Evolution to revolution

With the constant increase in the cost of gold, silver and the difficulties of working with non-precious and titanium alloys, the dental laboratory industry has been looking for alternative dental materials for many years. With the advent of digital scanning and advanced milling techniques, we have witnessed the growth of the zirconia restoration. Described by ceramic engineers as the “perfect dental material,” zirconia possesses great strength (Density of >6.0 g/cm, Vickers Hardness of 1,300 HV10, and compressive strength of 2,000 MPa); has the ability to be manufactured in the laboratory; when hand polished has the abrasion behavior similar to that of the natural tooth; and allows and intensifies the passage of light.

Laboratories could achieve superior esthetic restorations with very strong sub-structures and over-laying compatible veneering porcelain. We have now taken the next step, the Monolithic Restoration.

The monolithic restoration

The definition of monolithic is a single crystalline component, formed from a single crystal. The monolithic Zenostar zirconia restorations are designed in full contour and are produced in the milling machine Zenotech T1 from the zirconia Zenotech Zr bridge translucent material.

What separates the Wieland Zenostar restoration from similar restorations on the market is the level of translucency, the Zenotech Zr being the most translucent. For the natural coloring of the white zirconia material, a shading material Zenostar Color Zr has been developed by Wieland. The high translucency of the Zenostar material (Fig. A) in combination with an adjusted concept of shading  is responsible for a precise imitation of natural dentition.

Wieland has developed a three zone shading concept using the brush method to color restorations. With the Zenostar coloring system (Fig. B) lively chromatic shades are achieved, and in addition, effect colors are available for individual effects. For further individualization, Wieland also offers stains that can be applied after glazing. To achieve proper shading, the Zenostar Monolithic restoration requires seven easy steps. An experienced user needs only 20 minutes of actual working time (design, nest, shade, stain and polish) to produce a finished restoration.

Case presentation

01 Separate the work from the blank once the milling is completed (Fig. C).

02 Connectors are removed with the instrument of your choice-the technician must be careful at this stage because unsintered zirconia is in a powdered form and is delicate. The cervical and body zones should be gently smoothed with a sandpaper point; it is highly advantageous to remove all scratches at this point. The occlusal surface can be individually characterized by using grinding tools (Fig. D). It is essential to avoid causing cracking, flaking, sharp edges, grooves or undersized areas.

03 The cervical zone requires three circular passes with the brush, the brush should be dipped in the Zenostar Color Zr solution five times for each pass (Fig. E).

04 For the body zone the solution is applied in two vertical passes, blending the solution toward the incisal. Here too, the brush is dipped into the solution five times for each pass.

05 Effect shades are used to individualize the occlusal surface. Brown and or orange are recommended for central and secondary fissures; the effect white, ivory and gray violet for cusps and ridges. Finally, ivory or white can be applied to triangular ridges and cusp tips (Fig. F).

06 Before sintering the restoration should be fully dried at 80°C.

07 Polish restoration evenly with a bristle brush and a small amount of Zenostar Polish diamond paste. The occlusal surface must always be polished to a high shine (Fig. G).

Alternative stain may be applied for further characterization and the restoration glazed using Zenostar spray glaze. It is recommended to lightly sandblast the restoration prior to glazing (Fig. H).

Conclusion

A Wieland Zenostar full-contour monolithic restoration (Fig. I) is a highly esthetic, cost effective, biocompatible restoration with the abrasion behavior that compares to the abrasion of the natural tooth. You can create all-ceramic crowns and bridges with fully automatic design and manufacture. It is milled from innovative translucent Zirconia with high precision tools operating simultaneously in 5 axes. It can be individually brush shaded in 16 tooth shades to achieve better esthetics and quality than non-precious metals.

There have been defined moments in the history of the dental laboratory industry. We’ve seen ceramics replace acrylics, refractory investments change the way we made laminates, Empress and pressables have redefined our need for alloy, CAD/CAM and Zirconia have created a new vision, and today we have full-contour monolithic Zirconia restorations. New technology is leading the way for laboratories to be competitive in today’s environment-we cannot run our labs with the same techniques we used yesterday. We must embrace this new technology. Wieland’s Zenostar Monolithic Restoration is that technology.

About the Author

Vince Tauro, CDT, MDT has more than 30 years of experience in all phases of dental technology and completed his certification as a Master Dental Technician at New York University. Vince has studied with many of the world’s leading ceramists and received further training at the Degussa and Ducera headquarters in Germany. He has lectured throughout the United States and many international cities. Vince is well known for his ability to make his work stand out through the creation of truly life-like restorations by applying creative layering and sculpturing techniques. Vince is the Manager of Technical Resources for DENTSPLY Prosthetics in their West Coast facility in Yucaipa, Calif.