Silicas that provide improved abrasive action when incorporated in dentifrice compositions can be prepared by dehydrating a silica hydrogel to a low water content and then reintroducing water to gel. The silica hydrogel is prepared by neutralizing a sodium silicate with an acid. This hydrogel is dried by any convenient method so that the gel contains about 15% water or less. This dried gel is rehydrated to about 30% or more. The rehydrated gel provides improved abrasion values over the prior art xerogels and hydrogels.