It is not unusual for teeth to hurt after a filling or crown. If the filling is deep or near the nerve or pulp, the filling may ache or be sensitive for several days or weeks. When the cavity is close to the nerve, the body will build a layer of dentin over time to insulate itself from the pain transmitted to the nerve form the filling. Here are some usual reasons fillings will hurt after a tooth is filled:
1) Normal response to the trauma, this pain should subside in several days or weeks.
2) If the tooth hurts only when you bite, the filling may be too high, especialy if this in the first or only tooth you hit when you bite.
3) If the tooth hurts when you eat sweetss, this usually means the filling is leaking or there may be another cavity near this tooth.
4) If the tooth aches or throbs for no reason, or it wakes you up at night, then the nerve may be dying and the tooth may need a root canal treatment.
5) If the tooth hurts after cold foods or drinks but then subside, this is called a hyperemic pulp. This is a good sign. Although, this is annoying, when a tooth aches to cold but the pain quickly subsides, then there is a good chance the tooth will heal over time.
6) If the tooth hurts with hot fooda or drinks, and cold makes it feels better, this is not good and the tooth usually needs a root canal treatment. Pain to hot foods indicates the nerve is dying and will eventually need a root canal treatment.
The above symptoms apply also to teeth that have not been filled. Use the above symptoms to determine if your tooth needs treatment. The above symptoms, 3-6 are late symptoms. You should have your cavities fixed before these symptoms occur. The best time to get a cavity fixed is beofre the tooth hurts.