I do the same thing as Cheryl....take frequent breaks....speak to your assistant and let her know when you need to close your mouth to rest....I use hand gestures to my assistant to let her know I need a rest for my mouth. Open your mouth that is the most comfortable for you...you don't need to open real wide for a cleaning...just a small opening is fine. If my assistant needs me to open wider, she will tell me, usually when she is cleaning the back teeth. I have a very accommodating assistant because I spoke up to her about my tmjd, and most will be helpful to anybody that will speak up about their condition and make known what their needs are. When your tmjd condition gets better over time, you will fine that going to your cleanings will be more comfortable and your jaw won't be as sore or bothersome afterwards.