2mon. ago a snwboard fell on my shin. no pain after a few weeks but left behind a dent like a piece of bone brke off. no pain n jog reg. safe for mma?

Contusion: It sounds as if the snowboard left a soft tissue defect below the skin. The amount of trauma from a snowboard landing on your tibia or shin would most likely not cause a fracture. If there were a fracture of the tibia, it would be extremely painful and difficult to bear weight at all. It is safe to resume mma, but if pain in the area develops, back off of activity and get an xray.

Get it checked first: I would suggest you see an orthopedist first to get clearance for mma. An x-ray or maybe a ct scan would show how much a "dent " in the bone is really there. It would also be important to know that the rest of your tibia bone is intact.

Probably: If it has been 2 months and there is no pain you are probably safe to return to mma practice. I would be sure to use shin protectors if doing any leg kicks, but it shouldn't be a problem at all doing drills, grappling etc. If it starts to hurt see your doc.