Looking back on my own thoughts Part 3

http://dental-tidbits.blogspot.com/2014/09/a-thought-about-differentiating-between.html

"I had a good demonstration about how to manage a patient with painful teeth where pulp tests are ineffective. This generally means that the pulp is either too calcified to respond or the canal is necrotic or pulpless. In either of these situations, chances are there is some periapical involvement. A PA radiograph of TTP is a good sign of this. Also symptomatic questions are useful with a prolonged, intense dull pain which may wake the patient up at night.

A way to approach this would be to get the patient to bite down on a cotton stick saying you're going to test the teeth and you want them to bite down with firm pressure on 3 teeth 1, 2 and 3 and to tell them afterwards which hurt the most 1, 2 or 3."

A bit incoherent but I think I know what I was trying to get at.

-Pulp tests will give you an idea about the level of response of the nerves in the pulp which is not 100% correlated with the vitality/blood supply of the tooth.
-Calcified canals can give false negatives as the thickness of dentine and the mineral content of the teeth is higher allowing less cold to penetrate to the nerves. The use of CO2 which is significantly colder than spray can allow you to have a more effective test and get through thick restorations e.g porcelain crowns.
-It is even more effective to use electric pulp tests to reach calcified pulps as it does not rely on the transmission of cold through tooth structure but the increase in voltage which is can be increased significantly for more calcified teeth. Be sure to use a conducive medium i.e toothpaste on the tooth surface to ensure that the tester tip can conduct into the tooth. Generally the patient will need to hold some part of the tester to complete the circuit and they can let go when they feel pain.
-False negatives can appear with electric pulp testers when there are metal restorations which can conduct to neighbouring teeth or the teeth are not dry and saliva conducts the electricity to other parts of the mouth.
-Dental stimulation is unreliable, a "negative" test doesn't mean much if not put in the context of the other teeth in the mouth. No response to cold doesn't mean a tooth is necrotic if all the other teeth in the mouth don't respond either. I tend to test at least 4 teeth at least twice in different orders to make sure the response is reproducible.
-If there is a situation where all the teeth are responsive except one, you can suspect that the tooth is necrotic. Depending on the patient's presenting complaint, your aim is to reproduce that pain with stimulation. If the pain sounds like an irreversible pulpitis, you aim to reproduce prolonged pain to mild stimulus, if it resembles a reversible pulpitis you aim to reproduce short, sharp pain etc. The aim of pulp testing should be to confirm your diagnosis and to discover which tooth is in need of treatment.
-I disagree with the statement that in cases of calcified pulps AND necrotic teeth there is likely to be periapical involvement. Obviously calcified pulp chambers is a physiologic phenomenon and therefore should show no pathological periapical inflammation. Pulps that have been necrotic for an extended period of time should develop periapical inflammation in response to bacterial products exiting into the periapical space. This can actually occur in late stages of pulpitis and clinical signs (i.e tenderness to percusion) will precede radiographic  signs (I often quote at least 3 months for a PA lesion to appear after the inflammatory process has occurred as time is required for bone to resorb.
-Your radiograph should be used to confirm your diagnosis only. From the patient's signs and symptoms you should be able to form in your mind a good idea of :
1. Which tooth is involved
2. Pulpal diagnosis
3. Periapical diagnosis
4. Cause
-If something doesn't add up e.g commonly there will be signs of pulpitis and tenderness to percussion but no obvious cause, suspect an occlusal issue until proven otherwise. Stick them in a leaf gauge and see what happens to the tooth as they close down. Often times there will be an interfering cusp that causes a slide from CR into MIP leading to a crack or traumatic occlusion.

-I'd forgotten about the trick of biting onto cotton to check for tenderness in a tooth. My issue with this is that it doesn't differentiate between pain in a top or bottom tooth, doesn't differentiate between a true periapical inflammation and a debonded restoration or a crack. However it may be a useful tip when the pain is vague as the patient can bite a lot harder than you can tap.
-I still get them to tell me which one is painful i.e 1, 2 or 3. You can bang your head against the wall with some patients who are convinced they know which tooth is sore. When you are doing your diagnostics they won't answer your questions but try and figure out which tooth you have the cold on or are tapping and say "yes that's the one" or keep pointing at it during your tests. It is up to you to be firm and insist that they stop trying to figure out which is the painful tooth and just answer yes or no to if it is painful and if it has stopped being painful. Often times I will put a (usually male) patient through 5 rounds of cold tests because he refuses to answer yes or no to my question but keeps trying to point at the one he thinks is painful.