At my local dental clinic, I'm volunteering and shadowing at the same time. If I'm dental assisting, usually very poorly, I'm volunteering at the clinic and shadowing the dentist who I'm assisting, all at the same time. If I'm autoclaving the instruments, helping out with administrative work, or breaking down and setting up the rooms, I'm volunteering because there are no dentists around. If the dentist is in the same room or if I'm talking to the dentist then I'm shadowing. This all happens at the clinic so I put it down as both volunteering and shadowing on the application. This is one way to hit two birds with one stone.
Usually shadowing at a private practice means that you'll be seated where the dental assistant usually sits and you'll just watch. At a clinic, where every bit of help is needed, you'll usually be doing chores (autoclaving, cleaning rooms, calling patients into the rooms, organizing or retrieving files, and recording BP).
I agree that shadowing is incredibly boring. None of what you usually do as someone who shadows is representative of what you will do as a dentist. At best, it's a simulation of what it is like to be a dental assistant.
