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Biomedical subjects

D Riediger

Publications and source records attributed to D Riediger.

At least 19 recordsLinked to original sources
PubMed2004

[Chorioallantoic membrane of fertilized avian eggs as a substrate for assessment of cancerous invasiveness].

PURPOSE: Invasiveness is a characteristic feature of malignant tumors considerably determining the prognosis of affected patients. For assessment, apart from in vitro procedures with limited validity, tests on animal models have been established which certainly should be replaced by alternative methods whenever possible. The chorioallantoic membrane (CAM) of fertilized avian eggs represents an epithelial-lined membrane composed of all three blastodermic germ layers. In an "in ovo" assay cancer cells can be applied to this membrane after sinking (CAM assay). Tumor growth and invasiveness should be monitored in succession. MATERIAL AND METHODS: Hybrid chorionic carcinoma trophoblast cells were expanded in cell culture and spread over the CAM of hen's eggs after sinking followed by further incubation at 37 degrees C. The growth and development of the tumors were assessed macroscopically and finally (immuno-)histologically. Additionally, cytokeratin 19 was determined by enzyme-linked immunosorbent assay following homogenization of the tumor cells. RESULTS. Macroscopically, development of solid tumors was evident. Histological and immunohistochemical analysis revealed initial intraepithelial followed by cone-shaped infiltration of the CAM by the tumor cells. Tumor growth could be correlated with quantitative cytokeratin 19 measurements. CONCLUSIONS: Histomorphological appearance of the tumors was comparable with those results achieved in an immunodeficient mouse model. In addition, the CAM assay can be used for qualitative assessment of invasiveness of malignant tumors and yields quantitative results regarding growth kinetics. In contrast to conventional animal models, there is no need for official approval. Finally, this method is economical and facilitates processing many cases within a short time.

Animals↗
PubMed2004

The quantification of angiogenesis in relation to metastasis in oral cancer: a review.

Tumours need vessels to grow into clinically significant dimensions, and to metastasize. Varying results have been reported for the relation between angiogenic activity in oral carcinomas, and the occurrence of metastasis. Quantification of microvessels in tissue sections is mostly used to assess angiogenesis, but appears subject to biases as reflected in contradicting reports. Especially the choice of immunohistochemical staining technique appears pivotal. Although microvessel density measurements (MVD) appear promising for other tumour types, in oral carcinomas no unambiguous relation could be established. Furthermore, MVD assessment appears more elaborate than expected. New, more time efficient techniques may replace MVD as we know it.

Animals↗
PubMed2002

FE-simulation of bone modeling around an implant in the mandible in two-stage versus one-stage implantation.

On the basis of a FE-model for bone modeling which takes into account bone apposition and resorption as well as revascularization, the ossification process of the repair zone around a dental implant in the mandible is studied for two alternatives. The conventional two-stage implantation method consists of a healing phase (no direct loading of the implant) and a functional phase (direct loading). In the recently applied one-stage method the healing phase is omitted (early loading). The presented simulations show that both processes finally lead to the same degree of ossification of the repair zone. However, the relative displacements and rotations of the implant are considerably larger in the one-stage process and might therefore possibly lead to a violation of the bond between implant and bone.

Bone Remodeling↗
PubMed2001

Aesthetic and functional results of harvesting radial forearm flap, especially with regard to hand function.

There is controversy in the literature regarding donor site morbidity following radial forearm flap harvesting. The aim of this study was to verify possible functional and aesthetic impairments at the donor site. Thirty-five patients who underwent maxillofacial reconstruction using radial forearm flap were asked to give their subjective assessment of the aesthetic outcome at the donor site and of postoperative hand function. They were also examined for trophic status; cold intolerance and tactile sensitivity of split-thickness skin graft, palm and finger pads; grip strength and finger-to-thumb pinch strength; range of movement for the wrist and finger joints; as well as functional hand testing. Slight impairments regarding hand strength and mobility were observed. However, due to their small extent they were of no clinical relevance, as shown by 85.7% of our patients displaying optimal functional hand testing values (80-100%), and 88.6% giving a positive subjective assessment (80-100%) of postoperative vs preoperative hand function. The results show that donor site morbidity following radial forearm flap harvesting is low.

Cold Temperature↗
PubMed2000

[Microsurgical soft tissue transplantation].

Since the first microsurgical transplantation in 1971, numerous tissue regions which are appropriate for transplantation have been researched. In particular, cutaneous or fasciocutaneous and musculocutaneous, as well as jejunum and fat tissue transplants are involved. In maxillofacial surgery, predominantly radial underarm flaps and scapular or parascapular flaps are used. The indications for both kinds of flaps range from intraoral defects, including tongue defects, and defects after maxillary resection, to defects following tumor resection of the face. In the framework of radical tumor surgery involving regional lymph drainage ducts, the musculus latissimus dorsi flaps and the musculus rectus abdominis flaps are indicated for the covering of deep-reaching defects. Jejunum transplants are appropriate mainly in the region of the soft palate and pharyngeal walls. Free microsurgical fat tissue transplants are indicated for extensive subcutaneous defects. The technique of lifting transplants and transferring them is so refined that results are comparable to those attained by using conventional flaps.

Humans↗
PubMed1999

[Microsurgical anastomosis of the bone transplant as implant site in the maxilla].

A total of 27 vascularized iliac crest segments and four vascularized scapula transplants were transferred to achieve masticatory rehabilitation in 31 patients suffering from extensive maxillary defects; 83 Brånemark implants and 16 IMZ implants were inserted 4-8 months after the bone transplantation. The implants were uncovered 6-8 months after insertion. All patients were provided with a bar-fixed, removable prosthesis. At an average insertion period of 4.5 years, the implant loss rate was 18.8%. The effectiveness of a combination of microsurgical bone transplantation and implantation in treating serious maxillary defects is thus demonstrated.

Alveolar Ridge Augmentation↗
PubMed1998

[Correlation of odontogenic soft tissue infection and thermal effects with special reference to temperature sense. Statistical analysis of 2,111 patients].

A possible correlation between the thermal effects of the weather and the frequency of odontogenic soft-tissue infections was investigated with special regard to the so-called felt temperature (gT). Clinical data of 2111 patients of the years 1992-1996 in whom an incision was made because of an odontogenic soft-tissue infection were evaluated retrospectively and correlated to meteorological data for Aachen, collected or calculated by the "Deutsche Wetterdienst". In order to describe the thermal exchange between the human organism and the surroundings in a satisfactory way, the gT was chosen. The gT is a complexly calculated meteorological parameter which allows physiologically adequate estimation of the thermic surroundings of humans. Over the whole study time there was no impressive correlation between course and changing of the gT and the frequency of odontogenic soft-tissue infections. This result agrees with our finding that there was no seasonal accumulation of odontogenic soft-tissue infections over the year in Aachen. Nevertheless, there was a statistically significant negative correlation between values or weighted changes of the gT and the frequency of abscess and/or infiltration in the winter and less in springtime. A similar statistically significant correlation could not be found for summer or autumn.

Adolescent↗
PubMed1994

High resolution computed tomography of the inferior alveolar and lingual nerves.

Coronal and axial high resolution computed tomography of the mandible extends facilities in dentoalveolar surgery. Preoperatively the relationship between the mandibular canal and the roots of deeply displaced third molars can be determined precisely. After surgical removal of lower wisdom teeth iatrogenic defects of the lingual cortical bone can be detected. The additional information obtained when compared with conventional radiographs is demonstrated in case descriptions. Indications for this technique, radiation exposure and implications for surgery are discussed.

Adult↗
PubMed1994

Measurement of mandibular bone density after iliac crest grafting.

Nonvascularized and microsurgically revascularized iliac bone grafts used for mandibular reconstruction behave differently during healing. Quantitative computer tomography (QCT) was used to investigate these differences with respect to mineralization and macrostructure of the grafts after a period of adequate functional loading. It was shown that in nonvascularized grafts, reactive sclerosis occurs, as a sign of an irregularly reparative metaplastic process and mineralization. In comparison with the intact iliac crest, the bone density of the graft was markedly increased. The microsurgically revascularized grafts, however, showed retention of structural differentiation into homogeneous cancellous bone, and a smoothly demarcated cortex with essentially unchanged bone density. Possible explanations of these differences are discussed.

Absorptiometry, Photon↗
PubMed1993

Quantitative computed tomography--a new method in the assessment of autologous augmentation of the mandible.

Following autologous alveolar ridge augmentation with microsurgically revascularized iliac crest segments, quantitative computed tomography was used for the first time to examine mandible and graft. The results are shown by the example of 2 cases. Sufficient mineralization of the graft could be demonstrated macromorphologically as well as by means of bone densitometry. Insignificant variations of the grade of mineralization in the separate segments of the graft may exist, caused by the operation. There were no distinct reactive scleroses indicating an extensive process of transformation and adaptation.

Alveolar Ridge Augmentation↗
PubMed1992

Long-term follow-up of subcondylar fractures in children by electronic computer-assisted recording of condylar movements.

Twenty-eight patients have been followed up for an average of 15.1 years after uni- or bilateral subcondylar fractures sustained during their growth period. The conservative treatment, using orovestibular plates, has been evaluated with special reference to clinical, radiographic and functional parameters. TMJ function was tested using an electronic computer-assisted recording system. Condylar remodelling occurred in only about half of the individuals. Nevertheless, because of the good esthetic and functional results there seems to be no indication for operative reduction of the displaced condyle during the growth period.

Adolescent↗
PubMed1992

Esthesioneuroblastoma. A case report.

Esthesioneuroblastoma (ENB) is a rare neuroectodermal tumor originating from the olfactory mucosa and therefore usually arising from the nasopharynx. A case in which the diagnosis was made in connection with the extraction of a tooth is reported. Manifestation in the dento-alveolar region is unusual for this tumor. The case presented is also unusual in that the classic symptoms of ENB were not present. Diagnosis, classification, and therapy are described with a brief review of the literature.

Female↗
PubMed1992

[Changes in the condyle path following fractures with dislocation of the maxilla].

In spite of rigid internal fixation with miniplates after midfacial fractures, dislocation of the previously mobilized fragment in the dorsal direction is conceivable. Thus, the mandible would be forced into a dorsal position over the occlusion. As a result, changes of the condyle paths, such as limitations or deviations from the normal, would be possible. Six patients, who had sustained midfacial fractures with mobilization or dislocation of the maxilla, were followed up. The condyle paths were recorded at the earliest time possible after rigid internal fixation and after removal of the miniplates. We used the electronic computer-assisted registration system (ECRS), which allows three-dimensional registration without occlusal interferences. The patterns of the TMJ movements were not impaired, arguing against the dorsal transposition of the maxilla. The extent of the movements during the first postoperative weeks, however, was significantly reduced in some cases, even if intermaxillary fixation was not carried out. In our opinion, this is due to the periarticular infiltration and a varying elasticity of the articular capsule in different directions.

Adult↗
PubMed1992

[Nerve injuries following nerve blocking in the pterygomandibular space].

In a prospective study 506 patients with nerve blocks in the pterygomandibular space were examined before and 3-7 days after local anaesthesia. Clinical neurosensory testing including two-point discrimination revealed no differences between the neurological status before and after injection. Between December 1987 and April 1991 8 patients with 9 nerve injuries (lingual nerve n = 8, inferior alveolar nerve n = 1) after nerve blocks in the pterygomandibular space were treated. In addition to hypaesthesia or anaesthesia 5 out of 8 patients with injection damages of the lingual nerve suffered from a loss of taste sensations. Only 2 of the total of 9 nerve lesions showed a complete recovery of the neurological deficit. One patient with a persistent pain syndrome of the lingual nerve after an injection damage underwent partial nerve resection and microsurgical reconstruction after intraoperative monitoring of somatosensitive-evoced-potentials. The operation was successful for only a few weeks, afterwards a relapse of the pain syndrome took place.

Anesthesia, Dental↗