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Biomedical subjects

W Kullmann

Publications and source records attributed to W Kullmann.

At least 19 recordsLinked to original sources
PubMed1990

[Sorption and solution in autopolymerizing and light-cured composite materials].

When stored in water, polymeric filing materials with similar components but different activation systems exhibited similar tendencies in terms of sorption and solution behavior. After 7 days of storage, the uptake of water ranged between 12.1 and 58.9 micrograms mm-3. Solubility varied from 0.3 to 44.3 micrograms mm-3. Within the observation period the surface hardness of the 12 different test and reference materials was increasing. The polymerization of the photosensitive materials was considerably affected by the type of light source used.

Absorption↗
PubMed1989

[Dimensional behavior of six light-cured veneer acrylics].

During irradiation light-cured veneer acrylics underwent shrinking by 2.2 to 4.8%. In operation, the temperature in the irradiation chambers of the light units increased up to a maximum of 87 degrees C. The coefficients of thermal expansion a20/100 of the acrylics ranged between 49.2 and 72.2 x 10(-6)/K. Dimensional changes of the acrylics due to high polymerization contraction and/or due to a different thermal behavior than that of the metal framework may produce stresses in the bond system and possibly promote a deterioration of metal retention.

Acrylic Resins↗
PubMed1989

[Studies on the course of polymerization shrinkage of self-cured and light-cured composites].

The dilatometer method was used to study the linear polymerization shrinkage of five different composite filling materials which, although of similar composition, are available in both the self-curing and the light-curing form. The shrinkage of these materials has been recorded for 5 minutes after setting was initiated. While rapid length changes occurred in the light-cured materials usually within the irradiation period of 20 seconds, the process of polymerization shrinkage lasted longer in the self-cured materials, extending beyond the period of observation. After 5 minutes linear polymerization shrinkage varied between 1.1 and 1.8%.

Composite Resins↗
PubMed1989

[Etching pattern of drop-viscosity and pluggable glass-polyalkenoate lining cements under the scanning electron microscope].

The surfaces of six fast-setting glass-polyalkenoate cements of varying composition and consistency were etched with H3 PO4 for 10 and 60 seconds. Depending on the material used, the powder/liquid ratios, and the duration of acid exposure, typical etching patterns could be observed. In general the etched surfaces were characterized by the selective removal of the cement-forming matrix. Furthermore, those surfaces treated with a fine grain diamond showed a similar rough but rather irregular structure. The arithmetic mean roughness values Ra determined by an electric sectional scanning procedure ranged between 1.4 and 3.6 microns.

Acid Etching, Dental↗