Biomedical subjects
Publications and source records attributed to M Held.
The purpose of the present paper was to determine the time required for filling therapy. The authors deal briefly with the subdivision of time adopted for the present study. Conclusions as to planning in dental practice may be drawn from the results obtained only if values determined by different dentists are available for comparison.
On the basis of epidemiologic studies on 10 106 sugjects from the population of the town of Rostock, the authors deal with the frequency of filled tooth areas and their affection by secondary caries with special regard to filling materials (silver-tin amalgam, silicate cement, inlay). The low frequency of secondary caries in tooth areas restored by means of inlays is noteworthy. Finally, the authors give recommendations for practice.
The authors point to the diffusion processes in dental hard tissues and describe a personal method for determining the diffusion constant in dentine. The diffusion constant in the dentine of permanent teeth from adolescents is 0.74 - 10(-2) cm2/d, measured by means of radioactively labelled water. The necessity for further studies is emphasized.
The report is on metric examinations of the thickness of the hard substance coating of the first upper milk molars based on 122 tooth cuts (longitudinal and transversal) and on the shape of the crowns of these teeth. The measurements were made by means of a stereomicroscope SM XX number 551 190 (VEB Carl Zeiss, Jena), and the results were statistically evaluated.
Studies on the shape of interproximal contact in the lower side teeth region were performed in 203 persons and 73 models. In 74,9% of cases a spheric-plane and in 25,1% a more punctuous-plane contact was registered. These findings are compared with observations of the interproximal abrasion of the lower premolars and molars in roe.
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Total reconstruction of the auricle requires a skillful surgical technique and an appropriate material for the shape-supporting frame. Up to now, there is no such material apart from autologous rib cartilage. The combination of chronic microtraumatization of adjacent tissue caused by the mobility of an implant bed such as the auricle and the foreign-body reaction to currently available artificial polymers frequently results in extrusion. In our animal model (rats), polymers of different elasticity were implanted in a moving implant bed to analyse differences in foreign-body reaction related to implant elasticity. The results were significantly better for a rather stiff control material (porous polyethylene). A contributing factor may be better fixation of the implant material by tissue ingrowth into its micropores.
The cause of this condition is undetermined. Cessation of root development is associated with a variety of systemic, congenital or genetic disorders. External trauma, such as radiation and electrical burns, can arrest development.