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LabLine magazine is an English language publication catering to the field of lab-side dentistry. It provides comprehensive coverage of the latest techniques and trends in dental laboratory technology and materials, showcasing them via sophisticated, challenging and aesthetic clinical cases done by some of the most known experts in Europe. With its expertly curated content, LabLine serves as an invaluable resource for dental professionals seeking to enhance their knowledge and stay at the forefront of the industry.

In the SPRING edition of LabLine you can find a wonderful AESTHETIC CASE by Mikel Villar Gonzales and DT Pilar Ballesteros Galan. The patient, a 21-year-old female had a hypoplasia defect on her permanent teeth, 1.1 and 1.2., presumably due to trauma on her deciduous anterior teeth. Click the image below and check out how the case was done!

Shortly before KATANA™ Zirconia ML was launched at the IDS in Cologne ten years ago, I had the pleasure to be invited to Japan. We visited the KATANA™ Zirconia production facilities and learned from Kazunobu Yamada and Takuro Nagura how the new material worked. So far, all dental zirconia I had used was white and quite opaque.

I was immediately impressed by the complexity of the production procedure including all the measures taken by Kuraray Noritake Dental to provide for an extremely high material and blank quality. The blanks appeared to have an extremely homogeneous multi-layered structure and a high density responsible for stable edges and smooth surfaces. What we were told in the manufacturing plant was confirmed by Kazunobu Yamada, who shared his experience and showed us several full-contour cases. I was pleasantly surprised by the fact that he was able to produce impressive outcomes without adding any colour. Moreover, Kazunobu Yamada was obviously able to polish the surface of his restorations within seconds. The perfectly smooth surface would allow us avoid the use of glaze, which usually wears off very quickly, leaving a potentially rough surface that may harm the antagonist.

Based on what I had learned in Japan, I went back to Italy and started experimenting with the amazing new material. While Kazunobu Yamada had identified KATANA™ Zirconia ML as the solution for monolithic restorations in the posterior area, I started using it in every region of the mouth – with different design concepts from full-contour to micro-cutback with micro-layering in the vestibular area. The occlusal contact area was always held in plain, polished zirconia.

Fig. 1. Early example of anterior restorations made of KATANA™ Zirconia ML individualized with CERABIEN™ ZR using the new micro-layering technique.

Fig. 2. Possible cutback design.

During the testing period, I learned a lot about the new zirconia, which was so different from earlier generations. The most important insight was that that the processing conditions have a huge impact on the final outcome. Kuraray Noritake Dental provided valuable support e.g. in the form of sintering protocols and processing and finishing recommendations. This helped me develop my own workflow and concept based on a full-contour design in the posterior and different micro-cutback options with micro-layering in the anterior region. For me, this is a perfect combination of the new type of zirconia (KATANA) and the traditional porcelain material (CERABIEN™ ZR Luster Porcelain and Internal Stain).

In May 2013, at a meeting of the Noritake Study Club in Florence, Italy, I presented the new approach for the first time. Many colleagues were enthusiastic about it and started adopting it. While further developments like more translucent (cubic) material variants and a new generation multi-layered zirconia with a flexural strength and translucency gradient increased the application options and aesthetic potential, micro-layering became a truly popular approach used by dental technicians all over the world. In 2016, it was recognized as a relevat workflow during a closed meeting of the European Academy of Aesthetic Dentistry.

Fig. 3. Perfectly polished palatal zirconia surfaces of anterior restorations.

Fig. 4. More recent case showing a patient who received restorations made of KATANA™ Zirconia STML …

Fig. 5. … finished with CERABIEN™ ZR Internal Stains and a micro-layer of CERABIEN™ Luster Porcelain LT1.

But what is the major reason for the success of the concept and of multi-layered zirconia with KATANA™ Zirconia ML as the pioneer? In my opinion, it should not be implemented for greater simplicity or economic reasons, as one might assume at first thought. The time saved in the layering procedure should be spent on other tasks such as surface texturing and a fine-tuning of the processing procedure. The real benefit is that KATANA™ Zirconia ML and its successors allow for better solutions adapted to the patient’s needs. First of all, they enable us to save natural tooth structure, as the required wall thickness is reduced. They also offer mechanical advantages, as chipping is avoided, and the occlusal contact area remains smooth over time. In my dental laboratory, we changed our workflows completely and – preferring a more conservative approach whenever indicated for the case on hand – we often abandon full layering.

KATANA™ Zirconia can be considered as a great contribution to the digital workflow in the dental laboratory and office, which increases the efficiency of prosthodontic procedures. With the KATANA™ Zirconia Multi-Layered series, it is easy to hold our promise of delivering the best possible quality and aesthetics. The reason is that the materials support us in an ideal way, delivering the perfect combination of tradition and innovation.

Case by Michal Jaczewski

This patient came to the clinic to improve the aesthetics of her smile. After an aesthetic and functional analysis, it was decided to align and restore the teeth using a minimally invasive protocol with flowable composite.

INITIAL SITUATION

Fig. 1. The patient had worn teeth, visible abrasion, erosion and crowding in the lower arch.

Fig. 2. Situation after orthodontic treatment, full arch ready to restore.

Fig. 3. A silicon mould is used for the Flowable Injection Technique to restore the teeth with flowable composite. The silicone injection mould had injection channels prepared and was placed to check for proper fit.

Fig. 4. For this case it was decided to use CLEARFIL MAJESTY™ ES Flow Low in shade XW.

Fig. 5. Teflon tape was used, in order to separate the teeth.

Fig. 6. The restoration is completely additive; the teeth are not prepared at all. Total etching of the enamel is the best pre-treatment in this situation. K-Etchant Syringe (35% phosphoric acid) was applied for 10 seconds.

Fig. 7. A surgical suction tip was used in order to carefully remove the phosphoric acid gel and protect the isolations on the teeth. Followed by rinsing off completely with water in the usual manner.

Fig. 8. Each tooth was gently air dried for 10 seconds. CLEARFIL™ Universal Bond Quick was applied with a rubbing motion without additional waiting time. Followed by drying of the entire bonding treated surfaces by blowing mild air for more than 5 seconds until the bonding no longer moves.

Fig. 9. Light curing of each bonded tooth for 10 sec.

Fig. 10. The silicon mould is used to inject CLEARFIL MAJESTY™ ES Flow Low (optimal flowability, and properties for a case like this).

Fig. 11. Using the protocol „Treat one, skip one” several teeth are restored simultaneously.

Fig. 12. Situation directly after first round of injections.

Fig. 13. Situation after restoring all teeth, before polishing.

Fig. 14. To create a natural gloss the following polishing protocol was used: 1.) Sof-Lex™* discs, 2.) CLEARFIL™ Twist DIA for Composite polishing wheels, 3.) diamond paste and finally zinc oxide paste.

*Not a brand name of Kuraray Noritake Dental.

Fig. 15. High-shine results after polishing.

FINAL SITUATION

Fig. 16. Final restoration, immediately after treatment.

Fig. 17. Final restoration after 2 days.

Dentist:

MICHAL JACZEWSKI

Michał Jaczewski graduated from Wroclaw Medical University in 2006 and today runs his private practice in the city of Legnica, Poland. He specializes in minimally invasive dentistry and digital dentistry and is the founder of the Biofunctional School of Occlusion. Here he lectures and runs workshops with focus on full comprehensive patient treatments.

Interview with Yoshihisa Yamada
General Manager, Technology Division of Kuraray Noritake Dental Inc.

KATANA™ Zirconia ML was introduced ten years ago, at the IDS 2013 in Cologne, as the dental industry’s first zirconia product with a multi-layered colour structure. Since that event, KATANA™ Zirconia ML blanks have become very popular. Continued development efforts have led to the current line-up of multi-layered materials, KATANA™ Zirconia UTML, STML and HTML PLUS, and our latest product – KATANA™ Zirconia YML. Our new technology with colour, translucency and strength gradation is found in KATANA™ Zirconia YML.

Photo credits to MDT Giuliano Moustakis.

How important was the invention of the Kuraray Noritake Dental’s original multi-layered technology for the dental market?

Our impression is that the material has had a significant impact on the dental market. Being the first zirconia material with a multi-layered colour structure, KATANA™ Zirconia ML was our first product of its class to offer the properties needed for the efficient production of full-contour zirconia restorations with a natural look. Before its introduction, the “full-contour zirconia” concept had not been widely accepted due to the aesthetic properties of the zirconia materials available so far: Many of them lacked the desired level of translucency, while others needed to be treated with dyeing liquids or stains in a complex procedure to obtain a natural shade appearance. With the launch of multi-layered zirconia blanks, which successfully added natural colour gradation to the structure, aesthetic full-contour zirconia restorations started to become popular among dental technicians worldwide. The high potential of the technology was confirmed at the IDS 2013 show, when we saw not only end-users, but also engineers from competing companies come to look at this product.

4-layer colour structure of KATANA™ multi-layered discs.

Photo credits to MDT Daniele Rondoni.

What changes were driven forward by the introduction of KATANA™ Zirconia ML?

After the introduction of KATANA™ Zirconia ML, many companies started developing multi-layered zirconia discs, creating a new dental product category with an added technical and clinical value. We are convinced that the invention of Kuraray Noritake Dental has played a major role in the shift from zirconia exclusively used as a framework material to alternative approaches including full-contour zirconia restorations. If only monochromatic zirconia discs had been available, we imagine that an increased number of dental technicians would have embraced the concept of using liquid colourants to achieve a natural appearance of full-contour crowns and bridges. That would have prevented monolithic zirconia restorations from becoming as popular as they are today.

How did the KATANA™ Zirconia ML technology evolve over the past ten years?

Based on our unique core technology developed for inventing KATANA™ Zirconia ML, we have been continuing making efforts to create even better products. One of Kuraray Noritake Dental’s great strengths is its ability to develop all the raw materials for its zirconia products inhouse. This makes it possible for us to adjust the boundaries between the layers as inconspicuously as possible, even when discs consist of multiple layers. This enabled us to provide multi-layered discs with the required strength and aesthetic qualities, and with a stable, predictable shrinkage rate. In the past ten years, we have focused on adding new materials with different levels of translucency and strength to offer a portfolio that meets the demands of virtually every dental technician, practitioner and patient.

For example, the advent of KATANA™ Zirconia STML, which has even better aesthetic qualities than KATANA™ Zirconia ML, has made it possible to use it all by itself to create highly aesthetic restorations, with no need to characterize or individualize the restorations. Of course, if you use KATANA™ Zirconia Multi-Layered discs and treat the restorations with a surface staining agent, such as CERABIEN™ ZR FC Paste Stain, you can create even more aesthetic restorations in a shorter time.

What are the benefits of Kuraray Noritake Dental’s multi-layered technology, as compared with other manufacturer’s solutions?

KATANA™ Zirconia multi-layered discs offer the advantage of delivering the proper colour even when they are sintered at high speed. There are two reasons for this. First, we developed unique raw materials with suitable characteristics for high-speed firing. This allows the creation of restorations with the same strength, stability, and aesthetics to be achieved after both short- and long-time firing. The second reason is that we possess the technical know-how concerning excellent shading that Noritake Dental Supply, one of Kuraray Noritake Dental’s predecessors, cultivated during its many years spent developing ceramic materials. Noritake Co., Ltd., parent company of Noritake Dental Supply, is a long-established ceramic manufacturer that is famous for its tableware and other outstanding products. It is this background that allows us to properly control pigment coloration using our inorganic pigment know-how and to provide unique firing schedules. These two strengths enable us to bring unique advantages to our products. That is, they remain stable and retain appropriate colouration even under rapid firing schedules.

CERABIEN™ ZR FC Paste Stain being applied to KATANA™ Zirconia restoration.

Photo credits to MDT Roberto Rossi.

How did you manage to shorten the sintering times so significantly, resulting in your speedy sintering with uniform protocols?

When shorter sintering times became possible, Kuraray Noritake Dental recommended that KATANA™ Zirconia ML be sintered for seven hours. After that, when a new furnace claiming being capable of short-time firing was launched, we used it to fire KATANA™ Zirconia ML on a trial basis. We found, happily, that our zirconia material was uniquely compatible with rapid firing. This was the beginning of our full-fledged study of short-time firing of our zirconia material. You could say that we began investigating short-time firing almost by accident. Then, while developing KATANA™ Zirconia STML and KATANA™ Zirconia UTML, successors of KATANA™ Zirconia ML, we focused on incorporating short-time firing into their features and made various adjustments, finally achieving the optimal combination of factors for the successful short-time firing of zirconia.

What are the benefits of Kuraray Noritake Dental’s second-generation multi-layered technology, as compared with other manufacturer’s solutions?

One advantage of KATANA™ Zirconia YML is that it can be applied to treat a wider range of cases without complex limitations on position within the disc. The reason: it delivers this high level of aesthetics while still maintaining great strength. This advantage of being appropriate for a wider range of cases also simplifies inventory management. In addition, users benefit from our expertise in developing raw materials and reproducing colour with ceramics. This expertise enabled us to develop a zirconia product in which each layer has a different level of translucency, while great strength and admirable aesthetics are maintained throughout the whole blank.

The sintering recommendation is only a guideline; some adjustments may be required depending on each individual furnace. If the furnace cannot be set according to the 54- or 90-minute sintering schedule, speed sintering cannot be used.

* The restorations may be removed at 800°C or less depending on the circumstances.
** For the sintering schedule of KATANA™ Zirconia HT, please refer to the Handy Chart in product packaging.

Is it really possible to address every case using only KATANA™ Zirconia YML?

For every case that can be treated either with KATANA™ Zirconia STML, KATANA™ Zirconia UTML, or KATANA™ Zirconia HTML PLUS, KATANA™ Zirconia YML is also an option. Hence, it is possible to use only KATANA™ Zirconia YML for all your zirconia cases – which is probably one of the reasons for its great popularity. It features both great strength and excellent aesthetics, and – being so versatile – it helps simplify inventory management. Of course, Kuraray Noritake Dental’s other multi-layered materials feature outstanding properties as well. Depending on the features you need, it would also be an option to select from these products - KATANA™ Zirconia STML, KATANA™ Zirconia UTML, or KATANA™ Zirconia HTML PLUS – to realize your ideal restorations.

KATANA™ Zirconia YML, finished with CERABIEN™ ZR.

Photo credits to MDT Giuliano Moustakis.

Why is the KATANA™ brand in general so popular among dental technicians around the world?

We think that dental technicians choose KATANA™ because they find that they can create highly aesthetic restorations using simple, straightforward steps.

Is there any further development potential in multi-layered technology?

On the basis of our technical know-how, there is always room for improvement. That is why we never stop innovating and listening to the voice of our customers. Developing what supports them in improving their outcomes while providing for more predictable, less stressful procedures is our ultimate goal. Right now, we expect to develop products with even greater strength, increased translucency, and outstanding aesthetics that will have a natural look resembling real teeth, even when the material used is full-contour zirconia.

Dentist:

YOSHIHISA YAMADA

JUST COLOR: ESTHETIC COLORANT FOR KATANA ZIRCONIA

The natural tooth impresses with wonderful light-optical effects - characteristic features that result from the inner structure of the tooth. Imitating these specific effects in zirconia restorations with the staining technique or micro-layering has shown limitations so far. Kuraray Noritake has addressed this problem. Based on solid research and development work, an amazingly simple solution was created - Esthetic Colorant for KATANA Zirconia.

Mr. Stratos Chatzichristos CDT will present Esthetic Colorant in detail in this online webinar. He will show how the aesthetically individual effect of a zirconia restoration can be intensified with the new effect liquids and will showcase practical application and material science basics. Learn how to achieve a zirconia restoration with truly impressive aesthetics.

Topics:

•    basics about Esthetic Colorant for KATANA Zirconia
•    differences to traditional staining and infiltration solutions
•    areas of application of Esthetic Colorant
•    achieving a true color effect
•    masking effect for the zirconia framework (discolored stumps or metallic abutments)
•    economic advantages of using Esthetic Colorant
•    material basics of zirconia

PANAVIA™ V5 is the strongest dentin bonding cement we ever developed. It is our most esthetic cement and comes in five beautiful shades. There is no better way to durably cement your crowns, single-wing cantilever bridges and veneers. If you work in a lab? It’s the most reliable way to cement your implant abutments too.   

By Magdalena Osiewicz, DDS, MSc, PhD

Fig. 1 Defective composite resin restoration in molars.

Fig. 2 Application of CLEARFIL™ SE BOND 2 to cavities.

Fig. 3 Restoration of the cavities with CLEARFIL MAJESTY™ Posterior in the A2 Classic shade.

Fig. 4 Final restorations of Class I and II with CLEARFIL MAJESTY™ Posterior and polish with CLEARFIL™ Twist DIA.

CLEARFIL MAJESTY™ Posterior is a resin composite with high strength and great optical properties developed for posterior restorations and suitable even for the most demanding patients. Figure 1 shows the initial clinical situation with insufficient resin composite restorations in the lower molars. After removal of the old fillings, the cavities were treated with CLEARFIL™ SE BOND 2 (Figure 2).

Then, I restored them with CLEARFIL MAJESTY™ Posterior in the A2 Classic shade (Figure 3). The fissures were highlighted with brown color modifier. Finally, finishing was performed in three steps: The excess of composite resin was removed with a fine-grained diamond bur. Final contouring was accomplished with a carbide bur, before CLEARFIL™ Twist DIA was used to obtain a natural gloss (Figure 4).

CLEARFIL MAJESTY™ Posterior is characterized by high mechanical strength, hardness and bending strength, a low coefficient of thermal expansion, low polymerization shrinkage and good aesthetics. Due to these features and a reliable long-term behavior, CLEARFIL MAJESTY™ Posterior should have a place in every dental office for direct posterior restorations. Excellent outcomes are achievable and therefore I recommend its use.

Dentist:

Magdalena Osiewicz, DDS, MSc, PhD

Department of Integrated Dentistry, Jagiellonian University, Krakow, Poland.

Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.

Department of Integrated Dentistry, Jagiellonian University, Krakow, Poland.

Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.

At Kuraray Noritake Dental Inc. we are proud that our products are being developed using innovative technologies, paying attention to detail and keeping in mind the needs of our customers.

We are committed to offering outstanding products that provide dental professionals with the flexibility for self-expression and creativity, adding value and delivering superb aesthetic results to each and every procedure.

Usability, simplicity and, of course, quality always in mind - providing dental professionals with materials that will make their daily practice stress free.

As a prove that our products meet the needs of dentists and lab technicians alike, we are happy to share with you the EC Certificates of Full Quality Assurance System that we have received from The Notified Body.  Those can be downloaded below.

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