Dentistry: Computer-Aided Design/Manufacturing Now Costs Less

An Expert Interview With Parag Kachalia, DDS

Laird Harrison

October 25, 2012

SAN FRANCISCO, California — Editor's note: It has been 27 years since the first patient was treated with a ceramic reconstruction (CEREC) system that makes it possible for dentists to design and create indirect restorations in their offices. But only about 15% of dentists use this technology.

A presentation on computer-aided design/manufacturing (CAD/CAM) was featured here at the American Dental Association (ADA) 2012 Annual Session. Medscape Medical News discussed the technology with presenter Parag Kachalia, DDS, associate professor at the University of the Pacific in San Francisco, California.

Medscape: The technology for making digital impressions and indirect restorations in the office has been on the market for 25 years. Is it catching on?

Dr. Kachalia: The penetration is pretty low. Probably only 15% of general practitioners in the United States have these units. The numbers are not growing very fast; dentists take a while to change.

Medscape: Do you think the pace will pick up?

Dr. Kachalia: Yes. There are a few drivers of the change. One is that in the traditional process, there are a number of areas where errors can come into play. Digital technology can decrease the number of errors and provide a more predictable outcome. At the same time, there are not as many laboratory technicians being trained in the United States. The standard laboratory technician must have years of experience in ceramic work to create beautiful restorations. The trade school aspect of that training has decreased as time has gone on. Furthermore, if you look at the laboratory space itself, the vast majority of the technology has gone digital. Many of these laboratories are hiring gamers who grew up with their Xboxes and can manipulate software. That is the background change.

Do you want to be able to fabricate a restoration in your office, or do you just want to get rid of the traditional sort of goop-in-the-mouth impressioning process and still have the laboratory responsible for the fabrication? Maybe it is a little bit of each. Ultimately, I think all systems will be open architecture and you will be able to buy one brand of scanner and mill on something else.

Medscape: Are file formats becoming standardized?

Dr. Kachalia: Yes, they are trying to do that. Most will use an STL [stereolithography] file, but even that has been somewhat cumbersome. You may have 40% of the market open, but 60% will have a partial relationship. I think it will remain the standard. It seems like a common file type that everyone is comfortable with.

You can also bring other datasets in. You can merge with cone beam CT [computed tomography] information to see the patient's skeletal architecture. There is a company called Anatomage that is able to take multiple file sources and merge datasets to create surgical planning. The world of implant dentistry is where the biggest impact of the technology will be — to be able to scan a patient with cone beam CT, merge that with an intraoral scan, propose what the finished crown should look like, and develop a surgical stent to show where the implant should be placed. Before that, it was always a good educated guess by the surgeon.

Medscape: Is the intraoral scanning technology improving?

Dr. Kachalia: If we look at it from the scanning component — the technology that is used to image the patient's mouth — there have been tremendous leaps. Sirona launched their CEREC 1 system 27 years ago. We had 2 issues at that time. The scanning was very difficult; you had to coat the surface with titanium oxide, which is the same coating as the M on an M&M. The ideal scenario would be no powder at all but a very efficient scanning process that has a small tolerance in terms of error. We have to get between 25 and 50 microns of accuracy.

If we go 5 years back, we're looking at the Cadent iTero (now owned by Align Technologies). They hit the market as the first no-powder system. It worked phenomenally well. The downside of the system was that it was bulky. It was hard to position the unit in the patient's mouth. It was doable, but there was some weight and fatigue. Then 3M ESPE came out with the Lava chairside oral scanner, which is faster, but it reintroduced powder.

At the ADA meeting, 3Shape, from Copenhagen, introduced the TRIOS in the United States. That has a video scan that does not use powder and is very quick. It has a short image upload time, and price points have started to come down. 3M introduced the newest version of their system at the ADA, which has dropped in half; we were at $30,000, and the newest system is $12,000. The chance of the average practitioner being able to acquire this technology has increased substantially.

Medscape: I thought Align just made Invisalign clear plastic aligners. Are they getting into the CAD/CAM business?

Dr. Kachalia: Yes, they are. I think they see it as the future. One of Align's greatest costs is shipping a case. It goes first to Santa Clara, California, which is where, I believe, the cases are scanned. The designs happen in Costa Rica, where a set of orthodontists plan every case along with the prescribing clinician. I believe manufacturing occurs in 2 sites: Pakistan and Mexico. Their ideal would be that every practitioner have a scanner in their office. The practitioner would scan the patient and, within an hour, Align would have a proposal for the patient. If you flash forward 5 years, you could have what we call a printing unit in your office that would fabricate the aligners. I believe that is their goal.

Medscape: What about milling?

Dr. Kachalia: The mills have been very good for at least 5 to 7 years. The biggest change has been in the materials. Materials are being developed to work well with the in-office mills, so we have the right amount of strength but not enough to wear the mills down fast. The biggest advantage in that area has been a product called e.max by Ivoclar Vivadent. Historically, it was available as a product that was pressed. They created a mill version about 4 years ago. It has revolutionized dentistry; you can have a very strong product that takes a reasonable amount of time to make in the office, if you choose to mill it, and yet the patients are happy with the esthetic benefits.

Medscape: Is the quality of a crown made in the office as good as one made in the laboratory?

Dr. Kachalia: I would say strength is identical. It is a nonclinical variation. Esthetics become dependent on you as a practitioner. It just depends on how much of the artistry aspect you are willing to do and learn. There are dentists or support staff who go through training and essentially become in-office ceramicists, and there are others who do not do the training.

Medscape: The best esthetics always involve some staining and glazing, right?

Dr. Kachalia: Exactly.

Medscape: What about fit?

Dr. Kachalia: I would say today's fit is comparable. I would not have said that 2 generations ago.

Medscape: What else is important to know about this technology?

Dr. Kachalia: A lot of times when people think about dental imaging, they think of radiation, but there is no ionizing radiation involved in these scans.

Dr. Kachalia reports acting as a consultant for many dental materials/dental technology companies.