Black spot on last tooth. Till now!

A tooth is the only structure of the body that does not show healing. There are two possibilities of those black spots----either there is a cavity or there are extrinsic deposits on the teeth. Presence of pain is not the only criteria to judge the presence of a pathology. If it is a cavity it should be filled as soon as possible before it widens and deepens and the symptoms start to appear, and in that case or root canal treatment will be required instead of a filling. If it is the calculus deposit, it is not going to get removed by toothbrushing and will require professional cleaning by dentist by a procedure called as scaling. This opinion is based only on the verbal description that you have mentioned without any look at the clinical picture. So the most prudent step would be to consult a dentist as soon as possible so that the right diagnosis can be made and the right treatment options can be delineated for you. Regards.