Predictable In-Office Results: Applying CAD/CAM Technology in the Aesthetic Zone

INTRODUCTION
The digital revolution has taken over every facet of our lives. Our impulsiveness and the need for immediate gratification drive us. We want everything quick, easy, and now! The current iPhone is considered by many to be the best mobile phone on the market, until the next one comes out. Music albums, rotary telephones, and patient paper charts are now prehistoric. Keyboards have been replaced by touchscreens. This is seen in every area of our lives. Dentistry is no different. The thought of producing a crown in one day, in-office, was unfathomable 20 years ago. Now, it is becoming commonplace. To be able to produce a cosmetically beautiful anterior CAD/CAM restoration was, in fact, hardly ever done. The aesthetic component of CAD/CAM restorations has come a long way throughout the years.

In the past, the cost of installing CAD/CAM equipment was a major drawback; though now, the cost continuously decreases as technologies improve, portability increases, and more competitors emerge in the market each year. Any financial drawback can also be remediated with the fact that most CAD/CAM systems can actually be added incrementally. Systems (such as the Planmeca PlanScan [E4D Technologies]) have the ability to export data in a standard open architecture format (STL file) and can forward scanned data to the laboratory for fabrication of restorations. This allows the dentist to slowly emerge into digital dentistry and purchase additional equipment needed for same-day restorations.

Taking the time for education on how to do CAD/CAM dentistry has also been seen as a challenge to some dentists throughout the years. Learning how to scan, design, stain and glaze, and cement restorations is a shift in how we are accustomed to doing things; these steps were mostly left to lab teams to perform. Also, integrating CAD/CAM dentistry into a dental office makes a shift in the way we schedule patients. Oftentimes, the schedule needs to be adjusted and the dentist has to be able to quickly and efficiently add the technology into the office. When purchasing a system such as the PlanScan, comprehensive education in the use and integration of digital dentistry is part of the package. The education systems now in place make sure dentists are fully efficient in using their new system before they put it to use on patients.

Some dentists are reluctant to integrate digital dentistry because they feel that CAD/CAM restorations are inferior to the lab-fabricated restorations. Truthfully, the earlier in-office restorations may have lacked the precision, design, and aesthetics that are routinely seen today. This tide is shifting; as with most traditional laboratory impressions, most are not properly taken and are not producing the predictability that lab teams depend on to create an accurate restoration. This, however, can be quickly reversed with education. Accurate optical impressions can produce precise restorations with proper training in preparation technique. The beauty is, if the restoration does not fit, it can be adjusted digitally within the office (while the patient waits); and then re-milled. The patient does not need a provisional restoration. There is no risk of the temporary breaking, with the patient having to return and have another one made; or having the temporary come off with the need to be re-cemented. This means that the office saves time and money, and it is much better for the patient since there are less office visits required. Traditionally, if the crown does not fit, a new impression would have to be made, and yet another return trip for the patient. This is not the case with CAD/CAM dentistry. Any ill-fitting area can be digitally corrected, milled, and cemented on the same day in the office, thus avoiding the hassle, wait time, and expense for the dentist and the patient.

With the advent of CAD/CAM digital dentistry, a patient’s aesthetic concerns can be achieved quickly, with precision and beauty. With proper training, cosmetic cases can be predictably performed using CAD/CAM digital systems. With these types of cases, the treating dentist can opt to have a laboratory technician come in for the appointment to design and fabricate restorations for the dentist.

The case described below took 2 days to start and complete. The patient was prepped on Monday; final restorations seated on Wednesday of the same week. This case was scanned and designed with the Planmeca PlanScan, and milled with the PlanMill 40 (E4D Technologies) in-office milling unit.

CASE REPORT
Diagnosis and Treatment Planning
This patient never liked her teeth or smile (Figure 1). As seen in Figure 2, the patient presented with retained and ankylosed tooth letter C. Cross-bite malocclusion was noted (between teeth Nos. 10 and 11 and teeth Nos. 21 and 22) (Figure 3). She had excellent periodontal health and oral hygiene, and no previous dental restorations present.

The patient stated that she had a “half-smile” (Figure 4), and had always been self-conscious with regard to her smile (Figure 5). Treatment pros and cons were discussed with patient. Treatment options were given and she decided to proceed with porcelain veneers.

Figure 1. Pre-op photo.	Figure 2. Retained primary tooth letter C.
Figure 3. Cross-bite on patient’s left anterior.	Figure 4. Patient displayed a limited “half-smile.”

A diagnostic wax-up (MicroDental Laboratories) was obtained of the proposed restorations (Figure 6). The wax-up was shown to the patient for approval. From the wax-up, a matrix was fabricated for the temporary, and also the preparation reduction guides (Sil-Tech [Ivoclar Vivadent]). The wax-up was digitally scanned using the Planmeca PlanScan (Figure 7), so that the restorations would mimic the shape, size, and texture of the diagnostic wax-up.

Figure 5. Patient’s pre-op smile.

Figure 6. Diagnostic wax-up.	Figure 7. Scan of diagnostic wax-up.

CLINICAL PROTOCOL
Treatment in Three Phases
Phase 1: Pre-op Appointments and Preparations—The preoperative evaluation of the patient addressed her aesthetic needs and concerns. The diagnostic wax-up, once approved by patient (modified as/if needed, based on patient concerns), was then digitally scanned. All of this is done prior to the preparation appointment. Once the patient had a clear understanding of the procedure, the clinical work was started.

The patient was anesthetized and the teeth prepared. For the best aesthetic outcome, traditional preparations for veneers were used on teeth Nos. 6 to 11, and mesial-occlusal-distal-facial onlays on teeth Nos. 5 and 12. It is important to note that teeth Nos. 21 and 22 were slightly adjusted to allow adequate room for the veneers produced on the opposing arch; the patient was informed (with consent given) of this adjustment prior to starting the case. The reduction guides were used to ensure that proper material thickness would be achieved. All teeth were prepared according to the clinician’s preferences (all prior restorations, if any, are removed, all decay removed, all margins are smoothed and have a flowing curve circumferentially around the tooth), similar to the full frontal picture of prepared teeth in Figure 8, the right lateral view (Figure 9), and the left lateral view (Figure 10). After the preparations were completed, the teeth were scanned.

Figure 8. Frontal view of prepared teeth.	Figure 9. Right lateral view of prepared teeth.
Figure 10. Left lateral view of prepared teeth.	Figure 11. Scan of prepared teeth.
Figure 12. Overlay of clone and prepared teeth.	Figure 13. Margins were identified on prepared teeth.
Figure 14. The preparation was orientated to the diagnostic wax-up.	Figure 15. Clone anatomy was outlined; the final proposed tooth was to mimic this.

Figure 16. Final restorations.

After scanning was done (Figure 11), it was ensured that all landmarks of the unprepared teeth were synchronized with the diagnostic model scan. In addition, an EXAFAST NDS (GC America) silicone impression was taken for fabrication of model to try-in and to check the fit of the final restorations. Digital imaging is always preferred for the final restorations; scientific investigation has shown that digital impressions are more accurate than silicone impressions. One such study¹ found that crowns from intraoral scans revealed significantly better marginal fit than crowns from silicone impressions, and that marginal discrepancies in both groups (digitally scanned and silicone impressions) were within the limits of clinical acceptability. Also, crowns from intraoral scans tended to show better interproximal contact area quality, and both groups performed equally well with regard to occlusion.

Once scanned, temporaries were fabricated for the patient to have until final restorations were ready to be cemented. The temporary phase is very important, allowing the patient to re-evaluate the aesthetics and to make any additional changes to the final restorations, if desired. The patient was then dismissed.

Phase 2: Design, Mill, Stain, and Glaze—This phase was performed entirely within the office since a laboratory was not used to fabricate the final restorations.

With the Planmeca PlanScan laptop, proper overlay match of the diagnostic wax-up and the prepared teeth was achieved (Figure 12). It is vital to confirm that these 2 models line up and integrate with each other, as it is the only source to confirm that the “before” diagnostic wax-up matches perfectly to the existing dentition as seen in the mouth. If these do not match up, the patient may have to come back into the office to be re-scanned. Once it was confirmed that the models matched, the margins were digitally drawn on each prepared tooth (Figure 13). It was ensured that the prepared tooth had proper orientation and could correlate with the wax-up (Figure 14). The general shape of the patient-approved diagnostic wax-up tooth was outlined so that it could be translated to the prepared tooth space (Figure 15). Figure 16 shows that all teeth were smoothed, adjusted, added to or subtracted from, so that aesthetically pleasing restorations would be achieved.

Once restoration design was completed, the interproximal surfaces were checked and adjusted to ensure proper proximal contacts (Figure 17). Next, the final restoration material was chosen (in this case, IPS Empress CAD Multi Block BL3 [Ivoclar Vivadent]) (Figure 18). Then the restorations were sent to the milling chamber and, after milling, they were stained (as/if needed), and glazed to get the perfect aesthetic result for the patient.

Phase 3: Cementation—The final phase is by far the most rewarding for the patient, the team, and the dentist.

The patient was anesthetized and the temporaries are removed. Hydrogen peroxide may be used if any signs of bacterial leakage are noted on the preparations.
The restorations were tried in with NX3 Try-In Gel ([Kerr]) so that the patient could approve them prior to cementation. Once she approved the restorations, they were removed and, along with the teeth, were rinsed with water.

Figure 17. Proximal contacts confirmed and refined.	Figure 18. IPS Empress CAD Multi Block BL3 (Ivoclar Vivadent) was chosen.
Figure 19. Patient’s post-op smile.	Figure 20. Retracted post-op view.
Figure 21. Right-lateral post-op view.	Figure 22. Left-lateral post-op view.

Figure 23. A confident and full smile!

Next, the internal surfaces were etched for 20 seconds using 5% hydrofluoric (HF) acid (IPS Ceramic Etching Gel [Ivoclar Vivadent]). Then, after thoroughly rinsing off the HF gel, a universal primer (Monobond Plus [Ivoclar Vivadent]) was applied for 60 seconds, then dried with oil-free air.

For the teeth, the preparations were etched (total-etch technique) with 35% phosphoric acid (Ultra-Etch [Ultradent Products]) for 15 to 20 seconds. The etching gel was then rinsed off the teeth thoroughly with copious amounts of water. With the soft tissues properly isolated and no bleeding present, adhesive (Prime&Bond Elect [DENTSPLY Caulk]) was applied onto the preparations for 30 seconds (while agitating it with a microbrush), and then light cured for 10 seconds. While curing, restorations were loaded with NX3 Dual-Cure Resin Cement (Kerr). The veneers were then seated; the author usually places restorations from the midline back, moving posteriorly. Next, the centrals, then laterals, then canines, etc, were all tacked in place with the FLASHlite Magna curing light (DenMat). Excess cement was removed from the facial/buccal and lingual surfaces with an instrument of choice and the interproximals were flossed. The restorations were then light cured for 20 seconds on each surface. Once the veneers were resin cemented, a final evaulation was done to ensure that all excess cement and/or bonding agent had been removed from all surfaces, including all gingival areas. Finally, occlusal adjustments were done as needed.

The patient immediately loved her new smile. She has had her veneers for a year, has reported no problems, and now enjoys a high level of confidence every time she smiles (Figures 19 to 23).

CLOSING COMMENTS
Cosmetic cases can be done quickly and easily with the proper armamentarium and a quality in-office milling system. We are in a new age, one in which the dentist can achieve wonderful and predictable restorations without the use of a dental laboratory, if that is the choice. However, the dentist and office team must have training, knowledge, and skills with the CAD/CAM system being used to be able to provide success, as demonstrated herein, with aesthetic cases.

Reference

1. Syrek A, Reich G, Ranfiti D, et al. Clinical evaluation of all-ceramic crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling. J Dent. 2010;38(7):553-559.

Dr. Moroni graduated with his doctorate in dentistry from Case Western Reserve University in Cleveland, Ohio. He completed a dental residency at Cleveland Clinic with an emphasis on the treatment of HIV/AIDS and Alzheimer’s patients. In 1999, he moved to Colorado to open a private practice. Dr. Moroni utilizes both the CEREC and NEVO PlanScan systems in his office. He is a member of the American Academy of Cosmetic Dentistry, ADA, Colorado Dental Association, and the Metropolitan Denver Dental Society. He can be reached via e-mail at the address mikemoroni@miragedentalassociates.com.  

Disclosure: Dr. Moroni reports no disclosures.