So, precious metal is worked into jewelry through multiple methods. The great bulk of custom-crafted jewelry (which, grillz MUST be, if they are to fit well) are made using the lost wax casting method.

The term wax is nowadays used loosely, as a prototype can be made out of materials other than wax (such as resin, in the case of CAD prototypes). But, in the case of grillz, I would imagine that the process to make the SECOND item would be thus:

(1) - After acquiring the dental impression, you would shape jewelers carving wax to fit the dental impression. You are basically trying to make EXACTLY WHAT YOU SEE in gold, but in wax. I can about guarantee you that the dripping wax look of the design is NOT make by dripping wax, though! You see, jewelers use a wide variety of hand tools (both motorized and not) to carve a BLOCK of special wax into the shape you see above. Then they file, heat, file some more, file finer