The source of pain, frequently is due to bacteria penetrating the tooth and the tooth becomes decayed or due to bacterial build up around the tooth causing a gum inflammation. The decay will lead to an inflammation in the pulp , with pain symptoms being sharp or dull, constant or intermittent, localized or spread out. But usually the pain is triggered by a change in temperature or pressure. While the bacterial accumulation around the tooth leads to a gum inflammation that has a tendency to spread to the surrounding bone.  There are nerve fibers that convey pain, but there are no nerves that pinpoint, “it’s this tooth right here” and the brain tries to figure out the source of pain. Since one single nerve conveys the pain sensation from several areas the brain tries to form a picture of where the pain is coming from, using information what we see or feel for example: a brown patch that we see in the mirror, a tooth that feels different when we test it with the tongue or finger, a tooth that feels rough or fractured or a tooth that was treated with a filling and the dentist said that it may need a root canal treatment. Once the brain reaches a conclusion it will provide you with a location where the pain is or at times it cannot find the source and then it will feel as a dull pain .  But at times the location the brain has deducted is wrong, and the reason too. An example is when the person points for the wisdom tooth, when it is not there. This phenomenon is called  a “Red herring” and it is quite common. This among other is the reason that when I test for the source of pain I check all possible sources of pain including teeth on both sides of the same jaw and the  opposing one as well and I use the camera to take pictures. Only after I have examined all possible causes do I summarise the evidence and provide the diagnosis, this I found is the only way to reach the source of pain.