Do we need EPT as well?

These are additional questions from my colleague after reading my essay on cold test.

“Let me get this straight. You’re saying… CO2 gets about 90% right so we need to rely on other sources of information i.e. radiographs, symptoms, history and other clinical exam to increase the likelihood of getting it right.” Is that all we need to do? Do we need EPT as well?

EPT is not a routine test. That means we don’t do EPT for every single case, CO2, on the other hand, is a routine test.  EPT is indicated only when CO2 results are questionable. For example, in pulp canal obliteration cases where dentin is thick. Dentin is a very good thermal insulator so, we don’t expect that CO2 ice would be able to lower pulpal temperature enough to trigger nerve response in those cases.  This is when EPT becomes handy as pulpal nerve stimulation through electrical current occurs regardless of dentin thickness.

If EPT is that useful, why is it not a routine test?

According to Petersson’99, the probability that EPT results are truly representative of pulpal health in general is lower than cold test. When teeth are responsive to EPT, the chance that the teeth would be vital is 6% lower than that of cold test. Put it differently, if we were to replace cold test with EPT and it were to be conducted on every single cases, we would get 6% more false positive.  This is why EPT is not used as routine test, but used only when indicated as in an example above.

The same applies to heat test.

It is indicated only when patient complains of pain on warm drinks and we cannot localise the symptom to one tooth through other tests. Heat test is not a routine test for the same reason as EPT i.e. the chance that heat test will get it right in general is lower than CO2.  When teeth are non-responsive to heat test, the chance that the teeth would be non-vital is 41% lower than that of cold test.

If clinical exam, symptoms and radiographs point in one direction and vitality test points in the other direction, which should we go with?

In general, vitality test trumps other tests provided that the tests are conducted correctly and repeated tests give the same results.

Contradictory findings are not uncommon in clinical settings. If tests are all over the place, we can not create a coherent narrative-the story just doesn’t fit, doing nothing might be the best course of action. It’s possible that there might be something brewing, but our tests are too crude to detect changes at cellular or molecular levels. Schedule a review appointment later on is ok. It allows diseases to progress further and we might be able to detect them more reliably in the next appointment. If this is what you want to do, patient should be made aware that if the tooth becomes symptomatic they should be able to see you straight away.