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The Single AnteriorLuke Kahng

The single anterior can be the most difficult tooth recreate in cosmetic dentistry. The dentaltechnician challenges include shade mapping, the selection of material for the understructure,longevity and, of course, don’t forget function.

CASE STUDY

The patient came in with an existing crownon tooth 8 and did not like the esthetics.The crown was removed and a post andcore was completed. Impressions weretaken and the tooth was provisionalized.The dentist and the dental technician didthe shade mapping. A full-color mappingof all the colors in the patient’s tooth was completed.

The patient was looking to match perfectlytooth 9. The patient was told the choicesand procedures available and an all-ceramicrestoration was chosen to give him thehigher esthetics he sought. One of the issueswas that the understructure would need toblock the gold core from shining through.

The understructure material should beopaque to mask the underlying dark color.However, an advanced porcelain techniciancan still mask the underlying dark toothcolor by utilizing porcelains with detailedcolor-masking techniques. It is vital to avoidexcessive opacity, which is common inporcelain-to-metal restorations and oftenresults in lifeless-looking restorations. Onthe other hand, if you have too muchtranslucency, the restoration looks toogray and dark. You may see this on someof the all-ceramic restorations that are lessthan 1mm in thickness.

Metal-free restorations are not going toentirely replace porcelain fused-to-metal,but it is an alternative for more natural-looking restorations. It is a dentaltechnician’s responsibility to be educatedabout the latest materials, techniques andproper function of occlusion and muscleposition for esthetics, longevity and comfort.The dental technician needs to look at howlong a material has been on the marketand should review studies that have beencompleted about the material.

With a wide range of all ceramics to choosefrom, it is difficult to keep up with all of thenew or improved products. With the changeshappening so quickly, it can be confusing.

Some of the choices of materials orunderstructures are as follows:• Procera, Lava, Cercon, Everest, In-Ceram,

etc., are some of the systems using a zirconia understructure. Zirconia, as a whole, is very low in translucency and high in opacity.

• Procera, InCeram, etc., are have an alumina understructure. These are low in translucency and have moderate opacity.

• Pressed: Leucite-reinforced or Lithium Disilicate and Apatite Glass ceramics, such as Empress, OPC, Authentic, GC Initial, are higher in translucency and can be low or high in opacity, dependingon the pellet.

Each company will tell you about theirsystem and how it’s better or has moreadvantages than another. But there is moreto consider than just that. You need to knowthat the company you choose will be thereto support you. Many systems are quiteexpensive and you need to have quite aclientele to justify the costs. However, if youdon’t have the capital, but you have theneed, there are options. Instead ofpurchasing a system, you can outsourceyour frameworks until you have the marketto justify the purchase. Then once yourmarket share is stable, you can invest in acomplete system. Be sure the company youbuy from has a program in place to helpyou develop and implement a successfulmarketing strategy for your end product.

Today it is easy to get an understructurefabricated from an outsource provider.The dental technician sends the completedmodel to a dental laboratory with thedesired system. The lab will fabricate theframework and deliver it back to the dentaltechnician. Porcelain will then need to beapplied to complete the case. The porcelainwork is constructed on the framework andhow the restoration’s esthetics turn outdepends on the individual ceramist’sskills. This enables small laboratories tooffer different systems without a largefinancial investment.

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Fig 1. Preparation on tooth 8, gold post must be noted as stump shade. Fig 2. Temporary on tooth 8.

Fig 5. Porcelain teeth samples showing the morphology made by author. Fig 6. Teeth samples made by author.

Fig 3. Custom shade mapping using shade tabs from the GC Initialporcelain system.

Fig 4. Shade mapping completed by technician.

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Fig. 8. Testing samples made by author: from opaque to enamel.

Fig. 9. Under UV light.

Fig. 12. Enamel Intensive applied to the Incisal third, TM05-TM04 (1:1)is applied to the middle third to give gray band affect; enamel powderswere also applied.

Fig. 10. Internal stain applied on GC Initial Pressed Ceramic to modifythe base shade.

Fig 11. Cervical Translucent applied at gingival third and middle third,and then prepared for the addition of a grey band.

Fig 7. Under UV light.

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PRODUCT OVERVIEW

The layering porcelain the dental technicianapplies to the understructure is veryimportant. We are using GC Initialporcelain. The GC Initial line has fivedifferent porcelain powder systems andpressed ceramic ingots. The five ceramicsystems are uniquely formulated for aspecific substructure, e.g. zirconia, alumina,titanium, cast alloys and pressed all ceramic.Initial MC is for porcelain-to-metalrestorations and for veneers. Initial LF isthe lower firing temperature porcelain,used for porcelain-to-metal restorations,layering on top of a pressed frameworkfabricated with the GC Initial PC ingots,and also for porcelain veneers. The otherthree powders are GC Initial ZR forzirconium restorations, GC Initial AL for

alumina restorations and GC Initial Ti forporcelain-to-titanium restorations.

The GC Initial system has the same colortabs for all the different GC Initial systems.This helps when the case has different typesof understructures because the technicianhas the same color guides. Unfortunately,shade guides are not representative of thevalue of real teeth, which is why relying onshade tab assessment alone can beproblematic. You will need special shadetabs for the opalescence, fluorescence andtranslucency of natural teeth. The porcelainsystem has its own effect powders andcolor-matching tabs.

To give maximum esthetics, the materialchoice was GC Initial Pressed Ceramics with

layering porcelain. We decided on the GCInitial PC (pressed ceramics) because itgives us a wide variety of pellet colors. Theyhave 16 Dentin shades, four bleachedshades (AO, AOO, BO, BOO with 75percent opacity), three veneer shades, fourocclusal enamel light, four occlusal enamelmilky, four translucent and five opaqueingots. The opaque ingots are valuablewhen dealing with discolored preparationsbecause the opacity is at 85 percent. Thecolors are light yellow, pale yellow, redyellow, olive and white. When using pressedceramics we can often get too muchtranslucency, so more choices are valuable.The opacity level of the Initial PC ingotsranges from 30 percent to 85 percent.

Fig. 13. An endo tool is used where white stain will be applied. Fig. 14. The crown is covered with Translucent Neutral.

Fig. 15. Sample shade test made to check furnace temperature andporcelain colors at different thicknesses.

Fig. 16. After 1st bake, check the interproximals and texture showingcorrect firing temperature.

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Following dental laboratory procedures,the central was waxed to full contour and cut back for the layering porcelain.The wax-up was sprued, invested andprepared for pressing. Ingot selection isvery important. As with all the ingotmanufacturers, a wide variety of colors are available.

After pressing, it is important that you donot overheat the pressing when cutting offthe sprues or modifying the framework.When the cut-back framework is ready forporcelain application, check your thicknessand room for layering. Look at theframework’s shade and if needed, you canmodify with internal stains. GC Initial hasINvivo, INsitu and INover stains, so you canapply stains on the pressed ceramic material

and use internally or externally on yourporcelain build-up. The coping should thenbe checked to ensure there is adequateroom for ceramic layering.

The first layer of porcelain was the Inside(IN) powders using shade IN 44 (Sand).GC Initial IN is a specially developed,highly fluorescent primary dentine thatgives the color depth.

Dentin porcelain was applied, and shadeDentine A1 was laid over the gingival thirdand middle third and Dentine B1 over themiddle third and incisal third to give thecrown optimal chroma (saturation orstrength of the hue). The color is producedby reflection from the dentine. We cutback the dentin porcelain to give room

for the mamelon effect we desired. Theenamel intensive (EI 13 red), CervicalTranslucent (CT24 yellow), and a 1:1mixture of Translucent Modifier (TM05 grey+ TM 04 yellow) porcelain powders wereapplied for effects. Enamel Effect powderswere used at the incisal area and helpedgive the natural appearance that you don’talways find with just one enamel shade.

A thin layer of Clear Fluorescence (CLF)powder was applied. The CLF was used asa thin layer between the dentin layer andenamels on top of it. This was the so-called“sclerose dentin” and brought true-to-naturedepth into the tooth color. Translucentswere applied over the CLF. They areavailable in Translucent Neutral (TN) andTranslucent Opal (TO).

Fig. 18. Adjust the mesial marginal ridge and the mesial proximaltransitional surface.

Fig. 19. Create horizontal line,

Fig. 17. Locating concave and convex areas with a pencil.

Fig. 20. Checking the texture by marking with articulation paper.

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Fig. 22. Define texture with sandpaper.

Fig. 23. The crown is naturally glazed and mechanically polished. Photoangle shows texture on gingival third.

Fig. 21. Create vertical line angle with diamond.

Fig. 24. Checking the surface texture, the photo angle shows texture onincisal third.

Fig. 25. Incisal view showing the mesial and distal marginal ridges isrelated to the incisal ridge and form part of the incisal line angle.

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Fig. 27. Before: view of temporary on tooth 8. Fig. 28. Final restoration: GC Initial Pressed Ceramics tooth 8.

On the lingual of the crown, we appliedthe Inside Dentin (IN 47 Sienna), Enamelincisal and Occlusal build-up. The crownwas taken off the model and the contactswere added. The crowns were then readyto bake. After firing, any adjustmentnecessary to complete the restoration canbe made on the solid cast.

Surface texture can affect brightness, colorsaturation, luster and more. A natural toothin its unworn state does not present anabsolutely smooth surface. In general, it may

be seen as a gentle, undulating surfacetraversed horizontally with very finegrooves. Matching the surface texture isas important as matching the shade. Iflight should reflect off a restoration in adifferent way from the neighboring teeth,even if the shade is perfect, it will give theeffect of being an artificial restoration.

An anterior tooth is more obvious whenlooking at the tooth’s surface texture.Since the texture is more evident, it willappear heavier and will immediately be

visible. The horizontal parallel ridges orgrowth lines, and the small vertical ridgesthat run parallel to the marginal ridges,help blend the restoration into the oralenvironment. If you want an estheticrestoration, surface texture is crucial.

We may not think of using a pressed-ceramicrestoration out of fear that the substructurewould not keep the gold core from shiningthrough. Today, with the different opacityof ingots and the improved layeringporcelain, this is not always true.

Fig. 26. Completed GC Initial Press Ceramic restoration.

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BioLuke S. Kahng, CDT, is the founder and owner of Capital Dental Technology Laboratory, Inc. of Naperville, Illinois. His laboratoryspecializes in fixed restorations. Its division, LSK 121, provides highly personalized custom cosmetic work. Kahng developed theLSK 121 Treatment Plan that incorporates a wax-up technique that focuses upon a biomechanical design of occlusal surfaces forreconstructive and esthetic dentistry. He has also developed a series of shade conversion table for porcelain.

Kahng clinics for GC America, Bisco, Captek and others. He is a frequent lecturer and program facilitator, and has beenextensively published in clinical and technical journals.

He is master ceramist who has trained extensively with Russell DeVreugd, CDT, Dr. Frank Spear and Dr. Peter Dawson. He iscurrently a member of American Academy of Cosmetic Dentistry. Case courtesy of Nicholas Svarnias, DDS.

Contact InformationLuke S. Kahng, CDTTel.: (630) 355-6221luke@lsk121.com

Fig 29. Final outcome: The natural smile shows how the incisal edges ofmaxillary incisors follow the curvature of lower lip.

4. Spear, F.M. “Maintenance of the Interdental Papilla Following Anterior Tooth Removal.” Pract Periodontics Aesthet Dent. 1999; 11:21-28.

5. Sorensen, J.A., Torres, T.J. Improved Color Matching of Metal Ceramic Restorations, Part 2

6. Sulikowski, Alan V., Yoshida, Aki, “SurfaceTexture: A Systematic Approach for Accurate and Effective Communication.” QDT 2003. 26:10-19.

REFERENCES

1. Kois Jr., “New Paradigms for Anterior Tooth Preparation, Rationale and Technique.” Oral Health 1998, 88:19-30

2. Magne, P., Belser, V. “Boned Porcelain Restorations.” Chicago Quintessence. 2002, 82-83.

3. Shigeo Kataoka. Nature’s Morphology. Chapter 4-5.

7. Fundamentals of Color. Chapter 3, p. 52-68.

8. Nobel Esthetics Quick Guide. Professional Build-Up Illustration. 2004.