Prepain

Mostly the subjects experienced either no sensation at all, or pain; only a very small prepain range was found (a just noticeable tactile sensation, as described in Chapter 27).

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You can learn what to do at the first signals of prepain and thereby avoid the true disability that accompany a fullblown attack.

Source: wiktionary

As described above, pain and prepain are the only sensations that can be evoked by intradental nerve stimulation in human subjects.

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Even in trained normal subjects, the pain threshold, where prepain becomes just noticeably painful, is a composite of nuances and is difficult to judge.

Source: wiktionary