I would say write a letter explaining who you are and your plans and requesting your work experience, I had a few different letters depending on what it was (dental lab, ortho, community, GDP ect.) and then I drove to towns and typed dentist into my phone and went to each practice and asked to see the practice manager, had a chat/ dropped off my letter. Maybe I had it easy but I only had to do that with a couple of small close towns, once I did my first week experience one of the dentists put me in touch with other more specialist dentists he knew so I got to see some more advanced stuff as I went on.