Change Can Make Us Better

Each of these new materials and processes helped the author learn and grow. Most importantly, each added to the profitability of his business. The ability to control the design and fabrication processes as well as manage the quality of the end product has been a major benefit that was an outgrowth of the learning process.

As important as profitability is to businesses large and small, what the author focuses on and values most is the personal growth resulting from adopting each of these new fabrication systems and materials. Learning a new process empowers those in the laboratory business to become more of a resource to their clinical partners and increases their range of options for producing quality restorations.

Some welcome change; others avoid it. It is important to understand that the future hinges on moving forward. Embracing change increases the chances of excelling in the coming years. Of course, there are products and processes that are very “personal” and may be difficult to forego—such as one’s familiar long-used ceramic system. Having found a comfort zone with a particular ceramic system and understanding the material’s strengths and weaknesses may make it hard to look beyond using that system. The author has become comfortable using several ceramic materials. The challenge of learning and understanding a new material system is like becoming engrossed in a good book or interesting movie. Each material that catches his attention creates a need to understand its nuances and master the material’s esthetic potential. Sometimes the task seems daunting, which may make it hard to take the time required to learn when business is busy. However, not learning new systems places limitations on the laboratory’s ability to grow and improve the esthetic outcome of the work.

In the end, laboratory technicians’ job is to assess what material will work and look best for each patient’s individual situation. When working on larger cases, where the focus is on matching each other restoration, it sometimes becomes difficult to truly evaluate the esthetic abilities of newer materials. The values and chroma of the material are obvious but, ideally, when working on smaller cases, where the focus is on matching most of the natural teeth, it becomes invaluable to understand of the nature of the substructure material and its overlaying powders.

Zirconia is an example of a material that has evolved significantly since its introduction to the dental market. Several years ago, the author considered the reflective index of zirconia challenging and regarded the veneering ceramics more difficult than helpful in trying to achieve optimal esthetics. As products evolve, so must laboratory technicians, and today zirconia has become a much larger part of the author’s laboratory business. New materials and processes are viewed less as “business” opportunities and more as esthetic opportunities. When evaluating each case, the diagnostic process is what truly drives the author’s decision in the materials chosen to restore the case. Functional parameters, esthetic concerns, biocompatability with the oral environment—along with considerations on remaining tooth structure and the type of understructure—are always the driving force.

As challenging as it is to evaluate materials, the best way to truly develop and understand the material system is through an evaluation of the material next to nature. For the author, the most difficult choice is usually a single tooth restoration. Although this can be the most challenging, it is also where the most can be learned. A single central case presented itself recently with a patient who seemed intrigued by the process of replacing his original No. 8 restoration to improve his esthetic appearance. Matching a single central is daunting, depending on the patient’s expectations. The ideal patient to work on is one who lacks tooth display when smiling. Much more difficult is achieving the desired result in a patient whose high smile line shows a large portion of the dentition, which may require several tries (Figure 1 and Figure 2).

As the choice of materials has widened over the years, it is the job of laboratory technicians to understand the strengths and weaknesses of each substructure material in order to best restore a patient’s oral and esthetic situation. Most are very comfortable dealing with porcelain-to-metal as a substructure. Regardless which metal is used, the goal has always been to mask the underlying metal by using opaque materials, the choice of which depends on the purpose. Brighter opaques help increase the value of the restoration by being more light-reflective while higher chroma–based opaques absorb more of the light spectrum, appearing lower in value.

When zirconium oxide as a substructure came to the market years ago, it presented many pros and cons for ceramists. Optically, the original core material was white and very opaque, presenting the challenge of using liners or stain colorants to adjust the values.

As this restorative material has evolved, zirconium oxide has become more translucent and much more user-friendly as a substructure of choice. In addition, sintered colorants have become much closer in terms of color—as it relates to the scale of dental colors—and the ability to modify the core with staining materials or translucent, fluorescent liners has greatly aided technicians’ ability to create a much more esthetic substructure. Still, the onus is on technicians to know when to choose a more translucent substructure or more opacified one, based on the stump shade provided and the final shade results expected (Figure 3).

For this case, a zirconia subframe was selected, and for experimental purposes, several copings were made and treated in various ways to help evaluate their masking abilities and help support and evaluate the future layering material. It is important to note that although there are a many options for creating zirconia substructures today, the author chooses to use CAD for the framework, using the double scan technique. This involves creating a wax pattern and then scanning both the preparation and the wax-up (Figure 4). The option of creating the substructure in a 3D CAD space is very viable today. The author is doing more and more CAD designs but also believes from a control point of view that a simple wax-up works well, depending on the design complexity of the framework. For this case, a wax-up was fabricated and double scanned. Three higher-capacity 3M ESPE Lava™ copings and three Lava™ Plus translucent copings were milled from the same scan and CAD design (Figure 5) (www.3MESPE.com). All three sets of copings were treated the same way. The first set, which included one Lava and one Lava Plus coping, were dipped in A1 colorant and pre-sintered. Set 2 was sintered and treated with a fluorescent liner material, and the third set was sintered and untouched (Figure 6 through Figure 8). Each coping was evaluated on the cast with the use of black magic marker to create the illusion of a dark stump shade (Figure 9 through Figure 11). Each coping was also tried and photographed intraorally with a try-in paste to evaluate its base shade and masking ability (Figure 12 through Figure 15).

The key to using all-ceramic materials is developing a clear understanding of the materials’ opacity and translucency. This obviously starts with the choice of substructure material, but can be adjusted based on the strength of the layering system. Creating depth in small spaces requires opacified particles that create a reflective index for light reflection and yet support the correct chroma saturation to absorb light and create the proper value. In this case, shade photos were taken with special attention given to color, translucency, and the topography of the tooth surface. All six copings were layered following the same buildup formulation. Opacious dentin A3 and A1 were used, the latter for the interproximal and the former at the gingival mid-third to raise the value (Figure 16). A mix of dentins A3.5 and C2 was used over the opacious dentin proximally and on the cervical third. A mix of A1 and C2 dentin was used in the middle third and extended over the incisal of the copings (Figure 17). A canvas was finished with the use of enamel 59 (Figure 18). Opacious dentin B3 and A1 were then used as mamelon materials over the prepared canvas and covered with enamel 57, 58, opal, and clear, mixed with several dentins and stains (Figure 19 through Figure 22). Although the coloration was not yet as correct as it needed to be, each restoration was placed on a pre-darkened master cast and delivered for intraoral analysis (Figure 23 through Figure 25). Both were photographed to evaluate their masking ability and depth of the layering materials chosen (Figure 26 and Figure 27). Although each restoration had potential with a few minor adjustments, the original Lava core with fluoresence added offered the best internal value to work with on this particular case (Figure 28). A slight cutback was done, and a correction bake and glaze fire allowed the restoration to be brought to a closer matching point. The incisal edge was extended because, clinically, the adjacent central was to have composite added to match the incisal length (Figure 29). Final contouring and polishing finalized the color match and an excellent composite bond was achieved by Dr. Michael Soloway, who finalized the case (Figure 30 and Figure 31).

As with all single centrals, this case was a challenge. However, the learning curve offered the author the opportunity to establish a great understanding of what his layering materials could achieve. It is this ability to learn from each case that will help propel the industry toward the future and help to meet its esthetic needs.

Peter Pizzi, CDT, MDT
Owner and Manager
Pizzi Dental Studio
New York, New York