If there is osteonecrosis a pan X-ray will show dark areas where the bone is actually missing. My oral surgeon compared a pan X-ray taken 6 weeks after my HBOT ended with one taken before HBOT, and the new X-ray did not have dark areas but showed bone tissue growth as a lighter evenly colored area under my teeth and around my roots. I understand that use of the same X-ray machine is important when making comparisons and that good doctors want to read the original X-rays and do not want to see copies.