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DENTAL TEAM: Manfred Pörnbacher and Clemens Schwerin, Dentallabor Steger, Brunico, Italy and Dr. Lyndon Cooper, Professor and Chair at the University of North Carolina, School of Dentistry, Department of Prosthodontics
RESTORATIVE PROBLEM: A young female patient lost teeth #7 through #14 in a car accident and was already wearing a provisional restoration that had resulted in pronounced jawbone atrophy.
TREATMENT PLAN: The team opted for a fixed superstructure supported by six implants at sites #7 and #8 and #11 through #14. Due to inadequate bone structure, the restoration would be an occlusally screw-retained, full contour Prettau® Bridge with a gingival flange. Prettau Zirconia was chosen because it resists chipping and is ideally suited for implant-supported restorations, situations with limited space and restorations with a gingival flange.
FABRICATION PROCESS: The casts, waxup and articulated study casts were scanned using the S600 ARTI scanner. The articulator scan is used to check jaw relations so virtual casts can later be correctly occluded in the software; this allows static premature contacts to be identified with the matching virtual articulator in the software.
The bridge was designed using Zirkonzahn.Modellier software; the positions of the screw access canals, values for the cementation gap and marginal region parameters were defined. The customized titanium bases were virtually modified to optimize the alignment of the screw-access canals, and the software automatically adapted the virtual waxup to the gingiva and implants. A resin provisional was milled.
After several weeks, the necessary adjustments were made and the final bridge was milled using Zirkonzahn's M1 milling unit. The surface of the anterior teeth--#7 through #12--were manually cut back and customized. The incisal edges were left fully contoured to obtain edge protection and eliminate chipping. Acid-free Colour Liquids Prettau Aquarell were used for shading. The framework was placed under a drying lamp for about 40 minutes and sintered in the Zirkonofen 700 at 1,600°C.
Gingiva-Composite was used in the gingival area. The technician applied Stain Colour Glaze Plus and, after the stain and glaze firing cycles, the customized titanium bases were cemented with dual-curing cement. For esthetic reasons, unit #7 simply rests on the implant and is not occlusally screw-retained because the screw access channel would have been visible on the labial surface.
CONTACT: Call Zirkonzahn at 800-989-8931 or visit www.zirkonzahn.com.
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