Do you have a dark front tooth? Maybe there is one tooth that just doesn't seem to match the others.There is a good chance that this tooth has trauma in the past and is now necrotic(dead). This is something that may not be bothering you at the present, but it is something you want to take care of. If this is not treated, there is a good chance that it will swell because of infection in the future. To take care of this tooth, you will need to have the tooth evaluated to make sure it is decay or necrosis setting in.  If it is necrotic, you will need to have root canal therapy. then you will need to have either a crown or a filling to help further protect that tooth. The crown will also take care of any cosmetic issue you may have had with that tooth. Visit your family dentist today to have that tooth evaluated.