Biomedical subjects

W Höland

Publications and source records attributed to W Höland.

4 recordsLinked to original sources

PubMed2000

A comparison of the microstructure and properties of the IPS Empress 2 and the IPS Empress glass-ceramics.

The aim of this report is to analyze the microstructures of glass-ceramics of the IPS Empress 2 and IPS Empress systems by scanning electron microscopy. The main properties of the glass-ceramics were determined and compared to each other. The flexural strength of the pressed glass-ceramic (core material) was improved by a factor of more than three for IPS Empress 2 (lithium disilicate glass-ceramic) in comparison with IPS Empress (leucite glass-ceramic). For the fracture toughness, the K(IC) value was measured as 3.3 +/- 0.3 MPa. m(0.5) for IPS Empress 2 and 1.3 +/- 0.1 MPa. m(0.5) for IPS Empress. Abrasion behavior, chemical durability, and optical properties such as translucency of all glass-ceramics fulfill the dental standards. The authors concluded that IPS Empress 2 can be used to fabricate 3-unit bridges up to the second premolar.

Ceramics↗

PubMed2000

Needle-like apatite-leucite glass-ceramic as a base material for the veneering of metal restorations in dentistry.

A needle-like apatite-leucite glass-ceramic was prepared in the SiO2-Al2O3-Na2O-K2O-P2O5-F system. Nucleation and crystallization processes were studied in bulk and powdered samples. The crystallization of leucite follows the mechanism of surface crystallization. After the precipitation of NaCaPO4 crystals and another unknown crystal phase, the formation of needle-like apatite is based on a volume nucleation and crystallization process. The mechanism of the formation of needle-like apatite differs to those of apatite precipitation in glass-ceramics. The morphology of needle-like apatite is comparable to that of apatite in natural teeth. The properties of the glass-ceramic, especially the good chemical durability, the optical properties, as well as mechanical and thermal properties allow glass-ceramic to be used as a main component in a bio-material for the veneering of metal restorations in dentistry.

Journal Article↗

PubMed1985

Interface reactions between machinable bioactive glass-ceramics and bone.

A new biomaterial for bone substitution, a "machinable bioactive glass-ceramic" has been developed. The material contains two main crystal phases, mica and apatite, and is therefore machinable and bioactive. It has the advantage to be workable by the surgeon, if necessary, during operation. The preparation method of this glass-ceramic is described. Different types of the material can be produced in dependence of the composition, nucleation, and crystallization of the basic glass. In vivo and in vitro investigations showed a characteristic solubility of the material. A Ca-phosphate-rich interface layer with apatite crystals (from the basic glass-ceramic) and a thickness of about 5-10 micrometers grows as solid-state reaction between glass-ceramic and bone. This interface reaction is interpreted as a chemical process which includes a slight solubility of the glass-ceramic and a solid state reaction between the stable apatite crystals in the glass-ceramic and the bone.

Aluminum Silicates↗

PubMed1983

[Mechanically processable bioactive glass ceramics--a new biomaterial for bone replacement. 1].

Anorganic materials as glass ceramics with their main crystal phase apatite can be used as biomaterial for the bone substitute. An interior compound between bioglass-ceramics implants and the bone was showed in animal experiments. The apatite crystals in the bioglass-ceramics produce obviously the start point for this fusion process. The shear strength of the compound is on average the eightfold of highly compact Al2O3 ceramics. The bioactive glass ceramics could solve possibly the problems of implant loosening and defect bridging-over. Mechanical processable bioactive ceramics was developed and tested with regard to these employment spheres.

Animals↗