Dental composites based on x-ray-opaque mixed oxides prepared by flame spraying

Abstract

The present invention relates to dental composites comprising at least one nanoparticulate mixed oxide (a) of SiO 2 with X-ray-opaque metal oxides of one or more elements selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu which has been prepared by flame spraying.

1 - 14 . (canceled) 
     
     
         15 . A method for preparing a nanoparticulate mixed oxide based on Si with at least one metal selected from the group consisting of Y, La, Ta, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu by flame spraying and wherein the mixed oxides have at least one of:
 a) an amorphous structure,   b) a homogeneous element distribution,   c) a very low organic content,   d) an X-ray opacity which can be varied,   e) an index of refraction which can be varied,   f) a spherical particle shape.   
     
     
         16 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , by flame spraying as an X-ray opaque filler. 
     
     
         17 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the mixed oxides have a crystallinity index, determined by X-ray diffraction, of less than 0.1. 
     
     
         18 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the mixed oxides have a crystallinity index, determined by X-ray diffraction, of less than 0.05. 
     
     
         19 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the mixed oxides comprise less than 0.5% by mass of oxidizable carbon. 
     
     
         20 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the mixed oxides comprise less than 0.1% by mass of oxidizable carbon. 
     
     
         21 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the mixed oxides comprise no detectable organic carbon. 
     
     
         22 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , having an X-ray opacity in the range of from 50% Al to 800% Al. 
     
     
         23 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , having an X-ray opacity in the range of from 100% Al to 400% Al. 
     
     
         24 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , having an index of refraction in the range of from 1.46 to 1.70. 
     
     
         25 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , having an index of refraction in the range of from 1.48 to 1.60. 
     
     
         26 . A method for preparing a nanoparticulate mixed oxide, as claimed in  claim 15 , wherein the particles are spheroidal and display no preferential direction or edges in a transmission electron micrograph (TEM), comparable to the case of ideal spheres.