The tremor in your jaw or teeth chattering is your muscle spasm because of TMJD. Depending on why you have TMJ disorder will also determine why its in spasm. If your dentist has given you a splint and your chattering or spasming, the its the wrong splint for you or he needs to adjust it. If your jaw is in the correct position then it will immediately start to relax and this will go away. DO NOT listen to him tell you that your jaw will get use to it. Your jaw should be telling him where it needs to go, then you follow this and ajust teeth to siut the bite if needed.
My best advice is see a neuromuscuar dentist or a dentist that does TruDenta. Both practtices believe in relaxing the jaw to its correct position and then introducing a splint or mouth orthotic to help keep this position 24/7. If orthodontics or tooth restoration OR jaw surgery is the next step...then you'll know from there. If you do NOT relax the spasm and muscles and start splint therpay or moving teeth, it will be a hot mess you enter into.
Trust someone that has been through it all..