Dental pastes, dental articles, and methods

Abstract

The present invention provides a dental paste, a dental article, methods of making and using the dental paste, and compositions prepared therefrom. In one embodiment, the dental paste includes (a) a filler including porous, non-pyrogenic silica having a silane treated surface and being substantially free of heavy metals and (b) a filler including non-aggregated primary silica particles, with the fillers being dispersed in a hardenable resin.

1 . A method of preparing a filler in a dry powder form comprising:
 drying a silica sol, the silica sol comprising primary silica particles having an average particle size of about 20 nanometers to about 120 nanometers dispersed in a volatile liquid, to form porous, non-pyrogenic silica comprising aggregates of primary silica particles, wherein the aggregated silica has an average aggregate size of about 1 micrometer to about 20 micrometers, the silica being substantially free of heavy metals;   dispersing the aggregated silica in a volatile liquid to form a volatile liquid dispersion of porous, non-pyrogenic silica;   treating the surface of the porous, non-pyrogenic silica dispersed in the volatile liquid with a silane to form a volatile liquid dispersion of porous, non-pyrogenic silica having a silane treated surface; and   drying the volatile liquid dispersion to form the filler.   
     
     
         2 . The method of  claim 1  wherein the aggregated silica has an average size of about 1 micrometer to about 10 micrometers. 
     
     
         3 . The method of  claim 2  further comprising milling the dried silica sol to form the aggregated silica. 
     
     
         4 . The method of  claim 1  further comprising calcining the silica at a temperature of at most about 650° C. 
     
     
         5 . The method of  claim 1  wherein the filler has a bulk density of at least about 0.4 g/cm 3 . 
     
     
         6 . The method of  claim 1  wherein the filler has a surface area of at most about 100 m 2 /g. 
     
     
         7 . The method of  claim 1  wherein the aggregated silica comprises silica clusters having an average aspect ratio of at most about 4:1. 
     
     
         8 . The method of  claim 1  wherein the silica sol is a sodium stabilized silica sol. 
     
     
         9 . The method of  claim 1  wherein the silica sol is a non-sodium stabilized silica sol. 
     
     
         10 . The method of  claim 1  wherein drying comprises spray drying or gap drying. 
     
     
         11 . A method of preparing a dental paste comprising:
 drying a silica sol, the silica sol comprising primary silica particles having an average particle size of about 20 nanometers to about 120 nanometers dispersed in a volatile liquid, to form porous, non-pyrogenic silica comprising aggregates of primary silica particles, wherein the aggregated silica has an average aggregate size of about 1 micrometer to about 20 micrometers, the silica being substantially free of heavy metals;   dispersing the aggregated silica in a volatile liquid to form a volatile liquid dispersion of porous, non-pyrogenic silica;   treating the surface of the porous, non-pyrogenic silica dispersed in the volatile liquid with a silane to form a volatile liquid dispersion of porous, non-pyrogenic silica having a silane treated surface;   drying the volatile liquid dispersion to form a filler, and   dispersing the filler in a hardenable resin to form a dental paste.