What causes swelling and bruising of the cheek after a molar is filled?

Hello I am a Certified Dental Assitant for almost 10 years. The answer to your question depends on a two things; #1 This can happen from the doctor/assistants pulling on your cheek. Some people are more sensitive than others so pulling on your cheek is like if you hit your arm or leg and you then get a bruise. The swelling should go away with-in 3-5 days (sometimes less), and the bruising should go away in 7-10 (sometimes less) days. You can help this by using an ice pack on the OUTside of your cheek for 10 min on then 10 min off for the next few days. #2 If you are having toothache symptoms, and the tooth is OVERLY sensitive to HOT and COLD as well as when you bite, and the filling was quite large, you may need further treatment on this tooth. Call your dentist, he will take an xray and determine what needs to be done next. I really think that you are having #1, so don't worry. :) You will be fine.