patients was 37 (75.5 %) of all 49 included patients. The most frequent cause for the skin deficit was a tumor resection near the tip of the nose followed by skin deficits resulting after craniectomy. Interestingly, a higher number of expanders and a larger volume were significantly associated with a worse outcome. There was a trend of association between larger defect size and failure, too. CONCLUSIONS: The internal tissue expansion is a suitable technique for skin reconstruction in the head and face area. Compared to distant or free flaps, it often offers a better cosmetic outcome. In very large defects (>100 cm(2)) or when more than two expanders are needed, the failure rate increases. In these cases, other treatment options are recommended. CLINICAL RELEVANCE: The internal tissue expansion is a suitable technique for skin reconstruction in the head and face area.

• Comparison of various approaches for the treatment of fractures of the mandibular condylar process.

  Authors: Jörg Handschel, Tim Rüggeberg, Rita Depprich, Frank Schwarz, Ulrich Meyer, Norbert R Kübler, Christian Naujoks

  Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery. 03/2012;

  Fractures of the mandibular condyle process are the most common fractures of the lower jaw. Unfortunately, the type of treatment is still a matter of debate. PURPOSE: The aim of this investigationFractures of the mandibular condyle process are the most common fractures of the lower jaw. Unfortunately, the type of treatment is still a matter of debate. PURPOSE: The aim of this investigation was to compare the outcome of different treatment approaches regarding function and surgical side-effects. PATIENTS AND METHODS: 111 fractures of the mandibular condyle representing all types according to the classification of Spiessl and Schroll were included. Both closed reduction (CR) and open reduction with internal fixation (ORIF) including the retromandibular/transparotid, submandibular, preauricular and intraoral approach were performed. The clinical examination included functional and aesthetic aspects at least 1 year after the fracture. RESULTS: The majority of fractures (45%) were classified into Type II and IV according to Spiessl and Schroll followed by fractures without any displacement or dislocation (29.7%). The submandibular approach showed the worst outcome regarding permanent palsy of the facial nerve and hypertrophic scarring. No significant differences between the various approaches were detected in the functional status in any diagnosis group. CONCLUSION: Inferior condylar neck fractures benefit from ORIF by an intraoral approach whereas in high condylar neck fractures the retromandibular/transparotid approach shows the best results. Fractures of the condylar head were almost all treated by CR and our results cannot contribute to the debate of CR vs. ORIF in this type of fracture.

• CT-scan is a valuable tool to detect mandibular involvement in oral cancer patients.

  Authors: Jörg Handschel, Christian Naujoks, Rita A Depprich, Norbert R Kübler, Patric Kröpil, Julia Kuhlemann, Theresa Maria Jansen, Inga Boeck, Karl Christoph Sproll

  Oral oncology. 12/2011;

  In patients with oral squamous cell carcinomas (OSSC) it is desirable to avoid unnecessary bone resection without neglecting the overall surgical treatment goal of tumor-free margins. WhereasIn patients with oral squamous cell carcinomas (OSSC) it is desirable to avoid unnecessary bone resection without neglecting the overall surgical treatment goal of tumor-free margins. Whereas computed tomography (CT) is most commonly used to detect mandibular invasion, there are conflicting reports regarding the accuracy of CT. Therefore, the aim of this study was to reinvestigate the accuracy of CT in predicting mandibular involvement by OSSC. One hundred and seven patients with OSSC who received a mandibulectomy were included. Before treatment all patients underwent a contrast-enhanced multi-detector CT. Axial 3 or 1.25mm thick images were reconstructed for evaluation in overlapping technique and displayed in a bone (1400/400HU) and a soft tissue window (350/50HU). CT scans were examined by three investigators and compared with the histological findings. The radiological examination showed a high interrater reliability (Cronbachs alpha 0.982). Comparing the radiological findings with the histological results the CT showed 8 false-positive results and 8 false-negative patients. The quality criteria for detecting bone involvement of OSSC by CT were calculated as follows: sensitivity 82.6%; specificity 86.9%; positive predictive value 82.6%; negative predictive value 86.9%. However, in all false-positive patients a sagittal bone defect of 15.1mm could be found presumably caused by pressure of the tumor, but no histologically detectable bone infiltration. Modern CT (1-2mm sections) is a valuable tool for surgical treatment planning. If bone invasion is detected, a mandibulectomy seems always reasonable. In radiologically negative cases histological assessment is necessary to detect mandibular involvement.

• Role of brush biopsy and DNA cytometry for prevention, diagnosis, therapy, and followup care of oral cancer.

  Authors: Alfred Böcking, Christoph Sproll, Nikolas Stöcklein, Christian Naujoks, Rita Depprich, Norbert R Kübler, Jörg Handschel

  Journal of oncology. 01/2011; 2011:875959.

  Late diagnosis resulting in late treatment and locoregional failure after surgery are the main causes of death in patients with oral squamous cell carcinomas (SCCs). Actually, exfoliative cytology isLate diagnosis resulting in late treatment and locoregional failure after surgery are the main causes of death in patients with oral squamous cell carcinomas (SCCs). Actually, exfoliative cytology is increasingly used for early detection of oral cancer and has been the subject of intense research over the last five years. Significant advances have been made both in relation to screening and evaluation of precursor lesions. As this noninvasive procedure is well tolerated by patients, more lesions may be screened and thus more oral cancers may be found in early, curable stages. Moreover, the additional use of DNA image cytometry is a reasonable tool for the assessment of the resection margins of SCC. DNA image cytometry could help to find the appropriate treatment option for the patients. Finally, diagnostic DNA image cytometry is an accurate method and has internationally been standardized. In conclusion, DNA image cytometry has increasing impact on the prevention, diagnostic, and therapeutical considerations in head and neck SCC.

• Embryonic stem cells induce ectopic bone formation in rats.

  Authors: Maren Kahle, Hans-Peter Wiesmann, Karin Berr, Rita A Depprich, Norbert R Kübler, Christian Naujoks, Matthias Cohnen, Michelle A Ommerborn, Ulrich Meyer, Jörg Handschel

  Bio-medical materials and engineering. 01/2010; 20(6):371-80.

  Surgery often leads to massive destruction of the skeleton. Cell-based bone reconstruction therapies promise new therapeutic opportunities for the repair of bone. Embryonic stem cells (ESCs) can beSurgery often leads to massive destruction of the skeleton. Cell-based bone reconstruction therapies promise new therapeutic opportunities for the repair of bone. Embryonic stem cells (ESCs) can be differentiated into osteogenic cells and are a potential cell source for bone tissue engineering. The purpose of this in vivo study was to investigate the bone formation in various constructs containing ESCs (with and without micromass technology) and insoluble collagenous bone matrix (ICBM). Murine ESCs were cultured as monolayer cultures as well as micromasses and seeded on ICBM. These constructs were implanted in immunodeficient rats. After one week, one, two and three months CT-scans were performed to detect any calcifications and the rats were sacrificed. The radiological examination shows a steep increase of the mineralized tissue in group 1 (ICBM+seeded ESC). This increase can be considered as statistical significant. In contrast, the volume of the mineralization in group 2 (ICBM+ESC-spheres) and group 3 (ESC-spheres) does not increase significantly during the study. ESCs in combination with ICBM do promote ectopic bone formation in vivo. Thus, this cell population as well as the biomaterial ICBM might be promising components for bone tissue engineering.

• A histomorphometric meta-analysis of sinus elevation with various grafting materials.

  Authors: Jörg Handschel, Melani Simonowska, Christian Naujoks, Rita A Depprich, Michelle A Ommerborn, Ulrich Meyer, Norbert R Kübler

  Head & face medicine. 02/2009; 5:12.

  Several grafting materials have been used in sinus augmentation procedures including autogenous bone, demineralized freeze-dried bone (DFDBA), hydroxyapatite, beta-tricalcium phosphate (beta-TCP),Several grafting materials have been used in sinus augmentation procedures including autogenous bone, demineralized freeze-dried bone (DFDBA), hydroxyapatite, beta-tricalcium phosphate (beta-TCP), anorganic deproteinized bovine bone and combination of these and others. Up to now a subject of controversy in maxillofacial surgery and dentistry is, what is the most appropriate graft material for sinus floor augmentation. PURPOSE: The aim of this study is to provide a body of evidence-based data regarding grafting materials in external sinus floor elevation concerning the fate of the augmented material at the histomorphological level, through a meta-analysis of the available literature. MATERIALS AND METHODS: The literature searches were performed using the National Library of Medicine. The search covered all English and German literature from 1995 until 2006. For analyzing the amount of bone the parameter "Total Bone Volume" (TBV) was assessed. TBV is determined as the percentage of the section consisting of bone tissue. RESULTS: In a relatively early phase after implantation the autogenous bone shows the highest TBV values. Interestingly, the different TBV levels approximate during the time. After 9 months no statistically significant differences can be detected between the various grafting materials. CONCLUSION: From a clinical point of view, the use of autogenous bone is advantageous if a prosthetic rehabilitation (with functional loading) is expected within 9 months. In other cases the use of anorganic deproteinized bovine bone in combination with autogenous bone seems to be preferable. Donor side morbidity is ignored in this conclusion.

• Induction of osteogenic markers in differentially treated cultures of embryonic stem cells.

  Authors: Jörg Handschel, Karin Berr, Rita A Depprich, Norbert R Kübler, Christian Naujoks, Hans-Peter Wiesmann, Michelle A Ommerborn, Ulrich Meyer

  Head & face medicine. 02/2008; 4:10.

  BACKGROUND: Facial trauma or tumor surgery in the head and face area often lead to massive destruction of the facial skeleton. Cell-based bone reconstruction therapies promise to offer newBACKGROUND: Facial trauma or tumor surgery in the head and face area often lead to massive destruction of the facial skeleton. Cell-based bone reconstruction therapies promise to offer new therapeutic opportunities for the repair of bone damaged by disease or injury. Currently, embryonic stem cells (ESCs) are discussed to be a potential cell source for bone tissue engineering. The purpose of this study was to investigate various supplements in culture media with respect to the induction of osteogenic differentiation. METHODS: Murine ESCs were cultured in the presence of LIF (leukemia inhibitory factor), DAG (dexamethasone, ascorbic acid and beta-glycerophosphate) or bone morphogenetic protein-2 (BMP-2). Microscopical analyses were performed using von Kossa staining, and expression of osteogenic marker genes was determined by real time PCR. RESULTS: ESCs cultured with DAG showed by far the largest deposition of calcium phosphate-containing minerals. Starting at day 9 of culture, a strong increase in collagen I mRNA expression was detected in the DAG-treated cells. In BMP-2-treated ESCs the collagen I mRNA induction was less increased. Expression of osteocalcin, a highly specific marker for osteogentic differentiation, showed a double-peaked curve in DAG-treated cells. ESCs cultured in the presence of DAG showed a strong increase in osteocalcin mRNA at day 9 followed by a second peak starting at day 17. CONCLUSION: Supplementation of ESC cell cultures with DAG is effective in inducing osteogenic differentiation and appears to be more potent than stimulation with BMP-2 alone. Thus, DAG treatment can be recommended for generating ESC populations with osteogenic differentiation that are intended for use in bone tissue engineering.

• Osseointegration of zirconia implants: an SEM observation of the bone-implant interface.

  Authors: Rita Depprich, Holger Zipprich, Michelle Ommerborn, Eduardo Mahn, Lydia Lammers, Jörg Handschel, Christian Naujoks, Hans-Peter Wiesmann, Norbert R Kübler, Ulrich Meyer

  Head & face medicine. 02/2008; 4:25.

  BACKGROUND: The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics,BACKGROUND: The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. METHODS: A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. RESULTS: Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. CONCLUSION: The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.

• [Evaluation of hyperbaric oxygen therapy in treatment of patients with osteomyelitis of the mandible]

  Authors: Jörg Handschel, Sabine Brüssermann, Rita Depprich, Michelle Ommerborn, Christian Naujoks, Norbert R Kübler, Ulrich Meyer

  Mund-, Kiefer- und Gesichtschirurgie : MKG. 12/2007; 11(5):285-90.

  BACKGROUND: Chronic osteomyelitis of the jaw is a relapsing disease with multiple treatment strategies described in the literature. Hyperbaric oxygen therapy is one of them. The purpose of this studyBACKGROUND: Chronic osteomyelitis of the jaw is a relapsing disease with multiple treatment strategies described in the literature. Hyperbaric oxygen therapy is one of them. The purpose of this study was to evaluate the clinical outcome of hyperbaric oxygen therapy in these patients. METHOD: All patients with a chronic osteomyelitis of the mandible who received in our department hyperbaric oxygen therapy between 2000 and 2004 were included in this study. The clinical outcome (lack of symptoms e.g. pain, swelling, etc.) was the pivotal evaluation parameter. All patients were divided in three groups according to their medical history. Group 1: All patients with osteomyelitis of the mandible, who received no treatment before. Group 2: All patients with one local relapse, who received only antimicrobial treatment. Group 3: Patients with at least one local relapse after antimicrobial and surgical treatment. RESULTS: 27 patients were evaluated in this study. Seven out of 13 patients in group 1 were relapse free after performing 40 hyperbaric oxygen therapies. However, only 4 of 9 patients in group 3 were relapse free after treatment. In group 2 the hyperbaric oxygen therapy was successful particularly in the younger patients (3 of 4). CONCLUSION: Adjuvant hyperbaric oxygen therapy was successful in the treatment of patients with chronic recurrent osteomyelitis of the mandible. Therefore, it is an treatment option which can avoid ablative surgery in some cases.

• Additional use of DNA-image cytometry improves the assessment of resection margins.

  Authors: Jörg Handschel, Döne Oz, Natalia Pomjanski, Rita Depprich, Michelle A Ommerborn, Stefan Braunstein, Norbert R Kübler, Ulrich Meyer, Alfred Böcking

  Journal of oral pathology & medicine : official publication of the International Association of Oral Pathologists and the American Academy of Oral Pathology. 10/2007; 36(8):472-5.

  BACKGROUND: Despite the histopathologic findings of tumor-free margins, patients with oral squamous cell carcinoma (SCC) often suffer from local tumor relapse. The purpose of this study was toBACKGROUND: Despite the histopathologic findings of tumor-free margins, patients with oral squamous cell carcinoma (SCC) often suffer from local tumor relapse. The purpose of this study was to determine the prognostic value of DNA-image cytometry in the assessment of resection margins. METHODS: DNA-image cytometry was performed in 40 SCC patients with histologically tumor-free resection margins. The follow-up period since the tumor resection was at least 3 years. RESULTS: Twenty patients showed a locoregional relapse of the SCC. Fourteen of these patients had aneuploid cells in DNA-image cytometry. Two patients who were relapse-free revealed aneuploid cells too. The sensitivity of the adjuvant use of DNA-image cytometry was 70% and the positive predictive value was 87.5%. CONCLUSIONS: The additional use of DNA-image cytometry is a reasonable tool for the assessment of the resection margins of SCCs. DNA-image cytometry could help to find the appropriate treatment option for the patients and thus might improve their prognosis.

• Dentin dysplasia type I: a challenge for treatment with dental implants.

  Authors: Rita A Depprich, Michelle A Ommerborn, Jörg GK Handschel, Christian D Naujoks, Ulrich Meyer, Norbert R Kübler

  Head & face medicine. 02/2007; 3:31.

  ABSTRACT: BACKGROUND: Dentin dysplasia type I is characterized by a defect of dentin development with clinical normal appearance of the permanent teeth but no or only rudimentary root formation.ABSTRACT: BACKGROUND: Dentin dysplasia type I is characterized by a defect of dentin development with clinical normal appearance of the permanent teeth but no or only rudimentary root formation. Early loss of all teeth and concomitant underdevelopment of the jaws are challenging for successful treatment with dental implants. METHODS: A combination of sinus lifting and onlay bone augmentation based on treatment planning using stereolithographic templates was used in a patient with dentin dysplasia type I to rehabilitate the masticatory function. RESULTS: (i) a predisposition for an increased and accelerated bone resorption was observed in our patient, (ii) bone augmentation was successful using a mixture of allogenic graft material with autogenous bone preventing fast bone resorption, (iii) surgical planning, based on stereolithographic models and surgical templates, facilitated the accurate placement of dental implants. CONCLUSION: Bony augmentation and elaborate treatment planning is helpful for oral rehabilitation of patients with dentin dysplasia type I.

• Sinus lifting before Le Fort I maxillary osteotomy: a suitable method for oral rehabilitation of edentulous patients with skeletal class-III conditions: review of the literature and report of a case.

  Authors: Rita A Depprich, Jörg G K Handschel, Christian Naujoks, Tobias Hahn, Ulrich Meyer, Norbert R Kübler

  Head & face medicine. 02/2007; 3:2.

  BACKGROUND: Functional rehabilitation of patients afflicted with severe mandibular and maxillary alveolar atrophy might be challenging especially in malformed patients. METHODS: Treatment planningBACKGROUND: Functional rehabilitation of patients afflicted with severe mandibular and maxillary alveolar atrophy might be challenging especially in malformed patients. METHODS: Treatment planning using sinus lifting and implant placement before Le Fort I maxillary osteotomy in a patient with severe mandibular and posterior maxillary alveolar atrophy and skeletal class-III conditions due to cleft palate are described. RESULTS: A full functional and esthetic rehabilitation of the patient was achieved by a stepwise surgical approach performed through sinus lifting as the primary approach followed by implant placement and subsequent Le Fort I maxillary osteotomy to correct the maxillo-mandibular relation. CONCLUSION: Stabilisation of the maxillary complex by a sinus lifting procedure in combination with computer aided implant placement as preorthodontic planning procedure before Le Fort I maxillary osteotomy seems to be suitable in order to allow ideal oral rehabilitation especially in malformed patients.

• Prospects of micromass culture technology in tissue engineering.

  Authors: Jörg G K Handschel, Rita A Depprich, Norbert R Kübler, Hans-Peter Wiesmann, Michelle Ommerborn, Ulrich Meyer

  Head & face medicine. 02/2007; 3:4.

  Tissue engineering of bone and cartilage tissue for subsequent implantation is of growing interest in cranio- and maxillofacial surgery. Commonly it is performed by using cells coaxed with scaffolds.Tissue engineering of bone and cartilage tissue for subsequent implantation is of growing interest in cranio- and maxillofacial surgery. Commonly it is performed by using cells coaxed with scaffolds. Recently, there is a controversy concerning the use of artificial scaffolds compared to the use of a natural matrix. Therefore, new approaches called micromass technology have been invented to overcome these problems by avoiding the need for scaffolds. Technically, cells are dissociated and the dispersed cells are then reaggregated into cellular spheres. The micromass technology approach enables investigators to follow tissue formation from single cell sources to organised spheres in a controlled environment. Thus, the inherent fundamentals of tissue engineering are better revealed. Additionally, as the newly formed tissue is devoid of an artificial material, it resembles more closely the in vivo situation. The purpose of this review is to provide an insight into the fundamentals and the technique of micromass cell culture used to study bone tissue engineering.

• Adenomatoid odontogenic tumor of the mandible: review of the literature and report of a rare case.

  Authors: Jörg GK Handschel, Rita A Depprich, André C Zimmermann, Stefan Braunstein, Norbert R Kübler

  Head & face medicine. 09/2005; 1:3.

  Adenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor which is often misdiagnosed as odontogenic cyst. To acquire additional information about AOT, all reports regarding AOT and cited inAdenomatoid odontogenic tumor (AOT) is a rare odontogenic tumor which is often misdiagnosed as odontogenic cyst. To acquire additional information about AOT, all reports regarding AOT and cited in "pubmed" since 1990 onward were reviewed. AOT accounts for about 1% until 9% of all odontogenic tumors. It is predominantly found in young and female patients, located more often in the maxilla in most cases associated with an uneruppted permanent tooth. For radiological diagnose the intraoral periapical radiograph seems to be more useful than panoramic. However, AOT frequently resemble other odontogenic lesions such as dentigerous cysts or ameloblastoma. Immunohistochemically AOT is characterized by positive reactions with certain cytokeratins. Treatment is conservative and the prognosis is excellent. For illustration a rare case of an AOT in the mandible is presented.

• Cell-based bone reconstruction therapies--cell sources.

  Authors: Jörg Handschel, Hans-Peter Wiesmann, Rita Depprich, Norbert R Kübler, Ulrich Meyer

  The International journal of oral & maxillofacial implants. 21(6):890-8.

  Over the last few decades, reconstructive surgery has shifted from a resection-oriented approach toward strategies focusing on repair and regeneration of tissues. As the main aim of maxillofacialOver the last few decades, reconstructive surgery has shifted from a resection-oriented approach toward strategies focusing on repair and regeneration of tissues. As the main aim of maxillofacial reconstruction has been the restoration of bone form and function, surgeons used artificial tissue substitutes in the early decades of bone reconstruction. These artificial materials significantly improved the ability of surgeons to restore the form and, to some extent, the function of defective bones. Despite the fact that every artificial material has specific disadvantages, the use of biomaterials is a common treatment option in clinical practice even today. Due to the more detailed understanding that exists concerning transplantation of cells and tissues, autogenous grafts are the second mainstay in clinical practice. However, the main disadvantage of using autogenous grafts is donor site morbidity and donor shortage. Research is currently in progress into the use of cell-based approaches in reconstructive surgery, since cells are the driving elements for all repair and regeneration processes. Various cell populations have been reported on in the relevant literature. These cells can be classified according to differentiation capacity and the tissue from which they originated. In this review, unrestricted cells, multipotential progenitor cells, determined cells, and genetically modified cells are described systematically, and their advantages as well as limitations are discussed. (More than 50 references.)

• Cell-based bone reconstruction therapies-principles of clinical approaches.

  Authors: Ulrich Meyer, Hans-Peter Wiesmann, Karin Berr, Norbert R Kübler, Jörg Handschel

  The International journal of oral & maxillofacial implants. 21(6):899-906.

  Cell-based bone tissue engineering is a rapidly evolving therapy option in bone reconstruction strategies. Some cell-driven approaches, especially the biophysical stimulation of the host cellCell-based bone tissue engineering is a rapidly evolving therapy option in bone reconstruction strategies. Some cell-driven approaches, especially the biophysical stimulation of the host cell population surrounded by the bone defect, are common treatment methods in maxillofacial surgery. Others, such as autologous cell implantation, have now gained acceptance for clinical trials. More advanced or complex therapeutical options (extracorporeal tissue engineering, stem cell use, genetic engineering) have been tested in preclinical investigations but have not reached the level of clinical use. Two different aspects are of special relevance in cell-based bone reconstruction therapies. The source of cells used to regenerate bone (discussed in detail in a complementary review in this issue of The International Journal of Oral and Maxillofacial Implants) as well as the principal approach of a cell-driven bone regeneration therapy influence the outcome of such engineering strategies. All of the cell-driven repair strategies are under intensive investigation in an effort to provide surgeons with a limitless supply of tissue for bone repair and reconstruction in future procedures. An overview of the basic biological aspects as well as the inherent constraints of different cell-based approaches are given in this paper.

• Evidence-based evaluation of publications on tissue engineering and regenerative medicine.

  Authors: Christian Naujoks, Christian Gerges, Ulrich Meyer, Sahar Fazeli, Rita A Depprich, Norbert R Kübler, Jörg Handschel

  In vivo (Athens, Greece). 25(6):923-8.

  The performed study gives a literature review of preclinical and clinical publications on tissue engineering and regenerative medicine. Furthermore, an overview of the clinical application of theseThe performed study gives a literature review of preclinical and clinical publications on tissue engineering and regenerative medicine. Furthermore, an overview of the clinical application of these processes is given. The literature research was based on different electronic media, e.g. Medline of the National Library of Medicine. The quality assessment of this study was performed by standardized, evidence-based criteria. Studies were analyzed regarding the clinical area of application, organ systems, tissue types, level of evidence, cell types and release date. Since 1989, the number of publications in the field of tissue engineering has increased dramatically. The articles deal predominantly with three tissues (skin, bone or cartilage). Even if the number of clinical studies is increasing, there is still a lack of clinical studies with a high level of evidence. The research has moved from preclinical research to the field of applied medicine. There is a need for strategically planned clinical trials to establish clinical guidelines for this field.

• Complications after oral surgery in patients with congenital or drug-induced bleeding disorders.

  Authors: Jörg Handschel, Christoph Willamowski, Ralf Smeets, Michelle A Ommerborn, Christian Naujoks, Norbert R Kübler, Rita Depprich

  In vivo (Athens, Greece). 25(2):283-6.

  Bleeding disorders (BD) can cause significant problems during or after surgical procedures of the oral cavity. The aim of this study was to explore the risk of bleeding following oral surgery inBleeding disorders (BD) can cause significant problems during or after surgical procedures of the oral cavity. The aim of this study was to explore the risk of bleeding following oral surgery in patients with BD. The medical records of all BD patients referred to the department of cranio- and maxillofacial surgery were reviewed. Ninety-five patients (26 inherent BD, 69 taking antithrombotic drugs) were reviewed for this study. Interestingly, patients taking oral anticoagulants presented more bleeding complications than patients with inherent BD. During simple tooth extraction procedures, patients taking antithrombotic drugs had a higher risk of bleeding than patients with inherent BD. The currently available treatment protocols for surgical treatment of dental patients with inherent BD suffice. However, our data indicates that there is still a need for clear guidelines for the treatment of patients taking antithrombotic drugs, especially phenprocoumon.

• Nonvascularized iliac bone grafts for mandibular reconstruction--requirements and limitations.

  Authors: Jörg Handschel, Hirama Hassanyar, Rita A Depprich, Michelle A Ommerborn, Karl Christoph Sproll, Matthias Hofer, Norbert R Kübler, Christian Naujoks

  In vivo (Athens, Greece). 25(5):795-9.

  Treatment of intraoral malignant tumors often leads to continuity defects of the mandible. Whereas the use of free vascularised flaps has shortcomings regarding donor site morbidity and aTreatment of intraoral malignant tumors often leads to continuity defects of the mandible. Whereas the use of free vascularised flaps has shortcomings regarding donor site morbidity and a worse-fitting bone geometry, the nonvascularized iliac crest graft could be an alternative option. The purpose of this study was to describe the treatment outcome with nonvascularized iliac crest grafts over a 10-year period and to determine possible limitations of their use. Eighty-four patients with bicortical nonvascularized iliac crest grafts for mandibular reconstruction were examined at least one year after reconstruction. Patients' records and the radiological and/or surgical data were analyzed. Sixty-three patients (75%) showed complete healing, in 20 patients the treatment was not successful and in one patient the treatment result was unclear. Interestingly, comparing the successfully and the unsuccessfully treated patients, only the irradiation dose played a crucial role. Neither defect length nor defect localisation, nor time interval between resection and reconstruction were statistically significant parameters in graft success. Comparing only patients with malignancies, the non-irradiated patients had a higher success rate (77.3%). The nonvaslcularized iliac crest graft seems to be a reasonably reliable treatment option for reconstruction of mandibular defects up to about 5-6 cm in size. Radiotherapy is a strong confounder reducing the success rate. Necessary constraints are sufficient soft tissue conditions. However, primary reconstruction by free flaps (e.g. fibula flap) has a higher success rate in literature and should be preferred whenever possible.