Roberto Rossi

Case by MDT Daniele Rondoni and MDT Roberto Rossi

Full-contour or an anatomically reduced design? When we need to decide how we want to design and finish a zirconia restoration we are asked to produced, many factors need to be taken into account – from aesthetics to function and from time- to budget-related ones. As the outcomes are strongly dependent on the optical and mechanical properties of the zirconia used, however, we are convinced that the first thing to do is to select a portfolio of high-quality zirconia materials. By experimenting with them in the dental laboratory, using different designs and finishing approaches with aligned materials and by comparing the results, you will be able to select the most appropriate concepts for your everyday work. In addition, you will develop a clear idea on when to use which concept.

Our own selection

The zirconia portfolio used in our dental laboratory consists of the KATANA™ Zirconia Multi-Layered Series from Kuraray Noritake Dental Inc. It consists of three materials with a multi-layered colour structure designed to meet different needs with regard to flexural strength and translucency (KATANA™ Zirconia UTML, STML and HTML PLUS) and one material with colour, translucency and flexural strength gradation (KATANA™ Zirconia YML). Due to the favourable optical properties of this series and new effect liquids, it is often possible to opt for a full-contour design or – in the anterior region – for a slight cutback limited to the vestibular area plus a micro-layer of porcelain.

The effect liquids – Esthetic Colorant for KATANA™ Zirconia – were introduced n early 2023. They are applied to the surface of the milled zirconia to pre-treat tissue areas of large restorations, to add specific individual characteristics to the restoration or to prevent a greyish effect caused by the shining through of discoloured abutment teeth or metal parts. While most liquids are used on the outer surface of the restorations, the latter effect is achieved by applying Esthetic Colorant OPAQUE or WHITE to the intaglio.

Case example

The following case example describes the use of Esthetic Colorant in the context of producing a full-contour screw-retained implant bridge made of zirconia with a titanium bar. The zirconia part was milled from KATANA™ Zirconia YML, the vestibular morphology refined with rotating instruments and then, the vestibular, palatal and occlusal surfaces were treated with Esthetic Colorant as shown in Figures 1 and 2. The true colour effect is revealed after sintering.

Fig. 1. Frontal view of the milled zirconia structure after the application of Esthetic Colorant in the shades BLUE, GRAY, ORANGE and PINK.

Fig. 2. Occlusal view of the milled zirconia structure after the application of Esthetic Colorant BLUE, GRAY, ORANGE and PINK.

Fig. 3. Nicely pre-treated zirconia structure after sintering.

By adding some CERABIEN™ ZR FC Paste Stain and Glaze in the vestibular area and to the tissue parts, it is possible to finish this restoration in a nice way. The contact areas are always just polished to a high gloss in our approach, as it is the most antagonist-friendly way of treating the surface. As a final measure, the zirconia structure was connected to the titanium bar before it was sent to the dental office for try-in.

Fig. 4. Frontal view of the finalized zirconia part.

Fig. 5. Occlusal view of the structure after finishing.

Fig. 6. Connecting the zirconia superstructure and titanium bar.

Conclusion

With a well-selected zirconia portfolio and aligned finishing solutions, it is easy to establish concepts that allow you to respond to the needs of virtually every patient in a streamlined way. In our experience, the use of high-quality products with good aesthetic properties – a high translucency and naturally pre-shaded multi-layer structure – pays off as it allows us to reduce the thickness or do without a porcelain layer. In this way, we are able to increase the efficiency of our procedures without compromising the outcomes.

The KATANA™ Zirconia Multi-Layered Series and the new Esthetic Colorant for KATANA™ Zirconia support us in an ideal way by allowing us to efficiently produce a perfect base for whatever finishing approach we select.

Case by CDT Daniele Rondoni and MDT Roberto Rossi

Working with high-translucency, multi layered zirconia (KATANA™ Zirconia Multi-Layered series from Kuraray Noritake Dental Inc.) paves the way toward indirect restorations that are closely adapted to our patients’ needs. Reduced wall thicknesses allow for minimally invasive tooth preparations, while polished zirconia in the occlusal contact areas provides for an antagonist-friendly behaviour. All this is possible due to the high aesthetic potential and homogeneous structure of the materials, which work well with a full-contour design or slight vestibular cutback. For individualization or characterization, different options are available. The portfolio of finishing solutions from Kuraray Noritake Dental has just been complemented by Esthetic Colorant for KATANA™ Zirconia, a set of twelve dyeing liquids for the company’s multilayered zirconia. They are applied to the milled restoration surface prior to sintering.

Some readers may wonder why there is a need for effect liquids applied to pre-shaded zirconia with a multi-layered colour structure. Being aware of natural teeth’s unique play of colours stemming from the shape and shade of the dentin core, however, the reason is quite obvious: Esthetic Colorant diffuses into the zirconia structure, hence allowing us to create depth effects even in monolithic restorations. Moreover, it enables the user to pre-treat tissue areas, and even by using the liquids on cutback designs, we are able to reproduce case-specific internal optical characteristics quite easily. Our standard approach for the use of Esthetic Colorant on KATANA™ Zirconia HTML Plus is described by means of the following case example: An implant- and tooth-based twelve-unit bridge with a slight vestibular cutback design, finished with Esthetic Colorant and CERABIEN™ ZR Porcelain.

Fig. 1. Restoration with sintering support removed from the blank.

Fig. 2. Esthetic Colorant for KATANA™ Zirconia: Available shades.

Fig. 3. Frontal view of the milled restoration after the application of Esthetic Colorant. A chromatic map is not needed since the colours of the applied liquids are clearly visible.

Fig. 4. Occlusal view of the milled restoration after the application of Esthetic Colorant. The liquids were applied with the Liquid Brush Pen for Esthetic Colorant.

Fig. 5. Frontal view: Appearance of the restoration after sintering.

Fig. 6. Occlusal view: Appearance of the restoration after sintering.

Fig. 7. Beautiful translucency and mamelon structures in the incisal area.

Fig. 8. Situation after the application of a thin layer of CERABIEN™ ZR Porcelain, which creates an enamellike window effect and reveals the play of colours found underneath.

Fig. 9. Restoration after firing and glazing.

FINAL SITUATION

Fig. 10. Beauty shots…

Fig. 11. … of the final restoration.

Easy handling and application, impressive colour effects: Esthetic Colorant perfectly fits into our micro-layering approach with a cutback design adjusted to the age and needs of every patient. Being applied on the pre-sintered zirconia surface, the liquids do not require any extra heat treatment – the restoration is simply dried and then sintered as usual. Esthetic Colorant may be used instead of or in combination with internal stains, luster porcelains and liquid ceramics – whatever complements a laboratory’s existing approach to highly aesthetic zirconia restorations.