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Biomedical subjects

R Fuhrmann

Publications and source records attributed to R Fuhrmann.

At least 37 records · Page 2Linked to original sources
PubMed1996

Integration of three-dimensional cephalometry and 3D-skull models in combined orthodontic/surgical treatment planning.

In 15 adult patients with severe dentomaxillofacial deformities we integrated 3-dimensional cephalometry and 3D-model surgery with individually milled or stereolithographically built skull models in our combined orthodontic/surgical diagnosis and treatment planning. After the generation of contiguous axial CT-scans the CT data sets were transferred to a commonly used computing system (IBM-PC) to reconstruct 3D-images from any point of view. After the definition of measurement points, distances and angles at the skin and bone surface a 3-dimensional cephalometric analysis could be performed directly in the 3D-objects on the monitor. This allows a quantitative assessment of skeletal asymmetries. The transfer of CT data to life-size 3D-skull models and replacement of imprecise dental arches by dental casts different orthodontic and surgical treatment concepts could be evaluated. The 3D-model surgery represents a new quality of treatment prediction in the individual dentomaxillofacial morphology. The orthodontic set-up and 3D-model surgery permit a verification of the feasibility of the most suitable mobilization and placement of bone segments. The clinical treatment sequences indicated that the integration of 3-dimensional cephalometry and 3D-model surgery in patients with severe asymmetric dentomaxillofacial deformities allowed a higher precision of diagnosis and treatment planning.

Adult↗
PubMed1996

Three-dimensional interpretation of periodontal lesions and remodeling during orthodontic treatment. Part III.

In a clinical study of 11 adult patients, HR-CT-examinations were performed before or during and after orthodontic treatment with fixed appliances. The treatment period between the first and second CT-scanning varied from 12 to 24 months. Comparison of the first and second CT-examination permits three-dimensional evaluation of osteoclastic and osteoblastic alveolar remodeling. The incidence of periodontal lesions such as bone dehiscences, fenestrations and root resorptions was assessed in relation to the initial periodontal situation and the orthodontic treatment concept. Anatomical risks were a small alveolar process, thin buccal or lingual bone plates, eccentric position of teeth, basally extended maxillary sinus and progressive alveolar bone loss. Therapeutic risks were uncontrolled sagittal or vertical movements of incisors and cortical or intermaxillary anchorage preparation. CT-scanning of the alveolar process during orthodontic treatment with HR-CT allows three-dimensional interpretation of the alveolar osteodynamics, especially the development and repair of orthodontically induced bone dehiscences in relation to tooth movement.

Adolescent↗
PubMed1996

Three-dimensional interpretation of alveolar bone dehiscences. An anatomical-radiological study--Part I.

In an anatomical-radiological in-vitro study dental radiographs were compared with axial, sagittal and coronal CT-scans, with respect to the identification and quantitative assessment of bone dehiscences and the buccal or lingual bone plates over the roots of the teeth. After removal of soft tissue and metallic restorations in 16 dentate jaw specimens, 60 lingual or buccal defects of different dimensions were artificially created over the roots. None of the defects could be identified on conventional dental radiographs. In contrast, 42 of the 60 (70%) artificial defects were identified in the CT-scans. Identification and demarcation of the facial/lingual bone plate depends on the orientation of the CT-scanning, the visibility of the periodontal ligament space, the dimension of the defect, and the thickness and histological structure of the adjacent bone. A visible periodontal ligament space improves the measuring accuracy of buccal or lingual bone plates up to 0.2 mm.

Alveolar Bone Loss↗
PubMed1996

Three-dimensional interpretation of labiolingual bone width of the lower incisors. Part II.

For quantitative evaluation of the different imaging quality of cephalograms and computed tomography in the region of the lower incisors, the macroscopic and histological findings of specimens were compared with the corresponding radiological findings. After removal of the soft tissue from 11 mandibular dentate segments, 15 artificial bone defects of different dimensions were produced in the region of the lower incisors. In comparison with the microscopic jaw measurements, the mean labiolingual diameter of the frontal alveolar process of the single incisors was overestimated in the cephalograms by 0.3 to 1.2 mm. Most of the anatomical-radiological correlations of the cephalometric measurements was insignificant. Individual metric assessment of the labiolingual bone width or of the facial/lingual cortical bone plates or the identification of the artificial defects of lower incisors in the cephalograms were generally not possible. In the CT-images the mean labiolingual diameter of the frontal alveolar process of the single incisors was overestimated by 0.1 to 0.5 mm, but the correlations were highly significant. The facial/lingual cortical bone plates of the lower incisors were evaluated and measured in the CT-scans. Thirteen of 15 artificial bone defects (80%) were identified in the CT-scans. CT-scanning is the only imaging technique offering three-dimensional quantitative evaluation of the labiolingual alveolar bone width and the facial/lingual cortical bone plates.

Alveolar Process↗
PubMed1996

Concept and development of a measuring system for in vivo recording of orthodontically applied forces and torques in the multiband technique. Part I.

The cause of tooth movement with a multiband or multibracket appliance is the force system in the bracket, which is generated by an archwire and transmitted by a bracket to the respective tooth. Continuous arch wires are, from the biomechanical point of view, a statically multiply undetermined system. Quantitative determination of the forces and torques acting at the individual teeth, and thus observance of a non-critical level of applied forces, is therefore extremely problematic in practice, the force is applied by the orthodontist more or less "intuitively" on the basis of recommendations evolved in theory and in vitro. The measuring technique presented in this paper is designed to permit these force systems to be recorded in vivo for the first time, allowing account to be taken of the individual situation "tooth-periodontium-bone". Evolvement of an appropriate measuring principle was followed by development of the individual components of the measuring system. The results of the subsequent initial in vitro test series offer the prospect of successful clinical application.

Dental Stress Analysis↗
PubMed1995

[The radiological-histological interpretation of artificial bone defects of the basal maxillary sinus cortical bone].

Twenty-one lateral maxilla specimens were taken from human autopsy specimens and after removing soft tissue 40 differing tooth roots of 23 molars and premolars were ground to create large artificial bone defects in the supporting cortical bone of the basal maxillary sinus. Conventional dental radiographs and axial CT scans were then compared with the macroscopic findings in relation to the identification of the artificial bone defects. Next the jaw segments were dissected analogous to the axial CT scan and corresponding histological microsections were prepared for a radiological-histological comparison. None of the artificial bone defects were identifiable on the dental radiographs. In comparison to this, however, cortical bone defects were identifiable on 25 tooth roots (62.5%) on the CT scans. The lateral demarcation of the antral defects on the CT scans depends on the setting of the tooth root, on the adjacent bone morphology, and on the visualization of the periodontal ligament space. If the periodontal space shows up on the CT images, it becomes possible to demarcate of a thin, 0.2 to 0.5 mm, cortical bone layer of the basal maxillary sinus.

Bicuspid↗
PubMed1995

Diagnosis of infra-alveolar bony lesions in the dentate alveolar process with high-resolution computed tomography. Experimental results.

RATIONALE AND OBJECTIVES: Conventional intraoral radiography was compared with axial computed tomography (CT) scans for identification and classification of bony pockets in dentate jaw segments. METHODS: Fifty-five artificial bone defects were produced in six dentate jaw segments. The jaws were examined radiographically using a dental x-ray unit and by contiguous axial CT scans. Identification, classification, and vertical depth of the bony defects were compared among the specimens, radiographs, and CT scans. RESULTS: On the intraoral radiographs, 38 (69%) bony lesions were identified, and the vertical depth was underestimated by a mean of 2.2 mm, compared with the objective measurements on the jaws. In contrast, all artificial bony lesions (100%) were identified and classified on the axial CT scans and the vertical depth was underestimated by a mean of 0.5 mm. CONCLUSIONS: High-resolution CT improves the identification and metric assessment of the vertical dimension of infra-alveolar bony lesions compared with conventional intraoral x-ray films and allows these defects to be classified according to the number of existing walls into one-walled, two-walled, and three-walled bony pockets. In patients with apically extended metallic restorations, the image quality could be limited by artifacts.

Alveolar Bone Loss↗
PubMed1993

[3-dimensional imaging diagnosis with a personal computer].

During orthodontic and surgical treatment planning of severe dentofacial deformities, 3D-reconstruction imaging from axial CT-scans could previously only be handled by high-capacity computers in radiological centers. The improved performance of personal computers enables CT-scan data be transferred to a standardized MS-DOS computer. The presented software displays a 3D-reconstruction and secondary reformed vertical slices within seconds on the monitor. The symmetry of the 3D-objects can be evaluated with a freely definable grid. The distance between two different landmarks in the 3D-image can also be measured. Various tools for data manipulation permit surgical treatment simulation. The advantage of 3D-imaging with a personal computer is the user-specified orientation of the software. The off-line computing system permits a high degree of flexibility independent of any computing center.

Cephalometry↗
PubMed1993

[3-dimensional computed tomographic imaging of the dentate alveolar ridge. A radiological-histological comparison].

Human bone segments of the toothed jaw with ten upper and ten lower teeth were scanned by high resolution computer tomography in continuous parallel axial and coronal slices (Somaton plus, Siemens). In both directions scanning was performed to 1 mm and 2 mm thicknesses and at 1 mm and 2 mm intervals. The jaw segments were dissected analogously in 1 mm thick slices. Contact films of the corresponding bone segments were exposed and then histological thin sections prepared. The statistical comparison between the CT exposures, the contact films, and the histological sections revealed an average absolute deviation of 0.3 to 0.5 mm with the axial CT exposures and a deviation of 0.3 to 1.6 mm with the coronal sections. It was possible to interpret in a quantitatively detailed manner the teeth and surrounding bone compacta up to a 0.5 mm minimum bone thickness. Computer-enhanced secondary reconstructions made possible an additional qualitative interpretation of the bone upper surface and the freely definable planes. Continuous parallel axial CT slices enable an interference-free, proportionally accurate representation of the apical base, the periodontal bone structure, and the radice-root topography.

Adult↗
PubMed1993

[Video-supported dynamic B-mode sonography of tongue function during swallowing].

A dynamic B-mode ultrasound technique supported by video recording was employed on 51 patients between the ages of six and 45 years for the purpose of imaging the tongue at rest and in motion during swallowing. All patients either in their case histories or at clinical examination demonstrated orofacial dysfunction of the tongue or an abnormal oral phase during swallowing. The ultrasound sequences of a 5 MHz sector scanner (100 degrees, 30 images/sec) were videotaped for the purpose of analyzing the sagittal and vertical movement components during swallowing. The sagittal sector scan revealed a visceral swallowing pattern in 21 patients. Noticeably often patients with an Angle class III malocclusion also displayed an abnormal swallowing pattern. Ultrasound scanning in the coronal and sagittal plane is a noninvasive imaging technique free of the biological risks associated with radiation. The dynamic ultrasound technique may be employed for early detection and diagnosis of tongue discoordinations and is especially to be recommended for the objective imaging and identification of tongue thrust in orthodontic patients.

Adolescent↗
PubMed1993

[The digital reprocessing of under- and overexposed x-ray films with a personal computer].

An image processing work station for digitalizing and interactively manipulating under- and overexposed X-rays was set up by adding modules to an IBM compatible personal computer. Overexposed X-rays can be qualitatively enhanced by means of controlled manipulation of contrast and brightness and by means of the use of various digital filtering techniques. With underexposed X-rays an equalized grey scale can be achieved by means of regulating contrast and brightness. Digital filtering is not required. To assure a high degree of anatomical detail (periodontal ligament) in the digitalized image a maximum pixel of 0.1 mm was defined as a qualitative norm. Since in every digitalization process resolution is diminished, it proved best to select for interactive manipulation out of the total image only the section of interest.

Filtration↗
PubMed1993

[The significance of gingival invagination in orthodontic space closure. A clinico-radiological study].

23 extraction sites from group I (14 patients, average age 25 years, two months) which exhibited gingival invagination during orthodontic space closure with fixed appliances were compared with an equal number of extraction sites without gingival invaginations from group II patients (13 patients, average age 22 years, three months). Clinical analysis criteria were: interdental distance, treatment period, depth of gingival invagination, plaque index, gingival index, and probing depth. The marginal bone level at the teeth and the interdental bone height were measured by radiographs. Comparisons of the group I information with the information from group II obtained by applying the same analysis criteria revealed that, given proper oral hygiene, the presence of gingival invaginations (mean depth 2.7 +/- 1.1 mm) has no influence on the hygienic state and, the level of gingival inflammation in the invagination area. However, a marginal bone loss at the teeth mesial and distal to the extraction sites, a reduction of the interdental crestal bone height, and an extended time frame for orthodontic space closure must be expected.

Adult↗
PubMed1993

[High-resolution CT of the dentate alveolar ridge in comparison with histological thin section preparations].

Human bone segments of the toothed jaw were scanned using high-resolution CT with axial and coronal contiguous 1 and 2 mm slices. The bone segments were sliced analogous to the performed CT image positions. Contact films and micro-sections were made from the cuttings. Length and width of the teeth, the thickness of the alveolar bone and the distance between bone and dental surface were measured. Comparison of the CT measurements with contact films and histological specimen yielded best results for axial slices with 1 mm slice thickness (mean error 0.3-0.5 mm). Coronary oriented slices showed an error of 0.3-1.6 mm. 3D-reformatting can improve spatial orientation for axially produced image series. For CT imaging of the toothed jaw concerning the dento-alveolar structures, contiguous axial scanning with 1 mm slice thickness appears to be the concept of choice.

Alveolar Process↗
PubMed1992

[Early neurologic rehabilitation--an urgent requirement].

The majority of patients with severe craniocerebral damage can be enabled to return to a relatively independent life if early rehabilitation measures are provided. The number of beds currently available for early rehabilitation, however, covers little more than 10 percent of the demand at hand. Expanding the number of beds available hence is a pressing need. The present article contains pertinent information in view of qualitative and quantitative implementation of related efforts.

Activities of Daily Living↗
PubMed1992

[Experimental studies on the systemic toxicity of dental alloys free of precious metals].

The systemic toxicity of five non-precious dental alloys was evaluated by help of an animal study. The pulverized dental alloys, filled in gelatine capsules, were orally administered to laboratory rats using a special esophageal application device. For each alloy examined randomized groups of ten experimental animals and ten control animals were used. For a period of seven days the experimental animals received daily 1000 mg alloy powder per kilogram body-weight. The animals of the control groups received daily empty gelatine capsules (placebo application). After two weeks all animals were killed and autopsies of the animals were performed. Histopathologic examinations of the lungs, kidneys, liver, small intestine and large intestine of all animals were done. With statistic significance (p less than 0.001) rats whom nickel-chromium alloys were administered orally showed serious pathologic reactions more frequently than placebo-treated control animals. Nickel-chromium alloys containing beryllium and/or gallium caused the strongest organic lesions. In contrary to this a dental cobalt-chromium alloy showed a very low systemic toxicity. The results of the study underline that preclinical toxicity testing of dental alloys is necessary in order to avoid systemic toxic lesions in man.

Administration, Oral↗
PubMed1991

[Operative therapy in tumor involvement of the spine].

We report on 56 patients, who underwent operative treatment of tumorous lesions of the spine. We indicated dorsal instrumentation in 14 cases, ventral tumorectomy in 11 cases and a combined dorsal and ventral instrumentation in 31 cases. The median survival time was 14.8 months. Reduction of pain and the improvement of the preexisting neurological symptoms were the most important postoperative factors. According to our follow-up study, the combined dorsal and ventral instrumentation seems to be the best method for an operative treatment of tumorous spine lesions.

Bone Transplantation↗
PubMed1990

The importance of sonography and radiography in diagnosis and treatment of congenital dislocation of the hip.

The advantages of the sonography of the hip joint in the diagnosis and treatment of hip dysplasia in 1992 "policlinic" children and 1100 newborns are discussed and compared with radiological methods. The treatment concept at the Orthopädische Universitätsklinik Bonn is described as well as its modification after introduction of the sonography in the hip dysplasia screening-examination. These results confirm the necessity of making an early diagnosis. The osteonecrosis of the hip as a complication of the treatment of hip dislocation is discussed.

Casts, Surgical↗