Digital impressions: Creating the "aha" moment

Oct. 1, 2009
One of life's truly great experiences is the “aha” moment. That moment is a flash of creative insight ...

by Larry Emmott, DDS

For more on this topic, go to and search using the following key words: digital impressions, CAD/CAM, digital technology, photography, Dr. Larry Emmott.

One of life's truly great experiences is the “aha” moment. That moment is a flash of creative insight that brings together random bits of information to a suddenly obvious understanding. Researchers have even identified a surge of electrical activity in our brains when we experience an “aha”!

When considering high–tech dental options, the “aha” comes when we realize it is not about any single high tech device, but about the whole concept of creating digital ... everything!

One of the new and exciting digital “things” we will be hearing a lot about is digital impressions. This technology is used to digitize a solid object — that is, to make a highly accurate digital simulation of a real three–dimensional thing; for example, a tooth. This incredible technology is the basis for CAD/CAM, digital impressions, and even Invisalign®.

The most important element a dentist needs to understand about new digital–impression technology is not whether it can make a crown like we used to or how the technology works, but simply that it is digital. That changes everything — that is the “aha.” To understand the advantages of digital impressions, let's compare it to another digital system you have probably used and understand — a digital photograph.


Back in the olden days — you know, the last century, B.C. (before computer) — we took photographs with a film camera. This required a complex infrastructure that was purposely built for and exclusive to photography. The film, the camera, the chemicals, the processing equipment, and the printing materials were all exclusive to photography. In other words, you could not use the photography system to send a postcard or take an impression.

Conventional impressions also need single–purpose systems, from trays to impression materials and various stones, vibrators, mixers, and vacuum pumps, to create a model. You cannot use the impression system infrastructure to send a postcard or take a photograph.

Since the infrastructure is single purpose, complex, and expensive, most people do not try to do it themselves. Instead, they send the film to a special lab to be processed and printed.

Of course, the same is true of impressions. Most are sent to a special lab to be processed and the restoration created.

In addition to the infrastructure, there was the film process itself. You would take a photo, but you would need to put it through a long and complex process of developing and printing before you could use it, usually hours or even days later. If there was an error, such as poor focus or overexposure, you would not know about it until the photo was developed, printed, and returned to you. Then, of course, it was too late to fix it. If the photo was unneeded or just ugly (Aunt Tilly blinked), you already had invested the time and money to create it.

The conventional impression process is similar. You take the impression, but you do not get to see or use the model until hours or days later. If there is an error, a bad margin, a void, or distortion, it is too late to fix it.


Once you finally got the film photo print or slide you wanted, you then had to store it. At home, that meant randomly throwing the snapshot in a shoebox or taking the time to put photos neatly in a photo album. At the office, it meant labeling and dating the image and putting it in a patient chart.

Impressions are even harder to store. They need to be labeled, dated, boxed, and stored on shelves so they can be found later. Because this is so tedious, most models end up stored with the random shoe box technique or just thrown away.


If you wanted to send a film photo to a friend or a clinical film photo to a colleague, it would have to be copied back at the lab, put in an envelope, and mailed. The process would be expensive, the quality of the image would be degraded, and it would take days to accomplish.

Sending a copy of an impression would be similar, but even more complex, time–consuming, and expensive.

The change to digital photography

With digital photography, everything changes. The infrastructure is a computer network. This digital infrastructure can be used to capture, process, display, store, and transmit the photograph. It can also be used to send a postcard — an e–mail in today's terms. It can be used for impressions, records, diagnostics, and a whole lot more.

With the digital photo process, the user can see the image immediately. If there is an error, it can be corrected right now. There is no need to pay the processing costs — simply hit the delete button! The same is true of a digital impression. The user sees the image immediately and can make needed corrections and discard the mistakes.

Digital photos don't fill up shoe boxes or bulge out of files, but are stored as part of the patient record on a hard drive. Digital impressions also can be stored on a hard drive. The storage process usually requires three or four mouse clicks, and the hard drive is smaller than a shoe box and costs less than a file cabinet.

Sending a digital photo to a friend or colleague can be done online with just a few mouse clicks. It costs nothing, it happens instantly, and the image is exactly the same quality as the original. The same is true of a digital impression.


CAD/CAM stands for computer–aided design and computer–aided manufacturing. These systems take a digital impression of a prepared tooth, and the computer then designs a restoration and mills it out in a special chamber. The result is a one–step, lab–type restoration with no impression, no temporary, and no second appointment.

There are two dental CAD/CAM devices available. The first is CEREC® from Sirona, which was introduced over 25 years ago. The second is the E4D from D4D Technologies LLC.

Another application of this type of technology is a digital impression. A digital impression is simply the first step of CAD/CAM — it is the capture of a 3–D digital version of a tooth. There are two digital impression devices available. The first is iTero™ from Cadent™. The second is the Lava™ C.O.S. from 3M ESPE.

Full–arch images lead to the final use of virtual 3–D models, and that is Invisalign. Any dentist who has seen the virtual models created by the Invisalign Clincheck process has to have been impressed. Imagine having that type of system available in the office to create routine virtual study models. Currently, Invisalign still requires an impression, which is then scanned to create the virtual model.

Once it is digital, everything changes .... “Aha,” the future is coming and it will be amazing!

Dr. Larry Emmott is a leading authority on dental high tech and one of the most entertaining speakers in dentistry. He is also a writer and consultant. To find out about his high–tech training programs, Technology Guides, and other services, call (602) 791–7071 or visit

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