The sensitive area in your teeth near the gum margin is called cervical abrasion. It is due to either faulty brushing or in some cases it is seen when the person is suffering from acidity. To prevent this you should brush your teeth with soft tooth brush and that too gently. You have to clean the teeth not to scrub them. The teeth which already have the abrasion should be filled or they can get infected in the long run. For more information on tooth wear you can visit the following link on ourwebsite........http://www.identalhub.com/articlecategory-tooth-wear-59.aspx