How to Create Vitality in Zirconia Restorations

Lewis Sharp, CDT · Technical · Nov 2011

  • A 47-year-old male presented with an existing flipper replacing #4, #5 and #7. He hoped to get a more natural-looking, fixed prosthesis. In addition, he was unhappy with the esthetics of his crown on #6 as well as the deep overbite and rounded appearance of his front teeth. He opted for a bridge from #3 to #8 and a crown on #9 to correct these issues.

  • Step 1 Pre-op photos were taken and a diagnostic waxup was fabricated and approved by the patient.

  • Step 2,3,4 Dr. Heather Crouch, DDS, from Elko, NV, prepped the patient’s teeth and sent the impressions, bites and prescription to Sharp Dental Laboratory, also in Elko, NV. Step 3 The laboratory completed the pre-operative and working models and sent them with the instructions for a zirconia framework—with full contour zirconia linguals and occlusals from #3 to #9—to the milling center at B&D Dental, which specializes in CAD/CAM technology (Origin® CAD/CAM) and materials research and development. B&D Dental scanned and designed the case using the Origin Intelligence Dental System and milled it with the Origin milling system. Step 4 On a case of this size and complexity, it was important to scan in as much information as possible to ensure proper and accurate design. B&D Dental scanned in the preparation arch; opposing arch; pre-operative model; and each die with #4, #5 and #7 as pontics. The scanning process for the four dies and three full-arch models, plus an articulated scan to determine bite position, took about 15 minutes. Once in the design phase, the Origin software detects the margin line and gives you the ability to make minor adjustments to the margin line from point to point, a helpful tool with cases needing minor margin adjustments. Before the design process, it had been determined that all the copings would be designed as anatomical copings; this gave B&D Dental the ability to build the full crown first before specifying a cutback designed for porcelain support. The cutback line was simply drawn to exclude the portions that needed to remain full contour while cutting back everything else for porcelain layering.

  • Step 5 The diagnostic waxup was the primary source for the placement and position of each unit. The screen shot above shows the full contour design of the desired restoration.

  • Step 6 This screen shot shows the design of the facial cutback with the diagnostic waxup scan faded in. For optimum esthetics and strength, the interior proximal contacts of the bridge portion (#3-8) were left full contour while the exterior proximal contacts (distal of #3 and #9) were cut back for porcelain contacts.

  • Step 7 The final design is ready for the ORIGIN milling system.

  • Step 8a. The framework was milled out of the Origin LiveTM High Translucency full contour zirconia. It has a natural-looking, ivory translucency and a strength of 1360Mpa, strong enough for all substructure applications. The unique manufacturing process creates a consistently uniform density in the zirconia, providing distortion-free sintering that is particularly important on large cases. The framework was colored, sintered and returned to Sharp Dental Lab.

  • Step 8b.

  • Step 9 The laboratory applied IPS e.max® Ceram to the facial cutback areas on the bridge. The desired shade was A2. The bridge was built to full contour with A2 body porcelain and the incisal areas were cut back and layered with incisal and effect porcelain.

  • Step 10a. The translucency of the zirconia combined with porcelain layering produced the desired results

  • Step 10b.

  • Step 10c.

  • Step 11a. Dr. Crouch seated the restorations and no occlusal adjustment was required. The patient was extremely pleased with the results and the bridge was cemented.

  • Step 11b.

  • Step 11c.

  • Andrew Maples, RDT, CAD/CAM Support at B&D Dental in Salt Lake City, UT

  • Heather Crouch, DDS in Elko, NV.

  • Lewis Sharp, CDT, President of Sharp Dental Lab, Inc. in Elko, NV