Toothbrushing Mistake No. 7: Skipping Inner Tooth Surfaces

Most people forget to brush the inner surfaces of teeth -- the surface that your tongue presses against.

"The plaque you can't see is just as important to remove as the plaque you can see," says Price.  

The most commonly skipped area, dentists say, is the inner surface of the lower front teeth.



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