Written by Samuel M. Strong, DDS Wednesday, 30 June 2004 19:00
The use of all-ceramic restorations has received considerable attention by enhancing the aesthetic aspects of dentistry over the past several years. This article presents a case report in which the patient presented with significant restorative and aesthetic needs and requested a segmental approach to treatment. An all-ceramic material was used to restore the anterior maxilla to aesthetics and function.
|Figure 1. Preoperative facial view reveals unaesthetic reverse curve to incisal edges of anterior teeth and recurrent caries from existing, leaking composite restorations.|
The patient presented with a maxillary worn dentition, an unaesthetic reverse curve smile, and recurrent carious lesions adjacent to existing composite and crown restorations (Figure 1). Despite the author's recommendations for full arch rehabilitation, the patient agreed only to restorations on teeth Nos. 5 to 13. In the general dental practice, we often find it necessary to restore in segmental fashion if the patient declines more comprehensive therapy. The patient may realize the rationale for full arch treatment but accept only a segmental approach due to financial reasons or concerns about time, discomfort, occupation interruption, or other factors unknown to the clinician. In these cases, our task is to find mutual agreement about which areas to prioritize while recognizing the need for continued prosthetic treatment in other areas as soon as possible.
|Figure 2. Preoperative diagnostic casts were sent to the dental laboratory.||Figure 3. Diagnostic wax-up from lab represents the idealized changes in length and contour desired in proposed restorations. This will also serve as a template for the provisional restorations.|
|Figure 4. Multiple deteriorating composite restorations, incisal wear, and old crown restorations in preoperative view.||Figure 5. Preoperative retracted right lateral view.|
|Figure 6. Preoperative retracted left lateral view.|
Preoperative diagnostic casts, radiographs, bite registration, and photos were procured (Figure 2). An idealized diagnostic wax-up was produced by the dental laboratory to be used for fabrication of provisional restorations (Figure 3). Additional preoperative views of the case are shown in Figures 4 to 6.
|Figure 7. Rubber dam isolation is used for both the preparation and cementation appointments.||Figure 8. Stump shade tabs adjacent to the tooth preparations illustrate the multiple colorations to be blocked out by the Procera restorations.|
The patient was appointed for removal of caries, buildups of lost tooth structure, and full crown preparations of teeth Nos. 5 to 13. Note that teeth Nos. 10 and 11 required the replacement of existing ceramo-metal crowns. The rubber dam was placed for isolation of the arch using 13A clamps (Hygenic, Coltne Whaledent) positioned on the first molars (Figure 7). Removal of all existing amalgam, composite, and PFM restorations revealed significant caries extending near pulpal chambers in most of the affected teeth. These carious defects were rebuilt using a chlorhexidine scrub (Consepsis, Ultradent), 35% phosphoric acid application (Ultradent) for 10 seconds, followed by copious water lavage, primer, and adhesive applications (Kerr Opti Bond II), flowable composite (Revolution, Ivoclar Vivadent), and hybrid composite (Tetric, Ivoclar Vivadent) (Figure 8).
|Figure 9. The copings for the Procera crowns are made of a densely sintered aluminum oxide material produced via CAD-CAM technology.|
The underlying dentin color was very dark, especially under the old crowns on teeth Nos. 10 and 11. The material selected for full crown restorations on teeth Nos. 5 to 13 was Procera (Nobel Biocare). Procera restorations allow the clinician to combine a highly fracture-resistant coping of densely sintered aluminum oxide with a fired porcelain exterior (AllCeram, Nobel Biocare). The coping is analogous to a metal framework in the traditional porcelain-fused-to-metal restoration and is typically 0.3 to 0.5 mm in thickness1-4 (Figure 9). The Procera format allows the clinician to use either conventional cementation techniques or to bond the restoration using a resin-luting medium. Preparation methods are more similar to conventional PFM techniques, with a heavy chamfer margin design versus a 1-mm shoulder preparation required of various other bonded restorations. Another feature of the Procera technology is its ability to block out dark colors of underlying tooth structure by virtue of the coping while still allowing the technician to achieve an aesthetic result.
Gingival tissue management was accomplished with a retraction cord and hemostatic agent (Gingicord, Astringident; Ultradent). A final impression of the prepared abutments was made with an Impregum (3M ESPE) tray and light viscosity material. A silicone index (Sil-tec, Ivoclar Vivadent) was fabricated over the laboratory-produced diagnostic wax-up. Integrity temporary restorative material (DENTSPLY Caulk) was then placed in the silicone shim and seated over the prepared teeth. Upon reaching an initial set at about 2 minutes, the provisional material was removed from the mouth, trimmed with scissors, and allowed to complete curing to a final set. The splinted provisionals were then contoured and polished with carbides (Brasseler) and discs (Flexi-discs, Cosmedent).
|Figure 10. Provisionals replicate the diagnostic wax-up and serve as reference for the definitive restorations.|
The provisionals were spot bonded by etching a small area on the facial surface of each prepared tooth, placing the provisionals on the teeth with a small amount of flowable composite (Revolution, Ivoclar Vivadent), and curing them with an argon laser. Final finishing was performed with a 30-fluted carbide bur, fine diamond interproximal bur, and an incisal edge contouring disc (Brasseler). An alginate impression was made of the completed provisionals to aid the laboratory ceramist in determining length and final contours of the definitive restorations. A coat of light-cured, unfilled resin (Kerr) was then applied to the provisionals following etching with 35% phosphoric acid (Ultradent), which supplies an enamel-like sheen to enhance their aesthetic appearance during the interim period. Photos of the provisionals with a selected shade tab were sent to the laboratory ceramist for reference in shade determination (Figure 10). The patient was instructed to use a chlorine dioxide toothpaste and mouthrinse during the provisional period in order to maintain gingival health (CLOSYS II, Rowpar Pharmaceuticals).
The case was packed for shipment to the laboratory with detailed instructions for color mapping, gingivo-incisal length, and golden proportion dimensions (SMILES form, The Ultimate Practice). The patient was reached by phone on the evening of the preparation appointment, and she reported minimal postoperative tenderness or sensitivity. She had been given over-the-counter ibuprofen during and after the procedure. Five days later, she was contacted again to receive her input regarding the general contours, lengths, and shade of the provisionals in order to use them as a reference for any changes she might desire in the final restorations. The patient noted a high degree of satisfaction with the size and contours of the provisionals, but noted a desire for a whiter, brighter shade. This information was then communicated to the laboratory ceramist, who had a model of the provisionals as well as photos of the preoperative condition, preparations, stump shades, and completed provisionals with shade tabs.
|Figure 11. Completed crowns are examined on the master cast.|
Following evaluation on the master cast, the patient was seen 3 weeks after the preparation appointment for try-in and delivery of the final restorations (Figure 11). After anesthetic application, all provisionals were removed along with careful inspection and removal of residual flowable composite material used as a luting agent. The completed Procera crowns were seated individually and inspected for fit and general aesthetic appearance. The patient was allowed to view the Procera restorations seated on the teeth and express her approval prior to cementation. Following approval by the patient and the author, the rubber dam was applied and the crowns were cleaned and sandblasted interiorly (50m aluminum oxide, Danville Engineering). The crowns were cemented in a conventional manner with RelyX cement (3M ESPE). Cementation in this fashion simplifies delivery of the definitive restorations and significantly reduces the time required for this procedure versus bonding the crowns with a resin luting cement. The rubber dam was removed and the occlusion was adjusted using fine and superfine diamond burs (ET diamond finishing kit, Dialite polishing kit, Brasseler).
|Figure 12. Thermoplastic maxillary occlusal splint with hard acrylic exterior, soft interior for post-restorative wear during sleeping periods.|
The patient returned 2 weeks later for a postoperative check. Occlusion and marginal areas were evaluated and adjusted as needed. There were no problems with phonetics with the new restorations. The patient expressed complete satisfaction with the final restorations, noting in particular the marked improvement over her previous reverse curve appearance due to years of incisal edge wear. New alginate impressions were made for construction of a protective occlusal splint. The author routinely fabricates a bilaminar or thermoplastic appliance with a soft interior, hard acrylic exterior material. The patient is instructed to use the appliance, as with any bruxism splint, during sleeping periods. The postoperative models are mounted from a facebow transfer and centric occlusal bite registration, and the splint is fabricated for bilateral and anterior-posterior occlusal contacts on a flat exterior surface when the patient closes into contact (Figure 12).
Two years after completion of the anterior crowns, replacement of the existing porcelain-fused-to-metal fixed partial denture on the maxillary posterior right side (teeth Nos. 2 to 4) was begun, due to recurrent caries extending apical to the margins of the bridge. The bridge was removed under local anesthesia, caries removed, the abutments rebuilt and prepped, and impressions made for a new fixed partial denture. Integrity material (DENTSPLY Caulk) was again used for the provisional fixed partial denture. The new prosthesis was fabricated with a resin material (belleGlass HP, Kerr Labs) reinforced with Vectris (Ivoclar Vivadent). The bridge was tried in 3 weeks after the preparation appointment, approved by the patient and clinician, and bonded with a resin luting cement.
The fixed bridge preparations were bathed with chlorhexidine, rinsed thoroughly, gently dried with an air dryer (A-dec), and etched for 10 seconds with 35% phosphoric acid. Care was taken not to overly dry the etched preparations, consistent with the moist-etch technique employed by many clinicians today. Multiple coats of a primer and bonding agent (Prime and Bond NT, DENTSPLY Caulk) were applied, dried with brushes, and gently air-dried. The bridge was etched internally with 35% phosphoric acid, thoroughly washed and dried, and silanated (Silane, DENTSPLY Caulk). The catalyst and base of a dual-cure resin luting cement (Calibra, DENTSPLY Caulk) were mixed and applied to the interior of the bridge. Meticulous removal of excess resin cement was accomplished using microbrushes (Microbrush Products), a rubber point (Butler), and floss (Glide, W.L.Gore). Further cleaning of excess cement was done with a No. 15 blade scalpel, scaler, and floss. Each facial, lingual, and incisal surface was then cured for at least 2 minutes following initial with the curing light.
|Figure 13. Completed case with Procera crowns on teeth Nos. 5 to 12 and resin-reinforced bridge at Nos. 2 to 4 at 4-year recall.|
|Figure 14. Procera crowns on teeth Nos. 5 to 13, right lateral view at a 4-year follow-up.|
|Figure 15. Procera crowns on teeth Nos. 5 to 13, left lateral view.|
|Figure 16. Retracted view of completed anterior crowns.|
|Figure 17. Preoperative smile view with unaesthetic restorations and reverse incisal curve.|
|Figure 18. Smile view of completed crowns exhibits highly aesthetic appearance.|
|Figure 19. Preoperative facial appearance.|
|Figure 20. Postoperative photo reveals dramatic improvement in entire facial appearance.|
The scope of the final maxillary rehabilitation compared with preoperative views is seen in Figures 13 to 20. The case has now been followed for more than 4 years with no decline in aesthetics or function. These figures show significant improvement in aesthetics and function for the patient when compared to her pre-existing condition. In retrospect, the author notes that gingival recontouring of the area of teeth Nos. 9 to 12 would have produced a better architecture when the case is seen in a retracted view. However, from a practical standpoint, the patient's smile line does not reveal this gingival discrepancy and is of no concern to her. Sounding the bone in this area revealed that osseous and soft-tissue removal would be required in order to create symmetry, a procedure declined by the patient.
This case demonstrates the use of materials that can provide a high level of aesthetic improvement, especially with anterior teeth that exhibit dark, stained dentinal colorations, or in cases with wide variations in the color of the prepared teeth. Furthermore, when using Procera the clinician enjoys a choice of seating the restorations either with a conventional cementation technique or bonding with a resin luting procedure. The marginal fit of the Procera technology allows a precise adaptation of the crown margins while retaining a high level of fracture resistance.
1. Andersson M, Razzoog ME, Oden A, et al. Procera: a new way to achieve an all-ceramic crown. Quintessence Int. 1998;29:285-296.
2. Russell MM, Andersson M, Dahlmo K, et al. A new computer-assisted method for fabrication of crowns and fixed partial dentures. Quintessence Int. 1995;26:757-763.
3. Odman P, Andersson B. Procera AllCeram crowns followed for 5 to 10.5 years: a prospective clinical study. Int J Prosthodont. 2001;14:504-509.
4. May KB, Razzoog ME, Lang BR, et al. Marginal fit: The Procera AllCeram Crown [abstract]. J Dent Res. 1997;76:311. Abstract 2379.
The author would like to thank the artistry and commitment to excellence by the technicians at Micro Dental Laboratory, Danville, Calif, who fabricated all of the restorations and diagnostic wax-ups seen in this article.
Dr. Strong maintains a general practice in Little Rock, Ark, focusing on restorative aesthetic and implant dentistry. He conducts lectures and workshops within the United States and internationally. Dr. Strong is a diplomate of the International Congress of Oral Implantologists and a credentialed member of the Academy of Dental Sleep Medicine. He can be reached at (501) 224-2333, or visit strongdds.com.
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