Hi,
Yes I did witness all areas of dentistry. I shadowed a total of 32hours roughly. I could have shadowed for more lengths of time but I figure that I am motivated enough and will witness more dentists once I enter school. I shadowed endodontists, a large dental office, orthodontist, periodontist, and an oral maxillofacial surgeon. I could have asked for a recommendation(I actually did from the first dentist I shadowed). I probably should have waited and asked another dentist, since the first dentist didn't give me a stellar recommendation, but I asked him because I wanted my committee letter to be sent post haste. I first shadowed my personal dentist, and since his office was small, he didn't really want me around(only 4 hours). He was nice though. So I then looked up dentists in the phonebook until I found an endodontist who was exceptionally nice and shadowed him. He gave me more dentists to call who were also cool. I then looked up an orthodontist in the phonebook. I watched many different orthodontal cases, school was about to begin so there were MANY cases. The periodontist allowed me to watch a surgical case. I also watched him do preliminary exams. For the most part the dentists and specialists would explain and allow me to watch all phases of dentistry.
Good luck.