I had some pretty horrific experiences as a child with an incompetent dentist and find it very hard to relax even though my current dentist is amazing. After a visit where I clutched the arms of the chair with a deathgrip, he recommended a low dose of valium. It does require someone pick me up after the procedure, but it is well worth it. Because I am more relaxed they can use less medication during the procedure. I only use the valium for fillings or crowns (luckily none lately). I have built up a great deal of trust with this dentist and now I don't have much anxiety for cleanings. It may be worth discussing with your dentist.