How are tremors or chattering of the teeth/lips best diagnosed? would an mri be be appropriate? our doc asks why?!

Depends: Are there any other health issues present? Like parkinson's? Are there any medications that are being taken that have side effects of tremors? Was there a recent brain infection or trauma? Mri is one of many studies that can be done to look for certain things that are characteristics of certain diseases or conditions. A good evaluation and history will be taken by your doctor.

CONCERN: Can you pinpoint the time and place that these tremors began.? Was it after trauma, dental treatment, a chiropractic adjustment or some emotional event? I had a patient with similar symptoms several years ago, and it took a type of surgery- radio-frequency surgery- to alleviate the tremors. But i would not hesitate first to see a neurologist.