Advantage of ArgenZ Esthetic Transitionally Shaded Full-Contour Zirconia Over Pre-Shaded
Color full-contour zirconia before sintering for more shading options and better esthetics than pre-shaded zirconia
Pre-shaded zirconia is monolithic by design and therefore must be externally stained to simulate an incisal color. Incisal coloring is normally lower in value but also lighter in color than the dentin shade. To replicate this effect, it is necessary to mill the pre-shaded unit a minimum of one shade lighter and externally stain the dentin up in chroma and lower the value at the incisal to simulate a transitionally shaded crown (Figure 1).
The result of this treatment is heavy external staining that compromises esthetics and will leave a noticeable bright area if adjustments are made in the future (Figure 2).
Transitionally shaded zirconia is colored with pre-mixed liquids in the pre-sintered stage to create a natural incisal color transition to the desired dentin color. These liquids penetrate approximately 1.5 mm both externally and internally, completely penetrating the ZR unit, creating natural internal shading (Figure 3). External staining should be used only for enhancing the final shade match (Figure 4).
Recently I was at my dentist’s office for a routine cleaning. I had owned a dental laboratory more than 15 years ago, and this dentist had been my best client.
Before the cleaning, the dentist asked questions about full-contour zirconia as he was about to seat his first pre-shaded full-contour ZR unit. After the cleaning, I learned that the case had not gone well; the dentist was disappointed with the results and did not seat the case. He showed me the unit, and the reason was immediately clear. I asked to remake the crown in order to show him the difference between a pre-shaded ZR material and a transitionally shaded ZR material. The dentist agreed and said he was looking forward to the comparing the results of the two units. I sent the case to Argen Digital for production. ArgenZ Esthetic Zirconia is a highly translucent zirconia that can be transitionally shaded and custom colored in the green stage before sintering.
Steps for Coloring ArgenZ Esthetic Zirconia
Argen Digital uses a water based coloring system to shade ArgenZ Esthetic Zirconia, but there are several systems that work well; recommendations and technical support can be obtained by contacting Argen Digital.
Before coloring, according to the steps outlined below, the technician should follow the standard procedures for finishing, smoothing, and removing milling dust from the ZR unit. (Note: Pictures were provided for shade match.)
Step 1. Application of the incisal enhancer liquid (two coats) (Figure 5). The first coat covers the desired incisal length/blend, using uneven staggered application to blend into dentin color. The second coat is applied on the incisal edge, blending halfway down the first coat; the same process is used for the lingual and occlusal surfaces.
Step 2. Application of base shade/coloring liquid using dip technique (Figure 6). The zirconia unit is dipped in base shade liquid for 15 to 30 seconds and then blotted and blown dry. The unit is then air dried for 3 to 5 minutes before proceeding to enhancement shading.
Step 3. Application of gingival and occlusal shading liquid (enhancement shading) (Figure 7 and Figure 8). The desired shade enhancement color is applied in a staggered and uneven manner to the gingival one fourth for more color saturation and to create a better blend. A color one to two shades darker should be applied in the central occlusal fossa/grooves to highlight this area and create depth.
Sintering, Staining, and Glazing
Step 4. Sintering in furnace using Argen Digital’s recommended zirconia sintering instructions (Figure 9 and Figure 10). A thin layer of glaze liquid is applied to check the shade (no stain has been applied). Only slight stain enhancement is necessary to finalize shade.
Step 5. Staining and glazing (Figure 11). Only fluorescent stain and glaze systems should be used; the author prefers to apply and fire enhancement stain before glazing for better control.
As can be seen in the original pre-shaded ZR crown (Figure 12), the color was too light (high value) and did not blend well with adjacent teeth. After the above steps were followed for coloring, sintering, glazing, and staining, the ArgenZ Esthetic Transitionally Shanded Crown blends well with adjacent teeth (Figure 13).
The author would like to thank Richard Tomlinson, DDS, of Tahoe City Dental Group, for his contributions to the case.
Chris Lowthorp, CDT, is the owner of Digital Dental Aesthetics and is an independent consultant for education, research, and development.
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