I've never worked dental, but my office manager duties included something a little more subtle than what the article gets out. I did everything it mentions to keep the office running smoothly, but in my experience, you often wind up running interference between different staff members, especially at different levels. I tended to be a liaison between the assistants and the executives and I would also take over difficult phone calls if I could sense that someone on the other end was harassing one of them. (I worked in a university office with student assistants and tended to be very protective of them.)
You really need to be able to keep your cool and have a lot of tact and diplomacy. I worked in a day care center before I became an office manager and that was a real advantage.
I'm looking for a job in a dental or medical office as my husband is taking a job in a new city and there's no university there. Wish me luck!