Surface charge in foreign body carcinogenesis

Evaluation of soft tissue reactions at the interface of titanium limited contact dynamic compression plate implants with different surface treatments: an experimental sheep study

Five types of limited contact dynamic compression plates (LC-DCPs) of pure titanium with different surface treatments and an electropolished stainless steel LC-DCP were tested. The surface roughness parameters and chemical surface conditions were determined and checked for probable surface contamination. After an implantation period of 3 months on long bones of sheep, the soft tissue adjacent to the plates was evaluated histomorphometrically. The difference in roughness parameters was statistically significant for most surface conditions. A correlation was found between the surface roughness of the implants and the thickness of the adjacent soft tissue layer. The thinnest soft tissue reaction layer with a good adhesion to the implant surface was observed for the titanium anodized plates with coarse surface. Smooth implants, in particular the electropolished stainless steel plates, induced statistically significant thicker soft tissue layers. Profilometer roughness measurements combined with scanning electron microscopy techniques were useful methods to characterize the surface morphology.

What makes silica toxic?

Published data suggest that particle charge could be related to its toxicity. Respirable particles containing silica were therefore collected in foundries and their charge measured. These particles carried high levels of positive charge that were related to low humidity. Incubating these particles with pulmonary macrophages from mice produced detectable activities of collagenase, a precursor of silicosis. These experiments confirm that the toxicity of silica particles is likely to be because of the positive charge they carry.