Written by James M. Braun, DDS, MS Wednesday, 30 June 2004 19:00
|Figure 1. Preoperative maxillary labial view.|
|Figure 2. Preoperative maxillary anterior radiographs.|
|Figure 3. Preoperative maxillary lingual view.|
|Figure 4. Easyshade device, tooth No. 6.|
|Figure 5. Try-in of Fiber White post on tooth No. 9.|
|Figure 6. Initial model with every other tooth prepared.|
|Figure 7. Initial guided reduction of tooth No. 6.|
|Figure 8. Margination of tooth No. 6 with chamfer diamond.|
|Figure 9. Placement of cords into sulcus.|
|Figure 10. Injection of light body Affinis.|
|Figure 11. Final master impression of teeth Nos. 6 to 11.|
|Figure 12. Anterior bite registration.|
|Figure 13. Preoperative model and putty stent|
|Figure 14. Injection of Luxatemp into mold.|
|Figure 15. View of provisionals in place.|
|Figure 16. Cerec inLab CAD/CAM machine.|
|Figure 17. Internal view of In-Ceram crown No. 6.|
|Figure 18. In-Ceram crown No. 6 on die.|
|Figure 19. Final view of cemented In-Ceram crowns Nos. 6 to 11.|
In our society there is a great deal of emphasis on appearance and staying healthy. Never before has there been such attention on facial rejuvenation. A centerpiece of this revitalization is the intrigue of smile design. Due to television shows and print media, there is a type of frenzy in the marketplace. We as dental professionals are keenly aware of this major trend and have positioned ourselves accordingly. Along with an understanding of the science and the artistry of this regime, we have an astute sense that this is indeed a team effort. The goal in attempting this recreation is not only an admired look, but also the ability to harmonize with hard and soft tissues.
Unqualified success also depends on the restorative work being able to withstand occlusal function long term. These key factors have all been made obtainable due to the advent of new technology and new dental materials. When considering reconstruction of the maxillary anterior segment involved with the smile, it is beneficial to choose an all-ceramic system. The advantages and appeal of all-ceramic restorations include increased translucency and vitality due to inherent optical qualities. Along with this quality, the design of these restorations can create soft-tissue harmony due to proper emergence profile and very accurate marginal adaptation.
In addition to the increased fracture resistance of these crowns due to strengthened cores, they can be luted with adhesive resin cements to improve their physical properties further. With all-ceramic systems having been in place for quite a number of years, the restorative dentist can forge ahead feeling confident of a predictable and successful outcome.
The focus of this article is to outline the various clinical steps and laboratory procedures involved in the reconfiguration of anterior maxillary teeth that require full coronal restorations with all-ceramic crowns.
A 45-year-old female patient was referred to my office for evaluation of her smile. Her dental history included prior placement of PFM crowns on teeth Nos. 7 through 10 approximately 12 years ago (Figure 1). Upon interview, the patient reported that tooth No. 9, which had endodontics long ago, had fractured off recently at the gingival level due to an accident. Also within the last year, apical root surgery had been performed due to the development of a lesion. An anterior radiograph series depicts the overall condition (Figure 2).
It was confirmed with the endodontist that a lateral root lesion was treated and had a favorable prognosis. There was no residual swelling in the vestibule, and the tooth was asymptomatic to percussion. The patient also mentioned that the existing crown on tooth No. 7 was frequently coming loose. Further analysis of the dentition indicated generally increased attrition along with a very favorable periodontal status (Figure 3). Previously, it had been diagnosed that she suffered from tetracycline staining. Other recent treatment had included several weeks of bleaching (supervised by her general dentist), which had improved the appearance very little. Her chief concern for now was the treatment of the maxillary 6 anterior teeth. She desired a bright and energetic outcome with her new smile. The existing shape and length of her teeth were to be maintained. It was noted, however, that tooth No. 9 would need a gingiplasty to raise the free gingival margin similar to tooth No. 8.
Study models were taken, and a treatment plan was devised. Phase 1 was to undertake placement of ceramic crowns on teeth Nos. 6 through 11 and construction of an occlusal splint. Phase 2, to be completed next year, will entail the placement of porcelain laminate veneers on the mandibular anterior teeth. After analyzing this case, I recommended to the patient that we utilize the In-Ceram all-ceramic system (Vident). In this particular case, an aluminous oxide core would be chosen to be overlaid with a new, low-abrasion porcelain, VM7 (Vident). These copings would be produced by a new lab technology called Cerec inLab (Sirona). This CAD/CAM system is capable of milling restorations, which are extremely strong, well fitting, and very aesthetic. Plus, the core is capable of muting any underlying shades that would detract from the overall color harmony.
To gain a sense of her overall natural tooth shade, tooth No. 6 was evaluated. This was accomplished by the use of the Easyshade spectrophotometer (Vident) (Figure 4). The Vita 3D shade (5M1) was recorded as a reference point for future shade determination.
The initial clinical phase was to inject local anesthesia in the anterior corridor and remove the temporarily cemented crown on tooth No. 9. Due to virtually no residual coronal structure, it was necessary to place a post for buildup of a core foundation for crown retention. The treated canal was large and had been repaired previously. Due to this, plus the fact that we were utilizing an all-ceramic system with translucency, a fiber-reinforced post was selected. Not only was the post white in color, but it would also place less stress on the root complex, due to a modulus of elasticity similar to dentin. The canal was initially prepared by the use of a Gates Glidden drill, followed by the appropriate sized drill for reaming. The parallel-sided Fiber White post (Coltne/Whaledent) size 1.4 mm was tried in the prepared canal (Figure 5). After cleaning the canal thoroughly with a Peeso brush (Premier Dental Products) and flour pumice, it was rinsed, followed by injection of 37% phosphoric acid for 20 seconds, and rinsed again. After this, a self-cured Para Post adhesive (Coltne/Whaledent) was placed with a microbrush internally and dried with a paper point.
At this point, the self-cured Para Post cement was introduced by a Lentula spiral drill, and the post inserted. Immediately after this, a preselected Para core-form was utilized as a carrier for the fiber-reinforced, dual-cured resin core material (Para Core, Coltne/Whaledent). After initial assessment of angulations and position, the core was cured completely by the halogen light unit Optilux 501 (Kerr). Also at this point, crown No. 7 was easily removed, and it was determined that there was insufficient coronal structure remaining for predictable retention of a new crown. Therefore, endodontics was undertaken, and a subsequent post and core were constructed.
With the preparation phase underway, an important aspect of lab communication is to prepare every other tooth and take an initial VPS impression and model. This step will safeguard parameters such as length, width, and midlines of the replacement crowns (Figure 6). Special consideration for tooth No. 9 was to create a ferrule effect on the residual tooth structure during margin placement. This would aid in overall force distribution to the root/post complex.
At this point the soft-tissue correction was made to the labial gingival tissues by use of radiosurgery. Next was the continued task of tooth reduction on the remaining teeth. As with any restorative system, it is critical to utilize guided tissue reduction and magnification. These guidelines are critical for pulpal health and also provide the technician with ample space for the restorative materials. An overall recommendation is to plan on a 1.5-mm labial reduction for a 0.5-mm core (necessary for strength), and 1 mm of overlay porcelain for aesthetic reasons.
Before preparation, an Interguard (Ultradent) was inserted to protect adjacent interproximal areas. To accomplish this preparation, I began on tooth No. 6 with an appropriate diameter No. 801 round diamond (Alpen; Coltne/Whaledent). This is swiped mesial-distal, cervical-incisal to establish a depth cut and incisal reduction (Figure 7). After this portion, the confluence of the depth cuts was achieved by use of a No. 856 coarse diamond. The final axial smoothing and chamfer margin was accomplished with a No. 856 fine diamond. The margin was placed slightly subgingival to hide transition zones. Margin location will allow for proper oral hygiene to take place easily (Figure 8).
Once polymerized intraorally for a few minutes, the entire temporary was removed, trimmed with a carbide bur in the lab, and polished with pumice. The splint was returned, checked for shape, fit, and occlusion, and cemented with a noneugenol cement (Temp Advantage; GC America) (Figure 15). Even though home care is temporarily compromised, the splinting will prevent micro movement of the teeth and will aid in removal. Using the Vita 3D shade guide, the patient selected the 1M1 shade as her desired choice. After the impression was poured, the dies from the model were trimmed under magnification, and the case was mounted to be sent to the laboratory, as the case was to be constructed with inner milled aluminous cores via the Cerec inLab equipment (Figure 16).
At the laboratory, the dies were optically laser scanned to produce the copings. The new VM7 porcelain, which is matched precisely to the 3D shade guide, was overlaid and fired on the core. When returned from the laboratory, the case was inspected for fit, color, and shape. A close-up of the internal surface of crown No. 6 displays sharp details and a homogenous core (Figure 17). The crown on the die reinforces the precision fit attained through this process (Figure 18). All crowns were tried in for fit and occlusion and checked with Accu-film (Parkell). A quick snap alginate impression was taken and poured to provide a 3-D examination of the case.
After patient acceptance, the teeth were cleaned with pumice and a cord placed to prevent fluid contamination. The internal portions of the crowns were treated with silane for 60 seconds and air-dried. It was decided to lute the crowns with dual-cured Rely X Unicem resin cement (3M ESPE). Keeping the teeth moist, the cords were removed and the crowns were placed 2 at a time, right to left, and fit was verified. The Rotamix Machine (3M ESPE) mixes the contents of the cement capsule, and then it is injected into the crowns. After cleanup, the labial and lingual surfaces were light-cured for 20 seconds to improve the polymerization of the self-adhesive cement.
A final view of the completed case displays the vitality and beauty that can be achieved with this type of dentistry (Figure 19). A broad smile on the patient's face reflects the joy in performing this meaningful and rewarding phase of aesthetic restorative dentistry.
The author would like to thank Ky Hale, CDT, of KSH Ceramics, Rancho Cucamongo, Calif, for his fine work in this case. He can be reached at (909) 899-3444.
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