Four-axis vs. five-axis, wet vs. dry milling, open vs. closed, blocks vs. discs, tool changers, European, Asian or American-made? There are dozens of milling machines on the market now and behind all of the marketing language, what are the real differences? Kim Karpowitz, president of Turning Solutions, a manufacturer of dental milling systems, discusses the language, art and science of CAD/CAM; what really makes one machine better or worse than another; and, now that we have several years of service experience, an analysis of the REAL cost of ownership including materials, tools and maintenance costs.