Coloring Agents 1 Dentifrices 1 Double-Blind Method 1 Humans 1 Phytic Acid 1 Silicon Dioxide 1 Tooth Discoloration 1 Toothpastes 1 Treatment Outcome 1 coloring agent 1 controlled study 1 double blind procedure 1 extrinsic dental stain 1 human 1 phytic acid 1 randomized controlled trial 1 relative dentin abrasivity silicon dioxide 1 sodium phytate toothpaste 1 tooth discoloration 1 toothpaste 1 treatment outcome 1