Biomedical subjects

H Wehrbein

Publications and source records attributed to H Wehrbein.

At least 37 records · Page 2Linked to original sources

PubMed1995

Gingival invagination area after space closure: a histologic study.

The aim of this study was to show the micromorphologic findings (epithelium, connective tissue, bone) in a region of pronounced gingival invagination after space closure by analyzing a maxilla taken in autopsy from a 19-year-old woman who was orthodontically treated. The dental records were also at our disposal. The second left premolar was congenitally absent. This area displayed before therapeutic horizontal bone atrophy. For space closure, the first upper left molar was moved mesially with a fixed appliance. After space closure, pronounced gingival invagination was diagnosed. The lateral segments of the specimen were prepared histologically in the horizontal plane. The microscopic observations revealed deep epithelial proliferation, hyperkeratinization, and one isolated keratin pearl in the connective tissue. Irrespective of location, the broad connective tissue layer showed disparate characteristics. Cell-rich, loose connective tissue with low fiber density were dominant in the subepithelial layer. The epiperiosteal layer displayed multiple tough fibers, some running parallel, some with reticular meshing, permeated with many blood vessels. Very few inflammatory cells were detected in the soft tissue. The bone had been resorbed in the mesiopalatal area of the molar (tooth movement direction) apart from one small isolated bony islet. These observations suggest that inflammatory influences were unlikely for marginal bone loss mesiopalatal to the tooth.

Adult↗

PubMed1995

Human histologic tissue response after long-term orthodontic tooth movement.

UNLABELLED: The maxilla of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The specimen was prepared histologically in the horizontal plane. The type of tooth movement was reconstructed by comparing the treatment documents at outset (photograph of dental cast, radiograph) with the photograph and radiographs of the specimen. This permitted the histological findings to be correlated to the type of tooth movement. RESULTS: the localization and extent of tissue changes at the roots depend on the type of tooth movement and the structure of the bone. In case of an atrophied alveolar bone in front of the tooth movement direction, a partial increase of osseous tissue may be induced by bone apposition in the subperiosteal layer. After tooth movement in the maxillary sinus region, however, bone resorption was found in the subperiosteal layer in front of the roots. The histologic findings are more pronounced than the radiographs would suggest. Histologically verified bony dehiscences or fenestrations in the facial or oral cortical plate could not be diagnosed by macroscopic inspection of the specimen.

Adult↗

PubMed1995

Assessment of the dentate alveolar process with high resolution computed tomography.

The present study was undertaken to determine quantitatively the accuracy of modern high-resolution computed tomography (HR-CT) in imaging periodontal defects in vitro by means of comparative radiological and histological studies. The soft tissue and metallic restorations were removed from four mandibular and maxillary jaw segments. Eighteen lingual and buccal defects of different dimensions were artificially created over the roots of the teeth. Dental radiographs and 1.0 mm contiguous axial and coronal HR-CT scans were obtained. Histological specimens were prepared in the same plane as the CT scans. A quantitative analysis of the periodontal regions on the CT scans was feasible when the alveolar bone was 0.5 mm thick. A visible periodontal ligament space was found to improve the reliability of the measurement of buccal or lingual bone plates up to 0.2 mm thick or of the artificial dehiscences. In the axial HR-CT scans, 70% of the artificial defects could be identified. and in the coronal scans, 50%. In contrast, none of the defects could be evaluated on conventional dental radiographs. It is concluded that HR-CT scanning could be useful in assessing buccal and lingual alveolar bone morphology and in diagnosing larger dehiscences.

Alveolar Bone Loss↗

PubMed1994

[Endosseous titanium implants as orthodontic anchoring elements. Experimental studies and clinical application].

Part 1 of this study, which deals with experimental use of titanium implants in animals (Brånemark, dimension 10 x 3.75 mm), examines the long-term orthodontic application of force on the quantity of peri-implant and paraimplant bone and on direct bone contact (in %) at the implant surface. In the experiment 6 premolars (P3 mandible/maxilla and P4 mandible) were extracted from each of 2 foxhounds. After 12 weeks each dog received 6 implants (P3 and P4 areas). After the implants had healed for 25 weeks, the fixtures in the P3 areas were used as anchoring elements (test implants) for P2 distalization over a period of 26 weeks (continuous force applied: approximately 2 N). The implants in the P4 area served as the control group. Histological analysis revealed in the test implants (mandible) in comparison to the control implants (mandible) the following differences: broader cortical bone; wider peri-implant bone casing; denser, partly sclerotic spongiosa (pressure side); and thicker trabecula (tension side). Fluorescence microscopy revealed that these findings were the result of distinct lamellar bone apposition during the force application phase. In comparison, far less lamellar apposition was found in the test implants (maxilla). The mean percentage of direct bone contact at the implant surface was: Control implants (mandible, n = 4): 40.5%; test implants (mandible, n = 4): 51.6%; and test implants (maxilla, n = 4): 42.4%. Part 2, the clinical portion of the study, presents the suitability and feasibility of using endosseous implants as orthodontic anchoring elements, first, for orthodontic-prosthetic anchoring, and, second, for orthodontic anchoring only. Further, the significance of these aspects in relation to the implant site, to implant dimension, and to the type of implant anchoring are recorded.

Animals↗

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↗

PubMed1994

Periodontal conditions after facial root tipping and palatal root torque of incisors.

UNLABELLED: The maxilla of a deceased 19-year-old young woman who had been treated with a fixed appliance was removed during autopsy. The sagittal movements of the incisors could be reconstructed by using the treatment records, which were also at our disposal. The anterior segment of the specimen was prepared histologically in the sagittal plane and stained with toluidine blue. RESULTS: The tooth movements were executed in two phases: an uncontrolled tipping (root movement to vestibular) was followed by palatinal root torque. The histologic changes, induced by the palatinal root torque were (1) root resorption with apical slope from facioapical to orocoronal, and (2) pronounced subperiosteal bone apposition (palatinal) with partial protrusion of the cortical plate thinning toward coronal. No osseous perforations occurred. The extent and the localization of root resorptions were not verified in the orthoradial x-ray film of the specimen.

Adult↗

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

[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

[Computed tomographic imaging of the dentoalveolar-maxillary sinus lacuna of the dentate jaw].

A human bone segment of the lateral maxilla was scanned using high-resolution computed tomography (CT) in contiguous parallel axis slices in order to image the topographical relationship between upper molars and the maxillary sinus. The bone segment was dissected analogously in 1 mm thick sections. After exposing contact films from these jaw cuttings, microsections were made for histological interpretation. The radiological-histological comparison between the CT-scans, contact films and the histologic specimens revealed absolute differences of 0.2-0.6 mm. The high resolution CT allowed an interpretation of details located between teeth and bone when the minimum bone thickness was 0.5 mm or more. First experiences with the CT-technique in orthodontic patients were promising, especially for the differential diagnosis of the dentoalveolar maxillary sinus relation.

Adult↗

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↗

PubMed1992

[Intrusion of the anterior teeth with the segmented-arch technic of Burstone--a clinical study].

The purpose of this study was to examine the efficiency of intrusion mechanics as described by Burstone. Thirty-one cases of deep bite with an overbite equal to or more than 4 mm were analysed by means of cast models, lateral cephalometric views and dental films of the front teeth prior to and after intrusion. The following parameters were considered: 1. Extent of the intrusion relative to a selective point of force application, 2. duration of the intrusion, and 3. amount of root resorption. The average extent of the intrusion in the case of the upper front teeth was 2.3 mm, and in the case of the mandible 3 mm. The rate of intrusion per month was 0.53 mm in the maxilla, and 0.54 mm in the mandible. Analysis of the point of force application showed that the centre of resistance must be presumed to be more distal than previously assumed. For an average treatment time of 4.3 months in the maxilla, and 5.5 months in the mandible, the apical root resorption was minimized by applying dosed force using a calculable force system. A buccal root torque arch employed in three cases permitted, in class II/1 cases, a combined movement comprising lingual tipping of the crown and intrusion, the intrusion component being clearly delayed in comparison with tipping. The segmented arch technique allows an objective intrusion of anterior teeth. This depends on choosing the appropriate point of force attachment and the correct amount of force.

Adolescent↗

PubMed1992

[The initial morphological state in the basally pneumatized maxillary sinus--a radiological-histological study in man].

Twenty human autopsy specimens of the lateral maxilla with radiologically diagnosed extended basal maxillary sinus were prepared either in the horizontal, sagittal or transversal plane. Generally the cortical bone of the maxillary sinus showed a thickness up to 1000 microns. In areas with root contact histological findings could be described as follow: reduction of thickness, bone perforations, bone perforations combined with apical and or lateral root resorptions and root resorptions without bone perforations. These morphological findings could not be verified by X-ray examination.

Adult↗

PubMed1992

[Space closure with T loops (Burstone)--a clinical study].

The theoretically favourable aspects of orthodontic space closure with segmented arch technique and the T-loop type A are clinically reproducible. In our study of eleven patients we found for the isolated canine retraction, as well as for the en masse retraction, controlled types of movement for the active units and maximum anchorage situations for the passive units produced by the torquing force. Because of these good anchorage conditions space closure could be done without headgear. The level of the anchorage segments was negligibly influenced but in the anterior segments a marked tilting was found in several cases. Besides other factors the intrusive force of the T-loops type A must be considered. As a rule the positioning of the T-loop between central and lateral incisor is to be recommended.

Activator Appliances↗

PubMed1992

[The periodontal changes following orthodontic tooth movement--a retrospective histological study in man. 2].

UNLABELLED: The maxilla of an orthodontically treated deceased (19 years, female) could be taken in autopsy. Pretherapeutically atrophied alveolar bone and a basally exdented maxillary sinus was found. The specimen was prepared histologically in the horizontal plane. The type of tooth movement could be reconstructed by analyzing the treatment documents. RESULTS: Dependent on the tooth movement, a partial gain of osseous tissue in the atrophied alveolar region is possible by bone apposition in the subperiosteal layer. In the maxillary sinus region, however, bone resorption could be found in the subperiosteal layer in front of the tooth. The resultant apical perforation into the sinus could not be verified by radiographic examination.

Adult↗

PubMed1992

[The periodontal changes following orthodontic tooth movement--a retrospective histological study in humans. 1].

UNLABELLED: The maxilla of a deceased (19 years, female) who was treated with a straight-wire-appliance could be taken in autopsy. The specimen was prepared histologically in the horizontal plane. The type of tooth movement was reconstructed by comparing the treatment documents of the beginning (photo of the cast model, radiograph) with the photo and radiographs of the specimen. In that manner the histological findings could be correlated with the type of tooth movement. RESULTS: Localisation and amount of tissue changes at the roots depend on the type of tooth movement and the morphology of bone. The histological findings are more pronounced than the radiographs show. Histologically verified bony dehiscences in the facial or oral cortical plate are not to be diagnosed by macroscopic inspection of the specimen.

Adult↗

PubMed1991

[Tooth germ transplantation or gap closure--a comparative study in the loss of the first molar].

In our study 37 transplanted and 33 mesialized molars by orthodontics were clinically and radiologically compared. The teeth moved by orthodontics showed a better long-term prognosis. As vital teeth with functioning periodontal structures and only slightly shortened roots they were equivalent to healthy teeth. However, the disadvantage of orthodontic space closure is the requirement of a good compliance due to long treatment time. The prognosis of maintaining a transplanted tooth germ is uncertain. One third of the teeth showed an altered periodontium with resorption areas. The danger of a continuing resorption, as well as a late external resorption is still a risk after a long period of time and can eventually lead to tooth loss. As a treatment alternative, germ transplantation may serve as a replacement of a single missing 6-year-molar in adolescence. Orthodontic space closure is indicated at any age with an existing dysgnathia, the loss of several first molars, the loss of space and mesial tipping of the second molars.

Adolescent↗