Have you been told that you brush too hard? Do you feel that you have to "scrub" your teeth to get them really clean?
Plaque is a very soft biofilm that forms on the teeth, and is removed very easily with thorough gentle brushing. Think of plaque sort of like dust in your home; you wouldn't scrub or scour your furniture to remove dust. You would only have to gently wipe it away. The same rule applies to plaque in your mouth. After about 24 hours the plaque starts to harden on the teeth and is more difficult to remove, but if you are removing the biofilm on your teeth twice a day it is still very soft.
Brushing aggressively, too fast, or a back and forth motion can damage the gum tissue causing it to pull away from the teeth. This wearing of the gum tissue is called recession. When the gums, or gingiva, recede it exposes the root surface and can cause temperature sensitivity and discomfort. Also, the exposed root surface is not as strong as enamel and can decay very easily.
Once the gingiva has receded and left the root surface exposed now the tooth is at risk for having abrasion. Abrasion is when the tooth brush wears a notch in the tooth. Think of this like chopping down a tree; you slowly create wear on the root surface of the tooth that can weaken the tooth structure and cause pain.
When brushing, always use a soft tooth brush and use a gentle circular/sweeping motion. If using and electric toothbrush place the toothbrush on the tooth and let it do the work for you. Do not go back and forth or brush in circles while the electric toothbrush is brushing; that is like brushing twice.
Certain treatments can be done if there is an area of recession that has pain or sensitivity, so having regular dental exams is very important, but preventing recession and abrasion is key.