Zenostar Zr From Ivoclar Vivadent
Posted Nov 20, 2013 in Technical
DENTAL TEAM: Janet Jones, CDT, Technical Consultant, Ivoclar Vivadent and Jenny Sy-Munoz, DDS, MSD, University at Buffalo, Buffalo, NY
RESTORATIVE PROBLEM: A 36-year-old patient presented with a request to have teeth #30 and #31 restored as recommended by his general dentist. These molars had existing large pin-retained amalgam buildups that were starting to show signs of occlusal wear.
TREAMENT PLAN: Dr. Sy-Munoz prescribed monolithic crowns made from Zenostar full contour zirconia because of its strong physical properties, pleasing esthetics and optimal biocompatibility.
FABRICATION PROCESS: The teeth were prepared with minimal reductions (0.5mm axially, 1.0 occlusally, 0.5mm chamfer margins with rounded internal line angles), and impressions made. Provisional restorations were fabricated and cemented.
Casts were scanned using the 3Shape D810 scanner and the design was generated and approved. Jones chose the "Medium" shade of Zenostar Zr Translucent zirconia since the patient's shade corresponded to VITA B3. The crowns were milled using the Zenotec mini milling machine.
Gentle grinding was done to retrieve crowns from the zirconia block and remove minor irregularities. The crowns were sintered at 1,450°C and then fitted on the dies. Jones used fine diamond burs to make adjustments and fine-tune the contours, and polished the crowns with Zenostar polishers and diamond polishing paste. It's imperative that zirconia crowns be polished to a high glossy state before glazing and staining procedures to minimize occlusal wear of opposing teeth.
To achieve the desired chroma, Jones used B2-4 Empress Universal stain mixed with some Olive in a three-to-one ratio. She applied the stain to the gingival half, blending into the cusp area, and used shade Incisal 1 with some gray added to lower the value, blending the cusp tips into the gingival half. To add depth of color to the central fossa, she also used the B2-4 and Olive mixture on the occlusal. After firing in a Programat® (Ivoclar Vivadent) furnace, she made a low-value glaze by mixing Empress Universal Glaze paste with a little gray modifier.
The final crowns were cemented using Ivoclar Vivadent's Multilink® Automix adhesive cementation system.
CONTACT: Call Ivoclar Vivadent at 800-533-6825 or visit www.ivoclarvivadent.us.
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