The oxidation‐induced crack healing of an Al2O3 composite loaded with various volume fractions of Ti2Al0.5Sn0.5C repair filler particles was investigated by annealing in air at a relatively low temperature of 700°C. After annealing a composite with 20 vol.% repair fillers (with a particle size of ~5.6 µm) for 48 hours, artificial indentation cracks prepared on the surface, as well as pores near the surface, were completely healed by filling with condensed oxidation products. Additionally, minor fraction of metallic Sn was detected. A complementary study by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and energy dispersive X‐ray spectroscopy revealed that nano‐sized oxidation products (SnO2, TiO2, and α‐Al2O3 phase) were formed as major crack‐filling species. After healing, the strength recovery of the Al2O3 composites was significantly improved in the composites loaded with more than 10 vol.% repair fillers and achieved 107% at 700 for 48 hours.
The aim of this study is to evaluate the effects of nanoporous anodic aluminum oxide (alumina) with pore diameters from 15 to 40 nm on osteoblasts (hFOB) and fibroblasts (HFF). After 7 days, a significantly higher proliferation of osteoblasts with a regular cell morphology is visible on the 40 nm samples compared to the 15 nm pore diameter (p ¼ 0.003). Fibroblasts, on the other hand, have a significantly higher proliferation rate on the 15 nm pore diameter samples compared to the 40 nm samples (p ¼ 0.000). The pore diameter of AAO affects fibroblasts and osteoblasts in opposite ways and makes it possible to cope in a perfect way with different requirements of cells on the implant surface.
The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of nanoporous anodic aluminum oxide of different pore diameters on the bacterial species Streptococcus mitis and Streptococcus mutans. Nanoporous anodic aluminum oxide (AAO) surfaces with an average pore diameter of 15 and 40 nm, polished pure titanium and compact aluminum oxide (alumina) samples as reference material were investigated. S. mitis and mutans were evaluated for initial adhesion and viability after an incubation period of 30 and 120 min. After 30 min a significantly reduced growth of S. mitis and mutans on 15 nm samples compared to specimens with 40 nm pore diameter, alumina and titanium surfaces could be observed (p < .001). Even after 120 min incubation there was a significant difference between the surfaces with 15 nm pore diameter and the remaining samples (p < .001). AAO surfaces with a small pore diameter have an inhibitory effect on the initial adhesion of S. mitis and mutans. The use of such pore dimensions in the area of the implant shoulder represents a possibility to reduce the adhesion behavior of these bacterial species.
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