Abfraction is the commonly seen condition of notching of the teeth near or even under the gum line. Though a combination of hard toothbrush bristles and improper brushing techniques can cause enamel to be lost at the gum line, this is not the cause of abfraction.
When your bite is slightly off, it's common that one tooth may hit sooner than the rest. This causes undue stress on the involved teeth and they begin to flex. It's this continual flexing and stress that, over time, causes the enamel to separate from the inner dentin layer, forming the familiar looking notch associated with abfraction.
There are two steps involved in solving the abfraction problem. First, we need to adjust your bite. We may have to adjust only the tooth in question, or we may have to adjust all your teeth. Chewing forces must be evenly distributed among all your teeth. We may have to have you back several times as we carefully fine-tune your bite.
The second phase involves restoring the damage by bonding a filling in place. White, natural looking fillings can fill in the damage and restore the tooth to nearly its original color and shape.
Dealing with an abfraction problem early by adjusting your bite and placing a filling prevents further damage and restores your teeth to their normal shape and color.