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| Figure 1. Fractured amalgam. |
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| Figure 2. Preparation, adjacent tooth with a 6-year-old Concept onlay. |
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| Figure 3. Unicem bonded, paradigm inlay. |
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| Figure 4. Polished restoration. |
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| Figure 5. Impression model for Zirconia cerec inLab bridge. |
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| Figure 6. Finished bridge, cerec inLab frame with vita porcelain. |
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| Figure 7. Unicem extruded into bridge. |
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| Figure 8. Seated bridge cleanup with brush. |
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| Figure 9. Cemented bridge after cleanup. |
Over the years, all of our practice’s inlays and onlays were outsourced to a local laboratory. Gradually, the CEREC System (Sirona) was incorporated into the practice after gaining familiarity with it through involvement in a local user “study group.” While the continued use of the CEREC System certainly led to efficiently produced aesthetic restorations, bonding these restorations proved challenging. For starters, multiple steps are involved, and cleanup often proved frustrating, as several of the cement brands with low viscosity were messy.
This article presents 2 case reports that demonstrate a cementation technique for CEREC restorations that has proven to be both reliable and convenient and as easy as luting traditional porcelain-fused-to-metal crowns. Over the past 15 months, this technique has been used with more than 1,000 such restorations in my practice without any debonding. One case report involves an inlay fabricated from a Paradigm MZ100 block (3M ESPE), and the other case report involves a CEREC inLab 3-unit bridge.
CASE REPORT NO. 1
A man in his mid 40s sought to change an older amalgam filling on tooth No. 44 (Figure 1). Tooth No. 45 featured a 6-year-old Concept onlay (Ivoclar Vivadent), and the patient wished to remove the amalgam and improve aesthetics; treatment options included gold or bonded tooth-shaded inlays. The patient’s request for tooth-colored aesthetics in a single visit led to the choice of a CEREC inlay utilizing the Paradigm MZ100 block. This block material is particularly useful in challenging areas such as small multisurface inlays and large occlusal inlays, where ceramic material is challenged with minimal occlusal thickness.
The patient was anesthetized, and a rubber dam placed. Amalgam and bases were removed to sound tooth structure (Figure 2). Images were taken and the inlay was designed utilizing the CEREC 3D system. Imaging powder was washed off with air water spray and scrubbed with a brush, while the preparation was kept moist with a piece of cotton soaked in Tubulicid Red (Global Dental). Once milled and checked for fit, the inlay was polished and made ready for bonding.
The cementation technique utilized RelyX Unicem Self-Adhesive Universal Resin Cement (3M ESPE). This material reacts chemically with both the dentin and enamel surfaces, providing strong adhesion to the dentin and the cavosurface enamel. In addition, no etching, priming, or bonding of the tooth preparation is necessary. However, a slightly moist tooth surface is essential; overdrying of the preparation should be avoided. Because the product is encapsulated, the cement is mixed easily, injected directly onto the restoration, and placed on the tooth for curing and cleanup. (Note: When inserting a crown, inject into the crown intaglio and place a bead on the shoulder of the preparation. When inserting an inlay or onlay, place RelyX Unicem cement into the tooth preparation. With its gel state properties, cleanup can be accomplished quickly utilizing a rubber tip, brush, or metal instrument. Curing is accomplished without any difficulty.)
Immediately before cementation, the Tublicid Red was rinsed thoroughly from the preparation, and the excess water removed by suction. The restoration was silane treated, the preparation was coated with RelyX Unicem cement, and the inlay was placed with a positive seating force. The cement was tack-cured utilizing a curing light on the buccal and lingual surfaces for 3 seconds per surface. While holding the restoration in place, excess cement was cleaned and the contact flossed. Gross cleanup was accomplished, then all surfaces were cured for the appropriate amount of time. Final cleanup was accomplished utilizing gold knives and light sanding strips (Figure 3). Finally, occlusal contacts were checked and adjusted. If necessary, final polishing of the occlusal surface can be completed with points, discs, and cups following the usage procedures for Paradigm MZ100 Block for CEREC. Figure 4 shows the final inlay.
CASE REPORT NO. 2
A 65-year-old male presented with a missing maxillary right first bicuspid. In this particular case, treatment options consisted of an implant with a crown, a fixed 3-unit bridge, or a removable partial denture. As the patient preferred a fixed bridge over a removable partial denture or implant, a zirconia-based CEREC inLab fabricated porcelain bridge was chosen.
The patient had an existing crown on the second bicuspid, while the cuspid had received root canal treatment followed by insertion of a post and core. Both abutments were anesthetized and prepped for the bridge (Figure 5). Following the same procedure outlined in Case Report No. 1, the bridge was fabricated (Figure 6) and cemented with RelyX Unicem cement. For either a ceramic or metal bridge or crown, the cement is loaded into the intaglio (Figure 7), and a bead placed on the shoulder of the preparation. The units are then placed with firm pressure (Figure 8), while the excess is easily removed with an instrument or brush and the margin is light-cured. Following this, a 6-minute period is needed for the dual-cure cement to set. (Figure 9).
CONCLUSION
In each of the aforementioned case studies, the cementation technique allowed for easy placement and cleanup, in contrast to the dual-cured resin cement we utilized previously in our practice. In more than 1,000 cementations using this technique, sensitivity issues have been nonexistent. Further, there is no need to keep a series of different bottles of bonding chemicals in stock, which simplifies inventory and leads to a more time-efficient bonding procedure.
Dr. Andrews, a graduate of McGill University, Montreal, Quebec, maintains a private general dentistry practice in Vancouver, British Columbia. He can be reached at phacerec3@aol.com.
