Written by George Priest, DMD Monday, 31 January 2005 19:00
Ceramic veneers have become the foundation of the aesthetically oriented dental practice as a growing number of patients are seeking this popular and effective enhancement. Media exposure, from boutique magazine exposés to television series devoted to facial makeovers, has launched veneers as a routine service that patients demand as icons of beauty, youthfulness, and self-esteem.1,2
Patients and their treating dentists often have differing perceptions of aesthetic reality.3,4 Some patients seek an outcome beyond natural tooth color and contours that challenges traditional tenets of aesthetic dentistry. Aesthetic dentists, like plastic surgeons, must confirm that the patient is a good candidate for treatment with reasonable and realistic expectations. If the dentist believes that he or she cannot meet the patient’s expectations, for whatever reason, it is best not to initiate treatment. It would be disheartening for the dentist to seat the definitive veneers only to have the patient unhappy with the results.
Provisional veneers allow the patient to be involved in assessing acceptable alterations before the definitive veneers are made. They visually convey to the patient and the ceramist what the dentist’s perception of the outcome should be. The dentist also uses provisional veneers as a means of communicating to the patient any anatomical limitations that may compromise the outcome. Understanding patient expectations, even when they change during the course of treatment, is essential to higher patient satisfaction levels.
In a 15-year review of porcelain veneers published in 1999, Garber observed that retention of temporary veneers has proven to be problematic.5 Since that time, provisional veneer materials and fabrication methods have evolved to provide predictable retention and increased aesthetic potential.6-8 Current preparation techniques contribute to stronger and more rigid provisional appliances. Cementing agents provide adequate bonding between tooth structure and temporary resins.
This article includes a technique and materials for fabricating provisional veneers as well as a patient example for using them to assess aesthetic potential prior to fabricating definitive veneers.
DIAGNOSTIC CASTS AND MATRIX PREPARATION
|Figure 1. A 42-year-old female patient with congenitally missing maxillary incisors is unhappy with her smile.||Figure 2. Close examination reveals discolored teeth and canines that were orthodontically positioned in the sites of the missing lateral incisors.||Figure 3. Prior to anesthesia and tooth preparation, a digital image is made with the shade tab in place to assist the ceramist.|
Diagnostic casts are critical for planning the design of ceramic veneers. They are used to evaluate and plan modifications to occlusion, tooth size, proportions, contour, and gingival levels. Guidelines are readily available to help dentists and technicians establish ideal tooth proportions within the limits presented by the patient’s existing dentition.9-11 A waxing performed on these casts allows patients to visualize the anticipated result and involves them in the design (Figures 1 to 3). A polyvinyl siloxane matrix of the waxing is made from FRESH Putty (EXACTA Dental Products, Figures 4 to 8). This matrix will be used to make provisional veneers following tooth preparation and impression procedures.
|Figure 4. A diagnostic waxing establishes normal anterior proportions of the malpositioned anterior teeth.|
|Figure 5. Polyvinyl siloxane FRESH Putty is used to make a matrix of the waxing. Equal proportions of base and catalyst are removed from the containers.|
|Figure 6. The mixture is kneaded until a uniform color is achieved.|
|Figure 7. The putty is molded over the diagnostic waxing and allowed to set for approximately 4 minutes.|
|Figure 8. A detailed putty matrix is ready for making provisional veneers.|
|Figure 9. Thin, braided retraction cord is placed before veneer preparations are refined.|
Successful provisional veneers begin with ideal tooth preparation, which includes rounded line angles, incisal butt joint finish lines, and extension through proximal contact areas.12 This design reduces potential undercuts that would impede removal of the provisional restoration during initial set and produces a stronger mass of resin that is less prone to fracture. Extension through contact areas does not imply overpreparation. Some authors have observed a trend toward aggressive tooth preparation for veneers.13,14 When performed meticulously, preparations remain conservative with little likelihood of dentin exposure. Soft-tissue damage is avoided by packing thin, braided retraction cord (Sil-Trax, Pascal Company) prior to completing the gingival aspect of tooth preparation (Figure 9).
|Figure 10. Putty is mixed and loaded into a stock tray prior to injecting light-bodied material around the preparations.||Figure 11. Accurate veneer marginal detail is evident after removal of the impression.|
For impression-making, a suitable stock tray is selected and adhesive is applied. A polyvinyl siloxane putty material (FRESH Putty) is then mixed and placed into the tray (Figure 10), followed by a layer of light-bodied polyvinyl siloxane impression material (FRESH Impression Material, EXACTA Dental Products). As the dental assistant slowly removes the continuous piece of retraction cord, the dentist meticulously injects the impres-sion material around the preparation margins. The resulting impression should be free of voids and demonstrate crisp detail (Figure 11).
PROVISIONAL VENEER FABRICATION, SEATING, AND EVALUATION
|Figure 12. Bis-acryl resin is injected into the previously made matrix immediately after removing the final impression.|
|Figure 13. After initial setting of the resin, the provisional restorations are removed intact.|
|Figure 14. One minute and 10 seconds after initial mixing, the splinted anterior provisional restorations are ready for finishing.|
|Figure 15. The provisional veneers have been trimmed and polished, and a thin layer of glaze is painted on the surface and cured with a high-intensity light.|
|Figure 16. Provisional veneers allow the dentist, patient, and laboratory technician to assess the anticipated aesthetic outcome.|
Provisional veneer fabrication begins after the impression is made. EXACTA Temp Xtra (EXACTA Dental Products) bis-acryl temporary resin is injected into the putty matrix and timed for insertion immediately following completion of the impression procedure (Figure 12). After a minute and 10 seconds, the matrix and provisional restoration are removed intact (Figure 13). The resultant restoration is a close duplicate of the waxing and demonstrates accurate marginal detail (Figure 14). Voids and deficient margins can be easily corrected using a flowable composite resin such as EXACTA Flow (EXACTA Dental Products). Impregnated rubber Porcelain White Pre-Polishers (Brasseler USA) and 940 Ultra Thin Double-Sided Diamond Disks (Brasseler USA) are excellent tools for trimming and finishing bis-acryl provisional restor-ations. EXACTA Glaze, thinly painted on and light-cured, imparts a natural appearing luster to the finished provisional veneers (Figure 15). They are temporarily luted to place with a small amount of RelyX Unicem (3M ESPE), and excess cement is carefully removed (Figure 16).
The patient is instructed to evaluate the altered smile aesthetics and return to the office for re-examination in approximately one week before suggesting significant modifications. At first, a patient accustomed to his or her original appearance may not view the veneered teeth objectively and may perceive any change as a negative one. As the patient becomes comfortable with the provisional veneers, he or she becomes more objective and usually more accepting of the changes. If necessary, mutually agreed upon modifications are made to the provisional restorations and re-evaluated.
|Figure 17. Conservative veneer preparations with well-defined marginal form allow the ceramist to maximize aesthetic results.|
Laboratory procedures are initiated only after patient approval of the provisional veneers. Shade-matching information, either from visual shade selection or digital shade systems, is only one aspect of laboratory communication. Shade-mapping using fluorescent and opalescent porcelain modifiers helps to create a veneer color customized for the individual patient. Digital images of the unprepared teeth and prepared teeth display the existing color of the enamel and dentin to guide the ceramist to porcelain layering for the selected color and optical properties. Digital images of the provisional veneers may be the most valuable tool for the dentist to convey the patient’s perception of the aesthetic outcome to the dental ceramist. Then, using dies of the optimum preparations from an accurate impression (Figure 17), the ceramist creates the definitive restorations predicated on the patient’s input.
DEFINITIVE VENEER SEATING
|Figure 18. Removal of the provisional veneers reveals tooth-sparing preparations of the central incisors, canines, and first premolars (right lateral view).|
Using a hemostat, the provisional veneers are removed. RelyX Unicem creates predictable re-tention, but the provisional veneers are usually destroyed upon removal. If any cement residue remains, it is removed with a round diamond bur at low speed. Accurate marginal adaptation of the provisional veneers contributes to gingival health (Figure 18). Any bleeding or inflammation will negatively affect the bond between the teeth and veneers. Teeth are cleaned with a nonfluoride prophylaxis paste, and the veneers are tried-in with water. Contact areas are refined, and fit is verified. Most occlusal refinement is completed after cementation.
|Figure 19. Definitive veneers are predicated on the provisional restorations approved by the patient. Seated veneers establish optimal tooth proportions and color while maintaining healthy sulcular tissue.||Figure 20. The definitive veneers contribute to an improved smile.|
The patient closely examines the veneers under different lighting conditions, and after explicit patient approval, the veneers are luted to place. Each veneer is individually cemented and finished before proceeding to the next veneer. The completed restoration is a close approximation of the provisional veneers (Figures 19 and 20). If, however, the patient is not satisfied with the definitive restorations, the dentist should not proceed to permanent cementation. It is better to discuss and resolve the patient’s concerns, many of which can be addressed without remaking the veneers. Once cemented, the dentist’s options for modifications are severely limited.
Provisional veneers, once considered interim restorations only, are now an essential tool for the dentist and patient to communicate their differing perceptions for the aesthetic outcome. They can then be used to convey objectively their collective vision to the laboratory technician. At a time when patients’ aesthetic demands may be beyond the realm of natural beauty, their involvement in the planning stage is critical to ensuring a successful outcome. Materials and techniques are now available that allow practitioners to create interim restorations that are almost as visually pleasing as definitive restorations.
These objective tools will not guard against unreasonable patient expectations, even when the aesthetic dentistry is skillfully executed. However, provisional veneers will help dentists understand patients’ desires and minimize aesthetic surprises. Ultimately, dentists will more predictably deliver ceramic veneers that represent the best of their abilities, and their patients will view the veneers as symbols of their enhanced dental and facial aesthetics.
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Disclosure: Dr. Priest is a consultant and speaker for EXACTA Dental Products. He did not receive financial remuneration for this manuscript.
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