A filling is a filling no matter where you put it. It is either a spot that got a cavity or you could have worn away enamel in that area. A very common way is just aggressive brushing at the gumline wears the enamel.
It is really no different than a regular filling. You may have a little more bleediness while it is being prepared because of the location. They probably will use the same materials as a regular filling also.
