Aesthetics and Strength With One Restorative Material

INTRODUCTION
There has been an evolution of dental ceramics from early use in the late 1800s to present day. Abraham Weinstein invented the PFM crown in the late 1950s.¹ This system was the most dependable and most widely used tooth-colored restoration for many years. The introduction of bonding ceramics to tooth enamel was a game-changer in many ways. In 1983, Simonsen and Calamia² reported that porcelain etched with hydrofluoric acid could be predictably bonded to tooth enamel with composite resin. The same year, Calamia³ reported a system of fabricating facial feldspathic porcelain veneers with a refractory model technique. Around the same time, Horn⁴ wrote an article describing a technique for making porcelain veneers using platinum foil. Leucite-reinforced ceramics were introduced in the 1990s (IPS Empress [Ivoclar Vivadent]), and with these pressed restorations using the lost wax technique, the strength of the porcelain went from 90 MPa to approximately 150 MPa. The pressing technique also greatly improved the fit of the all-ceramic restorations made from this material.

Lithium disilicate, in pressable and millable versions, was introduced by Ivoclar Vivadent, beginning with IPS e.max Press in 2006. At that time, the IPS e.max Press material was reported to have strength of 400 MPa, while the millable IPS e.max CAD material demonstrated 360 MPa of strength. In the 10 years since their introduction, further research has confirmed strength values that facilitate their use for more conservative restorative dentistry. In recent months, Ivoclar Vivadent has released statements indicating that continuous quality testing has shown that IPS e.max lithium disilicate produces an average biaxial flexural strength of 500 MPa. Due to these proven strength values, a minimum of only 1.0 mm occlusal reduction is now recommended for IPS e.max lithium disilicate, when the restorations are adhesively cemented.

Since 2006, these pressable and millable lithium disilicate materials—available in many shades and 3 different opacities—have also undergone aesthetic enhancements in terms of shades, depth of color, and realism. Most recently, a new universal shade and stain system was introduced (IPS Ivocolor universal shade and stain system [Ivoclar Vivadent]), and new ceramic powders (IPS e.max Ceram Selection [Ivoclar Vivadent]) have been designed by world-renowned technicians to increase the value and brightness of restorations when a more translucent framework material is used.

CASE REPORT
Diagnosis and Treatment Planning
A patient presented to our office with 2 major concerns. She was very unhappy with the removable partial denture replacing her lower right lateral incisor and, in addition, she did not like the small upper incisors with chips and spaces (Figures 1 and 2). At the initial consultation, we determined that she was a potential candidate for adhesive dentistry, so she was scheduled to return for a comprehensive examination followed by a review of findings and treatment planning.

When the patient returned, she received a complete perio­dontal and comprehensive dental exam, followed by a complete series of digital radiographs, diagnostic casts mounted in centric relation, and digital photographs. At her review appointment, several options were discussed, including the replacement of the missing incisor with either an endosseous implant or an all-ceramic bridge (fixed partial denture). We also recommended 4 conservative ceramic veneers for the upper incisors. Also included in her diagnosis was the obvious lack of attached gingiva on the facial of tooth No. 25. After discussing her restorative options, the patient chose to proceed with a lithium disilicate bridge to replace the missing incisor and lithium disilicate (IPS e.max Press) veneers on teeth Nos. 7 to 10 as well as tooth No. 24. However, she elected to wait on a connective tissue graft until after the restorative procedures. Her periodontal health was good, so she elected to start her treatment with KöR whitening.

Clinical and Laboratory Protocols
Our patient was very concerned about whether closing the spaces between her incisors would make her teeth look too big or too long. We used our computer smile imaging program (Patient Gallery [Raster Builders]) to show her how she would look with the changes we would accomplish with her veneers (Figure 3). It is important to reassure the patient by explaining with the provisional restorations how any changes will be made, giving the individual all the time he or she needs to evaluate speech and appearance before proceeding with the final veneers.

Figure 1. Our patient was unhappy with her preoperative smile.	Figure 2. Pre-op photo, retracted view.
Figure 3. Digital smile design usingimaging software from Patient Gallery (Raster Builders).	Figure 4. Veneer preparations teeth Nos. 7 to 10.

Another set of alginate impressions were taken and the models were mounted with the original centric relation bite. The models and a detailed prescription were sent to our dental laboratory team at Trinident Dental Laboratory (Metairie, La) for the wax-up. The original models were then returned from the lab with detailed duplicate stone models of the wax-up. These models were used to make templates to fabricate the Radica temporaries (Dentsply Sirona).

Before making the appointment for veneer preparations, our patient underwent the KöR whitening process. After 2 weeks of tray whitening, she came in for power whitening in the office. She was very happy with the results, so we appointed her for her preparation phase.

The patient was premedicated (2.0 mg oral lorazepam) one hour before her preparation appointment. Her upper anterior teeth were anesthetized using 2 carpules of articaine 4% (1:100,000 epinephrine). A rubber dam (Hygenic [Coltene]) was placed from cuspid to cuspid for isolation and to retract the lips and cheeks. The 4 maxillary teeth were minimally prepared for veneers (Figures 4 and 5). The lingual margins were carried all the way through to the lingual to allow complete closure of the spaces. Enamel was left on the surfaces of all teeth (to the extent possible) to optimize adhesion. Radiosurgery (Ellman International) was used to allow the margins to be prepared subgingivally in the interproximal areas to prevent black triangles. A clear matrix was created on the wax-up model with a positive pressure thermoforming unit (Mini­STAR [Great Lakes Orthodontics]). This matrix was then used to ensure that there was adequate reduction for the final restorations. The rubber dam was removed and final impressions were made with hydrocolloid (Van R/Pentron) and Identic Syringable Bonding Hydrocolloid (DUX Dental/Kerr).

The lower anterior region was then anesthetized by infiltrating one carpule of articaine from teeth Nos. 24 to 27. A rubber dam was then placed and No. 24 was conservatively prepared for a veneer. Next, Nos. 25 and 27 were minimally prepared for full-crown bridge abutments (Figure 5). All margins were left in enamel and all of the lingual surfaces and some of the facial surfaces also had remaining enamel to optimize adhesion. The exposed root surface on No. 25 was intentionally left intact so the patient could have a connective tissue graft procedure later, after the restorative phase. The soft tissue on the ridge was shaped with radiosurgery for an ovate pontic to ensure that the pontic would be cleansable and without food traps. The preparations were then checked for proper reduction using a clear reduction matrix and multiple impressions were taken with 2 types of hydrocolloid impression material as was done previously with the maxillary arch.

While our patient napped in the massage chair in our recovery room, her temporary restorations were fabricated using Snap-Stone (Whip-Mix) models from the bonding hydrocolloid impressions. The 3 Van R/Pentron hydrocolloid impressions were then poured with die stone for the final restorations. Next, the provisional restorations were made indirectly (Radica in shade i2) using templates made on models of the wax-up using copyplast and biocryl thermoforming sheets. Once completed, the Radica provisionals were spot-etched and bonded on the prepared teeth (1.0 to 2.0 mm diameter spots on enamel) and cemented with Insure (shade yellow red light) (Cosmedent).

Figure 6. Patient’s smile with the Radica (Dentsply Sirona) provisional veneers and bridge.	Figure 7. After wearing the provisionals for one week, our patient returned to the office to discuss and re-evaluate her smile and function.
Figure 8. Close-up view of the provisional restorations.	Figure 9. No. 8 trial veneer placed with try-in gel.

All were placed except for the restoration on tooth No. 8. Another bonding hydrocolloid impression was taken to make trial veneers for No. 8. The final temporary was then cemented.
After checking the occlusion, another alginate impression was taken of the maxillary arch for fabrication of an Essix appliance to serve as a temporary nightguard. This appliance also doubles as an emergency retainer that can be placed over a loose or dislodged temporary until the patient can come in during regular hours for recementation. The patient was then given an appointment to return in one week to evaluate the provisional restorations and to try in the “trial veneer.”

Two full-arch models of the upper and lower arches were sent to Trinident Dental Laboratory, along with the trial unit model. This model was used to fabricate 2 trial units, using e.max HT BL1 for the first and e.max HT BL2 for the second. When the patient returned one week later, she was concerned that the incisors were too long. We shortened all 4 slightly and gave her another week to evaluate the shape and length. When she returned, she was happy with the provisional restorations as they were (Figures 6 to 8). We took an alginate impression of the approved provisionals, as well as close-up, smile, and facial digital images. At that same appointment, we carefully removed the No. 8 provisional and tried the 2 trial veneers on the prepped tooth with yellow red light Insure try-in gel. The HT BL2 seemed to be a perfect match (Figure 9). After taking several images, we replaced the provisional veneer.

To ensure the fit and occlusion of the final restorations were ideal, the trimmed and pinned models were mounted in the dental office by the dental assistant. The model of the approved provisionals was also mounted on the same Artex articulator. Since the Artex articulators can be intercalibrated, these models were then transferred to an Artex articulator at Trinident Dental Laboratory with ideal accuracy. Before being sent to the lab team, the case was checked by the doctor and the final prescription prepared. The final case sent to the lab included mounted pinned models, solid prep models, mounted model of the approved provisionals, digital photos of the provisionals, preparations, and face and the final detailed prescription.

Using the mounted model of the approved provisionals as a guide, the ceramist can fabricate the final restorations with predictability. The ceramist used an e.max HT BL2 ingot to press the restorations to full contour. The ceramist then did minor cutbacks and microlayered the facial ceramic to give the restorations a beautiful and lifelike look (Figure 10).

When the case was returned to our office, it was inspected to ensure that it matched the provisionals as instructed on the prescription. Each restoration was then tried on a third model that was retained in the patient’s case pan in the office (Figure 11). This model is referred to as the “hold-back” model since it stays in the office and is not sent to the lab team. The patient is not appointed until the doctor has confirmed that all restorations ideally fit all 3 models and the case matches the prototype (provisional) restorations. At this point, since the shape, shade, and fit of the restorations had been confirmed, the patient was scheduled for what would confidently be the final insertion appointment.

Figure 11. Each restoration was tried on a hold-back model before appointing the patient for delivery of the restorations.	Figure 12. The lithium disilicate veneers after bonding with Insure (Cosmedent) yellow red light resin veneer cement.
Figure 13. Post-op photo taken at one week. Layered lithium disilicate veneers and lower lithium disilicate 3-unit bridge (fixed partial denture).	Figure 14. Post-op smile.
Figure 15. Pre-op full face view.	Figure 16. Post-op full face smile.

The patient was not sedated for the final placement of the restorations. Local anesthetic was administered in the upper arch as needed, the provisionals were removed, and all provisional cement was thoroughly removed. All the veneers were tried in dry to confirm fit and contacts. Then, they were seated again using try-in gel to get the patient’s approval. Once the patient approved and signed a consent form, sedation was offered for the work to follow, but she felt that she did not need sedation for this final procedure.

The teeth were cleaned thoroughly using an air abrasion unit (PrepStart [Danville Materials]) set at low pressure (30 to 35 lbs). The rubber dam was then placed and the veneers bonded with CLEARFIL LINER BOND 2V (Kuraray Dental), CLEARFIL PHOTO BOND (Kuraray Dental), and Insure resin veneer cement (Figure 12).

Next, the lower arch was completed in the same manner. Then, the occlusion was perfected and all adjusted surfaces were carefully polished using a series of diamond polishing points (Komet). A maxillary acrylic nightguard was fabricated directly on the upper arch using iNterra (Dentsply Sirona). The patient was then appointed to return in 2 weeks for a final check and postoperative photographs.

CLOSING COMMENTS
Predictable results with adhesive cosmetic restorations can be readily achieved by following a system that allows each step to be completed before moving to the next. The first step, and most important step, is to listen carefully to patients as they describe their desired goals for treatment. Then, preplanning the treatment, using proper smile-design principles and an excellent wax-up, is critical to success. Taking multiple impressions to check and recheck the fit before seating each case is another important step that can virtually eliminate remakes.

Another important change in all-ceramic adhesive dentistry is the use of lithium disilicate, which has up to 4 times the strength of a feldspathic porcelain restoration and has been shown in recent studies (Ivoclar Vivadent) to have fracture toughness that is not statistically different from translucent zirconia materials. Even with a conservative preparation, a lithium disilicate 3-unit bridge has enough strength to replace anterior teeth predictably. In addition, lithium disilicate veneers, when used properly and as indicated, are just as aesthetic as any other ceramic system (Figures 13 and 14).

Our patient’s goals for having a more aesthetic smile and replacing the missing tooth were both achieved using the lithium disilicate all-ceramic option (Figure 15 and 16).

Acknowledgment
The author wishes to thank Gayle Vanderwall with Trinident Laboratory in Metairie, La, for her exceptional skill in the completion of the technical phase of this case.

References

1. DiMatteo AM, Reynolds TA. The evolution of dental ceramics. Inside Dentistry. 2013;9:52-62.
2. Simonsen RJ, Calamia JR. Tensile bond strengths of etched porcelain. J Dent Res. 1983;62. Abstract 1099.
3. Calamia JR. Etched porcelain facial veneers: a new treatment modality based on scientific and clinical evidence. N Y J Dent. 1983;53:255-259.
4. Horn HR. A new lamination: porcelain bonded to enamel. N Y State Dent J. 1983;49:401-403.

Dr. Malone graduated with a master’s degree from Louisiana Tech University and received his dental degree from the Louisiana State University (LSU) School of Dentistry. He maintains a full-time dental practice with an emphasis on cosmetic and reconstructive dentistry in Lafayette, La. He received a Fellowship in the AGD in 1988 and is a member of the ADA, American Equilibration Society, the Pierre Fauchard Academy, Catapult Group, and the Pankey Alumni Association. He has been a member of the American Academy of Cosmetic Dentistry (AACD) since 1988 and was accredited in 1992. In 1995, he became a member of the Accreditation Board of Examiners (ABOE) of the AACD and went on to become an Appeals Examiner for the ABOE. After serving 6 years on the board of directors of the AACD, he served as president from 2003 to 2004. He is also on the staff of LSU School of Dentistry as an assistant clinical professor in prosthodontics. He is a published author and speaks internationally on clinical cosmetic dentistry. He can be reached at mike@mikemalonedds.com.

Disclosure: Dr. Malone reports no disclosures.

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