there are production reasons you could want a full size industrial mill, but you have to get your head out of just milling the teeth. its the same reasons i spoke of earlier when trying to account for the use of a 3d printer in dental labs; you have to need a continuous supply of custom parts that are not teeth. with most 3d printers under 200G's you are constricted in material selection, same with milling machines. step out of that boundary however and you can custom make literally everything that drives your business forward in Merchandising.
if all you want to mill is prosthetic teeth then spend no more than 50k.
if you want to generate a brand name that is complete with logo, custom production boxes, branded delivery, right down to the tooling you use on a daily basis in your tech's hands then spend the coin to buy the machine that can mill graphite, granite, steel, titanium, magnesium. a 3d printer that can print carbon fiber.
creatively using that to generate your brand name will be the leverage you need to be a national competitor, and international player.