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Biomedical subjects

E H Helfgen

Publications and source records attributed to E H Helfgen.

12 recordsLinked to original sources
PubMed1995

[The intraoral bacterial colonization of temporary denture plastics].

Plastic materials used for temporary crowns and bridges in prosthetic dentistry are investigated with regard to the possibility of their microbial colonization. For this purpose four different kinds of materials, i.e. Resincap, Trim, Snap (Polyalcylmethacrylate) and Protemp (Bisphenol-A-Glycidyl-Methacrylate) were chose. With the help of 10 test persons in vivo experiments were carried out. After a period of two weeks it could be verified, that the bacteria have a stronger affinity to Protemp than to Polyalcylmethacrylate. The hypothesis, that the different intensity of colonization is due to the roughness of certain surfaces could be confirmed by additional experiments.

Crowns↗
PubMed1991

[Studies on the transversal movement capacity of the TMJ].

The range of transversal movements of the temporomandibular joint was determined by electronic measurements under different types of mandibular guidance. The results illustrate that there is a certain freedom in transversal movement. The mean transversal movement of the balancing condyle supported by the operator was 0.09 mm with a maximum at 0.4 mm. The results without guidance of the mandible or under tooth guidance were found to be smaller. The mean lateral operator-guided movement of the working condyle was 0.3 mm with a maximum at 0.9 mm whilst applying a horizontally directed pressure to the angle of the mandible. Furthermore after 0.5, 1 mm and 2 mm translation of the balancing condyle, the greatest transversal movements were observed again under operator-assisted guidance. The authors recommend rules for the selection of the adjustment of semiadjustable articulators, a wax-up to provide transversal freedom in movement and a technique to check fixed restaurations for proper occlusion and articulation.

Humans↗
PubMed1991

[Anterior guidance compared with curvatures of sagittal TMJ excursions].

The sagittal condylar paths of 17 healthy persons with class I occlusion were recorded by electronic axiography. Based on the radius values established for the geometry of each condylar path these could be compared with the protrusive facets of the incisors and the first premolar teeth. The results are important for our understanding of the movement profiles of the masticatory system. Correlations between the TMJ and the anterior teeth in terms of functional morphology were observed.

Dental Occlusion↗
PubMed1990

[Morphology of the laterotrusive paths in dentitions with normal function].

The occlusal surface of the posterior teeth of 20 subjects with class-I-occlusion were analysed by means of an electronic profilograph in laterotrusion. Each of the curvatures recorded was defined by an approximated radius as well as its angle to the occlusal plane. The software used was specifically developed to suit this particular purpose. The data showed characteristic regularities. The results indicate that the average radius of the canine is longer than that of the molars. An alternating increasing and decreasing tendency of the angles to the occlusal plane was observed. The results suggest that the concept of canine-protected occlusion may be strengthened by the fact that there is a genetic determination of the canine dominance.

Bicuspid↗
PubMed1990

[Relationship between transversal joint guidance and buccal curve morphology].

The relationship between the morphology of the curvature of laterotrusion facets and tooth-guided tracings of the mediotrusive condyle path was studied in 20 probands with normal function. The varying inclinations of the dominant laterotrusion facets in cuspid-protected or group-guided occlusion has no bearing on the angle of the mediotrusive paths relative to the horizontal plane. The morphology of the buccal curve allows no predictions as to the direction of the mediotrusive path curvature. Only the movements of the idling condyle were influenced by the type of occlusal guidance. In lateral excursive movements of the mandible with the teeth in contact group-guidance frequently resulted in an upward movement of the laterotrusive condyle and thus to a compression of the intraarticular soft tissues. Although valid conclusions regarding any type of interdependence are impossible unless we are able to measure real tooth and joint movements simultaneously, the results of our study contradict other hypotheses at any rate.

Dental Occlusion, Balanced↗
PubMed1990

[Pre- and post-eruption effects on the functional morphology of the articulating structures].

Profile traces of latero- and protrusive facets of subjects with class-I-occlusion showed characteristic regular patterns in curvature and angle to the occlusal plane. There was no significant correlation between the laterotrusive surface profiles and the corresponding transversal movement of the condyle which was recorded electronically in 3 dimensions. Curvature morphology was plotted as a function of tooth eruption, development of the dental hard tissues, and tooth wear. In conclusion the results were applied to comprehensive occlusal restorations.

Dental Arch↗
PubMed1989

[Comparative studies on the morphology of the curvature of the protrusive paths in anterior and posterior teeth].

The occlusal surfaces of 20 class I probands were recorded during protrusion with an electronic profilograph. Using a circular template, a definite radius could be attributed to each of the recorded curvatures. The radii and angles determined relative to the occlusal plane showed characteristic regularities. Thus, the radii of the anterior teeth are longer than those of the posterior teeth. The longest radius was generally found for the canines. The same tendency, although less pronounced, was observed with the angles. These phenomena can be explained by the fact that the masticatory system involves both "biting" and "grinding". Evolutionary and embryological theories have also been included in the discussion.

Dental Occlusion↗
PubMed1989

[Forms of eccentric posterior displacement of the articular disc].

The temporomandibular joints of 40 patients with suspected intraarticular soft tissue displacement have been examined clinically and with the aid of electronic recording methods. The disc position has been verified by means of magnetic resonance tomography. The results demonstrate that Farrar's reciprocal clicking noises, interpreted as an anterior displacement of the articular disc, are not pathognomonic for the presence of a centric anterior displacement, but may also be associated with eccentric posterior disc displacement. Non-invasive imaging procedures show them as posterior displacements of the articular disc in eccentric mandibular positions. Eccentric posterior disc dislocation out of the joint space is associated with reciprocal clicking, i.e. an initial or terminal dislocation click during opening and a terminal repositioning click during closure. Centric anterior dislocation, on the other hand, was not found to be associated with terminal joint clicking during opening.

Adolescent↗