A: Digital impressions are definitely the wave of the future. At some point we will all be taking digital impressions. However, at present, digital impressions have some limitations. The biggest problem is subgingival margins. You need to see the margins. If the wand cannot see the margin, it cannot capture it. Another issue is the size of the scanning wand. Access to second molars may not be easy in some patients with limited opening.
Some of the systems require the use of powder prior to scanning. The scans are sent via the Internet to either a lab or the company to produce a model that can be forwarded to your dental laboratory of choice. The models are fabricated via stereolithography. In some cases no model is necessary and a restoration can be fabricated completely from the digital image. The digital impressions can be more accurate than conventional impressions, with tolerances of about 10 microns. The claim is that the increased accuracy leads to reduced chair time when seating a restoration.
Currently, three digital impression systems are on the market, although others are in development. Cadent's iTero costs about $25,000 with a $25 to $40 scan fee, depending on the size of the scan. The 3M ESPE Lava COS system costs about $26,000, and the fee per scan is approximately $20. Sirona Dental Systems' Cerec AC is approximately $24,000 and $25 per scan. The Cerec AC can be upgraded with a Cerec milling unit if you decide to do your own CAD/CAM restorations.
Before purchasing any of these products, I recommend that you attend a lecture and demonstration so you can see the benefits and shortcomings of each firsthand.
Martin Jablow, D.M.D., is a practicing dentist and a self-professed technophile who lectures and blogs on a variety of technologies used in dentistry (dentechblog.blogspot.com). If you have a technology question for Dr. Jablow, e-mail it to us at firstname.lastname@example.org.
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