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Inside Dentistry

November/December 2007, Volume 3, Issue 10
Published by AEGIS Communications


Restoring Anterior Esthetics Using Metal-free Abutments and a Long-span Zirconia Restoration

Perry, DMD, MS; and John Orfanidis

The increasing use of implants in clinically appropriate cases has been paralleled by an increase in the use of yttria-stabilized zirconia as a restorative substructure material. The advantages of biocompatibility, esthetics, and durability offered by zirconia are unparalleled.1-4 The high-tech CAD/CAM methods used industrially to design implant parts are now available in user-friendly formats to dental laboratories. This enables the design and production of restorations with consistent and precise fit. Additionally, implant manufacturers have also increased the esthetic potential of their systems by offering metal-free zirconia abutments.

In this article, a case combining the precision-fit results available from a zirconia CAD/CAM system (Cercon® Zirconia, DENTSPLY Ceramco, Burlington, NJ) with the novel esthetic properties of a zirconia abutment (3i Implant Innovations, Inc, Palm Beach Gardens, FL) is described. New developments in these areas will continue to enhance the options available to dentists who provide care to the increasingly dentally aware patient.

Choice of Restorative CAD/CAM System: Cercon Zirconia

Many high-strength ceramic systems have recently emerged on the dental market. Of these, Cercon Zirconia has proven its durability and esthetics to the dental community since 1998.1-3

One of the desirable features about Cercon Zirconia is its applicability in a wide variety of restorations, from single units to long-span bridges. CAD/CAM systems have consistently been shown to deliver an improved and predictable fit. The fit of zirconia restorations is now in the 40 µrange.5,6 CAD/CAM technology reduces the effect of human variability and allows for more consistency from the dental laboratory. In the authors’ experience, there is no substitute for a clinician communicating his or her preferences to the dental laboratory clearly and in detail to achieve the desired results.

Zirconia is an excellent material choice for metal-free restorations, because of its biocompatibility, strength, and durability. It has been proven in clinical studies for more than 8 years.1-4 The news about the durability of this material is very promising. Research shows in vitro performance equivalent to porcelain-fused-to-metal (PFM) restorations.7

Another interesting aspect of the in vitro and in vivo research on zirconia is its biocompatibility; the material is nearly inert in the human body.4 Also, in one recent study zirconia was shown to have lower plaque-bacteria adhesion than titanium.8 As a result, it is being used in implant abutments such as Cercon Balance (DENTSPLY Friadent, Tulsa, OK), EstheticBase (DENTSPLY Friadent), and Procera® (Nobel Biocare, Yorba Linda, CA).

Clinical Case Report

A 45-year-old woman presented with a failing anterior 6-unit PFM bridge and extensive recurrent caries under the bridge. The case unfortunately did not allow an opportunity for conservative dentistry. Fortunately, the patient’s alveolar ridges and processes were in reasonable health. This suggested implant-supported fixed partial dentures as a restorative option with a predictable outcome.

There are a variety of esthetic materials and designs that could have been used in this case, especially in a lower-stress anterior situation. The author wanted to evaluate not only the fit but the esthetic potential of Cercon and the zirconia abutments. In combination, the light-transmitting potential of the zirconia abutments would enhance the esthetics. Cercon is indicated for bridges with a span of up to 47 mm, with multiple abutments available,as in an implant situation.

Placement of a transgingival implant substructure followed (Figure 1). The patient was provisionalized with a removable parial denture (Lucitone 199®, Portrait® IPN® teeth, DENTSPLY Trubyte, York, PA) (Figure 2). Evaluation through the healing and osseointegration periods ensuredsuitable progress.

Placement of the implant abutments with a suitable emergence profile and orientation was relatively straightforward. A light-cured resin custom tray (Triad® Custom Tray, DENTSPLY International, York, PA) was converted into an abutment orientation and placement jig for the model. A single Cercon framework was then designed to restore these abutments (Figure 3; Figure 4; Figure 5; Figure 6).

The core was fabricated and the patient was called for a try-in. The clinician used silicone to make molds of the existing removable partial denture and also sent other information such as midline lateral and protrusive occlusal bites and a facebow reading. The case was then mounted on a DENAR® 5A (Water Pik, Inc, Fort Collins, CO) and was then built up. The bridge was fitted once again in the bisque bake to assure marginal integrity of the core and labial contour of the porcelain. The silicone mold of the partial denture was used to follow the contours as closely as possible, but because of the implant placement some adjustments were required. The patient was not only pleased with the results (Figure 7 and Figure 8) but seemed more calm and confident and asked for the case to be finished.

Conclusion

Cercon Zirconia and its CAD/CAM systems have opened up new avenues of restorative possibilities. This system provides extraordinary strength and beauty with the capability of providing long-span metal-freebridges as well as single crowns.

A restorative case such as this one requires a crucial emphasis on the communication between the dentist, the dental technician, and the patient to maximize not only esthetics, but masticatory function. This case was presented after the patient lost her previous bridge and had some esthetic requirements that were unrealistic considering the implants were placed in different positions than the original position of her pre-existing natural dentition.

The open line of communication allowed the patient to arrive at a realistic restorative conclusion. Another benefit was that the patient felt calm, reassured, and confident, which in turn removed anxiety and fear.

Education is the key to success in traumatic restorations such as this one. The materials that were to be used were discussed and a zirconia substructure was the perfect choice. The gingival contours were also a consideration because of the high smile line. The Cercon system was used because of its precise milling and contouring ability.9

Long-span bridges can now be designed over implant abutments that are matched in light-transmitting esthetics and biocompatibility properties. Implant-supported restorations with enhanced esthetics and lower plaque-adhesion properties will be an interesting growth trend in the near future.

References

1. Filser F, Kocher P, Weibel F, et al. Reliability and strength of all-ceramic dental restorations fabricated by direct ceramic machining (DCM) [Published correction appears in Int J Comput Dent. 2001;4(3):184]. Int J Comput Dent.2001;4(2):89-106.

2. Sturzenegger B, Feher A, Lüthy H, et al. Clinical study of zirconium oxide bridges in the posterior segments fabricated with the DCM system. Schweiz Monatsschr Zahnmed.2000;110(12):131-139.

3. Studart AR, Filser F, Kocher P, et al. Cyclic fatigue in water of veneer-framework composites for all-ceramic dental bridges. Dent Mater. 2007;23(2):177-185.

4. Piconi C, Meccauro G. Zirconia as a ceramic biomaterial. Biomaterials. 1999;20(1):1-25.

5. Piwowarczyk A, Lauer HC. Determining the marginal fit of CAD/CAM bridge frameworks. International Association for Dental Research Pan European Federation Conference. Abstract 0254. Dublin, Ireland, September 13-16, 2006.

6. Ariko K. Evaluation of the marginal fitness of tetragonal zirconia polycrystal all-ceramic restorations. Kokubyo Gakkai Zasshi. 2003;70(2): 114-123.

7. Kiliçarslan MA, Kedici PS, Küçüke¾men HC, et al. In vitro fracture resistance of posterior metal-ceramic and all-ceramic inlay-retained resin-bonded fixed partial dentures. J Prosthet Dent. 2004;92(4):365-370.

8. Scarano A, Piattelli M, Caputi S, et al. Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol. 2004;75(2):292-296.

9. von Schroeter P, Jürgensen B, Zöllner M. Cercon move—a navigation aid for dental CAD applications. Int J Comput Dent. 2004;7(4):371-377.

About the Authors

Ronald Perry, DMD, MS
Director and Associate Clinical Professor,
Gavel Center for Restorative Dental Research
Tufts University School of Dental Medicine
Boston, Massachusetts

John Orfanidis
Research Associate
Laboratory Technician. Orfan Dental Laboratories, Inc
South Weymouth, Massachusetts


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Image Gallery

Figure 1  Lingual view of implant placement.

Figure 1

Figure 2  The custom tray for implant impression.

Figure 2

Figure 3  The implant core jig for insertion of implant cores in the patient's mouth.

Figure 3

Figure 4  The zirconia bridge framework.

Figure 4

Figure 5  The zirconia-based abutments in place.

Figure 5

Figure 6  Lingual view of the abutments.

Figure 6

Figure 7  The final restoration.

Figure 7

Figure 8  Postoperative smile view.

Figure 8