Enhancing a Smile With CAD/CAM Restorations

Today, many patients are already educated about cosmetic dentistry due to television shows like Extreme Makeover and The Swan. Patients are also educating themselves about different material choices available to dentists from manufacturers through the Internet. Whatever the source, today’s dental patient is much more educated about our profession’s services and materials. In fact, it is common to hear a patient request that his or her crown not be from overseas and be metal-free.
When the patient desires strength and aesthetics without metal, my first choice for the best material would be a zirconium-based restoration. Restorations like Procera Zirconia (Nobel Biocare), Cercon (DENTSPLY Ceramco), IPS e.max ZirCad (Ivoclar Vivadent), and Lava (3M ESPE) afford clinicians the opportunity to confidently place cosmetic, metal-free alternatives that demonstrate exceptional strength, aesthetics, color stability, and biocompatibility, even in the posterior region.
The preparation design for this type of restoration is similar to conventional porcelain-fused-to-metal alternatives; however, I have found that the elimination of metal from the substructure makes these restorations even more aesthetic. Some of the ad-vantages of zirconium-based restorations include a natural translucency or fluorescence and the elimination of dark lines at the margin.

CASE REPORT

Figure 1. Preoperative full-face view.	Figure 2. Preoperative retracted view.

Figure 3. Preoperative occlusal view of maxillary teeth.

A 50-year-old female presented dissatisfied with the appearance of her existing restorations and smile (Figure 1). She was especially displeased with the size and shape of her maxillary anterior teeth, as well as multiple failing composite restorations. Her goal was to achieve a symmetrical, bright, and aesthetic smile.
Clinical examination revealed multiple amalgam restorations with fracture lines or failing margins on teeth Nos. 2, 6, and 14. Unaesthetic porcelain crowns were also present on teeth Nos. 3, 4, and 13 (Figures 2 and 3). Her anterior maxillary teeth evidenced wear due to clenching and grinding. She had no temporomandibular joint symptoms at this time, but the ultimate treatment plan was to include the development of anterior protection of the posterior teeth with canine guidance and to increase her vertical dimension to a more comfortable position.1
Probing depths were within normal levels in the anterior region, and the patient’s periodontal health was within acceptable limits. The soft-tissue symmetry of her maxillary anterior teeth was also within normal limits.
A comprehensive treatment plan was developed and consisted of restoring her entire maxillary dentition, except for tooth No. 1, with all porcelain restorations from tooth Nos. 2 to 15. Teeth that had either failing composite or amalgam restorations would be cleaned out and restored with cores prior to crown preparation. A Smile Guide reference book (Discus Dental) was used to complete the smile analysis necessary for predesigning the case.2-5
From an aesthetic perspective, the patient’s maxillary anterior teeth were chipped, discolored, and worn. Facially, the failing composite restorations were very noticeable. The final crowns would be designed to create a harmonious and uniform white smile.
The patient had selected a bleach shade of 040 (Chromascop Shade Guide [Ivoclar Vivadent]). The lower dentition would be whitened using 16% carbamide peroxide (Pola [SDI]).
Because of multiple defective amalgam and composite restorations and some unattractive crowns, the restoration choices were limited to full-crown restorations. An all-porcelain crown system seemed the logical choice to accommodate the patient’s aesthetic and functional needs. In this particular case, the clinician felt confident with the aesthetics of porcelain-to-zirconium restorations, which require nothing more exotic than a conventional chamfer preparation and a traditional cementation protocol. A porcelain-to-zirconium system (Lava [3M ESPE]) would be used in this particular case.

PREPARATION

Figure 4. Occlusal view of preparations with Expasyl in place.

Once the patient provided informed consent, treatment was initiated. After anesthetic was administered, all teeth requiring buildups were properly cleared of old restorative materials, and any decay was removed with a carbide bur (Revolution Car-bides [Komet]). A seventh-generation bonding agent (OptiBond All-In-One [Kerr]) was applied following the manufacturer’s protocol and light-cured. Using a flowable composite (Premise [Kerr]), followed by a packable composite (Premise), the buildups were accomplished on teeth Nos. 2 to 15. The teeth were prepared sequentially using an S-Diamond Bur (Komet) for fast reduction, starting from the anterior maxillary segments to the posterior right and left segments, so that a bite would be captured at each portion.
Due to the severe staining in some of her natural teeth, it was essential to place the margins slightly subgingivally. Using Expasyl (Kerr), which is a viscous paste containing aluminum chloride that can be used in lieu of the traditional cord packing technique, we controlled any hemorrhaging and also achieved slight gingival retraction (Figure 4). Since the patient had a sensitive gag reflex, a quick-setting vinyl polysiloxane (VPS) impression material (Take 1 Super Fast [Kerr]) was selected to take the full-arch impressions.

TEMPORIZATION

Using a putty matrix (Sil-Tech [Ivoclar Vivadent]) fabricated on a model made from an impression of a direct composite mock-up, the provisional restorations were fabricated using a bis-acrylic temporary material (Pro-temp 3 Garant [3M ESPE]). Final trimming of the temporaries was accomplished using small composite polishing diamonds (Q-Finishers [Komet]) and discs (OptiDisc [Kerr]). The provisionals were then seated using TempBond Clear with Tri-closan (Kerr).
The patient returned the next day for a review of the length of her anteriors and the overall smile design. She was very pleased with the services she had received thus far and commented on how she had already received a lot of compliments on her temporaries. Phonetics were verified to confirm the position, size and length of her teeth. An alginate impression was taken of the temporaries and forwarded to the dental laboratory for further guidance in positioning, length, and contour. There was no need to take any stump shades because the zirconium copings would be able to mask the underlying tooth structure.

LABORATORY CONSIDERATIONS

During the laboratory phase, the full-arch VPS impressions were used to create a master model on which the restorations would be based. After the dental lab produced a sectioned model, the milling center digitized the model by using the Lava Scan optical scanner for any Lava restorations. Next, the restorations were designed virtually on a monitor using the Lava CAD software program. The data was then sent to a CAM milling unit (Lava Form), and the restoration copings were milled from a presintered zirconium oxide blank. They were colored by choice to a Lava Frame Shade of FS1, which corresponds to a B1 Vita shade, and then baked to their final density in a sintering furnace. The Authorized Lava Milling Center (ALMC) then returned the finished copings to the dental laboratory (Burbank Dental Laboratory), where the porcelain technician veneered and glazed them with Lava Ceram porcelains, giving them their final artistic finish.

CEMENTATION

Figure 5. Filling Lava crowns with Maxcem Elite self-etching self-adhesive resin cement.	Figure 6. Postoperative retracted view.
Figure 7. Postoperative occlusal view.	Figure 8. Postoperative full-face view.

After the provisional restorations were removed, the preparations were cleansed with plain pumice (Preppies Paste [Whip Mix]) and cleansed with a chlorhexidine solution. The preparations were then desensitized (Gluma [Heraeus Kulzer]), and the final porcelain-to-zirconium oxide restorations were tried in to verify marginal fit, contour, contacts, shade, and accuracy. The patient was very satisfied with the look of her new restorations and approved them for final cementation.
The crown restorations were seated utilizing a self-etching, self-adhesive resin cement (Maxcem Elite [Kerr]; Figure 5). Excess cement was easily removed from the margins and accomplished within a short amount of time before final curing with the curing light (DEMI [Kerr]) for 20 seconds. No finishing of the cement was necessary along the margins. The overall health and structure of the soft tissue and restorations was very good (Figures 6 and 7). The patient was extremely satisfied with the definitive results (Figure 8).

CONCLUSION

If the challenges of cases such as this are carefully diagnosed and analyzed, and a treatment plan is properly designed, they can be addressed successfully within the aesthetic demands of today’s society.
The keys to the process are to understand what the patient demands and to know the most appropriate, durable, and predictable restorative materials to facilitate the case. Porcelain-to-zirconium oxide crowns represent an alternative restorative material that enhances the dentist’s and technician’s ability to provide durable, aesthetic, and functional restorations in both the anterior and posterior regions of the mouth, especially when metal-free restorations is a primary desire of the patient. The zirconium-based restorations introduce yet another method of meeting the demands of today’s society. All patients deserve to be understood and to get what they want. By following certain guidelines in smile analysis, material selection, and laboratory instruction, the dental provider can exceed any aesthetic challenge.

Acknowledgment

The author thanks Burbank Dental Laboratory in Burbank, Calif, for fabricating these restorations.

References

Dr. Nazarian is a graduate of the University of Detroit-Mercy School of Dentistry. Upon graduation, he completed an AEGD residency in San Diego, Calif, with the United States Navy. He is a recipient of the Excellence in Dentistry Scholarship and Award. Currently, he maintains a private practice in Troy, Mich, with an emphasis on comprehensive and restorative care. His articles have been published in many of today’s popular dental publications. He also serves as a clinical consultant for the Dental Advisor, DentalCompare, and Dental Team Concepts, testing and reviewing new products on the market. He has conducted lectures and hands-on workshops on aesthetic materials and techniques throughout the Untied States. He’s also the creator of the DemoDent patient education model system. He can be reached at (248) 457-0500 or by visiting demo-dent.com.