Ceramco® Press Porcelain Pressed-to-Metal
Posted Apr 28, 2011 in Technical
RESTORATIVE CHALLENGE: A healthy, middle-aged business woman presented for evaluation of a bridge, teeth #8-10, with a fractured distal incisal angle and metal margins (see Figure 1). Though generally satisfied with the 20-year-old restoration, she wanted to replace it with a more esthetic restoration.
Clinical and radiographic findings fell within normal limits. An esthetic assessment by Dr. Ewoldsen revealed nothing unusual beyond a high smile line, which was acceptable to the patient provided metal display at the margin could be eliminated. The esthetic liabilities of an existing mandibular anterior bridge were not expected to compromise the occlusion, esthetics or function of the new maxillary bridge.
Restorative team: Robert Michael, CDT, manager of technical resources, Dentsply Prosthetics, Burlington, New Jersey, and Nels Ewoldsen, DDS, clinical director, Dentsply Prosthetics, York, Pennsylvania
Treatment plan: Photos comparing existing tooth form with the provisional were taken and e-mailed to the patient. The patient emphasized her desire for a conservative approach and requested a PFM bridge that was both practical and esthetic.
Dr. Ewoldsen prescribed a PFM design as the most straightforward case treatment. Predictable color could be created using a high-noble, yellow gold framework and ceramic butt-joint margins, eliminating discoloration at the facial margins. Because his preference is to review all bridges after a full-contour waxup, Ewoldsen prescribed pressed porcelain to ensure that the approved waxup would capture the contours of the final restoration. In addition, pressing also ensures an accurate fit at the ceramic margins. The dental team chose the Ceramco Press System because of its consistent, esthetic and high-quality results.
Case study: Dr. Ewoldsen made a custom incisal guide table using TRIAD® VLC; a pre-op model to preserve the form, size and arrangement; and two solid die models to preserve the spatial relationship of the abutments (see Figure 2).
At the laboratory, Robert Michael indexed the facial surfaces of the provisional restorations for the full waxup. The abutments allowed for a maximum thickness of pressed porcelain which can enhance translucency but minimize the porcelain support. Since the case was fabricated at the manufacturer's lab, Michael conducted an experiment: he designed two metal frameworks to compare how the color of the final restoration would be affected by different techniques.
Framework #1, a conventional framework, was a "full press" for the enamel cut-back or full-contour stain technique (see Figure 3, top row). The bridge was waxed as usual by creating only full coverage copings as abutments plus the pontic, then cast and finished. Both abutments had 360o pressed porcelain margins.
Framework #2 was a modified framework designed for porcelain support and an esthetic internal background (see Figure 3, bottom row). Michael created a full crown waxup, then removed the facial veneer. The linguals remained intact and mammelon-shaped lobes were left in the incisal areas. The bridge was then cast and finished. Both abutments had 180o pressed porcelain margins. The linguals remained in metal to minimize the lingual thickness.
Both frameworks were spray opaqued with an airbrush and fired twice. The full waxup was completed using the putty matrix of the original facial surfaces. The restorations were sprued, invested, burned-out and pressed using the Dentsply/Multi-Mat Touch and Press. The bridges were re-finished to enhance the details, stained and glazed. Modifications to the color were created with surface stains; no enamel porcelains were applied.
As the result of the lack of influence from the framework, opaque and translucency, Framework #1 produced a "cooler," lower chroma, more translucent shade (see Figure 4). Framework #2 exhibited a slightly "warmer" shade, influenced by the background and mild characterizations (see Figure 5). When presented with both finished bridges, the patient opted for design #2 as she preferred the warm shade and it reflected her desire to keep the lateral abutment normal size.
The bridge was sent to the dental office and cemented into place (see Figure 6). The patient was as pleased with the results as the dental team.
Contact Information: Dentsply Ceramco, Technical Education Department; 800-487-0100, ext. 1030; click here to visit the website
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