Inside Dental Technology
Matching the Natural Central
A ceramist’s view on esthetic implant restorations.
Esthetics are subjective. However, the requirement to match natural dentition with a prosthesis gives the dental team a fixed target to apply their collective skills and enhance patient satisfaction. In the author’s opinion, the most challenging restoration to create is a mirror image of a natural single central. The author’s laboratory has come across many non-conservative or less natural techniques, including preparing otherwise vital teeth for esthetic matching. However, with skilled operators, consistent dentist–laboratory communication, and esthetic materials available today, this is a challenge that can be met with a less invasive technique.
Careful treatment planning, collaboration between the dental team, and using metal-free material options are all key to enhancing anterior esthetics. In the case presented, a left central was replaced with a state-of-the art implant using a zirconia abutment and the Ceramco® PFZ system, creating a functionally and artistically restored smile.
Case Clinical Background
The patient presented to Dr. Kurt McKissick, the restoring dentist, with a left central (No. 8) that was not salvageable. However, the patient wanted the restoration to match his remaining vital teeth (Figure 1). Impressions and photographs were taken before extraction. After extraction and temporization, a photograph was taken with a shade guide in place to provide the lab with esthetic guidance (Figure 2). The natural teeth were chromatic and characterized, in the A3 to A3.5 shade range.
After discussion with the restoring team, including the periodontist, a zirconia abutment was chosen for esthetic enhancement. Resin was added to the temporary abutment to shape the tissue with the correct emergence profile. A complete set of impressions was taken and forwarded to the laboratory.
To reproduce esthetic ou comes for the correct emergence profile, models needed to be prepared and temporary abutments needed to be customized to give the correct finish line and volume of material in the neck and crown area (Figure 3). This was a complished by reshaping a temporary abutment with light-cured resin (Primopattern LC Gel, Primotec, www.primogroup.com). The optimized situation afforded input that will result in a custom-milled abutment and a sintered zirconia coping. Having similar materials enhanced both the structural and the esthetic integrity of the case.
The ceramic veneering process began after the fit of the coping was confirmed over the custom abutment. A layer of Ceramco PFZ margin porcelain with modifier ceramics was added to increase chroma and fluorescence in some areas of the tooth and to provide the right surface for the subsequent layers of ceramic.
The connection was created by mixing the Ceramco PFZ margin material with glaze liquid. The viscosity of the glaze liquid dispersed the ceramic particles, creating a very porous surface after baking up to 1,000°C under the vacuum with a 1-minute hold. This bisque layer provided physical retention for the layers of ceramics to be applied on top of it. Especially in this case, it was very important to have a high chroma in the internal layer leaving the external layer to give the translucency necessary of a typical older tooth (Figure 4 and Figure 5).
Because margin ceramics are a little more opaque, a small layer of this material was added on the mesial and distal of the coping to create a replica of the dentin (Figure 6). The dentin layer mixed with 15% of natural enamel clear was applied to the whole surface of the crown. Opaceous dentin was added with a mix of 15% mamelon yellow-orange to create a very subtle effect to better block the transition of light.
Following the esthetic techniques of Ernst Hegenbarth, the goal was to achieve improved dynamics between absorption and refraction of light (Figure 7). The stratification pattern shown reveals vertical layers on the incisal area enhancing the translucency and deepness of the crown (Figure 8). After baking the ceramic, the entire surface was covered with a material of greater translucency.
Layer thickness was deliberately controlled at a low level. This allowed for more control of ceramic contractions during each bake, as well as the chromatic effects; for example, a craze line (Figure 9). Ceramco PFZ stains were used in small portions and in internal layers of the ceramic. The vanilla shade was used to create this effect by simply mixing it with stain liquid and applying a minimal amount on the ceramic surface before it was fired. Stains were used internally to enhance control. Note that this program can be very fast (120°C per mi nute from 650°C to 840°C with no hold), and it will not affect the previous layers. The ceramic build-up process was continued with points of contact adjusted on the model (Figure 10), and the shape of the crown re-contoured to mimic the original model (Figure 11). The esthetic result of the craze line seen in Figure 9 was now visible (Figure 12).
Surface texture was the next challenge to be addressed. In this case, because of the patient’s age, the dental surface was very smooth due to erosion as well as the permanent contact with the internal part of the lip. Ceramco PFZ glaze and stains were used to finish the proper color and surface of this tooth. Most of the color comes from inside, but in aged natural teeth there is a lot of staining on the surface. Finally, the surface was polished with pumice and the case was done (Figure 14, Figure 15 and Figure 16). After the case was cemented, it was difficult to distinguish the crown on an implant (Figure 17 and Figure 18) versus the patient’s natural dentition. These lifelike results were very pleasing for the patient and rewarding for the entire restorative team.
The technician’s skills as well as communication between the entire team are key elements in the restorative process. It is great to work with the correct information because this brings out the best of the dental technician, who can see the desired finished product during the whole process, making the work much more enjoyable. The development of esthetic, wear-friendly ceramics—such as the PFZ system—gives the skilled dental lab technician a comprehensive single set of materials to fabricate all-ceramic restorations. The immediate advantages are enhanced reproducibility, excellent esthetics, a full spectrum of shades for prescription, as well as a reliable shade match in combination cases involving more than one type of restoration.
Carlos Montaner, CDT, has 30 years of experience. He is an international spokesman for DENTSPLY Ceramco, and has published many articles in Venezuela, Argentina, Brazil, and Spain. He now owns Montaner Dental Studio in Cary, North Carolina.
The author extends special thanks to Andreina Montaner for her support and collaboration on the development on this article. Clinical insights from Dr. Kurt McKissick (restoring dentist) and Dr. Paul Kazmer (implant placement) are sincerely appreciated.
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