A modified precipitated silica comprising precipitated silica and at least one polymer selected from the group consisting of poly(ethylene glycol) methyl ether methacrylate and poly(vinylphosphonic acid) is useful for the manufacture of peroxide-based whitening oral care compositions having improved stability over time. It is also useful for the manufacture of elastomeric compositions having a performing balance of properties including e.g. high rolling resistance and/or high wear resistance.