Is taking valium or chlordiazepoxide better before seeinga dentist, if it is tmj?

Neither: I can't recommend that you take either of these drugs before seeing your doctor or dentist. Tmj problems are known for being multifactorial, so you may not be treating the right thing by taking either one of these drugs.

None: If you want the dentist to be able to diagnose the cause of your tmj/tmd, then you shouldn't take any medication the day you see him/her.

None: You should present with your sign and symptoms as natural as possible.

May impair diagnosis: Doing anything differently before seeking a consultation changes the norm under which you normally function and may mask some of the symptoms or responses during the evaluation. It's like taking pain medication for a toothache and then presenting not knowing which tooth was bothering you or having the same response when stimulated.