Hi Peter I have had experience with the oral appliance and had the exact Issue you are concerned about. Result: I was out $2400. No refund from Orthodontist who I shared this concern with in beginning and he said no issue. My jaw was misaligned for 4 months over which time I made several visits back for adjustments. My mouth would not close right, my bite was off and teeth hit each other at times and my jaw was always stiff and sore. Chewing was an issue. Such a shame as it is more convenient that cpap. Doc also made a “realign” piece to help in morning to push jaw back into place but didn’t work. A real drag.