Matching a single

March 21, 2012

Our patient, a female in her mid-30s, is the sister of a dental hygienist. Because of this close relationship, there were two people carefully inspecting her dental work, one with plenty of knowledge about the field.

Our patient, a female in her mid-30s, is the sister of a dental hygienist. Because of this close relationship, there were two people carefully inspecting her dental work, one with plenty of knowledge about the field.

The temporary flipper the patient had been wearing for quite some time was not a good color match, making her very self-conscious and unwilling to smile naturally. Both the patient and her sister were interested in her restoration blending as closely as possible with all of her adjacent teeth. In an effort to brighten her teeth’s overall appearance, she had been bleaching for quite a while.

Following all the surgical procedures and subsequent healing period, she was ready to come into the lab for a custom shade match to her existing central tooth, No. 9.

I believe in allowing about 2 to 5 minutes for a custom shade appointment or else running the risk of losing that natural tooth color. When determining a custom shade, I always follow the same protocol:

  • Hydration – without it, the patient’s color will change. In addition, the patient should not drink any coffee, tea or dark soda right before the appointment. If she does, have her brush her teeth prior to determining the exact shade.

  • Note the base color, translucency and transparency first

  • Check mamelon and carefully make note of it

  • After dehydration check for surface texture

Our case study will revolve around demonstrating how to approach a custom shade match predictably and effectively.

Case Study

The flipper the patient had been wearing after her implant surgery had grown very tiresome (Fig. A). The color did not match and she was tired of hiding her smile.

01 In the laboratory setting, I removed her flipper (Fig. B), unscrewed the healing cap, took it out and put in the zirconia abutment. This way I could see the prep design to plan for the proper amount of room for the patient’s final restoration.

02 I also checked the base color of her adjacent tooth with a bleaching color shade tab and determined her to be 50% - 030 in base color (Fig. C).

An alternative to this standard method of noting a patient’s shade would be to use an LSK121 shade tab with a bleaching base color (Fig. D).

03 Part of the custom shade taking process is to check the incisal 1/3 to match the translucency (Fig. E) or transparency.

For consistent and beautiful esthetics, I have found I can depend on GC America’s GC Initial™ Zirconia porcelain for all ceramic restorations (Fig. F).

04 The next step in the procedure involved the application of dentin and enamel to the zirconia coping (Fig. G).

05 The coping was then ready to be baked at 810°C, (Fig. H) the low fusing temperature required for first bake.

06 GC America’s Lustre Pastes with porcelain particles included (Fig. I), in an array of colors, help create life-like and natural looking restorations.

07 A layer of enamel modifier created the blue and gray effect I sought (Fig. J).

08 After firing, an application of clear CLF was applied to the entire restoration (Fig. K).

09 For overall cover, CLW (window color) was the next layer (Fig. L) so I could see the depth of color and create natural looking enamel.

10 For texture and lobe (Fig. M) I sketched onto the restoration the areas in which I wanted special characterization.

11 Nobel Biocare provided the custom abutment and crown shown against a mirror here (Fig. N).

In the mouth, the final restoration is a perfect match (Fig. O), perfectly blended and harmoniously matched. Note the crack lines, translucency and grayish tone mimicked in the restoration, all taken into consideration and created in the final restoration.

Conclusion

Every dental professional knows the single central is the most difficult tooth to match. The reasons for this are numerous: coping color bleed through, the layering of the porcelain after firing, matching the exact contour of the teeth and the numerous lobe and angulation differences of adjacent teeth.

With all the different porcelain materials I use, I want consistency even throughout multiple firings. Knowing how difficult it is to duplicate natural teeth, we all need a specific strategy to memorize and use every time we are trying to match adjacent teeth. As technicians, we need to remind ourselves that 95% of the time natural teeth will not match with a two-color shade tab.

My recommendation is to first determine the amount of dentin underneath the enamel. This factor will play a role in deciding how much porcelain to apply to the restoration and also in what shade.

The effect it creates is crucial to the final outcome. For a lighter effect, use different enamel and dentin color. A white or monochromatic color will lead to a white base and the same overall effect.

After firing the restoration, expect a predictable shape. In addition, expect some shrinkage, but don’t overbuild your porcelain because this will only lead to having to cut back. Conversely, under-contouring will cause you to have to add porcelain. The problem is that if a crown is cut back too much, the color will have a low value and become very translucent.

If the adjacent teeth are that color, then it will be a match. But if not, there will be a problem with the final outcome in the mouth.

I follow these steps when working on a single anterior crown:

  • Build up the porcelain and cut it back if necessary

  • Decide which internal color to apply on top of the dentin

  • After firing, expect thickness and proper contour with the adjacent teeth. Finalize shape at this time

  • For modification, I find it’s essential to use Lustre Pastes as it is more translucent and therefore more life-like in its natural color.

To achieve the very best results and finalize our custom shade matching, we have to consider all of these steps and concepts and give them our very best thought, preparation and strategy. Once we have a plan, the reality of a beautiful restoration is close at hand!