CAD/CAM dentistry: Trapped by what you know?

Gary M. DeWood, DDS, MS

“I will never have one of those machines in my office.” I turned to face the source of that comment and smiled at a participant in our Facially Generated Treatment Planning (FGTP) workshop. He was pointing at one of the many CEREC machines we have in residence at our Scottsdale Center facility. He clearly had a strong opinion about its usefulness that he wanted to talk about.

Now I am no stranger to unbridled contempt for CAD/CAM dentistry. In the early days of this technology, I had an experience with CEREC 1 that soured me on the idea for a long time. So hearing an unsolicited outburst like this made me wonder what experiences had created such emotion for this individual.

As it turned out, he had purchased a CEREC 2, a machine that in his words cut essential corners that made the restoration mediocre at best. He had returned it, angry and disgusted, refusing to even look at the technology since. Wow! It’s déjà-vu all over again.

Like my friend, after my venture into CAD/CAM, I also remained staunchly opposed to this technology. I refused to even listen to those who sang the praises of the newest versions. Obviously they were easily swayed by the sales hype. I, on the other hand, knew the truth. I might still be actively dismissing this part of dentistry if not for my experience in Seattle when Frank, Gregg, and I were introduced to the CEREC AC machine and the Bluecam.

I was surprised and impressed. This was most definitely not what I had experienced years ago. It was easy, precise, and most importantly, it was accurate. I realized in that moment that what I thought I knew had held me back from seeing the evidence and adopting an excellent technology for my patients and my practice. My daughter is a second-year dental student at Midwestern University in Phoenix, and she is already working with E4D. This technology will be normal for her practice. CAD/CAM is not only a part of dentistry, it is also an important part of dental education. I am working on catching up.

The two restorations seen in Figures 1-3 were placed in 90 minutes for a friend visiting from the UK who broke a tooth. They are milled from a lithium disilicate (e-Max) blue block that I conditioned and glazed after milling. The oven even told me what program to run. Figure 2 shows the use of Gluma PowerGel to wet and desensitize prior to bonding the restoration to place.

Figures 4-6 show a milled composite overlay used to test an altered VDO and occlusal scheme for a TMD patient. Mounted casts were used to scan my “preps,” the existing surfaces of the mandibular teeth, and then design a new occlusion using a buccal bite technique to create a precise occlusion against the maxillary arch. Spot etching on cusp tips and seating with flowable composite provides a much better test than an appliance because the patient functions normally with the new occlusion at all times. The exception is the need to thread floss under the overlay.

As I have become more familiar with CAD/CAM, I have learned that there are some significant differences between what I was taught back in the 1970s and what works best for this technology. Preparation design is infinitely more important than it is with other restorative techniques. Square and sharp have been replaced by round and flowing. The margin must be as perfectly smooth as possible so it can be milled. Magnification becomes not just suggested but mandatory. The diameter of the milling diamonds must be known and the prep must conform to ensure that the restoration will not be overmilled, creating areas to accommodate the milling diamond size.

Better preparation is almost always the first thing people mention when they talk about how CAD/CAM has changed their practice. I also learned this. Unless you are retiring as you read this, CAD/CAM dentistry will change your practice, too. Don’t be trapped by what you know. This technology is not coming; it is here. I turned to the gentleman mentioned earlier who had made the comment at the FGTP workshop and said, “We need to talk.”

Gary M. DeWood, DDS, MS, earned a DDS from Case Western Reserve University in Cleveland, Ohio, and an MS in biomedical sciences from the University of Toledo College of Medicine. He serves as executive vice president for curriculum for Spear Education, teaching and practicing in Scottsdale, Ariz. Contact him at [email protected].