The Army National Guard is not really a scholarship but a stipend program during school and loan repayment when you graduate. When you join you would commission as a 2nd lieutenant. During school, you will drill one weekend each month. Most drills are Saturday and Sunday and only a couple include Fridays (since you are a student, you don't have to worry about the few Fridays). Also, there is an annual training (AT) of 2 weeks. Again, if there is a conflict you can work that out with your unit. But if you can attend AT, that would be some nice pocket change.
Also, you will be required to do BOLC within the first 36 months of joining. If there are conflicts in your school and/or residency schedule you can apply for a waiver.
When you graduate from school you will be promoted to Captain. You have to serve 1 full year after dental school before being eligible for the HPLRP. This loan repayment is $40,000/yr (28K after tax) for 6 years.
The National Guard is a great deal in my opinion. You can have any civilian job you want making max dollars while still getting a significant portion of your student loans paid off. Also, if you want to apply for the NHSC loan repayment you can do that in conjunction with the National Guard and accelerate the repayment of your loans.