Abrasive silica compositions and dentifrice compositions prepared therefrom

A silica abrasive composition comprising

• (a) silica gel (i) having a median particle size below about 7 microns, (ii) a pH of from about 6 to about 11, and (iii) a hardness defined by a powder RDA of 100 to 200, and a PCR of 100 to about 150 when said silica (a) is formulated by itself into a dentifrice paste;
• and
• (b) silica gel or precipitate having a median particle size of about 7 microns or greater and having a hardness defined by a powder RDA of about 50 to 180, and a PCR of about 80 to 105 when said silica (b) is formulated in a dentifrice paste;
• further wherein the weight ratio of (b) to (a) is at least 1:1.

A method of preparing a dentifrice composition comprising adding a silica gel additive:

• (i) having a median particle size below about 7 microns,
• (ii) a pH of from about 6 to about 11, and
• (iii) a hardness defined by a powder RDA of 100 to 200, and a PCR of 100 to about 150 when said silica (a) is formulated by itself into a dentifrice paste
• to a composition comprising an already existing abrasive silica gel or precipitated silica wherein the additive is added in an amount such that the ratio of the existing gel or precipitated silica to additive silica gel is at least 1:1 and the resulting dentifrice composition has an RDA of about 150 or below, and a PCR of at least 80 and up to about 150, and an REA of less than about 30, as measured on the IU scale.