Traditional Processes Meet Innovative Materials
Inside Dental Technology delivers updates on digital workflows, materials, lab techniques, and innovation in dental technology through expert articles and videos.
December 1, 2012
Volume 3, Issue 11, December 2012
Page(s):
As manufacturing science and technology advances the strength and esthetics of zirconia for dental restorations, its indications for clinical use have expanded. Today, the industry is experiencing a marked shift from traditional porcelain-fused-to-metal (PFM) restorations to all-ceramic. This step-by-step article demonstrates how simple it is to adapt the latest crown-and-bridge material
innovations to the traditional two-phase fabrication process.
The case presented represents a dental laboratory perspective on a provisionalization using DENTSPLY’s Radica® long-term provisional material, followed by a bridge of milled Cercon® ht zirconia and Cercon ht single zirconia units. The posterior section of the bridge was full-contour zirconia, while the anterior portion required a cutback, or reduction of the zirconia for porcelain layering. Additionally, the single units were layered with porcelain. The intent of this article is to show the feasibility of combining full-contour milled zirconia posterior teeth for strength and a coping design for a more esthetic porcelain layering technique in the anterior region.
The patient presented to the San Antonio, Texas, restorative dentist, David A. Little, DDS, with a failing porcelain PFM bridge from teeth Nos. 3 through 8 (Figure 1). After a thorough clinical examination, Dr. Little and the patient agreed upon a treatment plan, which involved a full-contour zirconia bridge for the posterior and layered zirconia for the anterior restorations. This included single-unit zirconia substructure crowns for teeth Nos. 9 through 12 and a zirconia bridge from Nos. 3 to 8.
The provisional restoration is an excellent tool for the patient, dentist, and laboratory technician (Figure 2 and Figure 3). It serves as a stepping stone for the final blue print in esthetics and shade.1 Radica is a visible light-cured (VLC) composite, can be easily contoured or added to, which satisfies the esthetic demands of most patients.2 It can also be used in the mouth for up to 2 years and can be used to temporize implant restorations (Figure 4 and Figure 5).
Before temporary cementation, the preparations were refined for acceptance of a zirconia restoration. As with most all-ceramic restorations, a chamfer margin with rounded contours was prepared to ensure the best designs. After refinement of margins, a final impression was taken. At that point, Dr. Little lined the provisional restorations with a Bis-GMA material, Integrity Multi-Cure (DENTSPLY Caulk, www.caulk.com), then trimmed, polished, and temporally cemented it in the patient’s mouth (Figure 6 through Figure 9).
Cercon ht was used for the zirconia structuring. Previous generations of zirconia proved to be extremely strong, but they were lifeless in their esthetic value. Cercon ht is up to 26% more translucent than conventional zirconia. In addition, research shows that Cercon ht causes very low antagonist wear—compared to PFMs and conventional all-ceramics—as delivered, after adjustments, and after repolishing, increasing confidence in the clinical reliability of the system.3 Cercon® all-ceramic CAD/CAM is the method in which the bridge and copings were engineered.
The CAD designs were then sent to Compartis® (compartisusa.dentsply.com) outsourcing service for the milling and manufacturing of the zirconia restorations (Figure 10 and Figure 11). All contours and esthetics were computer-generated from a 3Shape digital scanner (3Shape, Inc., www.3Shape.com) (Figure 12). In the full-contour areas, the restorations were simply stained and glazed for customization (Figure 13 and Figure 14). In the cutback areas, Ceramco® PFZ, a low-fusing esthetic porcelain, was
applied in the traditional manner.
A combination full-contour posterior and cutback anterior zirconia bridge has been presented. While the fabrication process follows the traditional protocol for all-ceramics, these materials expand their applications and indications, with greater predictability in esthetic and functional outcomes.4
The full-contour zirconia posterior should be fracture-resistant and the anterior regions will be as esthetic as any traditional methods (Figure 15). As new generations of zirconia evolve, dental laboratories will likely produce more and more full-contour, full-arch bridges.
Robert Winkelman, CDT, MDT, is the owner of Fort Washington Dental Lab, Inc., located in Fort Washington, PA
The author would like to thank David A. Little, DDS, Connie Nguyen, CDT, and Christopher Stricker for their contributions.
The preceding material was provided by the manufacturer. The statements and opinions contained therein are solely those of the manufacturer and not of the editors, publisher, or the Editorial Board of Inside Dental Technology.
*To see the clinical perspective of this case by David A. Little, DDS, look to the December 2012 issue of Inside Dentistry or visit www.dentalaegis.com/go/idt310
