Vermeer sc130 cutter teeth question?

[Anonymity]

I bought 4.5 sets (for pieces to a set) of grinder teeth, some like new and some need sharpening...can anyone educate me about how to go about getting these teeth up to spec again? A new set would cost $330 but I paid $150 for all of them? I heard about health risks, do I sharpen the face (flat side) or the edge? I also noticed that Toro has a machine that looks excactly the same as mine, but some models/years use a different cutting system with only 3 cutters (look like green teeth) I was thinking of changing over (anyone know if that's possible? Buy a Toro part and put it on my Vermeer?). Just wondering if someone could help me understand my machine and its setup?

Thanks,
Ken