Is silent recitation permissible during prayer for someone who suffers from Temporomandibular Joint (TMJ) Syndrome, clenching, and teeth grinding, which makes it difficult for him to move his tongue and lips for recitation?

Heartfelt recitation is not recitation; rather, it is contemplation, and it does not suffice for the recitation in prayer, because it is necessary to move the tongue during recitation. It is sufficient to merely move the tongue and articulate the letters from their proper places, even if the reciter does not hear himself.