Milling Remains Dominant
Automation, ease of use expand capabilities
Over the course of nearly a decade, I have been lucky enough to come in contact with and operate a variety of milling machines ranging from large commercial CNC machines to desktop mills for single-person laboratories. Over the past 3 years, I have been able to put my milling knowledge to the test after starting my own digital dental laboratory, where we specialize in implant-retained hybrid restorations. I have found that, to keep up with the functional and material demands of these restorations, milling is the only way to produce accurate, reliable, and lasting final restorations. Milling machines are essential for the foreseeable future and will continue to be the leading machine in any dental laboratory.
Latest developments: Several machining companies have pioneered their own versions of the automatic "puck loader" or "disc changer." This development increases the production capabilities of an average milling machine exponentially. One machine can run nonstop throughout several days' worth of milling with no human intervention. Additionally, you are not limited to one puck and one material when leaving your mill to run overnight or over the weekend.
Another important ancillary piece that has become available in recent years is the C clamp. This allows users to position a bridge at the edge of the puck. It takes advantage of the C-shaped puck holder to mill beyond the standard 30° axis tilt, leaving screw-retained bridges and digital dentures completely free of undercuts.
What to know when purchasing: Ask yourself if you need wet or dry milling, or both. Metal and glass-ceramics require wet milling, and the machines that provide this capability are typically more expensive. However, if your laboratory fabricates even a few titanium bars or chrome-cobalt frameworks for PFM restorations, buying a wet mill can completely eliminate the need to outsource to milling centers; the return on your investment will be seen in a matter of months.
If your milling needs are limited to zirconia, wax, or PMMA, the majority of 5-axis desktop mills can handle even the most complex implant bridges.
Invest in a robust machine with a high-functioning spindle if you will be milling a lot of PMMA or PEEK, as this will put a lot of wear and tear on your machine. Spindles come with a variety of speed, torque, and horsepower ratings. Higher spindle torque helps with more rigid materials such as titanium, PMMA, PEEK, CrCo, or glass-ceramics. Spindle torque as high as 2.5 kw usually results in a more accurately milled part and better longevity.
How to get the most out of your scanner: Nothing on the market is more productive than a milling machine with an automatic puck loader, which allows the laboratory to produce restorations for multiple cases with no labor required to keep the mill running. Creating a streamlined workflow that maximizes both milling time and the labor time that is saved can increase a laboratory's production dramatically. For example, technicians can spend most of the day designing, keep the machines running at night, and arrive at the laboratory the next day with all the work completed.
These automated milling machines will become the standard in most laboratories in a matter of time. Anyone milling more than a few bars or bridges per week should strongly consider the investment.
Key takeaway: Milling machines have become more automated, economical, and user-friendly in the last decade, allowing smaller laboratories to keep up with the technology of larger operations. Cost is always a factor, but should not be prioritized too highly. The quality of your milled parts can directly relate to the cost of the machine in many instances. However, costs of the machines, operation, and maintenance have decreased as the technology has evolved, and now anyone can mill—even if it isn't your last name.
About the Author
Matt Mills is the Owner of Hybrid Technologies, LLC in Orlando, Florida.