thanks for your query, i have gone through your question, the soft tissue what you have noticed at the line of occlusion on your cheek could be secondary to cheek biting resulting in frictional keratosis...nothing to worry about it it will not harm you...if the teeth cusps are sharp you can get it rounded off so that it minimizes trauma....using mouhguard or splint should be carefully advised...otherwise it might result in TMJ disorder..you should be careful in selecting splints or mouth guards....i advise to remove the cause of cheek biting by rounding off the cusps... consult a oral physician for further... i hope my answer will help you...take care...