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Case Study
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Provisionalization Using Bis-Acrylate and Polyvinylsiloxane Matrix

Learning Objectives:

As a result of reviewing this case study, the reader should:

  • Gain an understanding of a reliable provisionalization technique that maintains intraoral structures while facilitating the adaptation of the provisional restorations
  • Visualize the process of using bis-acrylic resin to fabricate restorations to achieve maximum aesthetic quality

Provisionalization is a necessary stage in the prosthetic restoration of the majority of patients that require tooth reduction during aesthetic enhancement. Through this process, the members of the treatment team are able to evaluate and perform aesthetic, phonetic, and functional adjustments to the provisional restoration while simultaneously preserving or enhancing the state of the dental and gingival tissues during the fabrication of the definitive prosthesis.1,2 Although provisionalization can be performed in numerous manners that include acrylic resin,3 the "sandwich technique,"1 direct composite bonding,2,4 and laboratory-fabricated provisional veneers,4 these techniques are often inefficient based upon the handling properties of the provisional material, the durability of the provisional restoration, or the expenses involved. These procedures may be complicated by the duration or difficulty of the chairside fabrication process as well. Provisional materials also exhibit a tendency to lose their color stability when placed intraorally for extended periods.

Consequently, it is essential that clinicians have a fundamental understanding of a provisionalization technique that maintains the intraoral structures while facilitating the adaptation of the provisional restorations to achieve the objectives of the treatment. In order to become a standard addition to the existing restorative armamentarium, this procedure must satisfy patient aesthetic concerns as well as be cost effective and easy to perform chairside.

 

Patient Presentation and Evaluation

A 20-year-old female patient presented with unaesthetic white spots on the maxillary anterior teeth that were caused by enamel mottling (Figures 1 and 2). The shade of the tooth structure that surrounded this mottling was unacceptable to the patient - even following tooth whitening. Once the patient's history had been documented, comprehensive clinical and radiographic examinations were performed. In addition, an occlusal analysis was completed to determine if the patient had any contributing temporomandibular joint pathology or occlusal discrepancies. Based on these findings, the patient's aesthetic expectations, and the objectives of the restorative team, porcelain veneers were selected to restore the natural aesthetics and function to the patient. Nevertheless, it was necessary to determine an optimal means of provisionalization that would permit the chairside fabrication and adjustment of the prosthesis while providing an efficient interim solution with a reduced associated expense.

 

Formulation of the Treatment Plan

While the definitive porcelain veneer restorations were fabricated in the laboratory, a single-unit provisional restoration would be created with acrylic resin and placed for a period of 3 weeks. The following preoperative measures were performed for the fabrication of the provisional restoration:

* The maxillary anterior teeth of the preoperative study model were waxed up to the ideal arch alignment and incisal plane position (Figure 3).

* An additional 0.5 mm of wax was added to the facial surface of the waxed-up model (Figure 4).

* A polyvinylsiloxane matrix was created from the waxed-up model. The additional layer (0.5 mm) of wax facially would allow the provisional veneers to be thicker buccolingually for increased strength and durability.

The six maxillary anterior teeth and the maxillary first premolars were conventionally prepared for veneer restorations (Figure 5). The premolar teeth were included in the treatment plan since the patient requested significant modification of tooth hue and chroma as well. Under water irrigation, the facial surfaces of the teeth were reduced 0.5 mm and the incisal edges of teeth #6 through #11 were reduced approximately 1.5 mm. Although the preparations extended halfway through the interproximal contacts, they did not in this instance completely break the contacts. All line angles were rounded with fine diamond burs. While the margins were extended less than 0.5 mm subgingivally with a fine chamfer bur, retraction cord was not utilized during this process.

 

Provisionalization

A bis-acrylate composite material was flowed through a syringe gun into the polyvinylsiloxane matrix that had been fabricated on the model. The tip of the syringe remained buried in the provisional bis-acrylate material as it was dispensed in the matrix so that air bubbles were not incorporated into the mixture. From the maxillary left first premolar to the right first premolar, the polyvinylsiloxane matrix was filled from the incisal to the gingival aspect of each tooth form (Figure 6). The preparations were thoroughly rinsed with water and left slightly moist. The loaded matrix was placed directly onto the maxillary arch until complete seating was accomplished. Excess provisional material was separated from the polyvinylsiloxane matrix with a periodontal probe and a round-end explorer to prevent iatrogenic damage to the gingival tissue.

The matrix remained in place for approximately 1 minute to allow the bis-acrylate to initially harden. While the material was stable at this phase, it did maintain a degree of flexibility. The matrix was removed from the preparations with a facial to lingual rocking motion. Flashing was trimmed from the restoration with thin surgical scissors and then with a fine sandpaper disk and a thin, fine diamond bur (Figure 7). Polishing was subsequently performed with wet pumice on a bristle brush. The eight provisional veneers remained connected. The embrasures were trimmed gingivally to the interproximal contact so that the embrasure areas could be rinsed thoroughly each day with a 12% chlorhexidine rinse. Once the accuracy of seating and marginal adaptation were confirmed, a sealing agent was applied to the facial surface of the restoration and light cured for 60 seconds to achieve a glassy sheen.

The preparations were cleaned with wet pumice in a prophy cup, rinsed with water, and wiped with a cotton ball soaked in a disinfectant. The teeth were dried and then isolated with cotton rolls. An adhesive agent was subsequently placed on the facial aspects of the preparations and the contact surfaces of the provisional veneers. Acid etching was not performed at this stage, and no dentin primer was applied to the preparations or the veneers. The provisional veneers were then placed intraorally on the preparations with finger pressure, which was followed by two cotton-tipped applicators. Firm seating pressure displaced excess adhesive from the gingival, lingual, and interproximal margins. As the provisional restorations were compressed against the teeth with the applicators, an air syringe was used to gently blow away the excess adhesive (particularly from the interproximal regions) onto cotton squares that were placed adjacent to the prepared teeth on the facial and lingual aspects. The margins of the provisional restorations were then wiped with a cotton ball, and the restoration was simultaneously polymerized from the facial and lingual aspects with two curing lights for 60 seconds.

Once the provisional restoration had been light cured into place, the incisal plane, centric occlusion, eccentric occlusal movements, and envelope of function were examined and adjusted as necessary. The incisal plane was parallel with the mandibular lip line, and the central incisors were dominant to the adjacent teeth (Figure 8). The patient received instruction on the maintenance of the provisional restoration. A postoperative regimen that consisted of daily hydrogen peroxide (3%) rinses and gentle brushing with a mechanical toothbrush was also prescribed. A 30-second chlorhexidine rinse (twice daily) was similarly recommended, and the patient was recalled after 2 weeks to permit evaluation of the adjacent gingival tissues. The tissue appeared healthy, and no inflammation or bleeding was apparent upon periodontal probing.

 

Seating and Cementation of the Porcelain Laminate Veneers

The definitive porcelain veneers were seated 4 weeks following tooth preparation. Prior to their final seating and cementation, the provisional restoration was removed using a round-end coarse diamond bur in a high-speed handpiece, which was used to place vertical depth cuts into the length of each provisional veneer. A plastic instrument was then placed progressively in each depth cut and turned (Figure 9), which created a torquing force on the provisional restoration. This force separated sections of the provisional veneer from the underlying tooth structure. Since the teeth had not been etched prior to the placement of the provisional restorations, the majority of the adhesive remained on the veneers. Any adhesive that remained on the preparations was removed with a pumice slurry applied with a prophy cup in a slow-speed handpiece. The placement of the definitive porcelain veneers - which is beyond the scope of this article - was then completed, and the final aesthetics satisfied the objectives of the patient as well as the restorative team (Figures 10 and 11).

 

Conclusion

When porcelain veneers are to be utilized in restorative treatment, the provisionalization phase should be time-efficient, aesthetic, functional, and cost effective. This presentation demonstrates a predictable means of achieving these objectives. In the use of this technique, however, it is important to 1) provide an additional 0.5 mm of thickness in the ideal preoperative waxup, 2) fabricate the polyvinylsiloxane matrix of the waxed model, and 3) fill the matrix with the bis-acrylate resin, and place it directly on the preparations. When each of these criteria is addressed in the clinical phase, the success of the final result is ensured.

 

* Private practice, Waco, Texas.

 

Related Reading:

 

  1. Magne P, Magne M, Belser U. The diagnostic template: A key element to the comprehensive esthetic treatment option. Int J Periodont Rest Dent 1996:16(6):561-569.
  2. Raigrodski AJ, Sadan A, Mendez AJ. Use of a customized rigid clear matrix for fabricating provisional veneers. J Esthet Dent 1999;11(1):16-22.
  3. Rada RE, Jankowski BJ. Porcelain laminate veneer provisionalization using visible light-curing acrylic resin. Quint Int 1991;22:291-293.
  4. Nixon RL. Provisionalization for ceramic laminate veneer restorations: A clinical update. Pract Periodont Aesthet Dent 1997;9(1):17-27.

 

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