A dental office will usually have a minimum of a dentist, dental hygienist, and someone to run the office like and office manager. The employment opportunities depend on how large the office is but will also usually include a receptionist. These are the minimum requirements for most offices but of course, there can be exceptions. If you think about it though, in order for the practice to survive they need a highly skilled person to take care of a variety of tooth related problems (Dentist), a slightly less skilled person to provide extra services like cleanings and x-rays (Hygienist), and at least one person to take care of everything else such as reception, billing, and patient follow up (Office Manager / Receptionist). Due to the nature of the business all of these people must be really sensitive and compassionate - and work well together as a team.
If you are looking to be a part of this profession, check out Dental Jobs to see whats available around you - there is almost certainly something (even if it is just "foot in the door" work).