Predictably Beautiful Coloring of Whip Mix Vericore PRO Zirconia
A simple and effective technique
Al Fillastre, CDT
As zirconia's popularity continues to increase, it is becoming more and more difficult to navigate the ever expanding variety of products on the market. It seems that every time one turns around, a new type of zirconia emerges with promises of its perfection. The huge variety of products on the market, including coloring liquids, has caused some technicians to opt for preshaded and/or multilayered zirconias. While tempting, these materials bring a slew of other challenges, including large inventory requirements, shade segregation, and nesting issues, as well as varying interpretations of shade and the inability to customize shade or effects without excessive staining.
This article is meant to demystify the coloring process for white zirconia and offer an approach that is fast, effective, and easy to understand. While the scope is quite narrow, an exhaustive study was done to evaluate the five most popular coloring systems and techniques; what is presented here is the result of that testing.
There are three basic types of zirconia available today developed in the following order: original HT, anterior translucent, and the new "hybrid" class that can be best described as a blend of the first two. For the Whip Mix line, these are named Vericore ZR HT (1255 MPa, most opaque), ZR HTX (670 MPa, most translucent), and ZR PRO (1140 MPa, in between), respectively. It should be understood that as the translucency of zirconia increases, the concentration of the coloring liquid must also increase to achieve the desired shade. Because of its superior strength coupled with natural translucency and value, the author uses only PRO zirconia to address any situation—from single monolithic, layered anterior, and hybrid abutments to Maryland bridges, etc. Green-state finishing is not discussed here; nonetheless, it is extremely important to do this well to avoid grinding post-sintered zirconia as much as possible.
Some shading liquids worked quite well, while others were much less satisfactory. For coloring the PRO material, the Origin 6.0 Chroma Full Contour Liquids (B&D Dental Technologies, origincadcam.com) at Liquid Chroma level 70% slightly diluted or the 70% + 80% mixed in a 1:1 ratio gave the best and most consistent results across the VITA shade guide. The author prefers the 70% concentration because it can be used for any of the three types of zirconia by simply changing the way it is diluted with distilled water.
In addition to shade, achieving a natural incisal blend is paramount. Blending incisal liquids by mixing the Origin Incisal Enhancer 1.5 (B&D Dental Technologies) with 3M Lava Ceram gray modifier (3M Oral Care, 3m.com) in varying amounts allows the dental technician achieve the required value and translucency.
For any basic shade, four different liquids are used. While the specifics vary slightly for anteriors vs. posteriors and singles vs. bridges, the concept is the same. This is a generic approach and can be varied to address each particular situation or philosophy.
Step 1. Chromatized areas: Apply one shade darker (A3, in this example) around the margin, inside and out, one coat only; underneath the pontics, multiple coats; interproximal embrasures (best if it runs into them while coloring underneath pontics); and buccal (lingual, too, if desired) developmental groove on molars, lingual fossa on anteriors (Figure 1 through Figure 5).
Step 2. Lateral segmental color: Add one coat of body shade (A2, in this example) up the facial center (anterior) or buccal cusp height of contour (posterior), margin to incisal. If a slight border is desired, carefully add a touch on the very incisal edge (Figure 6 through Figure 8).
Step 3. Apply appropriate incisal (medium, in this case) on the facial and buccal surfaces. Always do vertical brush strokes to keep application uneven; avoid straight lines. The following is a step-by-step coloring technique for shade A2 (Figure 9 through Figure 13).
1. Move along facial from mesial to distal, extending as far down the facial as appropriate but skipping over the lateral segmental color on the first coat. Typically it is appropriate to go a bit farther down on the mesial and distal corners.
2. Continue around the proximal onto the lingual. Go farther down the marginal ridges and across the incisal one-fourth to one-third.
3. Apply a second coat exactly the same, except this time cover the lateral segmental color. Use vertical strokes to avoid a horizontal line; sloppier is better.
1. Work around the occlusal table, applying incisal on the ridges only, avoiding fossae and developmental grooves.
2. Once back to where it started, apply the incisal on the buccal and lingual cusps as far gingivally as appropriate with vertical strokes to avoid straight lines. Skip over lateral segmental color on first coat.
3. Apply a second coat on the occlusal table exactly like the first coat on the ridges only.
4. Continue around the buccal and lingual cusps just like first coat but cover the lateral segmental color this time.
5. Apply occlusal warmth with A3.5 or A4 (one or two shades darker than body) onto the occlusal. Let the liquid run from the tip of the brush into the grooves, avoiding the ridges as much as possible. Apply three to five coats generously. It takes more than expected to get a noticeable effect.
Step 4. Dip in body color for 5 seconds at the most (Figure 14 through Figure 18). On bridges, dip even quicker to avoid over chromatizing the pontics. This way chroma inhibitor is not needed. Be sure to hold units with plastic tweezers so the inside of the units fill. Never let any metal touch the liquids. They are quite acidic and will dissolve metal into themselves, which will cause greying over time. For bridges, make sure there is an appropriate container already filled with body color that will allow full immersion of the bridge.
Step 5. Dry the units in a drying oven or under a heat lamp, then sinter per the manufacturer's instructions (Figure 19 through Figure 24). The author believes that fast-fire cycles diminish both the physical and optical qualities of the zirconia, but that is up to each laboratory.
While this technique can certainly be simplified if desired, coloring white zirconia is not only quick and easy, it gives the laboratory technician absolute control over custom shading and effects.
About the Author
Al Fillastre, CDT, is the owner of Ceram-O-Arts Dental Laboratory in Lakeland, Florida.
Disclaimer: The statements and opinions contained in the preceding material are not of the editors, publisher, or the Editorial Board of Inside Dental Technology.