Consistency, Reliability, and Support

Disc changers and other ancillary features are helpful, but the improved consistency of today's machines is the most important factor. They stay in calibration more consistently than older machines. Additionally, increased angulation makes a big difference, especially when milling hybrid dentures. Easier transitions between wet and dry milling are important as well; some new machines can pass from wet to dry fully automatically, so no human hand needs to touch it. That is a significant time saver, especially today as laboratories mill more lithium disilicate along with zirconia.

Look at your production and your needs. If you are only milling single units, then a 4-axis mill is more than enough; if you are handling more complicated cases, then you definitely need a 5-axis machine. If you want to mill lithium silicate, feldspar ceramics, etc, then you need a machine that can wet-mill. Of course, the biggest element I look at before buying is support. Mills are computers, so glitches are inevitable, and you need a company that can support you quickly and efficiently in those instances. Of course, you also want a reliable machine that will not have problems pop up every week.

Mills are like vehicles; they need to be cared for and maintained. The collet needs to be cleaned regularly to avoid premature failure and possibly extend the spindle's life. If you are utilizing both wet and dry milling without an automatic cleaning feature, then you must prioritize proper cleaning. One of the biggest reasons some machines have problems is that zirconia creates powder buildup, and if it is not cleaned properly, then switching to wet-milling creates a thick sludge that strains the axes, motor, spindles, etc. However, when maintained, with proper cleaning and calibration, these machines should run thousands and thousands of hours.

Material choices continue to make milling the most useful fabrication technology. 3D printing zirconia, lithium disilicate, and lithium silicate is not a viable option for most dental laboratories at this point. Even with PMMA, 3D printing options have evolved, but milled PMMAs have been proven over a longer period of time. Milling also requires fewer supports, which means less post-processing. For those reasons, milling remains a critical piece in the modern dental laboratory workflow.

Dimitri Tsichlis, CDT, is the Owner and President of Styledent in Laval, Quebec, and Winter Park, Florida.