Zirconia: the next best restorative material?

By Lewis Sharp, CDT

The dental industry is seeing rapid changes in all aspects. Economic pressures, new and emerging technologies, and soaring precious metal prices have caused a shift in restorative choices. As a material, zirconia is the strongest of the all-ceramic restoration materials available today. Zirconia ceramic materials have been used for more than 20 years in medicine, mainly for hip replacements, and is used in aerospace technology. These materials have shown over this long history that they are fully biocompatible. It is the new material of choice for dental restorative procedures. In a recent issue of the CRA Newsletter, a status report on all-ceramic vs. PFM restorations states: "Dental technology is moving rapidly toward computers and all-ceramics, with zirconia leading the trend currently."

Characteristics of zirconia:

• It has extremely high tensile strength, and is referred to as ceramic steel.
• It virtually eliminates any allergic reactions.
• It is not an electrical conductor, so it doesn't generate an electrical charge. Electrical conductivity contributes to the corrosion of other metals in the mouth.
• Being nonmetallic, there is no corrosion. Therefore, gingival reactions such as the common "black line" at the gumline of traditional porcelain-fused-to-metal restorations will not occur.
• As an insulator, it protects against unpleasant hot/cold sensitivity in the mouth.

Zirconia has evolved from a material used primarily for porcelain-fused substructures to full-contour restorations. As it has improved in esthetic properties, it is even becoming possible to use zirconia in anterior restorations. In our dental laboratory, we are excited about the future of zirconia restorations. Our Dura-Diamond full-contour restorations are becoming the restoration of choice with our clients. Prescribed for full-contour restorations or with facial cutbacks and layered porcelain, Dura-Diamond restorations are exceeding expectations. Case studies In our first case study, we received a case prescribing a Dura-Diamond bridge for teeth Nos. 3 through 5 with zirconia occlusal and lingual and layered porcelain facially. The models were scanned and the bridge was designed with the facial areas cut back for porcelain. The bridge was milled, colored, and sintered to the desired shade. Noritake^® CZR^® porcelain was then layered and fired to the bridge, and the entire restoration was glazed and delivered to the doctor (Figs. 1 and 2).

With the accuracy of the digital process, very few adjustments were needed (Figs. 3 and 4).

In our second case study, we received a case prescribing a Dura-Diamond bridge for teeth Nos. 4 through 8, once again with zirconia occlusal and lingual and porcelain facials. The esthetic demands of this case were more difficult. We had received photos of the patient, which were very helpful in achieving a good match of the surrounding dentition. Once again the bridge was milled, colored, sintered, and porcelain applied to the facial surfaces. The final restoration was delivered to the doctor and inserted (Figs. 5 and 6).

With the increasing demand for zirconia restorations, manufacturers continue to develop more esthetic zirconia materials that allow the technician greater flexibility to create beautiful, natural-looking restorations.Author bio Lewis Sharp, CDT, has more than 37 years of experience in dental technology and recently celebrated 27 years of business with Sharp Dental Lab, Inc. Lewis received his certification in 1994 and takes great pride in providing the finest restorations for his clients. For more information and a special offer on Dura-Diamond crowns, visit www.sharpdental.com.