You've got a great shot to be accepted. Be sure to purchase the ADEA book on dental schools. It lists acceptance stats for every school so you can see if they accept in-state versus out-of-state.
Air Force has the most competitive HPSP scholarship of any of the branches because they have the least number of scholarships. That being said, I've heard pretty much everywhere that Air Force is the best branch to be a dentist. I think you'd have a great shot on being accepted to it.
Also, since you mentioned that you have done a mission dental trip I have a huge warning for you. If you did anything illegal during your mission trip like actually giving dental care (extracting teeth, filling cavities, etc.) then keep it to yourself. A girl during one of my interviews told her interviewers "I've had a lot of great dental experiences...I went on a mission trip and spent two weeks extracting teeth in a South American country." Her interviewers went quiet, didn't respond for a minute, then told her that was super illegal and frowned upon. Needless to say, she wasn't accepted at that school.