Biomedical subjects

P Diedrich

Publications and source records attributed to P Diedrich.

At least 19 recordsLinked to original sources

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 relationship between cervical spinal posture and bite anomalies].

Comparisons of lateral X-rays obtained in 126 patient prior to and after orthodontic treatment showed that in cases in Angle's classes I and II hyperlordosis of the cervical spine is often found. This is seen to be corrected to a statistically significant extent by the end of treatment; Angle's class III patients did not reveal any clear tendency.

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

[The correction of fanned-out incisors--an important orthodontic contribution to aesthetic dentistry].

Account has to be taken of the increased aesthetic awareness of the adult patient by all sub-specialties of dentistry. Here, orthodontics often plays the role of a central link between periodontics and prosthetics. Taking pathological migration of the incisors as an example, the pathogenesis, therapeutic procedures and orthodontic possibilities for the restoration of normal dentofacial aesthetics are demonstrated and discussed.

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 tensile bonding strength of metal plasma-coated bracket bases].

The tensile bond strength of bracket bases coated with metal plasma were examined. The aim was to investigate, whether the conditioning of bracket bases by metal plasma is a possible means to increase the tensile bond strength. Two typical orthodontic adhesives were used. Three test groups were differentiated: 1. Metal mesh bracket bases (coated and uncoated with metal plasma), 2. metal bracket bases without mesh (coated with metal plasma), 3. ceramic bracket bases coated with metal plasma. Metal bracket bases with mesh, coated with metal plasma showed superior bond strength in comparison to usual uncoated mesh bracket bases. The former were nearly four times stronger than the uncoated bases with reference to the first adhesive and two times stronger referring to the second adhesive. The primary source of the enhancement of adhesion is due to the enormous increase of the retentive active surface created by the metal plasma. This structure guarantees an excellent micromechanical interlocking for the adhesive. The mean tensile bond strength of titanium coated mesh bases was 20.03 N/mm2 (= 286 N/bracket). Plasma coated bases without mesh reached average interlocking forces comparable to conventional uncoated mesh bases. Ceramic bracket bases were found not to be suitable for plasma coating. As a result of these experimental findings metal plasma coating of metal bracket bases can be regarded as an excellent means to increase the tensile bond strength.

Adhesiveness↗

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↗

PubMed1991

[Clinically relevant biomechanics. 2. Mechanics of non-symmetric front teeth-intrusion].

Front teeth can be intruded by the segmented arches described by Burstone. The article analyses the vertical forces under the influence of symmetric intrusion arches and examines the static situation caused by non-symmetric activation of symmetric intrusion mechanics. It shows that in some cases even extrusive forces can occur in the anterior segment, whereas intrusive forces are intended to be applied.

Dental Stress Analysis↗

PubMed1991

[Clinically relevant biomechanics. 3. Critical reflections about the Burstone intrusion mechanics].

A segmented arch for intrusion of front teeth, as described by Burstone, is compared to a coil-and-stylus-model. The mechanics of constructive modifications are analyzed and their consequences for the movements of front teeth are discussed. It is shown, that in some cases extrusive forces occur, while intrusive forces are applied. In these cases it is necessary to reduce intrusive forces below 0.20 Newton per side. In order to avoid extrusive forces, it is recommended to apply intruding forces between the centers of resistance of the central and lateral incisors.

Dental Stress Analysis↗

PubMed1991

[Limitations of intrusion of periodontally involved maxillary buccal teeth for furcation treatment].

In a study on three dogs 12 two-rooted premolars with reduced periodontia were intruded to reestablish marginal attachment. In eight roots intrusion into the basal cortical bone of the nasal sinus was found. The histological findings showed that in these cases a possible gain of new attachment in the interradicular space may be impaired by a loss of bone support in those sites where the root intruded into the sinus. The greater the extent of intrusion into the sinus the higher the expected loss of periodontal attachment.

Alveolar Bone Loss↗

PubMed1990

[The motivation and assessment of the success of adult patients undergoing orthodontic treatment--the interpretation of a questionnaire].

In order to analyze orthodontic treatment of adults concerning information, motives and retrospective evaluation 225 patients with fixed appliances were questioned. The dentist had a key position as a mediator of information. The decision to an orthodontic treatment was led by esthetic and functional motives. The extent of the respective motives depended from age, personal status, education and cooperation. Interest and understanding in functional improvements as they could be found above all by people with a higher education level were decisive for a durable regard of the treatment.

Adult↗

PubMed1990

[Experiences with Burstone's segmented arch technic in the adult dentition].

In comparison to the straight wire technique the segmental arch approach offers numerous biomechanical and clinical advantages. Three typical examples: controlled tooth movement, en masse space closure and deep overbite correction serve to show the spectrum and the efficiency of the segmented arch technique.

Adult↗

PubMed1990

[The effect of the maxillary sinus floor on orthodontic tooth movement].

By superimposing 40 pre- und post-therapeutic orthopantomograms the degree of tipping and kind of movement of 87 teeth could be described quantitatively, dependent on configuration and extension of the basal maxillary sinus. It has been shown that, with a more vertical extension (VL = 1) in front of the tooth to be moved one can expect an obviously higher degree of tipping (about 10 degrees) as compared to teeth moved through a more horizontal maxillary sinus base (VL = 2). In the group of teeth VL = 1 a correlation between the depth of the maxillary sinus recessus and the degree of tipping could be found (p less than or equal to 0.05); i.e. the deeper the maxillary sinus recessus, the higher the degree of tipping. For VL = 2 this correlation is statistically not significant. In the group VL = 1 rather a tipping movement, in VL = 2 a translatory movement can be expected.

Adult↗

PubMed1990

[Experimental bodily tooth movement through the bony floor of the nose--a pilot study].

Our experiment on animals was carried out in order to show to which degree the dog's bony nasal floor--taken as an equivalent of the recessus of the human maxillary sinus--is an obstacle to bodily tooth movement. The metric analysis showed that the movement of the upper teeth in comparison with the teeth of the lower jaw was markedly impaired by the basal cortical bone of the cavum nasi. Extended resorption of the basal bone of the nose was found histologically. The pressure side of the root surface too showed resorption lacunae which reached into the dentine deeply and were bordered by some osteoclasts.

Animals↗

PubMed1990

[Changes in periodontal parameters during orthodontic treatment].

Five different parameters, i.e. proximal plaque index, sulcus bleeding index, clinical crown height, width of keratinized gingiva and probing depth, were examined in 70 treated patients before, during and after orthodontic treatment. A total of 30,000 individual data were collected. All patients were examined at three different appointments. Differentiations were also made between male and female patients and between patients treated with fixed and removable appliances. Radiographs were taken in a part of the patients before and after treatment for assessment of the interdental septa and root integrity.

Dental Plaque Index↗