Advancements in zirconia technology have expanded its applications in contemporary dentistry, including its use in the anterior region and for chairside production using specialized CAD/CAM systems. Even without cutback techniques, KATANA™ Zirconia Block (STML) paired with CERABIEN™ ZR FC Paste Stain (both from Kuraray Noritake Dental) offers an outstanding aesthetic solution.

Case Overview

This case focuses on replacing aging porcelain-fused-to-metal (PFM) crowns on the maxillary central incisors. The treatment aligned with the patient's desires for improved aesthetics and was completed in a single appointment.

Case Presentation

The patient presented with PFM crowns on the maxillary central incisors that had been in place for approximately 30 years. She sought aesthetic enhancements and a slight repositioning of these teeth.

Treatment Plan

The agreed-upon plan included the following steps:

1. Removal of the existing crowns.
2. Digital impressions.
3. Production and bonding of new restorations, all within one session.

The patient's periodontium was healthy, and there was no bleeding. A preliminary silicone impression was taken as a precautionary measure to ensure temporary crowns could be fabricated if necessary.

Treatment Workflow

1. Removal of Existing Crowns
   Using a diamond bur followed by a tungsten carbide bur, the existing crowns were removed, revealing them as Richmond crowns. To avoid further damage, the crowns were trimmed and reshaped into inlay cores. Preparations were adjusted to accommodate new restorations.

2. Masking Challenges
   The main challenge was masking the metal of the coronal-radicular reconstructions. Fortunately, sufficient space allowed for complete zirconia crowns of adequate thickness.

3. Shade Selection and Digital Design
   The desired shade, A2, was chosen using a shade tab. Intraoral scans captured the preparations, and virtual models were used to design the crowns, accommodating the patient’s request for slight retraction of the central incisors.

4. Fabrication and Sintering
   The crowns were milled from KATANA Zirconia Block 14Z in Shade A2. Post-milling, the crowns underwent sintering for approximately 18 minutes in the SINTRA™ CS furnace. After sintering, the crowns were tried in to assess fit, shape, shade, and optical integration.

5. Finishing and Cementation
   To enhance aesthetics, the crowns were stained and glazed with CERABIEN ZR FC Paste Stain. After firing, the crowns were tried in again with a try-in paste to simulate the final appearance. The intaglio surfaces were sandblasted and primed with CLEARFIL™ CERAMIC PRIMER PLUS, while the prepared teeth were treated with KATANA Cleaner. PANAVIA™ V5 Tooth Primer was applied to ensure optimal bonding with the metal and hydroxyapatite surfaces.

   Each crown was cemented with PANAVIA V5 Paste, followed by light polymerization and excess removal. The process was repeated for the second incisor. The patient expressed immediate satisfaction with the aesthetics and comfort of the new restorations.

Results and Follow-Up

• Immediate Results: The newly placed crowns displayed excellent adaptation, position, and mimicry of natural teeth.
• Four-Month Recall: The patient’s smile remained aesthetically pleasing, with ideal soft tissue conditions and excellent functional outcomes. The zirconia’s optical properties effectively masked the metal posts, and the natural surface texture contributed to the overall success.

Discussion

While lithium disilicate has long been the go-to material for anterior prosthetics, zirconia has emerged as a robust alternative. It excels in milling precision, strength, aesthetics, and ease of assembly, with the added benefit of not requiring hydrofluoric acid for bonding. This case highlights zirconia’s potential as a transformative material in modern dental practices.

This article is sourced from: https://www.dental-tribune.com/c/kuraray-noritake/news/same-day-dentistry-replacement-of-two-pfm-crowns-with-zirconia-restorations/