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P Diedrich

Publications and source records attributed to P Diedrich.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Findings in the panoramic tomogram in orthodontic patients with functional disorders].

In our study of 107 patients, for whom data derived from clinical functional analysis, axiography and, in part magnet resonance imaging, were present, we were able to show that in routine orthodontic diagnosis the use of panoramic X-ray in the normal course of a general examination of the mandibular joint can also provide important indications of the presence of cranio-mandibular disorders. The panoramic X-ray revealed that in patients with Angle class II and front deep and open bite there were significantly mor changes in the form of the condyles. A definite morphologic finding of a retracted fovea pterygoidea was found frequently in patients with anterior disk replacement with or without reduction. Lastly, the panoramic X-ray showed that a change in form of the condyles, with in some cases a serious arthrosis, occurs significantly most frequent in patients with anterior displacement without reduction.

Adolescent↗
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

[Problems and risks in the movement of the mandibular anterior teeth].

The key role of the lower anterior incisors as well as the complicated anatomical relationship of this area play a significant part in orthodontic treatment planning. Three fundamental points of view are selected here for discussion: 1. the variability and clinical relevance of the initial periodontal findings, 2. the importance of the symphysis to sagittal and vertical tooth movement, and, 3. the specific problem associated with periodontal bone loss. The few clinical and experimental studies found in the literature indicate that every anterior tooth movement has to be oriented according to the structure and facio-lingual width of the alveolar bone and that movement should progress in a controlled fashion. Rapid tipping tooth movements are to be avoided so as to minimize the risk of bone dehiscences and root resorption. Orthodontic tooth movement should be avoided when the initial findings show a narrow symphysis or questionable labiolingual bone coverage. Pre-orthodontic thin gingiva and alveolar mucosa can be an indication for a mucosal graft aimed at preventing subsequent bone and gingival dehiscences. In the future, systematic 3-D CT analysis of pre-orthodontic and post-orthodontic findings will contribute to a better estimation of the case specific potential of compensatory bone apposition.

Humans↗
PubMed1995

[The development of a resorbable implant system for orthodontic anchorage. The BIOS implant system. Bioresorbable implant anchor for orthodontic systems].

The use of endosseous implants as temporary orthodontic anchoring elements has proven itself to be efficacious in many clinical applications. If, however, an implant is inserted into the jaw solely to correct a malocclusion without being used subsequently for prosthetic purposes, secondary surgery is required to remove the anchoring implant. The development of an orthodontic implant anchor system consisting of an implant made of biodegradable polylactide with a metal abutment may offer a solution to this problem. On the basis of its good mechanical properties, the BIOS implant system (bioresorbable implant anchor for orthodontics system) presented here is designed to assume orthodontic anchoring functions as long as necessary and then be resorbed by hydrolysis without foreign body reactions. Shear strength and maximum vertical strength were measured in biomechanical in vitro tests in which BIOS fixtures can be loaded with horizontal shear forces of 50 N with a mean deflection of 0.26 mm and mean vertical pull-off forces of 155 N. In a clinical case report the application of the BIOS implant system during orthodontic tooth movement is here illustrated. In vitro and in vivo results obtained to date suggest that the BIOS implant system can be used as an orthodontic anchoring system up to the time of degradation.

Absorption↗
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↗
PubMed1994

Separation of aminated monosaccharides by capillary zone electrophoresis with laser-induced fluorescence detection.

The six most abundant hexoses found in mammalian carbohydrates were derivatized to serve as standards for an oligosaccharide sequencing project. Glucose, galactose, mannose, and fucose were reductively aminated to produce 1-amino-1-deoxy alditols. Standards for N-acetylglucosamine and N-acetylgalactosamine were synthesized by reducing glucosamine and galactosamine to 2-amino-2-deoxy alditols. The monosaccharides were labeled with 5-carboxytetramethylrhodamine succinimidyl ester. By carefully adjusting the separation buffer, we have separated the sugar derivatives completely. The detection limit is 100 molecules of labeled sugar with a post-column laser-induced fluorescence detection in a sheath flow cuvette.

Amination↗
PubMed1994

[The diagnosis and orthodontic relevance of anterior disk displacement without reduction. Clinical, axiographic and magnetic resonance tomographic studies].

Magnet resonance imaging was used to diagnose 24 temporomandibular joints of 18 patients as having anterior disk displacement without reduction. By comparing clinical functional analysis, axiography, and magnet resonance imaging it was demonstrated that a valid diagnosis could be made on the basis of magnet resonance imaging alone. Former joint clicking and limitation and a dental Angle Class II were diagnostic indications of a disk displacement without reduction. Because of often only slight clinical symptoms or their absence, there is always a danger that disk displacement without reduction will go undiagnosed. In relation to orthodontic therapy, such patients are at risk, because pain can arise during treatment.

Adolescent↗
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

[Different orthodontic anchorage systems. A critical examination].

Every orthodontic measure requires a detailed analysis of the individual anchorage situation in order to absorb (stationary anchorage) or control (reciprocal anchorage) the reactive forces and moments. Basically, an anchorage is oriented to the quality of the biological anchorage of the teeth. This is influenced by a number of factors: size of root surface, attachment level, density and structure of alveolar bone, periodontal reactivity, muscular activity, occlusal forces, craniofacial morphology and the nature of the tooth movement resulting from the planned correction. The quality of the biological anchorage may be enhanced by selective modification of the position of the anchor teeth: cortical anchorage of the first molar (Ricketts), distal inclination of the molars (Tweed, Begg) and differential torque control (Burstone). In this context, undesired anchorage effects also need to be discussed, for example interaction between the teeth being corrected and compact bone structures (symphysis menti, floor of the maxillary sinus) or the loss of anchorage by periodontal hyalinization or excessive friction within the bracket slot. In addition, the anchorage situation of ankylosed teeth and endosseous implants, as well as the advantages and disadvantages of additional mechanical anchorage aids (head-gear, Nance holding arch, lingual arch) are discussed. On the basis of the complexity of the individual biological and biomechanical aspects, guidelines are derived with which to establish anchorage control matched to the specific situation.

Biomechanical Phenomena↗
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

[Occlusal splint therapy in reciprocal TMJ clicking. A critical observation within a follow-up study].

During post-treatment examination the effect of splint therapy on 14 temporomandibular joints (TMJ) with anterior disk displacement were examined using clinical and instrumental findings and magnet resonance imaging (MRI) to judge the therapeutical success of the treatment from an orthodontic perspective. A stable reposition of the TMJ disk was achieved in four joints, which showed no relapse over a two-year period of observation. The success of the therapy was dependent on the extent of the tissue damage to the TMJ and also on patient compliance. The MRI yielded therapeutically valuable information, which is not revealed in the clinical-instrumental analysis, on the tissue structure of the disk and the ligaments. In certain cases the use of MRI is necessary to confirm the clinical diagnosis.

Adolescent↗
PubMed1993

Endosseous titanium implants during and after orthodontic load--an experimental study in the dog.

An experiment was carried out to determine whether endosseous titanium implants (Brånemark) retain their clinical stability throughout a 26-week period of continuously applied force (2 N) and what kind of marginal peri-implant bone changes occur in the process. For this purpose 6 premolars (P3: mandible/maxilla and P4: mandible) were extracted from each of 2 foxhounds, and 12 implants (6 per dog) were positioned in the edentulous maxillary and mandibular areas after the alveolar healing period. Following a 25-week implant healing period, 8 fixtures (P3 areas) were used as anchoring elements for distalization of the 2nd premolars over a period of 26 weeks; 4 implants served as a control group (P4 areas of the mandible). There were no clinical or histological signs of implant dislocation after the load application period. In the presence of mild peri-implant gingivitis, no increase was found in the incidence of marginal bone resorption adjacent to the loaded implants compared with the non-loaded implants. In the absence of marginal resorption, subperiosteal bone apposition was detected especially around the test implants in the mandible. This suggests that endosseous titanium implants are suitable as anchoring units for longer-term orthodontic tooth movements. The applied force may moreover induce marginal bone appositions adjacent to the implants.

Animals↗
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

[Progressive pneumatization of the basal maxillary sinus after extraction and space closure].

By superimposing 32 pretreatment and post-treatment orthopantomograms, it proved possible to quantify the progressive pneumatisation of the basal maxillary sinus following extraction and orthodontic space closure. It was shown that if pneumatisation was present prior to treatment (more than 30% of root length), clear extension of the basal antrum could be expected. The tendency towards pneumatisation is significantly higher after molar as compared with premolar extraction. Possible reasons for these findings and their clinical significance are discussed.

Embolism, Air↗