The classic way of doing things works. Don’t let anyone tell you otherwise.
Sending a letter via the U.S. Postal Service allows one to communicate effectively with the intended audience. Taking a photograph and developing that photo in a dark room allows the user to view the subject on a piece of paper. Taking a traditional impression to capture the size and shape of a patient's teeth allows the clinician to see the state of a patient's dentition by pouring that impression in stone.
However, with each of these things, a digital method has evolved that not only also works but has become more popular and allows the task to be accomplished with greater ease. Now I’m not here to tell you the modern, digital alternative is better than the classic way of doing things. What I am here to tell you that there is a modern alternative and that modern alternative is making the old way of doing things obsolete.
One can argue that taking the time to write a letter instead of sending an email is the more personalized method of communication. Yet billions of emails are sent daily – not because they are better, but because they are more convenient.
Taking the time in the dark room to develop a photograph allows the operator to have complete control over their subject, allowing them to adjust the tone of the image and fine tune the end result by altering the type of paper that is used for developing the photo. Yet hardly anyone buys traditional cameras anymore because taking a digital photo and using your computer to modify the end result is just more convenient.
Similarly, prepping a tooth, capturing a PVS impression and pouring up the stone model to fabricate a dental restoration can yield some great results, yet more and more clinicians are venturing into the digital world. Why? Because for both the clinician and the patient, taking a single visit to do routine dentistry such as a crown, inlay or onlay is just more convenient than placing a provisional and having the patient return for a second visit.
I happen to have started a community that is the largest CAD/CAM community in the world, and the users of this community use the CEREC system. And as with the other examples given, using a CEREC doesn’t necessarily give you a better result over the traditional way of doing things. However, it sure is more convenient. It’s easier for the clinician, and it’s certainly more convenient for the patient.
Despite the growing popularity of the CEREC system and its ease of use for routine bread and butter cases, many feel that the use of the CEREC is just limited to the types of examples given above: a simple crown, a simple inlay. Despite the massive advancements in technology, many clinicians are just unaware of what is actually possible when a digital workflow is applied to their more comprehensive cases.
A Digital Workflow Case Study
Take the example of the case shown in Figure 1. A good friend and a great clinician forwarded the case to me asking whether it would be possible to make some overlays on the patient in anticipation of restoring the full mouth of the patient.
The mock up you see is designed and can be milled using the CEREC Omnicam and the MCX milling unit (Figure 2). Granted there is a lot of information missing in this case and by no means is this meant to be a definitive design. What this case does show is that we can use our digital workflow to potentially diagnose esthetic deficiencies and use the CEREC system to mill out esthetic prototypes as taught in the various workshops and seminars at the Spear campus.
Let's take this opportunity to discuss what is possible and then create a wish list of what would make the entire process more efficient in terms of a digital workflow.
Today the clinician can take a scan in the mouth or of a model and design a splinted overlay to determine esthetics and function. To get technical for a moment for the CEREC users in the audience, the restoration in the software is designated as a bridge and the user designates all the teeth as abutments. Then the clinician can marginate the teeth and receive a proposal (Figure 3). The various tools in the software are used to manipulate the proposal to get the best result.
Specifically in a case such as this where an unconventional restoration is being fabricated – a splinted bridge on unprepped teeth – the user should be prepared to use the new Biojaw tools in the 4.4 software (Figure 4). This powerful design algorithm gives the user the opportunity to manipulate the position, size and shape of the proposals to aid in getting a simplified design.
Finally, after receiving the initial proposals, the operator can use the Biogeneric Variation tool to adjust the anatomy and finish the design (Figure 5).
What you see is an esthetic prototype created with the CEREC system and milled from a 40 mm acrylic block. This can be used to test the patient's new vertical dimension, esthetics, phonetics and other aspects of the patient's new dentition.
As robust as the new software is, there are certainly some short comings in the system where the operators attempt to create out-of-the-box type restorations – such as an esthetic overlay – that the programmers of the system didn’t have at the forefront of their thought process.
Digital Workflow Wishlist
So as an avid CEREC user, what are some of the wish list items that I would like to have to make this type of treatment a fully digital process?
First, how do we accurately gauge the occlusion of the patient? At Spear, our philosophy is to use the facial esthetics to determine the size and shape of the teeth, and our goal is to start with the maxillary teeth as taught in the Facially Generated Treatment Planning workshop./p>
With the CEREC system, while there is a way to incorporate the patient's design with a photograph of the patient, a user would benefit from having the ability to import multiple photos of the patient – one possibly a lip at rest photo, another possibly a full smile. This would allow the operator to have a better visualization of the design of the digital restorations.
Occlusion has traditionally been diagnosed by mounting cases on an articulator. The CEREC system has a virtual articulator (Figure 6); however, programming the virtual articulator with the proper condylar information requires the doctor to incorporate additional software called the SiCAT Function software. The SiCAT Function software allows the user to use the patient's anatomy to get proper information to program the virtual articulator built into the software.
Some form of virtual preparation on the digital models would be helpful. It would help to create space for the restorative material. As you can see from the preoperative situation, there is significant overlap of the teeth (Figure 7). By not having appropriate restorative space, the clinician is limited in the design and is handcuffed by a lack of space. This frankly is no different than if the user sent the case to the lab and asked the laboratory to fabricate an esthetic prototype without prepping the teeth.
If a user was to send this case to a laboratory for the fabrication of a splinted bridge, the lab would lightly prepare the stone models and then fabricate an overlay on top. This is precisely what is needed in the CEREC software to make this process easier. Virtual preparations would greatly enhance the design of the restorations.
So as you can see, while we can do many larger cases with a comprehensive digital workflow, there are still some limitations until the CEREC programming team incorporates some simple tools as listed above to help us do these types of cases more easily. The advantages and disadvantages of a digital workflow and its shortcomings is precisely the topic of discussion at our upcoming esthetics seminar at Spear’s Scottsdale campus. At this seminar, we will explore the virtual articulator, and we will learn about SiCAT Function and how to program the virtual articulator. We will also explore the advantages and limitations of the digital design of the software for larger more comprehensive cases.
Whether you are a CAD/CAM user or not, and whether you use your CAD/CAM system for simple cases or more complex ones, you owe it to yourself to learn more about the state of CAD/CAM. Just as the frequency of sending emails has greatly surpassed mailing a hand-written letter, and taking photos with a digital camera occurs at a much higher rate than with a film camera, so too will the ability to design restorations digitally soon surpass taking a PVS impression and sending that impression to the laboratory for fabrication.
For additional information on the esthetic seminar listed above, please visit www.cerecdoctors.com/seminars.
Sameer Puri, DDS