Toothbrushing Mistake No. 5: Not Brushing Correctly

''Long horizontal strokes along the gumline can lead to abrasions," says Sesemann. "Aim your bristles at the gum line at a 45-degree angle and do short strokes or vibrations." Softly brush up and down your teeth, not across your teeth. The strokes should be vertical or circular, not horizontal.

Be sure to brush outer and inner tooth surfaces, the chewing surfaces, and your tongue.


cited from http://www.webmd.com/oral-health/healthy-teeth-10/brushing-teeth-mistakes?page=2