Are you working with children and their families, or is it orphans/abandoned kids? What's the age range?
Ideally, I think you would find out what the annual needs are from the people who live there. Your program director must have some contacts with health care providers in that part of Guatemala who could give some suggestions based on the cases they see. Let the needs on the ground drive the services/education you provide, and you will probably get more buy-in from the people you are helping. Give them agency in their own care.
Also, keep in mind that any services you offer for free may be diverting business from local providers (unless you're somehow means-testing the people you treat). If there are Guatemalan medical/nursing personnel in the areas that the dental program services, consider offering continuing education to them, instead of/in addition to direct care to patients. Building local capacity is usually better than creating dependence on foreign-provided care. Obviously, if you're in an area with no medical services whatsoever, that's not an issue, but please do consider.