Modern Material Collaboration

One case in point is the various options that accompany lithium disilicate restorations. Whether for monolithic or layered restorations, lithium disilicate’s popularity has skyrocketed in the last 5 years, making it one of the leading restorative materials on the market. Today, the number of uses for this innovative material has surged, as new products continue to roll out. The goal of this article is to show new solutions for restorations with products that were specifically designed to work with lithium disilicate.

Cases were sent to the laboratory with prescriptions for a popular brand of layered lithium disilicate restorations. The technician wanted to use a new ceramic to layer on the lithium disilicate, so he made phone calls to the dentists to request this change. Collaborating with dentist-clients on new materials can be challenging, because the dentists tend to prefer tried-and-true products so they can be certain of the final outcomes. However, these new products are FDA approved, which means that they have been vigorously tested and validated prior to the release. For the client, the crucial question is: Will it look better than the product that was initially requested?

In order to make a case with a client, a technician should have test results, samples, and photographs available to share. Once the technician gains the trust of the dentist regarding the effectiveness and success of the product, it is time to achieve the desired outcome.

Dental technicians always have looked toward nature as a guide, while the dental industry has worked to create restorative materials that can replicate it. Photoelastic images show just how dynamic natural teeth are (Figure 1), and Figure 2 illustrates how similar optically cross-polarized images of lithium disilicate are with nature. Figure 3 and Figure 4 show a comparison of nature versus lithium disilicate and how close they are optically. Lithium disilicate is the obvious decision for a restorative foundation or core to be layered on for vital-looking dental restorations.

When observing natural dentition, notice the fluorescent properties. Compare Figure 5, which shows the fluorescent characteristics of a natural tooth, with Figure 6, which presents GC InitialTM LiSi (GC America, gcamerica.com), the new ceramic to be layered on top of the lithium disilicate. Remember: When choosing a restorative material, allow nature to be the guide. Figure 7 shows natural anterior teeth, with Figure 8 demonstrating the same teeth demineralized, essentially stripping away the natural enamel to see exactly where dentin should be, i.e., the lithium disilicate core to be used. With this information, it is clear to see how to wax one’s core for pressable ceramic restorations to replicate nature. Once this information is understood, creating cutbacks for layering should be easy (Figure 9). With this information, the standard layering for lithium disilicate can be applied with LiSi: a wash fire, first bake, correction, stain, glaze, and bake (Figure 10).

Once initial testing has been performed in the laboratory on how the material handles, looks, and fires, it can be applied to clinical cases to see the results intraorally.

The first case was the restoration of a single central incisor (Figure 11). Before restoration, periodontal procedures were performed to balance the tissue levels. The lithium disilicate ingot was pressed with MO1 to block out the deep discoloration of the natural abutment (Figure 12). Once the core was cut back to use the cervical color of the underlying natural abutment, the case was layered according to pretreatment shade images for a final restoration (Figure 13). By achieving success with a single central restoration, the technician made it clear that using this material in larger cases would not pose any problems.

Figure 14 and Figure 15 show 10 veneers utilizing LiSi over layered-on pressed veneers clearly blocking out the underlying abutments and giving a bright natural result. The result of using a feldspathic ceramic in combination also allows for a much more natural surface and optics in comparison to natural dentition. Figure 16 and Figure 17 depict a simple 2-unit restorative case. Because of LiSi’s feldspathic properties, the treatment team achieved a harmonious outcome.

When using lithium disilicate cores, the dental technician must be aware of the underlying substructure and how that will work with the ingot selection. Figure 18 and Figure 19 show a case in which the underlying abutments can cause a restorative dilemma. Note the dark discoloration under the tissue due to oxidized metal from a previous post and core. Even if an ingot of correct opacity to block out the post was selected, the grey effect would still be noticeable at the delivery of final restorations. In order to avoid this situation and be able to use the desired ingot of choice, the 2 discolored metal posts were converted into tooth-colored buildups for an ideal starting point (Figure 20). Then, the creativity of dental technology can take place with natural layering (Figure 21). Once the case is completed, it is tried in for optimal esthetics and correction if necessary (Figure 22). At try-in, optical properties such as fluorescence and polarized lighting are checked to see if the restorations mimic the natural dentin correctly. Note the natural vitality that LiSi ceramic has intraorally for overall harmony (Figure 23).

A significant benefit from combining a feldspathic vital ceramic with lithium disilicate is that the restorative team gets the best of both worlds, delivering both strength and beauty. When restoring extensive rehabilitation cases, this becomes a priority. Figure 24 shows a Class III patient who declined surgical procedures to rehabilitate his smile. Through a year of temporization, the final result was able to be brought to completion with full-contour lithium disilicate posterior restorations for strength and minimal cutback using LiSi-layered anteriors (Figure 25). With the characteristics of strength and beauty, the restorative team was able to utilize this product with confidence to work out one of the most complex cases, with an excellent outcome. Figure 26 shows a first bake of a full-mouth rehabilitation before being fitted on a solid model after glaze.

Collaboration with dentist-clients on materials coming to the market is extremely important. Technicians tend to be more versed in dental materials, using them daily with many clients in various situations, and they typically know the pros and cons of material selection for cases. They must be ready and able to communicate to their clients about new products and how they can be used to offer their patients a better restoration.

Joshua Polansky, MDC
Owner
Niche Dental Studio
Cherry Hill, New Jersey