The mind kicks in and starts churning. Fear steps in and adds to the pain and suffering. How long will this last? Why is this happening to me? I shouldn’t have done such and such. Then I look for more causes: I look at my ancestry, where I can place the blame. Then I look to the future: How much is this going to cost me? How much time do I need to take off to fix this?
The pain is just an innocent sensation alerting me that something is wrong with my tooth. That is all. Whatever I add to this sensation is suffering. I can personalize it and make it seem that no one else has ever had to go through this misery. Or that the Universe has singled me out to torture. I can take it to a state of extreme anxiety: Fear that it will never end and I will be condemned to a life of agony.
This is how the process of suffering escalates. Then, when we go to sleep, again, the pain vanishes and all the mental activity, which is the suffering aspect, disappears as well.