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Biomedical subjects

R J Radlanski

Publications and source records attributed to R J Radlanski.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1989

Mathematical outline-analysis of eminence and fossa of the TMJ of Cercopithecus aethiops (Cercopithecidae, primates, Mammalia).

The contours of the eminence and the fossa of the temporomandibular joint (TMJ) of Cercopithecus aethiops, a monkey species, are analyzed in sagittal-vertical sections. The functionally relevant contours can be approximated by catenates for both the eminence as the protrusive guidance and the fossa as the retrusive guidance. This study reveals the more general character of the contour formula y = a cosh(x/a) - a. This may be true because all these catenates are similar to one another and since they can be found in the guiding contours of the components of the stomatognatic system in man as well as in Cercopithecus aethiops.

Animals↗
PubMed1989

[The orientation of the enamel prisms at the enamel surface].

The angulation that prisms obtain with the surface in human permanent teeth was analysed on broken enamel by means of the scanning electron microscope. In the cervical region the prisms end nearly perpendicular towards the surface, while the angle becomes more and more acute towards the occlusal region of the crown. In the cuspal area the deviation from the perpendicular direction of the prisms approaches 70 degrees. The size discrepancy between the inner and the outer surface of the enamel mantle can be explained by the more or less angulated position of the prisms.

Bicuspid↗
PubMed1988

The origin of tooth cusps--a hypothesis.

An embryological concept is offered to explain the formation of tooth cusps. The epithelium is considered to play the active part in morphogenesis. The folding of the inner sheath of the enamel organ must be seen to be the origin of tooth cusps. This folding can be considered to be a consequence of the ability to span only a certain area without folding. The regularity of the folding--and thus the regularity of the molar occlusal pattern--might be a result of the unique material properties of the inner enamel epithelium.

Amelogenesis↗
PubMed1988

The origin of tooth number of the human deciduous dentition: a hypothesis.

The constant number of 5 teeth per quadrant in the human deciduous dentition is seen to be a result of the mitotic activity within the dental lamina which leads to a constant number of centers in which cells are compressed together. These centers in which, due to the compression, the cells become narrow and cylindrical and, due to subsequent bulging, wedge-shaped, are the prerequisite for the formation of the constant number of five tooth buds per quadrant.

Dentition↗
PubMed1988

Plaque accumulations caused by interdental stripping.

Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.

Dental Enamel↗