ABSTRACT
Objective To find a new material for biomedical scaffold.Methods Composite films from poly-L-lactic acid(PLLA)and opal powder were fabricated.Osteoblasts seeded on the composite films and control ones were examined.Cell densities and morphologies on these films were studied by scanning electron microscopy(SEM).Cell growth and differential function were assessed by 3-(4,5-dimethyltyiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)test.Results SEM study showed that the addition of powder could improve the adhesion between osteoblasts and the composite films.MTT test proved that cell proliferation was improved when opal powder was added.This improvement came from the negative ion given off by the opal powder.The negative ions either accumulate at the cell membrane or enter into the cells.Accumulation of negative ions at the cell membrane leads to a change of electric potential difference across the cell membrane which should be in a proper range for the cells to perform their normal physiological function.If the negative ions enter the cells,they may take part in biochemical reactions whenever possible.In this way,the ions also affect the cell normal metabolism.Conclusion Osteoblasts grow well on opal/PLLA composites and the negative ion from opal powder is responsible for the enhancement of cell growth.This study provides a new material for biomedical scaffold.
ABSTRACT
Objective:To study the technical operation of self-developed investment (FUS-invest) for titanium crown and bridge. Methods:Orthogonal design was done. Four factors were taken into account, i.e. water/powder ratio, adhesive/hardener ratio, fine powder proportion in refractory and agitation time. And each factor was ranked into three levels. Slurry fluidity, initial setting time and setting time of every experiment group were studied. Grain size graduation of the best group was measured.Results:Fluidity, initial setting time and setting time were most greatly affected by water/powder ratio and secondly by fine powder proportion in refractory. When water/powder ratio was 7.5∶1 and the content of fine powder was 35%, slurry fluidity was better and initial setting time and setting time were appropriate. When the content of fine powder of AFS fineness number 300 was 31.31%, fineness number 100 was (40.09%), fineness number 70 was 18.05% and adhesive/hardness ratio was 200∶1, the perfect titanium castings could be fabricated. Conclution:The best rules of technical operation for perfect titanium castings are water/powder ratio (7.5)∶1, the content of fine powder 35% and adhesive/hardener ratio 200∶1.