Franz Heinloth MDT

Fig. 1 Initial situation – a fracture resulted in tooth 21 becoming discolored.

In such cases, treating both teeth 11 and 21 is a proven way to achieve a harmonious appearance with regard to form, shade, structure and reflection properties. The patient, however, declined this suggestion.

Deciding on the material

Selection of the material turned out to be difficult. In the anterior region, translucent materials are especially popular for their very natural look.

Over the years, lithium disilicate, for example, has proven effective here. Nevertheless, our material of choice has become zirconia reinforced lithium silicate, or ZLS, a sophisticated high-performance glass ceramic.  In fact, we have determined that VITA SUPRINITY (VITA Zahnfabrik, D-Bad Säckingen) has better light transmitting and at the same time higher hardness properties (fig. 2) in comparison to IPS e.max CAD (Ivoclar Vivadent, FL-Schaan). Due to the dark-spotted discoloration of the tooth stump there were doubts as to whether the necessary coverage could be achieved with ZLS (fig. 3). For safety, we produced crowns from both materials, and the try-in of the raw firing showed that our worry was unjustified. Since the VITA SUPRINITY restoration also has a convincing and attractively sunny opalescent effect, in the end the decision was an easy one.  The material has an excellent basic chroma and very beautiful translucency, florescence and opalescence (figs. 4 to 6).

Fig. 2: The high-performance glass ceramic consists of zirconia reinforced lithium silicate.

Fig. 3: Preparation for a full ceramic crown.

Fig. 4: The translucence,

Fig. 5: … fluorescence and …

Fig. 6: … opalescence of a VITA SUPRINITY crown

Block selection
To determine the shade we produced our own shade tabs.  The advantage here is that both T (translucent) as well as HT (high translucent) versions can be taken into account, making it possible to optimally match the shade. VITA SUPRINITY is available in the VITA SYSTEM 3D-MASTER shade 0M1 as well as in the seven classic VITA shades A1, A2, A3, A3.5, B2, C2 and D2. In this case we decided to go with a T block in A2 (fig. 7).

Fig. 7: Shade determination with an internally produced VITA SUPRINITY shade tab.

Digital workflow The digitalization of the jaw situation and preparation was done with an inEos-Scanner; design was done with inLab Software (both from Sirona Dental, A-Wals) in biogeneric reference mode (figs. 8 to 13). When creating the copy line on the reference tooth, here tooth 11, a larger rather than a smaller area should be marked for the replication if there is some uncertainty. It is important that no artifacts are included and that the copy line is not lower than the preparation margin (fig. 9). Otherwise, this will lead to deformation in the new tooth design. We worked with the latest software, version 4.2.5, and set the parameter for the spacer at 120 μm instead of 80 μm, which was common in the past. In the virtual articulator, standard values were used, since the attending dentist articulated using average values. Figure 12 shows the check of the incisal guidance as it would be with the lower jaw inserted in the articulator.

Fig. 8: Digitalization of the jaw

Fig. 9: Drawing the copy line on the reference tooth

Fig. 10: Design in biogeneric reference mode

Fig. 11: Virtual articulator

Fig. 12: Check of the incisal guidance

Fig. 13: Milling preview

When positioning the crown in the virtual block during the milling preview, make sure the sprue is not set approximally. The desired milling mode was chosen from the three available options: normal mode, fast mode and 2 stage mode. The last option was used in this case. The name of the mode indicates that during processing with inLab MC XL (Sirona Dental) grinding is first done with high contact pressure and then all contours are given a second finishing pass.

The gentle and precise finishing allows you to achieve a high fitting accuracy and the risk of edge chipping is further reduced. While this means the processing time increases to approx. 25 minutes in comparison to approx. 12 minutes in normal milling mode, it still makes economic sense as long as it is within the delivery time.

The dental technician is the most expensive unit in a business and having the technician re-fire damaged ceramic material uses up valuable time. Thus, whenever possible, processing should be relegated to machines.

Rework and individualization

Figure 14 shows the milled crown after fitting on the model and before crystallization firing. The semi-transparent structure is a real advantage here.

ZLS is comparatively stable. However, ceramic always remains brittle and it is somewhat fragile in this state. Those who like to take the safe route should only grind the sprue and fit it intercoronally before firing.

In this case, the crown was also reduced using the cut-back technique.

Figure 15 shows the result after crystallization. During the cut-back process, you should work with a water-cooled turbine and low contact pressure and avoid generating any heat.

Fine-grain diamond tools such as Komet Zr abrasives (Gebr. Brasseler, D-Lemgo) are recommended.

In addition, VITA SUPRINITY polishing sets offer various polishing instruments especially developed for pre- and high-gloss polishing of zirconia reinforced lithium silicate restorations in dental practices and laboratories (fig. 16).

Fig. 14: Fitted VITA SUPRINITY crown before crystallization firing.

Fig. 15: Crown made of zirconia reinforced lithium silicate after crystallization and minimal reduction in the area of the incisal edge.

Fig. 16: Polishing instruments designed for ZLS

Veneering was done with VITA VM 11, a veneering ceramic especially developed for ZLS (fig. 17). The low-fusing fine-structure feldspar ceramic range is designed for individualizing with the efficient cut-back technique. In this case, only a little incisal material was baked on. Figure 18 shows the crown in the patient's mouth during the try-in of the raw firing. It was determined that the restoration was cervically somewhat too bulbous and that an especially distally trapezoid form should be aimed for. At the same time the interdental papilla required somewhat stronger support. At the following try-in, we were able to fit the crown definitively.

Figure 19 shows the final result in situ.

Fig 17: VITA VM 11 for individualization following use of the cut-back technique.

Fig. 18: Try-in of the raw firing – small form corrections needed to be made.

Fig. 19: Esthetic final result

Summary

Altogether, ZLS proved convincing in terms of both esthetics and processing characteristics. VITA SUPRINITY is a CAD/CAM restoration material that can be superbly crafted, and thanks to its special properties it is predestined for restorations that narrow to thin edges.  Excellent results with minimal effort can be achieved with VITA VM 11 individualization with the cut-back technique. We have often achieved good results in the anterior region only by performing shade individualization with VITA AKZENT Plus stains.

Contrary to our initial assessment, the clinical case shown here proved to be quite simple in retrospect.  Thanks especially to the outstanding properties of VITA SUPRINITY, it was possible to efficiently solve the esthetic demands of the task. The expectations of the dentist and the patient were fully satisfied. While the discoloration of the natural tooth substance does show through the soft tissue, it is reliably covered by the VITA SUPRINITY crown.  This is due to the light-reflective properties of the material, which allows the surface to appear very life-like despite the unobtrusively formed texture individual to this patient.

Franz Heinloth MDT

Munich, Germany

•  1972 Certification as a Dental Technician, Freising
• 1975-1987 Employed in various dental practice laboratories
• 1987 Certification as a Master Dental Technician, Munich
• 1987-1989 Executive Director of Labor Creativ, Munich
• 1989-1991 Dentallabor Heinloth-Breuer, Munich
• 1992-1999 Dentallabor Heinloth, Gemering
• 1999-2007 Dentallabor Heinloth, Tutzing
• Since 2004 certified inLab Trainer
• 2008-2011 Dentallabor Heinloth, Munich
• 2011 Head of VITA Innovation Professionals
• Since 2011 Digitale Zahnmanufaktur Cera-Technik, Munich

We would appreciate a sample copy of any reprints.

VITA Zahnfabrik H. Rauter GmbH & Co. KG

Based in Bad Säckingen, Germany, VITA Zahnfabrik H. Rauter GmbH & Co. KG has been developing, manufacturing and selling consistently high-quality innovative solutions for dental prosthetics for over 90 years.  Users in over 125 countries benefit from the analog and digital product solutions manufactured by VITA for shade determination, shade communication, shade reproduction and shade verification, which are accompanied by a comprehensive range of service options. In the last 90 years, the interaction between tradition and innovation has transformed dental visions into reality, with VITA Zahnfabrik playing a fundamental role in shaping the future of dentistry.