The invention provides a chemical-mechanical polishing composition including first abrasive particles, wherein the first abrasive particles are wet-process ceria particles, have a median particle size of about 40 nm to about 100 nm, are present in the polishing composition at a concentration of about 0.005 wt. % to about 2 wt. %, and have a particle size distribution of at least about 300 nm, a functionalized heterocycle, a pH-adjusting agent, and an aqueous carrier, and wherein the pH of the polishing composition is about 1 to about 6. The invention also provides a method of polishing a substrate, especially a substrate comprising a silicon oxide layer, with the polishing composition.