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Biomedical subjects

H Wegener

Publications and source records attributed to H Wegener.

10 recordsLinked to original sources
PubMed1996

The extent of enamel surface fractures. A quantitative comparison of thermally debonded ceramic and mechanically debonded metal brackets by energy dispersive micro- and image-analysis.

This clinical study investigated the practical value of two methods for debonding brackets attached by the adhesive Concise to acid-etched enamel surfaces. Forty-two Ultratrimm Standard metal brackets and 42 Fascination ceramic brackets were collected from juvenile patients undergoing orthodontic treatment. All metal brackets were mechanically debonded by a conventional bracket removal plier, whereas the ceramic brackets were thermally debonded by a commercial Dentaurum ceramic debonding unit. All brackets were evaluated by scanning electron microscopy for the morphology of their adhesive fracture surfaces and for the occurrence of mineral-like particles attached to the adhesive fracture surfaces. These particles were analysed by an energy dispersive X-ray microprobe for their Ca/P ratios and by image analysis of scanning electron micrographs for measurement of their areas. The scanning electron micrographs showed 4 types of debonding fractures. The most frequent fracture was type 1 (between adhesive and bracket base) and type 2 (between adhesive and enamel surface). In the group of mechanically debonded metal brackets type 1 (38 per cent) and type 2 (45 per cent) showed a similar frequency, whereas thermally debonded ceramic brackets predominantly showed fracture type 1 (79 per cent) and only a minor percentage of type 2 (11 per cent). A statistical evaluation was applied to estimate the range of reproducibility of fracture types with a 95 per cent confidence interval (level of significance alpha = 5 per cent). In both groups the microprobe analysis of fracture surfaces lying completely or partly between adhesive and enamel surface identified the mineral-like particles as enamel mineral. They occurred partly as single particles (range of thickness: 5-25 microns, mean area: 3500 microns2) and partly as a coherent covering with a total area of 1.9-5.8 mm2. It is concluded that the thermodebonding technique is superior to conventional mechanical debonding, because the frequent occurrence of fracture type 1 after thermodebonding affords a protection for the enamel surface, whereas mechanical debonding entails a comparatively high risk of enamel fractures.

Acid Etching, Dental↗
PubMed1995

[The therapeutic effects after the dentoalveolar compensation of skeletal open bite in adults. The skeletal and dental parameters].

In the following study 20 adult skeletal open-bite patients were analysed after they had undergone dental compensation to camouflage the underlying skeletal discrepancy. The initial and final cephalometric records were analysed to determine the factors that led to the desired goal. The results showed no significant difference in the skeletal relationship. Molar intrusion was not recorded. The open-bite was correct mostly by reclining the upper incisors and by changing their position. Significant differences existed between the obtained results and the mechano-therapy employed. The geometrical model developed on the of the above makes it possible to predict and predetermine the targeted vertical dimension. Furthermore the results show extrusion of the front teeth as another dominant factor.

Adolescent↗
PubMed1992

[A comparison of the clinical and instrumental functional findings in subjects with Angle class II/2 versus a eugnathic group].

On the basis of a clinical and functional analysis, the diagnosis of a group of patients with Angle class II/2 malocclusion is compared with a control group with normal occlusion in a statistical study. The present study confirms the tendency revealed in the literature for patients with an Angle class II/2 malocclusion to more frequently show symptoms of a myoarthropathy. However, our results failed to confirm the assumption made in previous studies that class II/2 patients have a steep condylar axis. In particular in patients with relatively vertical upper incisors and a deep bite, a functional analysis should be done at the start of treatment. In the event of problems being found, the primary aim of therapy is the correction of the upper incisor angle.

Adult↗
PubMed1991

[Different indications for lower incisor extraction].

A general survey of literature between 1955 and 1989 is given about the different indications for incisor extraction in the lower jaw. The dominating indications from the orthodontist's point of view with varying ways of treatment are mentioned as well as trauma and missing incisors. A review of 10 treatment cases presents our indications which are discussed.

Adult↗
PubMed1990

Plasmid-encoded resistance to macrolides and lincosamides in Staphylococcus hyicus.

A small plasmid of 2.35 kb, isolated from a porcine Staphylococcus hyicus-culture, was found to be responsible for constitutive resistance to macrolide/lincosamide antibiotics. This plasmid-encoded property could be established by interspecific transformation experiments. The plasmid from porcine Staph. hyicus was designated as pSE2. It differed on the basis of its restriction map from the macrolid/lincosamid resistance (MLR-)-plasmids of other staphylococcal species from infections of humans. Furthermore, the pSE2 plasmid encoded two proteins of approximately 20.5 and 30 kDa.

Animals↗
PubMed1975

[The effect of an antihypertensive drug during psychological stress. A double-blind study].

A sample of 20 patients suffering hypertension (with a moderate rise in blood pressure) was randomly divided into two treatment groups of equal size. The patients of one group received antihypertension treatment with the combination drug Briserin¿ (containing 0.1 mg reserpine, 5 mg clopamide, 0.5 mg dihydroergocristin/per tablet); the other patients who served as control group, received a matched placebo. After a fortnight's treatment, the responsiveness of both groups to five different psychologically stressing situations (those with cognitive and/or emotional overload) was tested. Analysis of covariance revealed clinically significant differences in the mean systolic and diastolic pressure scores of the two groups. The scores of the treatment group were lower not only under stress but also at rest. There was in interaction between rise of blood pressure under stress and kind of stress in the two groups, i.e., in situations with heavy emotional and/or cognitive load the differences in the pressure scores of the two groups were less substantial than in situations with a low or medium load. The treatment had no systematic effect on heart rate in this sample. In the treatment group reaction time, perceptual speed, and short-term memory were impaired as compared with the control group; but these differences did not reach a level of significance.

Adolescent↗