Porcelain veneers are a very conservative approach to changing the shape, shade, and contour of teeth without resorting to a full coverage restoration.1 For the most part, these restorations rely upon the bond between enamel and the porcelain veneer. One needs an intimate relationship between the tooth surface and veneer, one not marred by temporary cements or their residue, in order to achieve a strong, durable bond.
There are a number of techniques for veneer temporization. Some clinicians advocate leaving the prepared tooth surface uncovered until placement of the final restoration, as there is a chance that the temporary material and/or temporary cement may contaminate the tooth surface and reduce the bond strength of the cement.2,3 Some clinicians have suggested that provisional veneers fabricated from composite resins be temporarily cemented with polycarboxylate or eugenol-free temporary cements.4-6 I feel that these surfaces should be covered with a temporary restoration that is aesthetic and easy to place and remove. The technique presented in this article addresses these issues.
This technique is a variation of a technique described by a number of authors.7,8 It involves the fabrication of a provisional veneer with a temporary resin or an intermediate, single-component resin material, which is spot-bonded to the prepared tooth surface. Intermediate, single-component resin materials have one common property in that they remain relatively soft after polymerization. This allows us to place and then easily remove the temporary restoration. Although they are soft, they do create a good marginal seal and resist moderate occlusal loading.
In the case presented, we used Interval LC from Temrex Corporation for temporization. The key features are its low solubility in oral fluids, which ensures a good marginal seal, and marginal compressive and tensile strength so that it can withstand moderate occlusal loading and yet be flexible enough to be removed from the tooth surface.
As with any temporary restoration, one needs to be concerned about occlusion and marginal adaptation. Proper gingival margin placement is important with any provisional restoration, but with veneers this has additional significance. Care has to be taken to ensure that there is no gingival excess that could cause tissue irritation leading to either gingival recession or bleeding at the cementation appointment. Occlusal loading can easily dislodge temporary veneers, and with time, dislodge or crack the permanent restoration. A detailed occlusal exam is necessary before placing the restorations. The most predictable occlusal scheme is canine guidance with no interference in lateral or protrusive excursions.9,10 Abnormal wear patterns on the opposing dentition may be a warning sign of occlusal problems.11
|Figure 1. Preoperative view.|
In this clinical situation, we were restoring the maxillary 6 anterior teeth (Figure 1). The bridge spanning from the maxillary left cuspid to the maxillary right central incisor was prepared first. We initially prepared these teeth and fabricated the bridge framework. This allowed us to do a frame try-in of the bridge so that we could easily examine all of the bridge margins. We could also then obtain an accurate model of the bridge framework and soft tissue for accurate porcelain placement.
|Figure 2. Veneer preparations completed and bridge framework in place.|
The maxillary right lateral incisor and cuspid were prepared using standard techniques.12 Care was taken in preparing along the gingival margins so as not to traumatize the tissues. Since the adjacent teeth had been prepared as abutments for a fixed bridge, we used the bridge frame and temporary bridge to provide us with some guidance for the tooth reduction for the veneers (Figure 2). Depth grooves were first placed on the buccal surfaces of the teeth, and then the veneer preparation was completed using diamond burs. Once the impression was completed, we began work on the temporary veneers.
|Figure 3. Spot-etching a small portion of the enamel surface before bonding the temporary material in place.|
In this technique, we only bond to a small portion of enamel in the middle of the facial surface. This area is approximately 3 mm in diameter and is located on sound enamel (Figure 3). It should not be located near any margin or interproximal area. The bonded area along with the intimate adaptation of the material to the facial surface will help to retain the temporary veneers. After etching, the area was treated with a conventional bonding agent, in this situation, Bond 1 from Pentron.
The temporary resin material, Interval LC, was applied to the facial surface and adapted to the etched area. This would act as a base, allowing us then to apply conventional composite resins on top to provide correct contour and color. The Interval LC was smoothed with a flat instrument that was coated with a bonding agent. We then cured the material for 40 seconds. Care was taken to ensure that there was no bulk along the margins and the facial surface was not over-contoured.
|Figure 4. Contouring the temporary veneer with SafeEnd Finishing Burs.|
We then applied a layer of conventional composite resin to the surface to provide additional color and contour. In this situation, we applied Epic A1 (Parkell) to the surface of the Interval LC. The temporary veneers were then contoured with SS White SafeEnd Finishing Burs and polished with Temrex Composite Polishing Pastes (Figure 4). The occlusion was checked to ensure there were no occlusal interferences that could dislodge the temporary veneers.
|Figure 5. Temporary veneers 3 weeks later. Note the stable color of the temporary veneers and the health of the gingival tissue.|
The final result was a temporary veneer that was well adapted to the margins and provided an aesthetic restoration for 3 weeks while the veneers and bridge were being fabricated. Figure 5 shows the veneers and temporary bridge in place after 3 weeks. Note the health of the gingiva and also that the temporary veneers have retained their color and shape.
|Figure 6. Removing the temporary veneer with a sharp instrument on the incisal edge.||Figure 7. View of the bridge and veneer preparations before cementation.|
The temporary veneers were easily removed 3 weeks later. A sharp interproximal carver was placed on the incisal edge and pushed under the veneer (Figure 6). With gentle pressure facially, the veneers came away from the tooth surface, leaving only a small amount of material on the bonded area of the enamel surface (Figure 7). Upon removal, we found that the gingival tissue was healthy and ready for cementation.
|Figure 8. Final view of the bridge and veneers.|
Before cementation, the tooth surface was polished with pumice and water. The area used in bonding the temporary veneers was smoothed with a green stone to ensure that no material residue remained on the surface. The veneers were then cemented with V-Bond (Temrex Corporation) (Figure 8).
Interval LC is compatible with all resin-based veneer cements, including V-Bond. The tooth surface only required etching in a small area to help retain the temporary veneers. The material did not contaminate the surface and allowed for easy removal and bonding of the porcelain veneers to the tooth.
Direct fabrication of temporary veneers appears to be a time-consuming step. I have found that the time involved in this technique is equivalent to some of the others cited in the article. This technique allows the clinician to fabricate temporary veneers easily without the use of any laboratory services. It creates an aesthetic restoration that can stay in place until final cementation without irritating the gingival tissues. These intermediate temporary resin materials, such as Interval LC, have a wide range of applications and are robust enough to act as temporary resins.
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The author would like to acknowledge the help and advice of Ron Klausz of Klausz Dental Laboratories in Toronto, Ontario. My partner, Dr. Warren Hellen, has always provided a willing ear in treatment planning and case management.
Disclosure: Dr. Abrams is a consultant for Temrex Corporation and has done some work with SS White Burs.