"Why are my teeth sensitive to hot things or when I bite?"

This problem is a little more serious.  When your tooth is sensitive to hot it usually means the nerve is severely injured, dead or infected.  Pain on biting can mean an infection or a fracture in the crown of the tooth.  Call Dr. Williams or Scott now (yesterday would have been better) and make sure you inform the person on the phone that the tooth is sensitive to hot or biting.  You need an appointment today or tomorrow.  These things tend to go downhill once the weekend is here and it's tough to find a dentist at midnight on Saturday.  Dr. Williams or Scott will advise you of the best course of treatment but usually this problem is fixed with a root canal and crown.