Dentifrices contain water, a cationic therapeutic agent, and an amorphous silica abrasive which has been pretreated with hydrofluoric acid. Preferably, the cationic therapeutic agent is a metal cation such as indium ion. The pretreated abrasive has improved compatability with cationic agents so that less cationic therapeutic agent is adsorbed by the abrasive and more is available for treatment of the teeth.
A process for producing precipitated silicic acid products having new and improved properties is disclosed. The silica products are produced by the simultaneous introduction of a solution of an alkali metal silicate and an acid, such as sulfuric acid, into an aqueous receiving medium which contains a salt or electrolyte. The pH of the aqueous receiving medium is adjusted prior to the introduction of the acid and silicate so that it is the same or equal to that pH at which the precipitation of the pigment is effected. The electrolyte is preferably a metal salt of the acid used for acidulation of the silicate. The acid and silicate are added to the receiving medium at a rate such that the precipitating pH is maintained constant. The products of the invention are characterized by their high abrasiveness and have a relative cleaning ability or scale (RCS) equivalent to high grade phosphates used as polishing agents in toothpastes and a superior fluoride compatibility to that of said phosphates. The silicates used in the process are preferably those which are partially polymerized and have a SiO.sub.2 /Na.sub.2 O ratio of at least 2.0.
A dentifrice in a liquid vehicle containing fumed silica with fluoride sorbed thereon giving free fluoride ions in the composition for the therapeutic treatment of teeth.
Amorphous silica is rendered hydrophobic by treating the silica with hydrogen fluoride vapors. The hydrophobic silica thus produced is useful in applications wherein either the sorbed fluoride values are desired or else the hydrophobic properties are desired. The hydrophobic properties are overcome by extended contact with water and the silica then becomes hydrophilic.
The corrosion and staining of unlined aluminum tube surfaces by dentifrices such as toothpastes, particularly when the dentifrices contain therapeutic agents, is substantially prevented by incorporation into the dentifrice of a controlled amount of an alkaline earth metal ion such as calcium ion, in the range of 0.005-0.2 weight percent, and preferably in the range of 0.005-0.070 weight percent of the dentifrice. The alkaline earth metal may be provided from any water soluble alkaline earth metal salt or as a reaction product of the alkaline earth metal salt with an amorphous silica abrasive and/or thickener.
Dental cream which readily disperses when agitated in the presence of water or saliva. The gel system of the dentifrice contains xanthan and an alginate in a weight ratio of about 3:1 to 1:3, preferably about 3:1 to 1:1. The dental cream also has desirable texture or "feel" in the mouth and undergoes slow drainage of liquid from foam produced during toothbrushing.
