An orthodontic attachment for patients with fixed prosthetic restorations.
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Adult↗
Biomedical subjects
R J Radlanski
Publications and source records attributed to R J Radlanski.
A scanning electron-microscopic study of developing human deciduous enamel on the dependence of the outline of surface pits on the angle of observation.
On the developing enamel surfaces of fetal human deciduous teeth, many of the surface pits were arcade-shaped with the arcade preferentially pointing in a cervical direction. The configuration of the interprism ridges between the pits contributed to this appearance. Surface cracks allowed verification of an incisal inclination of the subsurface prisms. This apparent paradox was solved when the specimens were tilted so that the pits were viewed in the directions of the prisms, giving the pits a compressed arcade-shape with the arcades pointing incisally. It is recommended that care should be exercised and due attention paid to the angle of observation when determining the orientation of pit arcades. Pit entry direction seems to be a more reliable feature for inferring the direction of tangential ameloblast movement.
Ameloblasts↗
In vitro investigation of novel calcium phosphates using osteogenic cultures.
A rat bone marrow stromal cell (RBM) culture was used to evaluate novel bioactive calcium phosphate ceramics. Three rapidly resorbable, glassy crystalline materials with the main crystalline phase Ca2KNa(PO4)2 were investigated (sample code GB 1a, GB 14, GB 9). These materials were designed to exhibit a higher degree of biodegradability than tricalcium phosphate. Additionally, a bioactive glass ceramic of low biodegradability was examined (sample code AP 40). RBM cells were cultured on the disc-shaped test substrata for 14 d. The culture medium was changed and calcium and phosphate concentrations of the medium were determined daily. Specimens were evaluated using light microscopy and morphometry of the cell-covered substrate surface, scanning electron microscopy and energy dispersive X-ray analysis. Except for GB 1a, the rat bone marrow cells attached and grew on all substrate surfaces. Of the different calcium phosphate ceramics tested, AP 40 facilitated osteoblast growth and the elaboration of the extracellular matrix to the highest degree followed by GB 9 and GB 14. The inhibition of cell growth encountered with GB 1a seemed to be related to its high phosphate ion release.
Journal Article↗
Computer-aided graphical reconstructions of the development of murine dental primordia and surrounding structures from day 12 until birth.
There are studies that discuss spatial impediment as an important co-factor during tooth morphogenesis, especially to the cuspal folding pattern in relation to the space available for the primordium. The aim of this study is to give a description of the 3-dimensional aspect of the dental primordia of the NMRI mouse in relation to their surrounding hard tissue structures, and covering all prenatal stages from lamina to late bell. Serial histological sections were prepared from 31 specimens of NMRI mice from intrauterine days 12-19 (birth), and computer-aided 3D-reconstructions were made from light microscopic traces. During the early stages of days 12-15, the bony structures were too far away to exert a direct mechanical influence. However, from day 16 on (early bell stage in molar primordia), partial bony encapsulations with distances around 100 microm were found. Up to birth, when the folding pattern of the inner enamel epithelium became more prominent, a progressive bony encapsulation, with distances reduced to 40 microm, could be seen. Spatial impediment may be a possible co-factor in bell stages of dental morphogenesis.
Animals↗
Morphological evaluation of osteoblasts cultured on different calcium phosphate ceramics.
The objective of these investigations was to develop an in vitro test system for evaluating novel rapidly resorbable calcium phosphate ceramics of varying composition. Rat bone marrow cells were cultured on the disc-shaped test substrates for 14 days. Five calcium phosphates were examined: R1 CaNaPO4; R1/M2, composed of CaNaPO4 and MgNaPO4; R1/2, composed of CaNaPO4 and Mg2SiO4; R1 + 9% SiO2 consisting of CaNaPO4 and 9% SiO2 (wt%) and R17, Ca2KNa(PO4)2. Two studies were performed. In study I cultures were re-fed every two to three days. In study II the medium was changed daily, and calcium and phosphate concentrations of the medium were determined daily. Specimens were prepared for light microscopy and morphometric evaluation of the cell-covered substrate area, scanning electron microscopy and energy-dispersive X-ray analysis. With all materials tested except for R1/2, an increase of cellular growth was observed after changing the medium daily. Of the different calcium phosphate ceramics tested, R17 and R1/M2 facilitated osteoblast growth and elaboration of extracellular matrix to the highest degree. The inhibition of cell growth encountered with R1 in study I and R1/2 in both studies seemed to be related to a high phosphate-ion release from these materials.
Absorption↗
Risk of pulp damage due to temperature increase during thermodebonding of ceramic brackets.
The purpose of this study was to perform in vitro measurements of the temperature increase at the enamel-dentine interface during electrothermal removal of ceramic brackets, and to analyse, in vivo, whether signs of pulp damage can be observed 4 weeks after the procedure. In vitro study: a total of 29 caries-free human teeth were cut into buccal and lingual halves. The buccal halves were bonded with ceramic brackets, and miniature thermocouples were placed from the pulpal side into holes drilled to the enamel-dentine interface under the centre of the bracket slot. From the onset of thermodebonding, the temperature increase relative to room temperature was recorded for a period of 43 seconds. The maximum temperature increase at the enamel-dentine interface was 6.9 degrees C. In vivo study: a total of 12 human premolars scheduled for extraction for orthodontic reasons were bonded with ceramic brackets. Electrothermal debonding was performed the following day. After 4 weeks, the teeth were extracted and prepared for histological examination. Following demineralization, sections were prepared for light microscopic examination. No signs of pulpal inflammation were observed.
Acrylic Resins↗
Incremental lines in root cementum of human teeth: an approach to their ultrastructural nature by microscopy.
In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-micron thickness were no longer visible in semi-thin sections (thickness, 1-2 microns) of the same specimen in the same area. The assumption that annulations could be caused by super-imposing structures in the depth of field of the light microscope's objective lens was not verified by CLSM. Fiber bundles of higher density than the surrounding matrix in TEM micrographs could not be connected unambiguously with annulations in LM micrographs. After all, the ultrastructural nature of cemental annulations remains an open question.
Age Determination by Teeth↗
Cephalometric investigations concerning the geometry of the viscerocranium of human anencephalic fetuses.
Cephalometric investigations were carried out on 16 macerated skulls of anencephalic fetuses aged around 6 months and compared with the values obtained from a group of 18 normally developed specimens. The skull geometry of the anencephalic fetuses was different from normal proportions: anencephalic fetuses showed a clear mandibular prognathism, and a maxilla tilted in anterior direction. The values describing length of maxilla and length of the anterior cranial base, and NS-Ba angle were found to be within the normal range. From the results it can be concluded that the defective development of the forebrain seems to have no effects on the length development of the anterior cranial base although it does influence the form of the surrounding bony structures. The formation of the mandibular prognathism cannot be brought into direct connection with the defective brain development.
Anencephaly↗
Development of the parotid gland and its closer neighboring structures in human embryos and fetuses of 19-67 mm CRL.
The fetal development of the human parotid gland was studied by means of serial sections of human embryos and fetuses ranging from 19 mm to 67 mm CRL. Analysis of computer assisted 3-dimensional reconstructions and anatomical drawings leads to the following observations: 1. The parotid gland anlage is found at the most lateral and cranial point of the sulcus buccalis. 2. The location of the orifice of the parotid duct is dependent upon the developmental processes of the fetal skeleton. 3. The anlagen of anatomical structures dominating the parotid bed in the adult are found prior to the enlargement of the parotid gland. 4. The surface of the parotid gland shows impressions of the surrounding structures. 5. There is no evidence that the parotid gland is subdivided into two lobes by the facial nerve.
Adult↗
Development of the submandibular gland and its closer neighboring structures in human embryos and fetuses of 19-67 mm CRL.
The fetal development and arrangement of the human submandibular gland was studied by means of serial sections of human embryos and fetuses ranging from 19 mm to 67 mm CRL. Computer assisted 3-dimensional reconstruction leads to the following observations: 1. The orifice of the submandibular duct is located in the medial paralingual sulcus. 2. There is evidence that the extension and location of WHARTON's duct is influenced by the surrounding structures. 3. The surface of the submandibular gland primordium shows impressions of the neighboring structures. 4. The glandular tissue is encapsulated in condensed mesenchyme.
Embryo, Mammalian↗
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↗
[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↗
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↗
[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↗
[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↗
[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↗
[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↗
[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↗