I think the only 2 measurements required are the length of the front edge of each tooth from point of eruption from gum to tooth tip and the diameter of each tooth at the point of eruption from the gum.
Add both length measurements together and then subtract the difference in length (eg 85mm + 87mm = 172mm less difference 2mm = 170mm).
Repeat for diameter.
Add length and diameter totals together.
The info I have on medals (which is a few years old is- 150-159.99 bronze. 160-179.99 silver. 180+ gold.