The first place to start as usual is taking a good dental history. The patient may already tell you that they had a recent filling or crown procedure done and since then the tooth has been painful.
You should always ask about any previous history on the tooth that you think is causing the problem.
One should never assume that the tooth that the patient is having problems on is in fact the one producing the symptoms.
You would ask the patient such as location of the area of pain, when did the pain start, how intense is the pain, what causes the tooth to become aggravated and is there anything that causes to relieve the pain. Importantly ask if they are taken any painkillers and how long does the pain last for.
Is the pain a sudden mild sharp pain or is it a diffuse severe throbbing pain.
In the intraoral examination, you would check especially for any caries, failing restorations, cracks and exposed dentine.
For recent crowns/fillings, check the occlusion which frequently can be confused with pulpitis. If so, you just need to remove the premature contact point.
You would perform a TTP, percussion test to assess for acute periapical periodontitis.
For a cold test, you can either use an ice stick or you can cold spray. For these tests always use a healthy tooth first so the patient knows what to expect and you also then can compare as well.
For a heat test you can use hot water in a syringe such as in a Monojet. You may need to isolate using rubber dam or cotton wool rolls. Another way to reproduce heat is to use a heated gutta-percha stick.
You should wait a bit before going onto the next tooth as sometimes the pain can be delayed which may indicate an irreversible pulpitis.
An electric pulp test, EPT, can also be very useful. Once again you should try this on a healthy tooth first and only increase the electrical stimulation slowly.
Radiographs can be used and typically these would be by bitewing radiographs and periapicals. You will look out for large restorations, caries including secondary caries and widening or breaking of continuity of the periodontal ligament. Where the pulp is already necrotic then you should also look out for loss of lamina dura and widening of the PDL space.
Pulpitis can sometimes be very difficult to diagnose especially when the patient has a heavily restored dentition with multiple crowns and large fillings. In these cases, sometimes you will need to inject a tooth that you think is responsible using an intra- ligamentary injection so as to isolate the tooth .Cracks can also be extremely difficult to diagnose and in these cases you may sometimes have to take out a suspect restoration to examine inside for cracks and place a temporary restoration to be reassessed for the following visit.