CAD/CAM Smile Design for the Modern Patient

For the most part, the patients whom the author had encountered in earlier years just wanted a beautiful smile; they weren’t educated about the materials used. However, patients today are more sophisticated regarding their understanding of the materials and options available to them. While having an informed patient base is good for dentistry, it can also be challenging for the dentist/technician team. Technicians have the restorative materials to match patients’ expectations, but it can be difficult to try to meet the timeframe demanded by both the patient and dentist. Digital dentistry has become the silver bullet that technicians can use for most cases that they encounter, as long as the team does not observe major parafunction in need of correction. If any correction is required, the team will provisionalize the patient to address the parafunction and protect the patient and restorations.

When analog fabrication methods were the only choice, the dental team members would begin a smile makeover case with preliminary impressions that they could pour up and mount. Then, a diagnostic wax-up was made to see if the team could create a solution that pleased the patient. Once this was accomplished, the patient would return to the practice, and the team would begin preparing the teeth and making temporaries to be worn by the patient for several weeks, or even months, to ensure the contours and shade of the final restorations were acceptable. This also enabled the dentist to resolve functional issues that might have arisen. Once everything was deemed ready, the patient would return for final impressions. After weeks of such preparation, the case would arrive at the laboratory.

That’s when the usual 2-week journey of completing a smile design case would begin. That may seem too long for some patients, but it’s important to consider the steps needed to create a smile using conventional methods. The models must be poured and mounted with a facebow or bite stick provided by the dentist. Then the diagnostic wax-up is transferred to the working model. Once the wax-up is finalized and the margins are flowed in, the crowns can be sprued. All this occurs in the first 2 days. In the next day or two, the units are invested, pressed, and devested. This method is something of a silver bullet and is usable for almost all cases.

In most cases, the pressed units are ready to contour by the fifth day, barring any complications with this process. When compared with the CAD/CAM method, the traditional press process presents more opportunities for problems, such as voids in the investments, exploding rings in the burnout oven, and mis-presses.

After contouring, the restorations are stained, glazed, and returned to the dentist so he or she can call the patient back for the seating appointment.

Patients today expect a faster case turnaround. So the challenge the author faced was this: How can he produce smile designs in 1 day that are comparable with those on which considerably more time was spent?

To find the answer, the author began a digital journey and determined many good CAD/CAM systems were available. He just needed to realize that it was acceptable that a machine could rival or even more consistently produce what he thought he was uniquely qualified to do.

Ever since embracing digital technologies, the author has found his approach to dentistry has been revolutionized. Same-day and next-day digital dentistry smile design is now routine, and this has increased the author’s ability to meet his dentists’ and patients’ desires. Finding a system that made it easier to communicate with his clients and do more for them was important to him. Digital impression technology from Planmeca along with the milling unit and design software combined with an open-architecture platform met those needs and paved the way to business growth and increased turnaround time not only on smile design cases, but also daily production.

A female in her 20s, who was competing in beauty pageants, presented concerns about her smile esthetics (Figure 1). Previously placed composite veneers on teeth Nos. 7 through 10 were chipped, stained, and worn, and she displayed worn natural dentition on teeth Nos. 6 and 11. She also had lower anterior crowding with hypocalcification (Figure 2).

The patient was seeking treatment just prior to the Mrs. Texas pageant, believing improving her smile would also raise her level of confidence on a public stage. After a complete examination, the treating dentist decided that Planmeca PlanScan would be used to digitally scan and design IPS e.max® (Ivoclar Vivadent, ivoclarvivadent.com) restorations. The dentist provided the laboratory with preliminary polyvinylsiloxane (PVS) impressions, along with a bite registration for the design of a diagnostic wax-up.

It is during case preparation that the battle for treatment success is won or lost. Digital smile design makeovers are all about preparation and ensuring that digital transfer of the diagnostic wax-up to the digital working model can be performed. Because the model on which the veneers would be designed would be created from intraoral digital scans (Planmeca PlanScan), it was vital for the PVS impression used for the diagnostic wax-up to have intricate detail on as many hard- and soft-tissue landmarks as possible for the software to accurately overlay the images. This process still requires a skilled hand for capturing an accurate impression of the dental architecture. Proper preparations were achieved using prep guides that were fabricated from the diagnostic wax-up. (The team uses Ivoclar bleach shade guides and photographs to determine the final shade for the crowns.) After tooth shades and prep shades were determined, the patient was provisionalized using temporary matrices provided by the laboratory (Figure 3).

Once the patient provided final approval of the provisionals, the digital and conventional impressions were sent to the laboratory to pour up and design the final restorations. The traditional challenge was to take the diagnostic wax-up and convert it to the final product.

After mounting and scanning in the final models and wax-up (Figure 4), the author was able to begin designing the case. He predefined the margins for each restoration to be fabricated and instructed the computer to clone the corresponding tooth (Figure 5). Cloning is just like it sounds in that it copies the wax-up in the final crowns. This is where it is determined whether all the preliminary work had been done correctly and would produce superior esthetics.

As a result of the accuracy and amount of detail that the treating dentist provided when he took the impression for the wax-up, an exact match between the scanned model and the digital impression was made. (This is how to tell that the software had been given the data needed to properly line up the clone with the working model and actually do most of the design work.) After generating all of the veneers, the author began refining the contacts and contours until they matched the clone/pre-op (Figure 6 through Figure 10). Cloning and mirroring are not the same process—mirroring is a reverse image, and cloning is an exact copy.

After the design was complete, the team used the block that was selected during the planning phase based on the patient’s desired shade and its relationship with the underlying prep color. This relationship would determine whether to use a high-translucency or low-translucency block. In this case, the patient had an ND1 prep shade, so a BL3 low-translucency block gave the best shade and value to match the current dentition. The crowns were milled in approximately 3 hours, using the PlanMill wet milling unit. The crowns were cut off the blocks and fitted to the stone model using a combination of a green stone and diamond burs. Fitting the crowns to the model would ensure that there would be no hang-ups when the crowns were seated in the patient’s mouth. Proper interproximal contacts were ground in, so that the veneers had a passive seat on the model with a slightly lingual contact point (Figure 11 through Figure 13). Occlusion and margins were achieved on all the units.

After function of the restorations was worked out in the diagnostic wax-up, it was expected that minimal or no adjustment would be needed to ensure proper anterior guidance. The reason preparation was performed meticulously was specifically to be able to reap those rewards.

Once the mechanics of the crowns were satisfied, it was time to put the facial anatomy and surface texture into each veneer (Figure 14 through Figure 16). Anatomy was drawn on the restorations with a red pencil to ensure that they were even from side to side (Figure 17 and Figure 18). When the anatomy was carved in, the crowns could be smoothed and the final surface texture could be placed (Figure 19). The crowns were steam cleaned, dried, and placed in a porcelain furnace to crystallize. Stain was then applied using the IPS e.max stains to enhance the body and incisal portions of the restorations. The veneers were fired in a porcelain furnace, and glaze was then applied using IPS e.max Fluo Glaze. The veneers were given a third and final bake and acid etched for 20 seconds with a 5% hydrofluoric acid solution.

The team had turned what would have taken 6 or 7 days into 1 day. Final impression to completed stain and glaze was completed the same day. This is an estimated 10-hour process.

There is generally excitement on the day of delivering the restorations. The treating dentist likes to show the patient the restorations on the models first and then anesthetize before prototype removal. After the temporaries were removed and the teeth were cleaned with pumice, the restorations were placed on the preps with either water or a try-in paste from Ivoclar (Figure 20 and Figure 21). At this point, the dentist showed the patient the results of the CAD/CAM digital design. The treating dentist also likes to let the patient see the results under the office lights and, if possible, in the outside light (Figure 22 and Figure 23).

CAD/CAM technology has improved the ability of both the dentist and dental technician to communicate more effectively and efficiently with each other and the patient. This article has demonstrated the the team’s capability for taking the patient from prep to seat in a day and a half. The author prepped, impressed, and fabricated the crowns on the first day, and the restorations were stained and glazed on day two. The dentist then seated the crowns. The end result is a much faster turnaround and a patient who receives a beautiful smile design and improved self-esteem. This confidence may lead to a better performance in life and in competition (Figure 24)

Jimmy Fincher, CDT
Owner
Cosmetic Advantage
Lewisville, TX