I'm not as familiar with Ameriplan but it sounds like a discount plan to me. Essentially you pay Ameriplan to get access to their network of dentists. These dentists, in turn, agree to charge you a preset reduced fee from what is defined as usual, customary or reasonable. What those fees are, I'm not sure. But my assumption is that it is reduced. But Ameriplan does not pay for any of your care. You will essentially be paying 100% of your costs but at a reduced rate.
I agree with Dr. Tsang. This is a discount plan, not dental insurance. Unfortunately many dentists choose not to participate in it.