Sensitive teeth are primarily caused by gum recession. Gums recede for many reasons, like brushing too hard, age, and periodontal disease leaving "tubules" exposed. These tubules lead directly to the nerve of the tooth and cause pain.
AMAZINGLY easy way to make a dress form. I am definitely going to do this. <- this is great, instead of several hundred dollars, your out a couple rolls of ducktape, some stuffing, and a cheap t-shirt!