“How do I calm down before going to the dentist?”

Talk to your dentist about taking sedatives before your appointment if appropriate....

David M. Garazi, DMD

It sounds like you need to explore whatever fears you have about going to the dentist with someone who can help sort out what triggers anxiety the most. It may be finding a sympathetic dentist who can talk to you about this at length (they do exist) or maybe a counselor who can help with it also. We had many patients who had significant anxiety about going to the dentist, but they managed to overcome it by having assurance that we would explain everything in detail beforehand and being understanding when they had trouble with anything. Identifying what has created this anxiety about dentistry is the first step.
Best wishes in your quest.