Bioabsorbable materials are of great interest for bone regeneration applications, since they are able to degrade gradually as new tissue is formed. In this work, a fully biodegradable composite material containing polylactic acid (PLA) and calcium phosphate (CaP) soluble glass particles has been characterized in terms of surface properties and cell response. Cell cultures were performed in direct contact with the materials and also with their extracts, and were evaluated using the MTT assay, alkaline phosphatase activity, and osteocalcin measurements. The CaP glass and PLA were used as reference materials. No significant differences were observed in cell proliferation with the extracts containing the degradation by-products of the three materials studied. A relation between the materials wettability and the material-cell interactions at the initial stages of contact was observed. The most hydrophilic material (CaP glass) presented the highest cell adhesion values as well as an earlier differentiation, followed by the PLA/glass material. The incorporation of glass particles into the PLA matrix increased surface roughness. SEM images showed that the heterogeneity of the composite material induced morphological changes in the cells cytoskeleton.
Titanium dental implants with sandblasted and/or acid-etched surfaces have shown clinical superiority in comparison to their smooth, machined counterparts, and are now state of the art. Sandblasting of finished, sintered zirconia implants, however, will damage the surface structure and affect the mechanical properties. To improve osseointegration of zirconia dental implants without impairing the original mechanical strength by crack initiation and partial phase transformation from tetragonal to monoclinic, roughening of the zirconia surface by sandblasting before the final sintering step was employed. Impact of the treatments on cellular reactions of SAOS-2 human osteoblast-like cells was investigated. Sandblasting of Yttrium-stabilized zirconia (Y-TZP) with 120 μm and 250 μm Al2O3 enhanced average roughness (Sa) from 0.28 μm to 4.1 μm and 5.72 μm, respectively. Cell adhesion of SAOS-2 osteoblasts was enhanced up to 175% on sandblasted surfaces, compared to the machined zirconia reference (100%). Metabolic activity and proliferation in the logarithmic growth phase (24-48 h) were not significantly affected. Sample surface coverage by the cells after prolonged incubation (72 h) was markedly decreased on the roughened samples, indicating a shift towards increased differentiation on these surfaces. The approach investigated here to roughen zirconia implants by sandblasting before sintering shows potential to improve the clinical performance of ceramic dental implants.
FDM showed the superior dimensional accuracy and best skin surface reproduction. Moreover, digital acquisition and CAD postprocessing seem to play a more important role in the outcome than the additive manufacturing method used.
This study presents the first in vivo comparison between NMR field probes and Moiré phase tracking. For the gradient echo images, the field probes had a similar motion correction performance as the optical tracking system. For the MP2RAGE measurement, however, the camera yielded better results. Still, both tracking systems substantially decreased image artifacts in the presence of subject motion. Thus, the motion tracking modality should be chosen according to the specific requirements of the experiment while considering the desired image resolution, refresh rate, and head coil constraints.
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