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Biomedical subjects

R J Radlanski

Publications and source records attributed to R J Radlanski.

At least 19 recordsLinked to original sources
PubMed1995

Morphogenesis of human tooth primordia: the importance of 3D computer-assisted reconstruction.

Three-dimensional reconstruction of embryological structures from histological serial sections is necessary when researching questions concerning formal development and mutual influences due to neighboring relationships. Graphical reconstructions can be performed by personal computers. In the present paper the need for 3D-reconstructions is explained, and examples showing the development of human dental primordia and their surrounding structures of specimens ranging between 18 and 64 mm CRL are presented. The contour-line plots that are provided by the software HISTOL are graphically reworked to anatomical drawings. Spatial impediment as one of the factors responsible for development of tooth form is discussed on the basis of the 3D-reconstructions.

Animals↗
PubMed1994

[Morphometric studies on the fetal development of the human mandible].

Serial sections of eleven human mandibles of embryos and fetuses ranging in size from 18 mm CRL to 66 mm CRL were computer-graphically reconstructed. The extension of the Meckel cartilage and the mandibular bony structures were morphometrically studied. In emphasis the study encompassed measurements portraying length, width, dorsal opening angle, and the position of the mental foramen. In addition five mandibles of human embryos and fetuses with a size range between 30 and 50 mm CRL were radiographically examined. Results showed that in the younger specimens between 21 and 29 CRL size development of the structures of the mandible and the development of overall fetal body size take place independently from each other. During further development a change in the form of the mandible from a wide V over an acute V to a more rounded U form was observed.

Cartilage↗
PubMed1993

Demonstration of cells of the mononuclear phagocyte lineage in the periodontium following experimental tooth movement in the rat. An immunohistochemical study using monoclonal antibodies ED1 und ED2 on paraffin-embedded tissues.

In this immunohistochemical study two monoclonal antibodies, ED1 and ED2, which recognize exclusively cells of the mononuclear phagocyte system (MPS) in the rat, were applied to study the presence of these cells during remodeling of the periodontal tissues following mechanically induced orthodontic tooth movement. The immunohistochemical procedure was carried out successfully on routinely processed, paraffin-embedded histological sections using the avidin-biotin-peroxidase-complex (ABC) technique. Cells of the MPS could be demonstrated on positive control sections of rat spleen and bone marrow. For the study of remodelling of the periodontal tissues only the ED1 antibody proved to be suitable. With this antibody, positive mononuclear and multinuclear cells, i.e. macrophages and osteoclasts, were seen throughout the periodontium even in the control animals. After the induction of orthodontic tooth movement activation of macrophages, osteoclasts and odontoclasts was demonstrable, all of them showing a clear-cut positive reaction to ED1.

Animals↗
PubMed1991

[Changes in opening mobility due to surgical advancement of the mandible].

A prospective follow-up study of 21 class-II patients, who were treated with a combination of orthodontics and orthognathic surgery, revealed typical postoperative changes in opening mobility. Their characteristics were: a strong initial loss of mobility and a regeneration period of about one year. Because the increase of mobility could not completely compensate for the initial reduction, a significantly reduced mobility was detected 25.5 months postoperatively. This reduction was considered as clinically acceptable, since former studies showed more unfavorable developments. However, individual changes of mobility are worth of notice. The comparison of condylar-related axiographic measurements with incisal measurements showed that the reduction of the length of axiographic tracings was more prominent than the "clinical-effective" reduction of the combined condylar rotation and translation.

Adult↗
PubMed1991

[Histomorphometrical study of physiological tooth movements in humans].

Quantitative analysis of remodeling activity was done using microradiographs of horizontal ground sections of human alveolar bone obtained from autopsies. The results demonstrated no significant age- or sex-dependent variations. The local distribution of remodeling activity in younger individuals pointed to a tipping mesial movement of the teeth. In older individuals this distribution showed a more random pattern.

Adult↗
PubMed1991

[Situation and extension of epithelial excrescences alongside the lip furrow band and the dental lamina].

3-D-reconstructions of serial sections of human embryos show that the margin of the lip furrow band is irregular and consists of an abundance of individual epithelial excrescences. Additional foldings of the lip furrow band extending over a length of up to 160 microns were found. The hypothesis that epithelial foldings in this region may be early anlagen of a perlacteal dentition is discussed and rejected.

Gingiva↗
PubMed1991

[Alveolar bone remodelling following orthodontic tooth movement in aged rats. An animal experimental study].

Orthodontic tooth movement of upper first molars was performed in twelve aged (500 days old) rats. It was demonstrated by histomorphologic findings as well as by vital polychrome staining that the remodelling process of the periodontal tissues in the aged animals was qualitatively similar to that in younger ones. The first molar in all animals was tipped mesially, while its mesial root was intruded. According to the vital polychrome staining the bone formation rate at the mesio-apical bone surface of the mesial root was determined as 7-8 microns per day. After 14 days comprehensive root resorption in the pressure zone distal of the bifurcation was found.

Aging↗
PubMed1990

[Scanning electron microscopic research on the clinical use of interdental stripping].

The morphology of approximal enamel that has been stripped for therapeutic reasons was evaluated under the scanning electron microscope (SEM) twelve weeks and one year after treatment. In part one of the study the teeth were extracted before evaluation, in the second part replica were taken. For comparative reasons the morphology of the natural approximal enamel surface was evaluated under the SEM, too. After twelve weeks the edges of the furrows were seen to be smoother and plaque accumulations were found in the depths of the furrows. One year after there was found essentially no difference. In some of the specimens there was found a certain levelling of the edges in the approximal contact area, but not in the cervical region of the artificially abraded tooth surface. The natural enamel surface of the contact area showed excavations of similar size as the furrows that remain after stripping and finishing. But our study shows that the therapeutic approximal abrasion leaves furrows in the cervical region that even after one year had not undergone repair. The question is discussed, if thus predispositions for periodontal pathologies and caries could be created.

Bicuspid↗
PubMed1990

[Changes in the functional status of the stomatognathic system due to orthodontic multiband treatment in the adult].

Ten patients who undergo an orthodontic therapy with a full-band modified straight-wire-appliance were examined clinically and by means of an electronic axiographic device (SAS-system) at the beginning of treatment and after an average of 12.6 months, respectively. While the clinical functional status showed only minor changes, alterations of all examined axiographic parameters could be detected. This finding reemphasizes the necessity of modern axiographic means to get additional information about the functional status of the TMJ. The alterations point to a shift in the functional pattern of articular and muscular components during orthodontic treatment. In the majority of cases, axiographic parameters remained constant, however. In that respect, it might be of special interest that even uncoordinated tracings, mainly in the horizontal plane, kept up its characteristic appearance. These findings show clearly, that alterations of occlusal relationships must not influence articular functional patterns immediately.

Adult↗
PubMed1990

[A technic for cementing orthodontic bands; SEM research on the enamel and filling damages and a protective wax technic to avoid them].

Damage of enamel and filling margins occurs during the removal of zinc phosphate cement with hooks and scalers after band cementation. This was revealed by scanning electron microscopy in different stages of the study in vitro and in vivo. When glass ionomer cement was used, and although the surplus cement was wiped off still being plastic, it could not be avoided that cement was wiped into the fissures and stuck to the slopes of the cusps. A protection of the occlusal surface with wax as described in this study is helpful for both using glass ionomer and zinc phosphate cement. Contamination of the occlusal surface with cement is avoided, and the isolating effect reduces the necessity to scratch off cement surplus.

Cementation↗
PubMed1990

[Embryologic studies on the development of tooth form].

3-dimensional reconstructions were made from serial sections of human embryos in order to trace back the development of the anlagen of the deciduous dentition. It could be shown that in the stage the late cap/early bell back contours of the inner enamel epithelium resemble the outlines of the later completed tooth. It is discussed that the shape of the earlier stages may set the preconditions for the further formation processes resulting in the occlusal morphology.

Fetus↗
PubMed1990

Quantitative determination of alveolar bone density using digital image analysis of microradiographs.

Horizontal 100 microns ground sections of 20 alveolar bone specimens from adult human mandibles obtained from autopsies were prepared for microradiography. Quantitative analysis of bone density of the alveolar cortex was performed using a semiautomatic digital image analysis system (KONTRON). The results demonstrated that bone density was higher in the lingual than in the labial alveolar cortex (p less than 0.05). In addition, the coronal portion of alveolar cortical bone was significantly more porous than the medical and apical ones (p less than 0.05). These variances were primarily due to increased canal size rather than to an increased number of canals. No significant age dependent changes in bone density could be determined.

Adolescent↗
PubMed1990

[The orientation of prisms in the dental enamel of human permanent teeth].

Enamel of human permanent teeth was sectioned and ground with 2 planes perpendicular to each other extending centrifugally from the dentino-enamel-junction to the crown surface. Prisms were made visible by acid etching before evaluation under the SEM. In the vicinity of the dentino-enamel-junction more prisms were found to be cut longitudinally, while close to the crown surface more prisms were cut transversely. In the perpendicularly ground plane the corresponding prisms were seen to deviate the more from the centrifugal orientation the more close they came to the crown surface. In a geometric model the angle under which the prisms deviate from the centrifugal orientation was calculated in dependence from the distance to the dentino-enamel-junction. The results correspond with the SEM-findings. We conclude that--since the prism diameter is today known to be constant--the form of the enamel mantle is created by a specific orientation of the prisms: They stand perpendicular at the dentino-enamel-junction, and the farther away they run towards the periphery the more they deviate from the perpendicular path. By this increasingly oblique orientation of the prisms the volume increment of the enamel mantle is created. The maximal angle of deviation is found morphologically and mathematically between 60 degrees-70 degrees at the crown surface. This arrangement of the prisms demonstrated by us is now seen to be the reason for erroneous assumptions about an increase of the prism diameter when ground sections were used. Because the prisms are oriented more and more oblique towards the periphery, correspondingly larger effective diameters must be produced while making ground sections tangential to the crown surface.

Dental Enamel↗
PubMed1989

[The results of scanning electron microscopy research on interdental stripping in vitro].

In an in-vitro study the abrasive qualities of different orthodontic finishing strips were evaluated on the enamel surfaces of human teeth by means of a scanning electron microscope. As a result we can state that even the use of the finest finishing strip cannot eliminate the deep furrows that resulted from prior abrasion with a strip that is more coarse. The remaining furrows caused by the abrasive procedure are so deep and wide, that plaque accumulation may well be expected therein, and thus be predisposing for caries and periodontal pathology.

Dental Enamel↗
PubMed1989

[Early development of human tooth germs including the surrounding structures].

It could be shown by means of 3-dimensional reconstructions made from serial sections of human embryos, that the dental lamina of the lower jaw as well as that of the upper jaw is spatially impeded at its distal ends by the presence of the mandible and Meckel's cartilage. This spatial impediment of the odontogenetic epithelium can be seen to be of influence during the formation of the tooth buds.

Humans↗
PubMed1989

[Application of digital image processing techniques in cephalometry].

Digital image processing methods were applied to cephalometric analysis. Conventionally taken x-rays were captured by the aid of a video-camera. Digital processing was done using the IPS-System (Kontron). The resulting average error of the method at this stage of development was comparable to that of the traditional method using a light box.

Cephalometry↗