Inside Dental Technology
Mixing shades to recreate nature with IPS e.max® over zirconia
Many technicians have at least one case on the shelf that they wish would complete itself. Most often it involves anterior teeth, high expectations, and insufficient information. Daily work often continues as cases come and go, and yet that particular case seems to have a ticking mechanism audible from work or home. Without question, these cases are stressful. Recently, nonmetal restorations have narrowed the gap between success and failure in the esthetic arena. The advent of zirconia has, in a relatively short amount of time, become a mainstream choice to replace metal-supported restorations. Top-tier materials and technology have become valuable to the dental laboratory ceramist. Digital photography has provided a fast way to receive important and necessary information. And yet, re-treatments continue to stream in from dissatisfied patients and clinicians. How can these expectations be met? More importantly, can successful results be repeated?
Though most recognize that teeth are just as original and unique as human personalities, many technicians still fall into the habit of using a set formula to layer crowns. While this can be somewhat successful in the posterior dentition, it rarely works in the smile line. Form and function, proportion and color, value and translucence are all unique to the teeth of the individual to whom they belong. Maximum esthetics can only be obtained if this information is clearly represented to the ceramist. Most cases have limiting factors and they almost always have a direct effect on the lifelike properties of the restoration.
Recently, the author overheard his 4-year-old daughter explaining to her brother what their daddy did for a living. She said, “Transbrilliance is what makes it look real.” This sounded funny at first, but on further contemplation made perfect sense. That one “word” hit on one of the most troublesome problems technicians face—value.
The relationship between translucence and brilliance seems like a paradox and yet is undeniable. How can translucence be bright? Moreover, translucence suggests lower value. However, everyday technicians are faced with replicating bright teeth with deep translucence. How is this achieved? This article will show step-by-step from start to finish how a similar case was managed and layered with porcelain.
A middle-aged woman presented with an existing bridge from teeth Nos. 6 through 11, which was double abutted to laterals and cuspids. Both central incisors were missing. The chief concerns were the axial inclination of the anterior dentition, the alveolar defect in her maxilla in her edentulous region, black triangles, and the overall look of her smile (Figure 1 and Figure 2).
The diagnostic wax-up completed was attentive to the patient’s desires, paying particular attention to the axial inclination. The result was oversized teeth with gaping V-shaped embrasures leading to non-existent papilla. From a technician’s standpoint, it was clear that pink tissue was needed to replace alveolar bone, along with connective tissue and free gingiva to achieve a pleasing look.
The second wax-up (Figure 3 and Figure 4) gave the clinician a place to start with the temporary restoration. The patient wore the temporary for a number of days. On the return visit, several changes were made. After several more days, the clinician addressed a few minor changes before settling on a position. An impression was taken of the approved temporaries for the technician to use as a guide (Figure 5).
Using the cast of the approved temporaries, a Prettau Zirconia (Zirkonzahn, www.zirkonzahn.com) framework was milled (Figure 6 and Figure 7). The author chose to start from a bleach-white zirconia color to control the hue and value from a “blank canvas.”
From images sent by the clinician, shades for both the dentition and gingiva were selected (Figure 9 and Figure 10). The importance of studying the translucency and brilliance at this stage cannot be stressed enough. If value is too low here, the technician will spend time attempting to reverse the mistake with each succeeding layer that is fired.
An internal stain was then placed over the ZirLiner using essence stains (Figure 11). It is crucial to note that while staining zirconia, the stains must be at the correct consistency. If they are too wet, they will “pool” up at the margin—too dry and the true color will not be visible. The author recommends a consistency similar to glaze paste. (Note: a long drying cycle must be used when firing.) It is the author’s opinion that when building on zirconia, the sooner the coping represents the final shade and translucency, the better. The framework was then ready for porcelain.
A thin layer of A1 Deep Dentine was layered over the treated coping. This helped increase color saturation near the cervical section and to break up the silhouette of the coping (Figure 12 and Figure 13). The area over the tissue was left bare.
A1 Dentine was then built up to the beginning point of the mamelons (Figure 14). A1 Dentine was mixed 70/30 with Opal Effect 1 and layered in the same pattern, extending it incisally and laterally (Figure 15). The OE 1 provided an added amount of translucence, allowing the underlying mamelon forms to slightly show through and giving the beginning of much needed opalescence. A 50/50 mix of A1 dentine and Translucent brown/grey was layered over the gingival one third and outlining the middle mamelon (Figure 15). Opal Effect 4 was layered in a 1-mm band at the junction of the middle and gingival one third and extending up the mesial line angles to the projected incisal edge position. A1 Deep Dentine was placed along the roots of the gingiva to provide a “bony” appearance for the tissue-colored porcelain to be placed over later. The bridge was then fired.
In Figure 16, the brilliance across the middle and mesial is clearly observed. The opalescence along the distal and the brown/grey is also visible. The overall shade was matched against the shade tabs while referring to the photographs. The surface was then smoothed using a fine diamond before proceeding to the next layer.
The technician began to layer by placing a transitional mix of 50/50 dentine A1 and Transparent Incisal 1 along the distal line angle to the incisal edge (Figure 17). Using lateral segmentation, a 50/50 mix of OE 1 and TI 1 was alternated with straight dentine A1 across the incisal edge. A splinter of MM Salmon was placed at the incisal most edge of each mamelon. A 70/30 mix of OE 4 and TI 1 was layered in a band where the gingival and middle thirds meet, extending up to the mesial incisal edge. A 50/50 mix of Translucent brown/grey and clear was layered along the gingival one third. A 90/10 mix of G4 and IG 2 was placed along the border of the connective tissue.
After firing, the translucence and brilliance were easily recognizable (Figure 18). Again, the shade was checked against the shade tabs and photographs. The prosthesis was smoothed with a fine diamond in preparation for the next layer. (If the shade or value is off, this is a good time to do internal modifications using the Essence stains. For this cycle, the author prefers to fire 10 to 20 degrees cooler than a body bake without vacuum and a 30-second hold. Note that every oven is different and will require a slight modification.) It is important that the color be very close to the desired final prosthesis before proceeding to the next cycle.
The technician then placed a 50/50 mix of TI 1 and Clear over the entire surface (Figure 19). The TI 1 kept the value high while the Clear added desired translucence. A thin veneer of straight TI 1 was placed over the previous layer (Figure 20). A 70/30 mix of G4 and OE 1 was placed along the connective gingiva and straight G3 was placed along the free gingival space, creating the papilla (Figure 20). The bridge was then fired.
The result was an almost completed prosthesis with nearly accurate color and contour (Figure 21). The technician completed one more correctional bake with straight Clear before finishing and texturing. The final bake consisted of very minor color alterations before firing a glaze cycle. The bridge was now complete (Figure 22 through Figure 24). The final prosthesis was inserted and, judging from the finished photograph, the translucence and brilliance were both maintained (Figure 25).
The partnership between the patient, clinician, and technician is important in any case, but nowhere is it more in evidence than an anterior case with the potential for spectacular success or disaster. The need for information on all fronts is paramount and must be communicated. A comprehensive treatment plan must be constructed and followed while keeping the goal in sight. If the technician encounters a potential obstacle that might affect that goal, it is imperative to communicate the information to the clinician without delay. This increases the chance for success. After all, each crown is a brick in the wall of the technician we become.
The author would like to thank Dr. Joe Chichetti of Esthetic Dental in Charlotte, North Carolina, for providing the case.
About the author
LAB 33, Inc.
Winston-Salem, North Carolina