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RESTORATIVE CHALLENGE: A female patient in her early twenties presented with severely calcified anterior teeth (see Figure 1) that she wanted to replace with esthetic restorations.
Restorative team: Flemming Behrend, MDT, CDT, flemmingsdental, and Augustin Vega, DDS, both of Olympia, Washington
Treatment plan: The team decided to fabricate four anterior crowns using Elephant's Carrara Press System, which consists of a pressable core material and the low-fusing Carrara Interaction porcelain. The system was chosen because the core material has a high transverse bending strength (134 MPa), a high compressive strength (Fm=2,450 N), and is available in six shades coordinated with the Vita® shade system, and includes bleach shades. Elephant Carrara Interaction porcelain is designed to emulate the functionally layered structure of natural teeth, with color and fluorescence closest to the core, covered by translucent and opalescent layers. The characteristics of Interaction porcelains are coordinated so the interplay of materials and colors exhibit a natural appearance under all lighting conditions.
Case study: Pre-operative impressions were taken. Dr. Vega prepared the teeth with a conservative full crown preparation and took full arch impressions.
At the lab, Flemming Behrend poured the pre- and post- impressions and mounted them on a Hanau articulator. He created a full anatomical waxup on a master model to use later during porcelain buildup.
Another set of dies was cast for use as a working model for preparing the copings. The copings were waxed, sprued and attached to the press former (see Figure 2). The wax models were invested in the Carrara Press muffle using Carrara DL Universal investment. The wax was burnt out in a standard burnout furnace and immediately Behrend placed the core material pellets in the space created in the investment by the former, and then placed a plunger on top of the pellets.
Behrend then placed the hot muffle in his regular porcelain furnace and baked according to the Carrara Press furnace program (see Figure 3). At the end of the firing program, he removed the muffle from the furnace and immediately placed it in the CP 200 Press (see Figure 4). The press was activated using compressed air to force the molten core material into the model. After cooling, the copings were devested and the sprues were removed using a diamond wheel (see Figure 5).
Behrend fit the copings to the working model and checked them against the master model; little adjustment was necessary. He applied conditioner to the copings, built up the Carrara Interaction porcelain and then fired, using standard porcelain buildup and finishing procedures. Behrend used the anatomical waxup to ensure that he matched the detail of each crown during buildup. To characterize the crowns during buildup, he used Carrara Action-I Dentins.
Dr. Vega tried in the crowns, determined that no adjustments were necessary, and cemented the completed crowns in place. He was pleased with the color and marginal fit and the patient was very satisfied with the esthetic result (see Figure 6).
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