We are pleased to share with you short training videos for CERABIEN™ ZR (CZR) porcelain.

Check out the below working steps and learn more about how to achieve outstanding aesthetics using this tried and proven material.

It is strong, it is pre-shaded like natural teeth, and it is reliable: KATANA™ Zirconia HTML, the highest strength version among KATANA™ multi-layered zirconia series. Now, Kuraray Noritake Dental Inc. has carefully optimized the product to further improve its optical properties and to harmonize the sintering schedules with all other materials of the KATANA™ Zirconia Multi-Layered Series.

The new KATANA™ Zirconia HTML Plus offers all popular properties of its predecessor, including the multi-layered colour structure and uniform strength distribution throughout the blank. It is suitable for a variety of indications including long-span bridges with a minimum wall thickness of just 0.4 mm in the anterior and 0.5 mm in the posterior region. This allows for minimally invasive preparations, while the user may choose between a monolithic, cut-back or framework design combined with the preferred finishing technique.

The PLUS refers to additional benefits like the material’s improved optical properties: KATANA™ Zirconia HTML Plus offers an increased translucency of 45 percent (compared to 43 percent KATANA™ Zirconia HTML) and an even more natural shade appearance of the manufactured restorations. “As the colour of the restorations appears deeper, more vivid and more saturated, and the translucency is closer to that of natural teeth, a great optical integration is achieved straight away. This leads to a reduced finishing effort”, says Mathias Fernandez Y Lombardi, EU Scientific Manager Dental Ceramics & CAD/CAM Materials at Kuraray Noritake Dental. At the same time, the high flexural strength (1,150 MPa) is maintained, providing for an unlimited range of indications.

Like its predecessor and all other materials of the KATANA™ Zirconia Multi-Layered Series, KATANA™ Zirconia HTML Plus is the result of an in-house development, powder compilation and blank production process that is able to control every detail. This enabled our specialists to achieve a precise alignment of the desired properties, while maintaining a high blank quality that leads to the accurate milling results with smooth surfaces and regular edges users of KATANA™ Zirconia HTML are familiar with.

The unique powder composition and specific in-house blank production procedure also allowed us to streamline the sintering protocols. For single-tooth restorations and bridges with up to three units, three different protocols are available: a 54-minute high-speed sintering programme specifically developed for remake and rush cases, a 90-minute schedule and the traditional seven-hour sintering programme. The latter is also suitable for long-span restorations.

These three options and identical schedules are available for KATANA™ Zirconia HTML Plus, KATANA™ Zirconia UTML, KATANA™ Zirconia STML and the new KATANA™ Zirconia YML with additional flexural strength and technical translucency gradation. With this feature, it becomes extraordinarily easy to standardize procedures despite an indication-specific selection of the best-suited KATANA™ Multi-Layered Zirconia.

Mathias Fernandez Y Lombardi concludes: “KATANA™ Zirconia HTML Plus is completely in line with our philosophy of developing products that support their users in streamlining and simplifying procedures without limiting choices. Users may choose from a whole range of highly specialized or universal zirconia solutions, may opt for their preferred design and finishing technique, and can select the sintering protocol that suits their individual needs. At the same time, the manual effort is reduced and the risk of starting the wrong sintering programme is eliminated.”

One for all: With KATANA™ Zirconia YML (yttria multi-layered), Kuraray Noritake Dental Inc. has launched a true allrounder covering traditional and new zirconia indications. At the KATANA™ Zirconia YML Virtual Kick-Off Symposium on July 3, 2021, professionals from the clinical and technical field as well as scientific experts from Kuraray Noritake Inc. provided insights into the properties and benefits of the innovation. We had a conversation with three of them about the specific features of KATANA™ Zirconia YML and its potential role in the dental practice and laboratory. Mathias Fernandez Y Lombardi, EU Scientific Manager Dental Ceramics & CAD/CAM Materials, provided insights from inside the company, while Prof. Dr. Florian Beuer MME, Charité – Universitätsmedizin Berlin and MDT Nondas Vlachopoulos, owner of the dental laboratory AestheticLab in Athens, shared their external perspectives.

Prof. Dr. Florian Beuer MME and Mathias Fernandez Y Lombardi during the conversation at the Kick-Off Symposium in Munich.

MDT Nondas Vlachopoulos virtually attended the meeting.

What are the most important features and benefits of the new KATANA™ Zirconia YML?

Mathias Fernandez Y Lombardi: KATANA™ Zirconia YML is a 5^th generation zirconia featuring next-generation multi-layered technology: it offers colour, translucency and flexural strength gradation in one disc – for a virtually unlimited indication range. As it may be used as the only zirconia or even ceramic CAD/CAM material in a laboratory or milling centre, it is designed for everyone who would like to simplify and standardize laboratory procedures. It may be sintered within 54 minutes, offers a high accuracy of fit and may be finished using time-saving techniques.

The new discs presented at the KATANA™ Zirconia YML Virtual Kick-Off Symposium.

Multi-layered structure of KATANA™ Zirconia YML.

What are the benefits of using a single zirconia for every indication from the dental technician’s perspective?

Nondas Vlachopoulos: The use of a universal zirconia solution with a high aesthetic potential and well-aligned mechanical properties allows dental technicians to reduce their inventory and streamline their procedures – from designing to finishing. Nowadays, we all know that, in order to optimize the outcomes, it is essential that we develop a deep understanding of a material’s properties, respect its design parameters (like minimum wall thicknesses) and adhere to the sintering protocols. It is much easier to accomplish this for a single material than for many different ceramics, and the potential for errors is minimized with a single-material approach. With KATANA™ Zirconia YML, this approach enables us to produce very different outcomes depending on where the restoration is placed in the multi-layered blank.

What are the benefits of using KATANA™ Zirconia YML as the only ceramic material from the dental practitioner’s perspective?

Florian Beuer: To my mind, the most important benefit of using a single zirconia every time lies in a simplified documentation. When different ceramic materials are used in the dental laboratory, we need to keep track of the material selected in every single case. Only in this way, it is possible to make the right cementation decisions (regarding cement selection and the appropriate pre-treatment of the restoration). In addition, when it comes to failure of the restoration, we need to know which material was used to prove that it has been processed correctly and is suitable for the actual indication. This is much easier when a single material is used every time. Zirconia is predestined for this approach as it is forgiving, supports minimally invasive preparations and – in case of KATANA™ Zirconia YML – almost everything can be done with it.

What are the secrets of KATANA™ Zirconia YML that allow for excellent treatment outcomes despite the one-for-all approach?

Mathias Fernandez Y Lombardi: KATANA™ Zirconia YML is based on a completely new, seamless multi-layer technology combining different, newly developed raw materials with varying yttria concentrations in a single blank. The inhouse development of the powders and their precise adjustment of each other in terms of properties like shrinkage and coefficients of thermal expansion are prerequisites for a smooth transition from one layer to the next. Only if the layers are very well integrated, it will be possible to reliably produce even long-span restorations with a delicate design, perfect fit and flawless aesthetics (without transition lines). The aesthetic properties were also optimized by integrating clinical instead of purely technical translucency.

Please explain the term clinical translucency.

Mathias Fernandez Y Lombardi: Usually, translucency of dental materials like zirconia is measured in its white, pre-shaded state. This so-called technical translucency value is increased by adding yttria to the formulation, which makes the zirconia itself appear brighter (increasing the whiteness). The translucency of the final restoration, however, is also affected by pigments and other additives in the formulation. Consequently, monolithic restorations made of different materials with the same technical translucency value may vary widely in terms of their actual, clinical translucency, which affect the overall aesthetic potential. The formulation of KATANA™ Zirconia YML has been optimized by carefully selecting and combining the right additives to obtain a natural, tooth-like translucency.

Translucency and shade appearance of KATANA™ Zirconia YML (left column) compared to various other 5^th generation zirconia materials.

Nondas Vlachopoulos, is this measure of optimizing the clinical translucency a key feature enabling the one-for-all approach of KATANA™ Zirconia YML?

Nondas Vlachopoulos: The positive effect attributed to this measure is noticeable, as KATANA™ Zirconia YML has a particularly warm and natural appearance especially in the body area some other materials with flexural strength gradation are lacking. This leads to an exact colour match with the VITA classical A1-D4 shade guide, and reduces the need for manual shade adjustments. This is important for a one-for-all approach, as the material should be a perfect basis for the production of monolithic restorations, which are not covered by a thick porcelain layer able to mask any imperfections. However, there is another key feature that facilitates the zirconia’s use for virtually every indication: Its exceptional design flexibility. It enables users to control the translucency and overall aesthetics by positioning the restoration quite freely within the blank. For restorations with up to three units, there is a complete freedom of placement. Larger restorations with four or more units need to be positioned in a way that at least 50% of the connector cross-section is in the bottom half of the disc. This is easily accomplished and gives us optimal options to exploit the various properties of each layer depending on the aesthetics and strength needed in each specific case.

Positioning guidelines for KATANA™ Zirconia YML.

What is the recommended finishing procedure?

Mathias Fernandez Y Lombardi: In principle, all designs and finishing options are available for KATANA™ Zirconia YML – from a monolithic design individualized with liquid ceramics to microlayering after a minimal vestibular cutback or even full ceramic layering on frameworks. As the aesthetic potential of the zirconia is already high, however, we believe that in most cases, the first option is absolutely sufficient. In this case, a monolithic restoration is milled and the surface subsequently treated with our liquid ceramic system CERABIEN™ ZR FC Paste Stain. The pastes are easily applied in ultra-thin layers, very well controllable and wear resistant.

Anterior and posterior crown made of KATANA™ Zirconia YML after sintering (left part) and after sintering and finishing with CERABIEN™ ZR FC PASTE STAIN (right part).

Nondas Vlachopoulos, what is your preferred finishing procedure for restorations made of KATANA™ Zirconia YML?

Nondas Vlachopoulos: In the posterior area, I often opt for monolithic restorations individualized with CERABIEN™ ZR FC Paste Stain. The technique leads to beautiful outcomes a large majority of patients would love to see even in the anterior region. However, as orders for the production of anterior restorations coming my way are usually placed by clinicians and patients with the highest possible aesthetic demands, I often go for a framework design and full porcelain layering with CERABIEN ZR Porcelains. The materials (like EX-3 portfolio for metal frameworks) are based on synthetic feldspathic porcelain with a structure and particle distribution very similar to natural dentin and enamel. All in all, I like the fact that I can select the most suitable finishing technique for every individual case, and I believe that it is often possible to reduce the finishing effort to a minimum.

Clinical translucency, design flexibility, mechanical properties: Apparently, the differences between the available zirconia materials – even of the 5^th generation – are huge. How can users ensure that the material they select is of high quality and offers favourable mechanical as well as optical properties?

Florian Beuer: When the first-generation zirconia materials appeared on the dental market, laboratory testing revealed that there are huge differences in quality between materials of different manufacturers. Although independent studies comparing the properties and behaviour of 5^th generation zirconia are still scarce, it may be assumed that differences do exist. My recommendation is to select a several materials from well-known manufacturers supporting clinical studies, compare the study results already available, and test the selected options in the laboratory setting. Directly comparing design concepts, the processing quality and final appearance will most likely reveal which material is a dental technician’s favourite. I am sure that KATANA™ Zirconia YML is among the materials worth being tested.

Thank you for this insightful conversation.

A while ago Mr. Takuro Nagura of Kuraray Noritake Dental put in an appearance at the Mardent Dental Trade event in Breda to provide some practice-oriented information to the attending dental technicians about the application of CERABIEN ZR FC Paste Stain in combination with KATANA™ Zirconia. The result was a fruitful afternoon, filled with questions, insights and tips.

Those in attendance were all dental technicians with ample experience of working with KATANA™ Zirconia. Mr. Takuro Nagura was therefore able to enjoy the experience of being surrounded by a group of enthusiastic KATANA™ fans, all of whom also use Noritake porcelain and PANAVIA™ V5 to their full satisfaction. The excellent aesthetics, perfect fit and ease of use were frequently-heard endorsements in favour of the use of Kuraray Noritake Dental products.

The session began with an introductory presentation, with an in-depth focus on the technical properties of the materials, instructions for baking, shade taking and staining techniques. Then it was time for the group to get started themselves. A KATANA™ Zirconia UTML molar and front crown had been prepared for each participant, and these were then characterised by means of CERABIEN ZR FC Paste Stain. The shades A+, Grayish Blue and Reddish Brown were used as starting points.

The entire front crown was first treated with glaze, after which external stain was applied; first in a horizontal direction, whereby dentine A+ was used cervically and enamel Greyish Blue incisal. Finally, dentine A+ was also applied vertically to emphasize the marmelon structure. Mr. Nagura offered the useful tip of first scratching in the eventual necessary crack lines with a sharp instrument such as a needle, and then colouring them in with external stain.

Glaze was initially applied to the full surface of the molar too, after which external stain was applied horizontally. A+ was used for the cervical and occlusal plane, with enamel Greyish Blue for the occlusal cusps. A+ was then applied to the vertical lines, and the fissures were finally coloured in using Reddish Brown.

Examples of staining with fc paste stain

Using different zirconia materials depending on the indication and on patient-specific needs allows for the best possible outcomes, yet comes with the danger of mixing up processing protocols. Kuraray Noritake Dental Inc. (Kuraray Noritake Dental) eliminates this problem by offering a complete portfolio of KATANA™ Zirconia Multi-Layered materials with harmonized sintering schedules. The latest member of the KATANA™ Zirconia Multi-Layered Series, KATANA™ Zirconia HTML Plus, is available since September 1, 2021. In addition to the aligned sintering schedules, it offers an increased translucency and optimized colour without compromising its flexural strength.

KATANA™ Zirconia HTML Plus is based on its tried and proven predecessor KATANA™ Zirconia HTML and also offers a multi-layered colour structure and uniform strength distribution throughout the blank. It is suitable for a variety of indications including long-span bridges with a minimum wall thickness of just 0.4 mm in the anterior and 0.5 mm in the posterior region. This allows for minimally invasive preparations, while the user may choose between a monolithic, cut-back or framework design combined with the preferred finishing technique.

Careful in-house optimizations in the material composition and structure have paved the way for an increased translucency of 45 percent (compared to 43 percent KATANA™ Zirconia HTML) and an even more natural shade appearance of the manufactured restorations. The colour appears more vivid and more saturated, which leads to an improved optical integration with the adjacent teeth and gums. At the same time, the high flexural strength (1,150 MPa) is maintained, ensuring an unlimited range of indications.

When it comes to sintering, three options are available for single-tooth restorations and bridges with up to three units: a 54-minute high-speed sintering programme especifically valuable for remake and rush cases, a 90-minute programme and the traditional seven-hour sintering programme suitable for long-span restorations as well.

All three options and identical schedules are also available for the other materials of the portfolio: KATANA™ Zirconia UTML, KATANA™ Zirconia STML and the new KATANA™ Zirconia YML (yttria multi-layered) with additional flexural strength and translucency gradation. Due to this feature, standardizing manufacturing procedures for a minimized risk of errors and consistent outcomes becomes extraordinarily easy. More information about KATANA™ Zirconia HTML Plus and the whole product family is available at our website.

The inventor of the original zirconia multi-layer technology, Kuraray Noritake Dental Inc., has just introduced its latest development in the evolution of dental zirconia – KATANA™ Zirconia YML (yttria multi-layered). At the KATANA™ Zirconia YML Virtual Kick-Off Symposium on July 3, 2021, four world-renowned experts reported on their first-hand experience with this highly versatile material that complements the existing KATANA™ Zirconia Multi Layered Series very well.

The chairman of the event, Prof. Dr. Florian Beuer MME (Charité – Universitätsmedizin Berlin, Fig. 1), represented the perspective of scientific researcher and clinician. MDT Daniele Rondoni, MDT Roberto Rossi (Savona, Italy) and MDT Nondas Vlachopoulos (Athens, Greece) shared their impressions obtained from processing KATANA™ Zirconia YML in the laboratory setting and focused on possible indications and finishing methods.

Fig. 1 Prof. Dr. Florian Beuer MME.

Scientific facts about YML

Following the welcome speech of Kazumitsu Nakatsuka (Head of BU Medical, Kuraray Europe GmbH, Fig. 2), Prof. Dr. Beuer started a journey through the evolution of dental zirconia. He described the different steps taken to transform an opaque, white framework material into a translucent, tooth-coloured material with a multi-layered structure suitable for monolithic restorations. In this context, he explained that KATANA™ Zirconia YML is a fifth-generation dental zirconia featuring colour, translucency and flexural strength gradation. High strength in the lower (body) part of the blank makes the zirconia well-suited even for long-span bridges, while the high translucency in the upper part facilitates natural aesthetics (Fig. 3). As a result, the material is recommended for virtually every indication (Fig. 4).

Fig. 2 Kazumitsu Nakatsuka, Head of BU Medical, Kuraray Europe GmbH.

Fig. 3 Multi-layered structure of KATANA™ Zirconia YML.

Fig. 4 Overview of the KATANA™ Zirconia portfolio and the recommended indications: KATANA™ Zirconia YML is the only material that is suitable for all indications from single tooth restorations to long-span bridges.

In order to leverage the desired properties such as high translucency for an anterior crowns or high strength for a long-span bridges, the restoration simply needs to be positioned in the correct part of the blank. The design flexibility of KATANA™ Zirconia YML is high and restrictions are few: the connectors of bridges with more than three units simply need to be positioned in the lower half of the blank for sufficient strength.

Additional benefits of the new material are a controlled firing deformation and high accuracy of the manufacturing process leading to a precise fit, the option of fast processing with a sintering time of just 54 minutes for short-span restorations and aesthetics comparable to glass-ceramic materials. After sharing these facts, some scientific data and clinical pictures, Prof. Dr. Beuer confessed that zirconia is his favourite material: it is forgiving, allows for minimally invasive restoration procedures and is suitable for virtually every indication. He usually opts for veneered zirconia in the anterior and monolithic zirconia in the posterior area. Like with every innovative dental material, he is looking forward to seeing more clinical data being shared with the community in the forthcoming years.

(Ultra) micro layering: Aesthetics easily achieved

MDTs Daniele Rondoni and Roberto Rossi focused on easy-to-achieve aesthetics with KATANA™ Zirconia YML. They presented different clinical cases to demonstrate how they obtain beautiful outcomes with a monolithic design (zero cutback), a small vestibular cutback or a micro cutback, and appropriate stains and porcelains from the CERABIEN™ ZR series (Kuraray Noritake Dental Inc.). Restorations with a monolithic design are typically individualized with internal stains and the liquid feldspathic ceramic material CERABIEN™ ZR FC Paste Stain (Figs. 5 and 6) or FC Paste Stain only (Fig. 7), a procedure that was demonstrated in a hands-on session. FC Paste Stain allows for application in ultra-thin layers and yet, it creates desired 3D effect. When opting for a (vestibular) micro cutback, microlayering with internal stains and a single luster porcelain (LT1) completed in a single bake may be the solution. All techniques are easily implemented and possible only thanks to the high aesthetic potential of the base material (KATANA™ Zirconia YML), which reduces the manual processing effort and time without compromising quality and aesthetics.

Fig. 5 Recipe for the use of CERABIEN™ ZR Internal Stain …

Fig. 6 … in combination with CERABIEN™ ZR FC Paste Stain Clear glaze on a monolithic surface (presented by Daniele Rondoni and Roberto Rossi).

Fig. 7 Example of a Toronto bridge made of KATANA™ Zirconia YML A2, finished in the gum areas with CERABIEN™ ZR Tissue Kit and on the teeth with CERABIEN™ ZR FC Paste Stain (presented by Daniele Rondoni and Roberto Rossi).

When starting to work with a new zirconia, the speakers recommend to analyse its optical properties in different light conditions, compare it with other materials and use a spectrophotometer discover its specific optical behaviour. What the speakers like most about KATANA™ Zirconia YML is the fact that all indications are covered with a single material.

Combining different finishing techniques: High-end aesthetics

According to Nondas Vlachopoulos, KATANA™ Zirconia YML is a great solution that combines the strength of second-generation zirconia like KATANA™ Zirconia HTML and the very high translucency usually found only in materials with reduced strength like KATANA™ Zirconia STML. The speaker showed several clinical case examples from complex implant-based restorations to crowns on teeth and implants, which were all solved with the new material (Figs. 8 and 9). He usually applies monolithic zirconia individualized with CERABIEN™ ZR FC Paste Stain in the posterior area, while on the six anterior teeth, he opts for complex porcelain layering techniques leading to the exceptionally aesthetic results that have made him famous.

Fig. 8 Wear case solved with monolithic KATANA™ Zirconia YML restorations in the posterior and layered restorations in the anterior area (presented by Nondas Vlachopoulos).

Fig. 9 Maxillary left central incisor restored with a layered crown with a KATANA™ Zirconia YML coping on an implant (presented by Nondas Vlachopoulos).

Highly versatile material

In the discussion following the presentations (Fig. 10), two experts from Kuraray Noritake Dental Inc. – Mathias Fernandez Y Lombardi and Antonio Corradi – stressed that the high processing quality of KATANA^™ Zirconia YML is due to the end-to-end in-house production process, ensuring that the company has control over every detail. The speakers agreed that the new product leads to numerous benefits for dental technicians and clinicians, as it allows for standardized procedures, a reduced inventory and simply produces beautiful outcomes with the preferred technique.

Fig. 10 Discussion with the experts in the studio and online.

Watching the renowned experts, their presentations and the final discussion, it became clear to the participants that KATANA™ Zirconia YML is a true all-in-one solution suitable for virtually all types of restorations and finishing techniques. With its well-aligned composition and smooth transition from one layer to the next, it is a great choice for everyone striving for aesthetic and reliable outcomes. More information about KATANA™ Zirconia YML is available at our website.

If you would like to watch back the event recordings click here.

We are pleased to share with you short training videos for Super Porcelain EX-3 porcelain.

Check out the below working steps and learn more about how to achieve outstanding aesthetics using this tried and proven material.

Interview with Mathias Fernandez Y Lombardi, EU Scientific Manager, Kuraray Europe GmbH

Kuraray Noritake Dental Inc. reinvented its original zirconia multi-layer technology by integrating newly developed raw materials with different yttria content into the proven multi-layer colour structure. The material that is based on this innovative technology, KATANA™ Zirconia YML, offers a well-balanced flexural strength, chroma and translucency gradation throughout the blank.

According to pilot users of the new zirconia discs, the greatest benefit of using KATANA™ Zirconia YML is in the true empowerment of the laboratory. We asked Kuraray Noritake’s EU Scientific Manager Dental Ceramics & CAD/CAM Materials, Mathias Fernandez Lombardi, to explain how the new material is able to positively affect work routines in the dental laboratory.

The greatest benefit of using KATANA™ Zirconia YML is in the true empowerment of the laboratory.

Mathias Fernandez Lombardi, who should consider working with KATANA™ Zirconia YML?

KATANA™ Zirconia YML is designed for laboratories and milling centres with a strong focus on simplification. With its strong body and highly translucent enamel layer, it offers exactly the properties required for an unlimited indication range. Being perfectly suited for the production of durable monolithic long-span posterior bridges and of highly aesthetic anterior crowns or partial restorations, KATANA™ Zirconia YML is a true all-rounder that eliminates the need for another zirconia or even ceramic CAD/CAM material. At the same time, it supports highly automated production procedures and requires minimal hand work.

What are the benefits of using a single material for every indication?

Several benefits are related to the use of a single, all-round material. It leads to a reduced number of blanks to be stored, which simplifies inventory management and minimizes the storage space needed. Moreover, it facilitates standardization of laboratory workflows. Using the same material every time means that there are no differences in the basic design and milling parameters like minimum wall thicknesses and connector strengths, in the sintering protocols and finishing options to be taken into account. Hence, errors are less likely to occur and routines are easily established. Finally, the risk of cross-contamination is eliminated when a single material is processed with the available equipment (milling machine, milling and finishing tools, and sintering furnace). Predictable outcomes and flawless aesthetics are usually the result.

What are the benefits related to the use of KATANA™ Zirconia YML as the only ceramic CAD/CAM material?

I guess that the most important argument is that aesthetic outcomes are easily and efficiently achieved with KATANA™ Zirconia YML for all kinds of restorations, even for long-span bridges. It is usually sufficient to produce monolithic restorations for the posterior region, which are just polished or glazed. Anterior restorations may be designed monolithically or with minimal cut-back, and the user may choose between CERABIEN™ ZR (CZR) FC Paste Stains and CZR Internal Stains plus glaze to obtain a natural look. Another benefit of KATANA™ Zirconia YML is its seamless multi-layer structure combined with an extraordinary blank quality.

Why is this seamless structure and high blank quality important for users?

The seamless multi-layer structure, that is a smooth transition from one layer to the next, is the precondition for structural integrity and flawless aesthetics. It ensures that the material is free of transition lines, offers accurate dimensions after sintering (due to uniform shrinkage) and shows a reliable long-term performance not compromised by internal tensions. In KATANA™ Zirconia YML, a completely homogeneous composition, with carefully aligned CTE-values and shrinkage ratios in all parts of the blank, is responsible for this benefit.

Aesthetic outcomes are easily and efficiently achieved with KATANA™ Zirconia YML for all kinds of restorations, even for long-span bridges.

For its development, Kuraray Noritake Dental leveraged its long-standing expertise in dental ceramics and the advantages of an end-to-end in-house blank production process, without which it would have been impossible to reach the requested quality level. Due to the fact that the material is so well aligned, it was even possible to develop a 54-minute sintering programme that produces equally good results as the proven 90-minute or 7-hour programmes and becomes the go-to option for all rush cases. With this feature, KATANA™ Zirconia YML becomes the “jack of all trades” material: It offers highest comfort and security like an SUV, but when it comes to speed, it is in no way inferior to a sports car.

The above sintering recommendations represent only a guideline; depending on each individual furnace and condition, some adjustments might be necessary. If the 54 or 90-minute sintering program is not programmable in your furnace, it is not possible to set the furnace according to one of these schedules. *The material is removed from the furnace at 8000C. A furnace with a configurable YML sintering program is required.

Users who have already tested ceramic materials with a strength gradient know that positioning of long-span restorations in the blank can be tricky. What are the rules to be respected when positioning a long-span bridge in a YML blank?

Positioning of restorations in KATANA™ Zirconia YML discs is extraordinarily easy. The reason is that the gap between the lowest flexural strength found in the enamel area and the highest flexural strength found in the lowest body layer is comparatively small. Moreover, the Body Layer 1 that is found adjacent to the enamel layer already offers a flexural strength that is higher than the 800 MPa requested for bridges with four or more units. Consequently, users are on the safe side whenever they place their long-span restorations in the middle of the blank. More specifically, half of the connector cross section needs to be in the lower half of the disc, which is quite different from other materials with strength gradation that allow for connector positioning in the body area only. KATANA™ Zirconia YML restorations with a maximum of three units may be positioned in any layer. In this context, the fact that the thickness of each layer increases proportionally with the height of the disc comes as a benefit: The enamel layer is large enough to exploit its aesthetic potential in single-unit or small bridge cases.

Positioning of long-span restorations in the middle of the disc.

What would you recommend dental technicians who would like to empower their laboratory or milling centre?

I can truly recommend testing KATANA™ Zirconia YML in the laboratory environment to see how it handles and to assess its potential. The exceptional blank quality and seamless integration of the different layers, the ease of positioning and processing efficiency are factors potential users need to experience in real life to understand what they mean for their daily work. Similarly, the aesthetic outcomes need to be assessed in the clinical environment for an authentic impression of the natural look and feel obtained. I am sure that KATANA™ Zirconia YML will be able to convince virtually everyone who wants to empower the laboratory with an easy-to-use, efficient universal zirconia solution that fits virtually every patient’s and every dentist’s needs! Kuraray Noritake Dental knows that dental technicians and practitioners are in need of products that support their striving for simplification, standardization and increased efficiency so urgently needed in present times. Therefore, our product innovations are all focused on delivering more performance with less effort. KATANA™ Zirconia YML is the latest addition to a whole series of materials pursuing this goal.

Minimum connector cross-sections are to be respected during the computer-aided design of KATANA™ Zirconia YML restorations.

Mathias Fernandez Y Lombardi

EU Scientific Manager
Dental Ceramics & CAD/CAM Materials
Kuraray Europe GmbH

2013
Successful completion of an apprenticeship as a dental technician at Seuthe dental laboratory in Plettenberg, Germany

2018
Successful completion of dental technology studies at the University of Osnabrück, Germany. Graduation as an engineer in dental technology

Since March 2018
Employee of Kuraray Europe GmbH

In January 2019, Kuraray Noritake Dental proudly hosted a symposium dedicated to the KATANA™ Zirconia Block. Dental professionals from across Europe gathered in Berlin to hear a number of experts detail their research into, and clinical experiences with, this all-zirconia solution. Among those presenting were Dr Alessandro Devigus and master dental technician Daniele Rondoni, both active members of the European Academy of Esthetic Dentistry.

Devigus and Rondoni’s presentation was focused on discussing the possibilities of the KATANA™ Zirconia Block for restorations in the aesthetic zone. Devigus, who is the founder and president of the Swiss society for computer-aided dentistry (SGcZ), spoke of the dual meaning of the word ‘digital’—though it refers to numbers, it also can be used to describe something performed with one’s digits, or fingers. Digital dentistry, he explained, thus combines the reliability of computer-aided design and manufacturing with the creativity and aesthetic possibilities of handcrafted restorations. “This combination of hands and machine is, simply put, what defines digital dentistry,” Devigus said.

The evolution of KATANA™

Rondoni highlighted the evolution of Kuraray Noritake Dental’s work, particularly with zirconia. Having been an international instructor for the company for many years, he spoke of witnessing the development of the KATANA™ family into a solution that can truly replicate the appearance of natural dentition. “Thanks to the multilayered nature of this material, we can obtain a mimetic effect in regards to the optical properties of a natural tooth,” he explained, and described how these multiple layers effectively reproduce the shade gradation of teeth and work to create a three-dimensional effect.

Fluorescence is crucial

Both presenters emphasised the importance of fluorescence for the aesthetic qualities of dental restorations. “My concern was always that, with zirconia, there was no fluorescence,” Devigus admitted. This fear was easily allayed, however, with the use of Kuraray’s Cerabien™ ZR FC Paste Stain, a product optimised for full-zirconia restorations.

A true chair side solution

To demonstrate their experiences with the KATANA™ Zirconia Block, the two presenters then showed a number of clinical cases that they had worked on together in Devigus’ dental practice in Bülach in Switzerland. Devigus praised the speed sintering that is made possible through the block’s integration with Dentsply Sirona’s CEREC system, saying that, “For me, if a material can be used to complete a restoration in less than two hours, then it is truly a chair side material. You cannot expect a patient to sit there and wait there for four hours in your dental practice—but this is not a concern with the KATANA™ Zirconia Block.

The KATANA™ Zirconia family of multi-layered CAD/CAM blanks has a new member: KATANA™ Zirconia YML (yttria multi-layered). Based on Kuraray Noritake Dental Inc. (KND) proprietary multi-layer technology, this new material offers multiple layers with different levels of chroma and translucency PLUS different concentrations of yttria in a single blank. We talked to two experts from Kuraray Noritake Dental’s Research & Development Department in Japan, Atsushi Matsumoto and Yuta Tajima, about the new product and its specific features.

Mr. Matsumoto, Mr. Tajima, KND already offers a broad range of zirconia materials covering virtually every indication. Why did you decide to start developing yet another dental zirconia?

The KATANA™ Zirconia series has indeed received high praise and great feedback from the market. Users particularly appreciate the remarkably high strength of HTML, the well-balanced aesthetic and strength properties of STML, and also the high translucency of UTML. Although there has been a large increase of zirconia materials in the dental market recently, we have received many requests from our customers for a more universal material that offers the excellent properties of all variants of KATANA™ Zirconia in one product. This product should allow them to fabricate all kinds of restorations from a single disc, from single crowns to full bridges, while maintaining high aesthetic and mechanical properties for both anterior and posterior restorations. As the developer of the KATANA™ Zirconia series, the invention of KATANA™ Zirconia YML is our response to these desires expressed by our customers.

What is the main difference between KATANA™ Zirconia YML and the other available products of the KATANA™ Zirconia Multi-Layered Series?

All layers of KATANA™ Zirconia UTML, STML and HTML are produced from the same basic powder composition and therefore offer the same strength throughout the whole blank. Depending on the case specific requirements, users need to select the most suitable type of material, either a high-strength zirconia or a highly translucent variant. KATANA™ Zirconia YML is an all-in-one zirconia suitable for all cases: It consists of a high-translucency enamel layer, an intermediate layer offering well-balanced strength, translucency and colour, and a high-strength body layer. The raw materials used for this product are developed and produced by KND exclusively for YML. This is another milestone in advanced product development KATANA™ Zirconia.

We have received many requests from our customers
for a more universal material.

In general, the currently available zirconia materials with an integrated strength gradient do not have a very positive image in the eyes of many dental technicians and specialists, due to the fact that in the incisal area, the materials seem to be insufficiently strengthened. This can lead to fractures when it comes to long-span restorations, especially if they are inadequately positioned within the blank. How carefully did KND focus on these problems and how did they try to solve them in order to stand out from the competition?

The current yttria-based multi-layer products on the market are facing complicated limitations in connector position in large cases, such as full-arch restorations, due to the lack of an ideal combination of aesthetics and strength. To overcome this challenge, KND developed well-balanced raw materials of high strength and high aesthetics, and by including these raw materials in the intermediate layer between the enamel and body layers. The result is that even for long-span restorations, it is very simple to position the connectors thanks to its excellent balance between high strength and high aesthetic properties. Due to these unique attributes incorporated in our new product, the risk of deformation and breakage is avoided.

Another problem is the often clearly visible line between the different layers containing different amounts of yttrium oxide, which can be seen at a more detailed inspection after sintering. How did you address this issue?

At KND, we achieved both, adequate translucency gradation and invisible transition lines, even for zirconia layers with different yttria content. This has been accomplished thanks to our multi-layer zirconia manufacturing technology refined over many years, which includes mixing the appropriate amount of each layer's boundary to intentionally avoid transition lines. In addition, the newly developed interlayer raw materials and a newly designed sintering schedule were the keys to success.

How is it possible to have a sintering protocol that works for different zirconia components within the KATANA™ Zirconia YML blank and allows for the shortest sintering times ever?

The amount of shrinkage during sintering is determined by different factors such as the number and quantity of additives (yttria, alumina etc.) it contains. If the shrinkage ratio of each layer is different, transition lines are likely to appear between the layers, which might produce tensions in the material structure. The newly developed raw material for KATANA™ Zirconia YML enables us to control and unify the shrinkage ratio for all layers, even for raw materials with different yttria contents.

The use of proprietary raw materials produced in-house with excellent properties suitable for high-speed sintering was the main precondition that allowed for the development KND’s high-speed sintering schedule (54 min for restorations up to 3-unit bridges), which is available for all products of the KATANA™ Zirconia multi-layered series. This option improves the efficiency of the dental technician’s work and simplifies the workflow.

Are there any differences in milling and adjusting KATANA™ Zirconia YML compared to competitor products?

All KATANA™ Zirconia products from KND have an appropriate hardness with less chipping during the milling process thanks to the raw materials manufactured and refined in-house. Also, after the sintering procedure, it offers excellent chipping resistance, especially during very challenging marginal adjustments.

Is there anything else that sets KATANA™ Zirconia YML apart from other products with an integrated strength gradient?

Yes, KATANA™ Zirconia YML offers reduced sintering deformation, thanks to in-house developed raw materials, based on proprietary technology to control shrinkage rate. Moreover, we offer a wide range of shades (14), which is another important aspect (apart from the material’s well-balanced aesthetic properties and absence of transition lines) for the creation of lifelike restorations. Finally, since three out of four layers meet the conditions for an ISO class 5 classification, there are few restrictions on the design variation of the prosthesis.

Why should a dental technician consider using KATANA™ Zirconia YML instead of any other dental zirconia (in your opinion)?

Atsushi Matsumoto:

It is now possible for dental technicians to produce strong and aesthetic restorations with just one material, KATANA™ Zirconia YML. This allows for a reduced inventory, while working time is significantly shortened due to the possibility of high-speed sintering.

Yuta Tajima:

To my mind, the most convincing properties are excellent firing accuracy due to well-balanced material properties across all layers, the wide range of shades available and the great design flexibility even when designing long-span bridges. Last but not least, the trusted quality of the KATANA™ brand and the label “Made in Japan” are reasons to opt for this new product.

All blanks from the KATANA™ Zirconia Series stand out from other dental zirconia materials due to their particularly fine-grained, densely pressed microstructure, which is the basis for a superior surface quality, edge stability and the resulting accuracy of fit. What is the secret behind this exceptionally high blank quality?

Since we do not know the correlation between marginal stability properties (chipping, etc.) and material compositions, structures etc., it is very difficult to answer this question. It may depend on the structures of the zirconia crystals, the raw material itself, the correct strength level after pre-sintering or any other minor factor during the manufacturing process of the disc. All these factors together, of course, are important.

We are using pigments developed by KND, which have an excellent colour stability without fading even after the final sintering procedure.

Even if the restoration margins have been milled to a very thin profile, they still show smooth margins without any chipping.

A clear advantage of the KATANA™ Zirconia series, much praised by KND's Key Opinion Leaders, is its colour stability and shade match to the "VITA classical shade guide". Can you explain the importance of an in-house conducted addition of additives and color pigments in form of metal oxides to satisfy the user and distinguish KATANA™ Zirconia from competitors’ products?

We are using pigments developed by KND, which have an excellent colour stability without fading even after the final sintering procedure. The particle size is appropriately controlled. In addition, our professional "colour mixing" staff, reflecting the opinions of clinically experienced dental technicians both inside and outside the company, have achieved a pigment mixture that shows only a slight change in shade even in cases with different thicknesses.

What is your vision with regard to future developments in dental zirconia?

Since the introduction of zirconia on the dental market, many significant material advances have been achieved. Today, there are high-strength, low light-transmitting zirconia materials up to high light- transmitting, low strength zirconia materials available on the market. Furthermore, there are now also high light-transmitting, low strength zirconia materials in mixed systems (YML series) offered. Our foremost goal is to develop the ultimate zirconia in near future, combining both high strength and high light transmission, which breaks the general expectation of a compromise between strength and translucency within zirconia materials.