I spend a lot of time discussing diagnosis of pain originating from the pulp with students. We have mostly been brought up on making diagnoses of irreversible or reversible pulpitis based on signs and symptoms - spontaneous pain, length of pain, reaction to thermal stimuli, percussion, electric pulp testers, ethyl chloride, bladebladebla. And what I realised a while ago was that some of those teeth - based on these criteria - that I had determined as irreversibly damaged or non-vital actually turned out to respond well to simple temporary dressings without going anywhere near the pulp i.e. the inflammation in the pulp was actually reversible.
So I was pleasantly surprised to come across a systematic review that looks at the sensitivity and specificity of signs, symptoms and diagnostic tests commonly used to make decisions about whether a pulp is alive and well or ailing.
Diagnosis of the condition of the dental pulp: a systematic review
Of 18 studies, none were high quality according to pre-specified criteria, 2 were moderate and the rest were low quality.
Regarding signs and symptoms as indicators of the inflammatory status of pulp the authors concluded: "there is insufficient evidence to determine whether the presence, nature and duration of toothache offer accurate information about the extent to which dental pulp is inflamed. The evidence base is also insufficient to assess the accuracy of other commonly used clinical markers of pulp inflammation "
and with regard to sensibility and vitality testing they conclude: "there is insufficient evidence to determine the diagnostic accuracy of tests used to assess pulp vitality".
I think this is borne out by my experience and suggests that, with plenty of discussion with the patient, we take a conservative view in deciding whether a tooth needs to be opened up or extracted. It may be that, in the absence of a clear diagnosis, we are best temporising and warning the patient the pain may get worse.
One thing, however, is that this review did not take into account the use of radiographs. We often don't see apical changes with irreversible pulpitic teeth but a tooth that does not respond to sensitivity testing and that has an apical radiolucency plus a potential cause for pulpal necrosis (deep filling, caries, fracture) may be diagnosed more confidently as being non-vital.