Biomedical subjects

Ulrich Joos

Publications and source records attributed to Ulrich Joos.

At least 19 recordsLinked to original sources

PubMed2007

Cell cycle regulating proteins p21 and p27 in prognosis of oral squamous cell carcinomas.

Cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDKIs), such as p21 and p27, exert a direct control on the cell cycle. p21 and p27 are negative regulators of cyclin-dependent kinases and in this function they are negative check-point regulators of the cell cycle. We therefore aimed to evaluate p21 and p27 expression in oral squamous cell carcinomas (OSSC) to determine the value as a prognostic marker. One hundred and ninety-two patients with histologically proven, surgically treated squamous cell carcinoma of the oral cavity were eligible for the study and investigated for the expression of p21 and p27 by means of tissue microarrays (TMAs). Immunohistochemical screening under identical condition were carried out with antibodies against p21 and p27. Correlations between clinical features and the expression of the respective antibodies were evaluated statistically by Kaplan-Meier curves, log-rank and chi(2) tests. The expression of p21 correlated significantly with an increased prognosis in the log-rang test (p=0.01). No significant correlation was found between the expression of p27 and the overall survival rate. In multivariate Cox analysis, p27 was indicated as independent predictor of survival prognosis in the subgroup of nodal positive carcinomas, p27 positive tumours showed a significantly better survival prognosis (p=0.03). p21 and p27 in carcinoma of oral cavity seem to be predictive parameter in regulation and prognosis of squamous cell carcinomas. A p21 negative subgroup of OSCC may benefit from additional radio or radiochemotherapy.

Adult↗

PubMed2006

Influence of treatment concept, velopharyngoplasty, gender and age on hypernasality in patients with cleft lip, alveolus and palate.

OBJECTIVES: The aim of this study was to analyse cleft patients for hypernasality following velopharyngoplasty. PATIENTS AND METHODS: 95 subjects (43 females, 52 males) with cleft lip, alveolus and palate (4 - 25 years old) were analysed. Forty-three patients were treated according to the current protocol of the Cleft Palate/Craniofacial Malformations Centre of the Department of Cranio-Maxillofacial Surgery in Muenster ('MS+' group) and 52 patients were treated elsewhere according to different protocols. In 19 of the 95 patients a velopharyngoplasty had been performed. Hypernasality was judged perceptually and nasalance data was measured objectively using the NasalView system. RESULTS: Patients of the 'MS+' group showed significantly better results concerning hypernasality and nasalance data. Assessment of hypernasality and nasalance measurement showed no significant differences between subjects following velopharyngoplasty and those who had not had this operation. Gender and age did not correlate with hypernasality either. CONCLUSION: A functionally orientated treatment with early closure of lip and palate ensures optimal velopharyngeal function, optimal oro-nasal balance of resonance, low hypernasality and excellent nasalance data.

Adolescent↗

PubMed2006

Treatment of hemimandibular hyperplasia: the biological basis of condylectomy.

Treatments to correct skeletal deformities in patients with hemimandibular hyperplasia differ, particularly about the age at which the operation is done and the operation itself. To some extent, the differences can be attributed to the unknown biological basis of disease. The aim of the present study was to evaluate clinically the outcome of a rationale for the operation based on condylectomy on the affected side. Histological, radiological, and nuclear methods were used to get a more detailed insight into the reason for the operation. Six patients with hemimandibular hyperplasia were treated by a combined orthodontic-maxillofacial protocol. All patients had the affected joint removed. The histological morphology of each condylar specimen was compared with the bone scintigraphy to try and find a correlation between the methods. The clinical evaluation showed morphological and functional rehabilitation of all six patients. During the 2-year follow-up, all patients had stable symmetrical mandibles with no disturbance of temporomandibular function. Remodelling of the joint and the destruction of the cartilaginous layer was accompanied by much bone scintigraphic activity. We conclude that condylectomy can correct hemimandibular hyperplasia, even in patients with active condylar growth, by removing the underlying disease.

Adult↗

PubMed2006

New paradigm in implant osseointegration.

During the last years, implant dentistry has seen an dramatic increase as a treatment option in oral rehabilitation. This is based to a large extent on scientific advances and clinical improvements in implantology. The extension of indications has broadened the opportunities to rehabilitate patients that were formerly considered to possess restricted indications to place implants. Additionally, patient desires (high aesthetic demands, fast prosthetic rehabilitation) were placed more in focus, resulting in new approaches in implant dentistry. As a result, the scientific and clinical community has reached high standards and at the same time has founded the basis for new opportunities in implantology. The advances are mirrored by a high number of high quality scientific papers, published in conventional and open-access journals. A major shift has thereby been observed in the understanding of implant healing, leading the basis for new implant systems that allow fast rehabilitation protocols. The term osseointegration needs a new understanding since an immediate osseointegration state can be present under distinct conditions.

Dental Implantation, Endosseous↗

PubMed2006

Melanotic neuroectodermal tumor of infancy: systematic review of the literature and presentation of a case.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, distinctive neoplasm of early infancy with rapid expansile growth and a high rate of recurrences. Most commonly the lesion affects the maxilla of infants during the first year of life, but it may also occur in the mandible, skull, brain, epididymis, and other rare locations. The origin of the tumor is the neural crest. The expansive, destructive, and rapid growth of MNTI and its effects on the surrounding tissues are the most obvious clinical features. Microscopically, large polygonal epithelioid cells resembling melanocytes, with variable deposits of melanin, and smaller neuroblast-like round cells characterize MNTI. Malignant transformation may occur. Since the first description in 1918, only 215 cases were reported up to the last extensive review in 1992. The present review supplements another 140 published cases of MNTI up to 2004, including an original case report. Clinical features, treatment alternatives, and follow-up are discussed.

Head and Neck Neoplasms↗

PubMed2006

Biological and biomechanical evaluation of interface reaction at conical screw-type implants.

BACKGROUND: Initial stability of the implant is, in effect, one of the fundamental criteria for obtaining long-term osseointegration. Achieving implant stability depends on the implant-bone relation, the surgical technique and on the microscopic and macroscopic morphology of the implant used. A newly designed parabolic screw-type dental implant system was tested in vivo for early stages of interface reaction at the implant surface. METHODS: A total of 40 implants were placed into the cranial and caudal part of the tibia in eight male Göttinger minipigs. Resonance frequency measurements (RFM) were made on each implant at the time of fixture placement, 7 days and 28 days thereafter in all animals. Block biopsies were harvested 7 and 28 days (four animals each) following surgery. Biomechanical testing, removable torque tests (RTV), resonance frequency analysis; histological and histomorphometric analysis as well as ultrastructural investigations (scanning electron microscopy (SEM)) were performed. RESULTS: Implant stability in respect to the measured RTV and RFM-levels were found to be high after 7 days of implants osseointegration and remained at this level during the experimented course. Additionally, RFM level demonstrated no alteration towards baseline levels during the osseointegration. No significant increase or decrease in the mean RFM (6029 Hz; 6256 Hz and 5885 Hz after 0-, 7- and 28 days) were observed. The removal torque values show after 7 and 28 days no significant difference. SEM analysis demonstrated a direct bone to implant contact over the whole implant surface. The bone-to-implant contact ratio increased from 35.8 +/- 7.2% to 46.3 +/- 17.7% over time (p = 0,146). CONCLUSION: The results of this study indicate primary stability of implants which osseointegrated with an intimate bone contact over the whole length of the implant.

Journal Article↗

PubMed2006

Cytokeratin 8/18 expression indicates a poor prognosis in squamous cell carcinomas of the oral cavity.

BACKGROUND: Intermediary filaments are involved in cell motility and cancer progression. In a variety of organs, the expression of distinct intermediary filaments are associated with patient prognosis. In this study, we seeked to define the prognostic potential of cytokeratin and vimentin expression patterns in squamous cell carcinomas (SCC's) of the oral cavity. METHODS: 308 patients with histologically proven and surgically treated squamous cell carcinomas of the oral cavity were investigated for the immunohistochemical expression of a variety of intermediary filaments including high- and low-molecular weight cytokeratins (Ck's), such as Ck 5/6, Ck 8/18, Ck 1, CK 10, Ck 14, Ck 19 and vimentin, using the tissue microarray technique. Correlations between clinical features and the expression of Cytokeratins and vimentin were evaluated statistically by Kaplan-Meier curves and multivariate Cox regression analysis. RESULTS: The expression of Ck 8/18 and Ck 19 were overall significantly correlated with a poor clinical prognosis (Ck 8/18 p = 0.04; Ck19 p < 0.01). These findings could also be reproduced for Ck 8/18 in primary nodal-negative SCC's and held true in multivariate-analysis. No significant correlation with patient prognosis could be found for the expression of the other cytokeratins and for vimentin. CONCLUSION: The expression of Ck 8/18 in SCC's of the oral cavity is an independent prognostic marker and indicates a decreased overall and progression free survival. These results provide an extended knowledge about the role of intermediary filament expression patterns in SCC's.

Adult↗

PubMed2006

Central giant cell granuloma of the jaws: a clinical, radiologic, and histopathologic study of 26 cases.

The clinical behavior of central giant cell granuloma (CGCG) of the jaws is variable and difficult to predict. Clinical data and follow-up information of 26 patients with CGCG were analyzed. Histologic features were correlated with the clinical course of the disease. In 16 patients the CGCGs were asymptomatic; 10 lesions presented with aggressive growth, pain, massive swelling, root resorption, cortical perforation, and/or recurrence. These patients were younger and the lesions were larger than in the nonaggressive group. The histomorphometric analysis proved a significant increase in large giant cells, fractional surface area, and mitotic activity in aggressive CGCG lesions. Immunohistologic investigation (Ki-67 and p53 stain) revealed no significant differences. After surgical treatment, 3 patients with aggressive lesions developed a recurrence. The data show that clinical and histomorphometric features may be reliable indicators for the differentiation between aggressive and nonaggressive CGCG. This should be accounted for to improve the individual planning of the treatment and follow-up.

Adolescent↗

PubMed2005

Strain driven fast osseointegration of implants.

BACKGROUND: Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved. METHODS: We examined the bone reaction around non- and immediately loaded dental implants inserted in the mandible of mature minipigs during the presently assumed time for osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide surface, allowing direct bone contact after insertion. The external geometry was designed according to finite element analysis: the calculation showed that physiological amplitudes of strain (500-3,000 ustrain) generated through mastication were homogenously distributed in peri-implant bone. The strain-energy density (SED) rate under assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak dislocations were lower then nm. RESULTS: Bone was in direct contact to the implant surface (bone/implant contact rate 90%) from day one of implant insertion, as quantified by undecalcified histological sections. This effect was substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond during the experimental period of either control or experimental animals, indicating that immediate load had no adverse effect on bone structure in peri-implant bone. CONCLUSION: In terms of clinical relevance, the load related bone reaction at the implant interface may in combination with substrate effects be responsible for an immediate osseointegration state.

Dental Implants↗

PubMed2005

Vascular basis of mucosal color.

BACKGROUND: Besides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics. METHODS: Standardized photographs of defined areas of the alveolar gingiva in operated and non-operated patients were taken and assigned to groups with same characteristics after color comparisons. In addition, histologic and immunohistologic analyses of gingival specimens were performed for qualitative and quantitative assessment of vessels and vascularization. Finally, colors and number of vessels were correlated. RESULTS: Our results demonstrated three different constellations of colors of the alveolar gingiva in healthy patients. The operated patients could not be grouped because of disparate depiction. There was a clear correlation between color and vessel number in the alveolar gingiva. CONCLUSION: Our investigations revealed the connections between vascularization and gingival color. Recommendations for specific change or even selection of colors based on the results cannot be given, but the importance of vascularly based incision lines was demonstrated.

Color↗

PubMed2005

HIF1-alpha overexpression indicates a good prognosis in early stage squamous cell carcinomas of the oral floor.

BACKGROUND: Hypoxia-inducible factor 1 (HIF-1) is a transcription factor, which plays a central role in biologic processes under hypoxic conditions, especially concerning tumour angiogenesis. HIF-1alpha is the relevant, oxygen-dependent subunit and its overexpression has been associated with a poor prognosis in a variety of malignant tumours. Therefore, HIF-1alpha expression in early stage oral carcinomas was evaluated in relation to established clinico-pathological features in order to determine its value as a prognostic marker. METHODS: 85 patients with histologically proven surgically treated T1/2 squamous cell carcinoma (SCC) of the oral floor were eligible for the study. Tumor specimens were investigated by means of tissue micro arrays (TMAs) and immunohistochemistry for the expression of HIF-1. Correlations between clinical features and the expression of HIF-1 were evaluated by Kaplan-Meier curves, log-rank tests and multivariate Cox regression analysis. RESULTS: HIF-1alpha was frequently overexpressed in a probably non-hypoxia related fashion. The expression of HIF-1alpha was related with a significantly improved 5-year survival rate (p < 0.01) and a significantly increased disease free period (p = 0.01) independent from nodal status and tumour size. In primary node negative T1/T2 SCC of the oral floor, absence of HIF-1alpha expression specified a subgroup of high-risk patients (p < 0.05). CONCLUSION: HIF-1alpha overexpression is an indicator of favourable prognosis in T1 and T2 SCC of the oral floor. Node negative patients lacking HIF-1alpha expression may therefore be considered for adjuvant radiotherapy.

Adult↗

PubMed2005

Relationship between lower wisdom tooth position and cyst development, deep abscess formation and mandibular angle fracture.

AIM: There is an ongoing controversy about indications for prophylactic removal of third molars. The purpose of this retrospective study was to clarify the risk of preservation of lower third molars. MATERIAL AND METHOD: In a 5-year period, 316 patients were registered who had received in-patient treatment for deep abscess formation, cyst formation or mandibular angle fracture in relation to lower third molars. A radiological analysis (panoramic radiographs) was performed to determine whether major pathological changes associated with lower wisdom teeth are related to their position. Third molar positions were studied in this in-patient group and in an out-patient group. The latter consisted of 300 consecutive patients with prophylactically removed impacted third molars without any pathology. The relationship between the positions and the different pathological changes associated with impacted lower wisdom teeth was analysed statistically using a new 'position score'. RESULTS: The study revealed that the highest 'position scores' corresponding to a leading aberrant position correlated significantly with cyst formation. Lower scores corresponding to moderately aberrant or slightly irregular position were found with angle fractures, abscess formation, and in the control group as a whole. CONCLUSION: This study indicates that prophylactic third molar surgery for teeth with high and strongly elevated 'position scores' is appropriate in order to prevent cyst formation or mandibular angle fractures in a population at risk for facial trauma. In addition to other factors, 'position score' data could be useful for development of a model for predicting severe complications related to (removal of) impacted lower wisdom teeth.

Abscess↗

PubMed2005

Surgical treatment of persistent macrocheilia in patients with Melkersson-Rosenthal syndrome and cheilitis granulomatosa.

BACKGROUND: Various conservative methods for treatment of labial swelling in patients with cheilitis granulomatosa have been attempted, often with only moderate success and sometimes with persistent disfiguring lip swelling. Severe macrocheilia can produce an unaesthetic facial deformity associated with functional disturbances. In patients with persistent macrocheilia, reduction cheiloplasty with excision of excess tissue may be indicated when conservative treatment has proven ineffective in reducing swelling but may have been successful in stabilizing disease. OBJECTIVE: To evaluate long-term results after reduction cheiloplasty in patients with macrocheilia caused by Melkersson-Rosenthal syndrome or cheilitis granulomatosa. DESIGN: Follow-up study in 7 patients with severe persisting macrocheilia, including 3 patients with Melkersson-Rosenthal syndrome and 4 patients with cheilitis granulomatosa in a stable state of disease, treated by reduction cheiloplasty at our hospital between January 1, 1987, and December 31, 2002. Preoperative and postoperative medical histories were obtained, and criteria for the success of surgical treatment were evaluated by clinical examination. Different techniques of reduction cheiloplasty are described and demonstrated in representative cases of severe macrocheilia. RESULTS: Surgical treatment in all 7 patients showed satisfying aesthetic and functional outcomes that persisted throughout follow-up (median follow-up, 6.5 years). CONCLUSIONS: Reduction cheiloplasty is an effective method to correct persistent macrocheilia and improve lip aesthetics in patients with Melkersson-Rosenthal syndrome or granulomatous cheilitis in the persistent state of disease. With careful planning, proper sequencing of treatment, and proficiency in the various surgical techniques, optimal results can be achieved.

Adolescent↗

PubMed2005

VEGF-activated angiogenesis during bone regeneration.

PURPOSE: The aim of this study was to investigate the influence of controlled release of recombinant human vascular endothelial growth factor (rhVEGF(165)) on angiogenesis and osteogenesis in a mandibular defect model. MATERIAL AND METHODS: A total of 56 rabbits were operated and bicortical holes were placed at the lower border of the mandible. The defects were filled with type-I collagen, with collagen complexed with 0.8 mug rhVEGF(165), or left without any filling. After 3, 7, 14, and 28 days, specimens were taken and histologic, histomorphometric, and immunohistologic analyses were carried out concerning number of vessels, cross-sectional area of vessels, and area and density of regenerated bone. RESULTS: Bone formation occurred in a typical centripetal direction and showed all stages of bone regeneration and maturation. New vessel formation took place in front of the osteogenic regeneration front. The number of vessels increased in all groups until day 14, followed by physiologic regression in the control groups as opposed to persisting high numbers in the study group. The area of newly formed bone showed no difference to the control group but the density of regenerated bone was significantly higher in the study group. CONCLUSION: Blood vessels are an important component of bone formation and maintenance and the bone tissue differentiation is related to the local presence of blood vessels. The activation of angiogenesis using rhVEGF(165) leads to more intensive angiogenesis and bone regeneration.

Animals↗

PubMed2005

Agressive fibromatosis involving the mandible--case report and review of the literature.

BACKGROUND: Aggressive fibromatosis (AF) involving the mandible is rare, and surgery is often complicated by a high recurrence rate. CASE REPORT: A 4-year-old boy was referred because of a fast growing painless mass which involved the entire left angle of the mandible. Excisional biopsy revealed AF, and local excision of the tumor was performed. Six months after surgery a recurrence was detected. The tumor was determined to be unresectable and the boy was treated with low-dose chemotherapy including methotrexate and vinblastine for 1 year. With combined chemotherapy and surgical debulking, mutilating surgical resection will be delayed as long as possible or until completion of facial growth. CONCLUSION: According to the literature, surgery is the most common treatment of AF in the head and neck region. However, particularly in children, alternative modes of therapy must be considered because of the high recurrence rate and to avoid mutilating operations.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Biological and biomechanical evaluation of bone remodelling and implant stability after using an osteotome technique.

The influence of the osteotome technique on the osseointegration and biomechanical behaviour of cylinder implants (SLA, ITI was compared with conventional preparation of the implant site in an animal model. A total of 56 implants were placed in the cranial and caudal tibia condyle of six Gottinger minipigs. The implant site was prepared either by the conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Resonance frequency measurements (RFMs) were made on each implant at the time of fixture placement and at the time of scarification. Half of the minipigs were sacrificed 7 days and 28 days after implant placement and the implants were removed with the surrounding bone. Bone tissue responses were evaluated by histological analysis and removal torque testing. For histological evaluation 30-50 microm-thick ground sections were examined. Biomechanical testing revealed a significantly higher stability of implants in the control group (A) than in the experimental group (B) (P = 0.004) at day 7. After 28 days implant stability in the control group remained significant higher (47%) than those of group B (P > 0.001). RFM demonstrated no significant difference between both groups and during the experimental course. Histological analysis demonstrated fractured trabeculae in peri-implant bone in the experimental group at day 7, while they were not posed at day 28. We conclude that the decreased implant stability by using the osteotome technique is based on microfractures in peri-implant bone.

Animals↗

PubMed2005

Interface reaction at dental implants inserted in condensed bone.

PURPOSE: The influence of the osteotome technique on the interface reaction of cylinder implants (SLA, ITI) was compared with the interface reaction of conventional implant insertion in an animal model. MATERIAL AND METHODS: A total of 64 implants were placed in the cranial and caudal tibia of 8 Göttinger minipigs. The implant site was prepared either by a conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Bone tissue responses were evaluated by histomorphometry, fluorescence microscopy and scanning electron microscopy after 7 and 28 days of osseointegration. RESULTS: The average initial (7 days) bone-to-implant contact ratio was not statistically significantly different for the osteotome technique (35.88+/-2.94%) than for the control group (43.78+/-3.39%, P<0.095). After 28 days, the bone-to-implant contact ratio became statistically significantly higher when implants were inserted by conventional preparation (44.81+/-3.07% (group B), 63.47+/-4.87% (group A), P=0.003). Whereas fluorescence and immunhistologic examination revealed new bone formation with osteocalcin deposition directly at the implant surface in both groups, the extent of direct bone/implant contact was enhanced in conventionally prepared implant sites. SEM analysis confirmed an intimate bone to implant bond without fibrous tissue formation in places of direct contact at an ultrastructured level. CONCLUSION: Implant placement in conventionally prepared implantation sites is accompanied by an improved interface formation at an early stage of implantation.

Animals↗

PubMed2005

Incision design in implant dentistry based on vascularization of the mucosa.

OBJECTIVES: The delivery of an adequate amount of blood to the tissue capillaries for normal functioning of the organ is the primary purpose of the vascular system. Preserving the viability of the soft tissue segment depends on the soft tissue incision being properly designed in order to prevent impairment of the circulation. A knowledge of the course of the vessels as well as of their supply area are crucial to the decision of the incision. The aim of this study was to visualize the course of the arteries using different techniques, to perform macroscopic- and microscopic analyses, and to develop recommendations for incisions in implant dentistry. MATERIAL AND METHODS: The vascular systems of seven edentulous human cadavers were flushed out and filled with either red-colored rubber bond or Indian ink and formalin mixture. After fixation a macroscopic preparation was performed to reveal the course, distribution and supply area of the major vessels. In the area of the edentulous alveolar ridge specimens of the mucosa were taken and analyzed microscopically. RESULTS: The analyses revealed the major features of mucosal vascularization. The main course of the supplying arteries is from posterior to anterior, main vessels run parallel to the alveolar ridge in the vestibulum and the crestal area of the edentulous alveolar ridge is covered by a avascular zone with no anastomoses crossing the alveolar ridge. CONCLUSION: The results suggest midline incisions on the alveolar ridge, marginal incisions in dentated areas, releasing incisions only at the anterior border of the entire incision line, and avoidance of incisions crossing the alveolar ridge.

Cadaver↗