According to WebMD, any sensitivity from a filling should be gone within two to four weeks. If pain still exists after this period, WebMD recommends that patients consult their dentists.
The Colgate Oral and Dental Health Resource Center identifies several possible reasons why teeth are sensitive after fillings. A common cause of pain is that a filling is too high, and Colgate indicates that a dentist simply needs to lower the filling's height for the patient to feel relief. Colgate also describes a sharp electric shock that occasionally occurs when different metals from fillings touch. This sometimes happens when top and bottom fillings made from different metals meet.