Toothpaste abrasive. Coloured scanning electron micrograph (SEM) of abrasive crystals in toothpaste. The abrasive is usually an insoluble salt such as dicalcium phosphate. Although brushing the teeth without toothpaste, powder or gel removes food debris and some dental plaque, a slightly abrasive substance is needed to remove the remaining plaque and the pellicle (a thin film formed from saliva). Magnification: x1,300 at 5x7cm size. x2,960 at 8x6, x1570 at 9x7cm master .Macleans toothpaste"