Importance of high-quality prosthodontic treatment

High-quality treatment is probably the most important element on the road to patient satisfaction. During every single appointment, the patient wants to feel well cared for by a skilled professional, while chair time and the number of appointments should be reduced to the necessary minimum. This implies that, in the context of prosthodontic treatment, a restoration needs to fit perfectly straight away and be stable over time to avoid remakes and extra appointments.

But how is it possible to deliver perfectly fitting, high-quality restorations every time? Among the potential sources of problems with the quality of indirect restorations are common mistakes made in the dental office or laboratory, communication issues and – often overlooked – the use of low-quality dental zirconia.

Zirconia restorations – contemporary and aesthetic dental solution

More than 20 years ago, zirconia entered the dental market as a substitute to metal used for the production of crowns and bridges. Both materials – zirconia and metal – were usually combined with a layer of porcelain, forming porcelain-fused-to-metal or porcelain-fused-to-zirconia restorations. In the years to come, several leading manufacturers of dental zirconia (like Kuraray Noritake Dental Inc.) focused on material improvements. These improvements gradually transformed the original white-opaque framework material into a ceramic material with tooth-like optical and excellent mechanical properties. The latest zirconia variants, available with different levels of translucency and strength, are regarded as the best-possible treatment option in a wide variety of patients and indications by many dental professionals around the world. One reason is that they require just a small or no layer of porcelain. Another is that, with low minimum wall thicknesses, they allow for conservative tooth preparations, while they offer a favourable long-term behaviour – that is, if a high-quality material is used.

Quality differences of dental zirconia

Zirconia product quality may vary depending on various factors such as the purity of the raw materials (not only zirconia, but also alumina and yttria as well as colour additives etc.), the exact chemical composition, the grain size and particle distribution. Every step in the blank production process – from powder compilation to blank pressing and pre-sintering – has an impact on the final quality, i.e., the mechanical and optical properties of the zirconia, too.

Common issues resulting from low-quality zirconia

Whenever there is something wrong with the optical properties of a restoration – with its translucency, its overall colour or the transition from one layer to the next in blanks with a multi-layered colour structure – the problem will become apparent after the final sintering procedure in the laboratory. A remake might be necessary and eventually, the blemish might be identified during try-in, which will most likely have a negative impact on patient satisfaction. The same is true for cases with an improper fit resulting from inhomogeneities in the material structure, for example. What is even worse is an inferior biocompatibility, surface quality, edge stability, flexural strength or fracture toughness. These issues are identifiable only with testing equipment that is very expensive and usually not available in dental laboratories. This means that flaws of this kind usually remain undetected until a real clinical problem – like gingival recession, increased plaque accumulation, higher wear or an early failure that might cause pain and discomfort – occurs.

Overview of potential problems and clinical consequences for patients

Certification and standardization of dental zirconia

That is why specialists have developed an ISO standard (ISO 6872:2015), which describes in-vitro tests every manufacturer of dental zirconia used in Europe or the United States needs to conduct in order to pass FDA approval and receive the CE mark. The described tests are used to measure the flexural strength and fracture toughness, the two probably most important properties determining the long-term behaviour of restorations produced from the material. Every material used in Europe or the United States needs to have passed these tests.

How to avoid placing low-quality dental zirconia restorations in your patients’ mouths

Hence, everyone using this certified dental zirconia should be safe and able to minimize material-related risks. However, the increasing popularity of dental zirconia has attracted the attention of companies trying to have their share of the cake without undergoing the necessary efforts needed to safeguard a high product quality and pass certification. Non-certified products that lack CE marking have one thing in common: they definitely put your business and patient at risk.

So how is it possible to safeguard zirconia product quality from the dental office? The good news is that there are some simple rules available. By following them, you are able to avoid placing counterfeit or low-quality dental zirconia restorations in your patients’ mouths.

Avoid placing counterfeit or low-quality dental zirconia restorations in your patients’ mouths.

Three golden rules to provide your patients with high-quality zirconia restorations:

• Only order restorations that are produced domestically or in a region with the same standards as your own: restorations produced in dental laboratories in China, for example, need to fulfil lower standards (thus lacking CE mark) and might not live up to your expectations.
• Talk to your (domestic) laboratory partner about the source of their zirconia: make sure they are purchasing zirconia from leading manufacturers (e.g. Kuraray Noritake Dental Inc.) via authorized distributors or sellers they really know.
• Avoid deals that are too good to be true: low prices may be tempting, but the final cost of a treatment may be even higher than usual when complications occur.

Long-term impact for patients when using certified zirconia restorations

Making certain that the zirconia placed in your dental office fulfils the highest possible quality standards is an important contribution to long-term patient satisfaction. Even if the initial cost of high-quality zirconia restorations is somewhat higher than that of inferior-quality work, the overall investment may be lower when the restorations last longer and remakes are eliminated. Your happy patients are likely to be more engaged and compliant with oral hygiene regimens as well as loyal, with a positive impact on your reputation and patient base.

Research zirconia options and choose for products from certified manufacturers

If you would like to go one step further, you can even compare certified zirconia variants from several manufacturers and detect differences. Kuraray Noritake Dental Inc., for example, is one of very few manufacturers of dental zirconia carrying out the whole manufacturing process including raw material production in-house. In this way, the company is able to control every step in the procedure and provide for an outstanding product quality – no matter which material variant is selected. With the available portfolio consisting of KATANA™ Zirconia UTML (ultra translucent multi-layered), KATANA™ Zirconia STML (superior translucent multi-layered) and the high-translucent multi-layered HTML PLUS as well as YML (with additional strength and translucency gradation), it is possible to cover virtually every indication.

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.

Dentists:

Case by Kanstantsin Vyshamirski

A male patient (47 years of age) presented to his dentist with severe damage to his teeth. His main request was to increase aesthetics, to achieve a more pleasing envisaged aesthetic area. A side request was to achieve a ‘whitening but natural look’. This was achieved by using a lighter colour palette of zirconia and porcelain materials.

The final result was achieved through the creation of a wax-up, followed by a mock-up, provisional restoration and finally adhesive bonding of the zirconia crowns.

INITIAL SITUATION

Fig. 1. Initial situation. Male patient (47 years of age).

Fig. 2. Planning the new smile according to patient’s aesthetic and functional parameters.

Fig. 3. Mock-up in place to check the new look in the patient’s mouth.

Fig. 4. KATANA™ Zirconia YML shade A1 crowns with labial cutback after milling.

Fig. 5. Crowns after sintering on the plaster model.

Fig. 6. Noritake CERABIEN™ ZR porcelain layering map.

Fig. 7. Finishing the labial surface using both polishing and selfglaze. On the palatal side of the crowns only CERABIEN™ FC Paste Stain stains and glaze were used for finishing. To aid in optimisation of the soft tissue condition the palato-cervical and near proximal areas were polished.

Fig. 8. Finished crowns on the plaster model.

Fig. 9. Try-in using PANAVIA™ V5 White try-in paste, to confirm the proper appearance. For the final adhesive cementation PANAVIA™ V5 White has been used.

FINAL SITUATION

Fig. 10. Situation after seven months. The result is aesthetically pleasing and the gingival condition excellent.

Fig. 11. Recall after 1.5 years.

Dentist:

KANSTANTSIN VYSHAMIRSKI

Kanstantsin started his dental technician career in 2014. His speciality is aesthetic prosthetic porcelain works. Kanstantsin is an experienced user of KATANA™ Zirconia and Noritake porcelains. He owns his lab in Riga, Latvia.

Photo credits to Giuliano Moustakis

Can you imagine a world without multi-layered zirconia? The invention of a zirconia material with natural colour gradation and well-balanced translucency and strength led to fundamental changes in the way zirconia-based restorations are produced. When the first product of its kind – KATANA™ Zirconia ML – was introduced to the dental market exactly ten years ago, dental technicians all over the world suddenly started rethinking their manufacturing concepts.

Since then, the trend towards a decreased thickness of the porcelain layer, a limiting of this layer to the vestibular area and the production of monolithic restorations is clearly perceivable. Technicians have developed their own concepts of micro-layering, which allow for more patient-centred approaches. This is also due to the fact that the total wall thicknesses of the restorations may be decreased without compromising the aesthetics. The line-up of multi-layered zirconia currently available from Kuraray Noritake Dental Inc. (KATANA™ Zirconia UTML, STML, HTML Plus and KATANA™ Zirconia YML with additional translucency and strength gradation) enables users to make indication-related material choices for the production of restorations that are precisely aligned to the individual demands of each case.

The reasons to choose KATANA™ quality

But why choose KATANA™ Zirconia instead of any other multi-layered zirconia disc? According to experienced users of the KATANA™ Zirconia Multi-Layered series, there are many reasons to opt for KATANA™.

For Jean Chiha, owner at North Star Dental Laboratories and Milling Center in Santa Ana, California, it is the combination of optical and mechanical properties that makes the difference: 

“KATANA™ Zirconia is the game changing material with well-balanced esthetics and strength!”. 

Naoki Hayashi, president of Ultimate Styles Dental Laboratory in Irvine, California, aesthetics is the most decisive argument to opt for the discs from Kuraray Noritake Dental Inc. He states:

“KATANA™ Zirconia discs offer trusted esthetics which gives me confidence in my clinical cases”.

Naoto Yuasa, chief ceramist at Otani Dental Clinic in Tokyo, adds predictability as an important factor:

“KATANA™ sustains my passions for aesthetic restorations and those of a predictable future in the long run”, whereas dependability is the key element.

For Hiroki Goto, the laboratory manager at Sheets and Paquette Dental Practice in Newport Beach, California reports:

“Without KATANA™ there is no pride. Haven’t experienced it yet? You have to see how reliable it is!”

Finally, we have asked Kazunobu Yamada, a pioneer in making porcelain laminate veneers using complementary color techniques and a first-hour user of KATANA™ Zirconia, what comes to his mind when thinking about KATANA™ Zirconia. According to the president of CUSP Dental Laboratory in Nagoya City, there is a clear link between the product name and its characteristics:

“Did you know that the word "KATANA" also means "protection against misfortune and evil"? Katana zirconia, the culmination of many years of research and development by Kuraray Noritake, has an unparalleled quality. KATANA™, for me, is truly "Protection for all technicians".”

The origin of well-balanced properties

It seems that the KATANA™ Zirconia Multi-Layered line-up stands out due to set of valuable properties enabling a dental technician to produce beautiful, high-quality restorations every time. The secret of success lies in meticulous raw material selection and controlled processing from the powder to the pre- sintered blank carried out at the production facilities of Kuraray Noritake Dental Inc. in Japan. They provide for the high product quality that is responsible for the materials’ outstanding behaviour supporting the best possible outcomes.

Clinical Case by DT Ghaith Alousi

What does it take to reconstruct teeth according to the patient’s individual sense of beauty? Experience shows that copying nature is the secret of success. To become a good duplicator, it is essential to develop an eye for detail with regard to tooth forms, surface morphology and the internal colour structure of the teeth to be copied. In addition, the duplicator needs to develop an understanding of the materials and tools used to copy those details. The last key success factor is taking pleasure in interacting with patients.

Read the clinical case created by Ghaith Alousi and published in the LabLine magazine’s Autumn edition now and learn about his approach to creating aesthetic restorations, mimicking nature and truly individualising restorative treatments.

Interview with Andreas Chatzimpatzakis

Fewer bakes, fewer ceramic powders - there is clearly a trend toward simplification in the production of zirconia-based prosthetic work. This is also true for implant-based restorations, which often involve gum parts. DT Andreas Chatzimpatzakis, international trainer for Kuraray Noritake Dental Inc., and the owner of ACH Dental Laboratory in Athens, Greece, shares his approach to high aesthetics in implant prosthodontics in the following conversation.

You are a user of the CERABIEN™ ZR portfolio from the outset. When did you test the products for the first time and why?

Well, it was many years ago when I finished my very first zirconia-based restoration. The reason to test CERABIEN™ ZR was that when I asked the dental technician who had milled the framework which porcelain system to use. He suggested to use CERABIEN™ ZR, which I did. I was immediately impressed by the system and by the outcome I was able to achieve on the first attempt.

Did you ever test any other porcelain systems for ceramic layering?

Yes. Before I becoming an international trainer for Kuraray Noritake Dental Inc., I had the opportunity to test many other porcelain systems for layering on zirconia. Based on this experience, I can say that CERABIEN™ ZR is unique and the best system I have ever used. The reason is that its translucency and chroma are extremely close to natural teeth. In addition, due to a controlled firing shrinkage, a One-Bake Technique may be employed even in long-span restorations.

Your hands-on demonstration at the Kuraray Noritake Dental booth during the IDS 2023 in Cologne focused on White and Pink Aesthetics achieved with CERABIEN™ ZR. Is there a specific concept you use?

Nowadays, everyone producing dental restorations – no matter whether based on natural teeth or on implants – is confronted with increasing aesthetic demands of patients and dental practitioners. The high demands are developed because life-like restorations and cosmetic dental treatment outcomes are presented everywhere in the web and on social media. The showcased quality of outcomes is simply expected, even if the financial budget is limited. To be able to fulfil these demands in the field of implant-based prosthodontics, I have developed an approach that allows me to achieve high aesthetics with little effort. My concept is based on using not too many ceramic powders. For extra chroma and special characterization, I rely on the power of the internal live stain technique, first introduced by Hitoshi Aoshima-sensei.

Please summarize the most important details of your presentation.

The first important detail is the design and characterization of the framework. Before sintering, I apply Esthetic Colorant for KATANA™ Zirconia. After the sintering process, shade base stain and internal stains are mixed and applied. In this way, I create a nice canvas that helps me to achieve a life-like result with only a few selected ceramic powders. In most cases, three to five powders are enough to produce a great result. Among the powders used most frequently are Opacious Body, Body, LTX, Mamelon and CCV. After the first bake and a little grinding, I make use of internal stains again. They offer support in the controlling of the chroma and the integration of special characteristics. When this step is completed, the final build-up is done with one or two ceramic powders, most of the times LT1 and Enamel or LT0. Pink aesthetics are usually created with Tissue 1, 3 and 5. For the free gingiva, LT Coral is my go-to solution. The major goal is always to obtain maximum quality in a minimum of time. To achieve this, a good knowledge of the materials and of course practicing – on both, porcelain build-up and morphology – are strictly required.

Fig. 1. Complex implant-based restoration: Framework design.

Fig. 2. Esthetic Colorant …

Fig. 3.  … applied prior to the final sintering procedure.

Fig. 4. Appearance after sintering.

Fig. 5. Final outcome.

Are there any concrete tips and tricks you would like to share?

For the characterization of the framework, I mix the internal stains with shade base stain powders; mostly with SS Fluoro. For the first bake, especially when the restoration is large and the amount of ceramic to be applied huge, I reduce the heating rate up to 38 degrees per minute. I also increase the drying process up to 17 or even 20 minutes depending to the restoration. Experience shows that these measures optimize the aesthetic outcomes.

You often mention that it is extraordinarily important to understand the morphology of natural teeth to be able to produce beautiful restorations. Why is this the case?

A successful prosthetic restoration needs to offer proper function and aesthetics. Function means a precise fit, perfect contact points and occlusion, a proper emergence profile and interproximal embrasures for self-cleaning etc. All this is described by the term morphology. Aesthetics, on the other hand, is guided by shape and colour. The effort required to establish a proper morphology is much higher (about 70 percent of the total work) than the effort involved in obtaining the right translucency, opalescence and chroma.

What instruments do you use to imitate the morphology of natural teeth and how do you do it?

I usually make use of the Optimum™ Spring Ceramic Brush Size 8 (MPF Brush Co.), stones and diamond burs for detailed grinding and carving after the final bake. I studied morphology at the Osaka Ceramic Training Centre in Japan with Shigeo Kataoka-sensei. According to him, a key factor in creating a perfect macro and micro morphology lies in the shadows. To be able to take into account the interference of light and shadow during grinding, a light source is placed on one side of the restoration.

How many bakes do you need to produce highly aesthetic restorations?

It depends on the case, although in many situations, I nowadays opt for some kind of micro-layering. Lately, I have used micro-layering a lot with internal stain directly on the zirconia framework. In other cases, I do a quick first bake, then the internal staining, a final bake and glazing. For small or single-unit restorations in the posterior region, a One-Bake Technique is often sufficient. Even a Zero-Bake approach using Esthetic Colorant on a monolithic zirconia restoration may be appropriate here, and it is very convenient. If there is a restoration with high aesthetic demands – these are typically single anterior restorations – the technique I select depends on the shade. In some cases, using only the internal stain technique is enough to reach a high aesthetic level, while in other cases, additional steps need to be taken. To my mind, there is no single technique that fits all cases. As mentioned before, I try to achieve high aesthetics in a minimum of time.

Fig. 6. Clinical example of achieving high aesthetics in a minimum of time: Before …

Fig. 7. … and after crown placement.

Fig. 8. High aesthetics …

Fig. 9. … achieved in a minimum of time.

Did your approach change due to the availability of high-translucency zirconia materials with colour (and flexural strength) gradation?

Well, yes! My overall approach changed more to micro-layering. Several years ago, we needed to consider how to mask the framework and how to achieve translucency in areas with limited space. The problem was solved for single-unit and small anterior bridge restorations with the availability of KATANA™ Zirconia UTML and STML. With the introduction of KATANA™ Zirconia YML, a high-translucency material became available for long-span or implant-based restorations as well. We have strength and translucency all in one disc. In most of my cases, the framework material replaces the dentin with regard to morphology and shade. Hence, I need to focus on adding the enamel by applying the transparent and translucent powders. The powders of the internal stain technique are used to characterize the framework, and with a micro-layer of porcelain, the goal of creating an aesthetic restoration in the minimum of time is achieved. This is exactly why I am sure that micro-layering is the future.

What drives you to share your knowledge with others?

My passion! I love my work! And I love to see technicians become better and better. Dental technology is an exciting journey, a journey that begins when the first impression arrives in the dental laboratory, and it ends when the final restoration is cemented into the patient’s mouth. And this journey is so exciting because we change lives. We change people’s personalities, we give them back their smile, we give them back their self-respect. Consider that every day, every single moment working on our bench trying to imitate nature… there is nothing more exciting than that!!!

My approach as an instructor is to lead dental technicians to master the art of observing natural teeth. This is the way every individual will understand morphology and shade. You need no special talent to be a very good dental technician. You need to observe! Your eyes see, your mind understands, and your hands will follow.

Alexander (Alek) Aronin is a master dental technician who dedicated himself to the creation of high-end, handmade porcelain restorations. He runs a dental laboratory and morphology school in Spain, and travels the world as a lecturer and teacher.

The greatest source of inspiration in his professional life is the book Collection of Ceramic Works by Hitoshi Aoshima. Through reading it in 1996, he discovered superb outcomes of working with dental ceramics. Moreover, the book’s content made him realize that the creation of handmade porcelain work is a result of special education and manual skills. Those who want to become masters need a lot of commitment and a striving for continuous improvement, which Alek shows in his work and his classes. We talked to him about his philosophy and his enthusiasm for the creation of lifelike restorations. He shared with us his perspective on the future of dental technology and gave some practical tips on how to achieve a high level of professional satisfaction.

Photo courtesy of Dennis Debiase

Alek, many dental technicians decide to focus on CAD/CAM technology and automated processing of dental ceramics. Due to improvements on the material side, a handmade porcelain layer is no longer necessary in many clinical cases. In this context, the manual refinement process is reduced to a minimum. Why did you decide to take a completely different path and focus on fully manual dental craftsmanship?

The shift towards automated processing is not a matter of choice for dental technicians rather, it is a natural response to the evolution of technology. The high-end manual refinement process remains unchanged. The human element, from communication to hand crafting among skilled individuals and demanding clients, has been a constant so far throughout history. This traditional connection remains stable for centuries.

Digitalisation is not the revolution in the dental industry, and I do not see the benefit of it in our narrow specialization yet. In the area we are working, we do all steps of our case faster, incomparably more precise and more profitable. But we are keeping eye on machines and waiting for a suitable one.

Machines and automated processes widely serve mass production businesses focused on fast, affordable and uniform results in a highly competitive field. Our goal and workflow are different - we provide individual work and personal attention to each of our partners and patients.

So, we do not compete with the production labs and do not interrupt each other, we coexist in parallel worlds as always. A small number of dentists and their patients will always demand personal attention and valued restorations and service of the highest quality.

Many dental technicians admire your work. Yet, you continue to strive for improvement. Why is this the case?

On one side, we are limited by static ceramic material used to mimic dynamic natural teeth that keep changing for a lifetime. On the other side, we are limited by our manual skills. I am still far away from my teachers and Japanese colleagues. My target is to improve the fabrication process. My goal is to achieve the simplicity and imperfectness like Aoshima-sensei.

Alek lecturing at the IDS 2023 in Cologne.
Photo courtesy of Dennis Debiase

We are enjoying the outcome, but prefer to focusing on the improvement of the process, and move on to create a better one. This is what I am learning in Japan, and this is what I teach my students.

Talking about learning: What are the most important aspects a dental technician who wants to improve his skills should have in mind when looking for a good teacher?

Manual skills are very important, but not the only aspect that should be taken into account. Every individual should be motivated and guided and this is a teacher’s job.

I love the traditional Japanese way of teaching and learning: The teachers are passionate, leading the way by evoking emotions and manual skills to bring the best out of every single student. My personal advice for dental technicians who want to become masters in the creation of lifelike high-end dental restorations is to select their teachers carefully and go to a private school or courses whenever they have the chance.

What are the most important tools a dental technician needs to use when trying to create high-end lifelike restorations?

I suggest to focus on four aspects:

1. Documentary dental photography - required for documentation and communication with the dental office and patients using constant (once set and never changed) parameters of the photo equipment.
2. Focus to the biomimetic additive dentistry. This is a minimum machine invasive field. Dental technicians and dentists should be able to develop a deep knowledge about clinical and lab-side procedures to be able communicate with each other.
3. Mastering morphology and function (shape carving), and anatomy (internal staining), which comes with value control and mimicking fine tooth details for best integration in the mouth.
4. Written communication (stop phone calls) is very important, this is the way how to exchange the information between the patient, clinic and lab by strict protocols.

I teach these complex skills in my morphology school and in many of my trainings worldwide. Focusing on the four aspects, a dental technician has a great chance to become a good specialist in a relatively short period of time in a narrow field.

Is material selection important for achieving great results?

I’ve been using Noritake ceramic for most of my life, and the reason is simple: Noritake created their EX-3 porcelain over 40 years ago, and it was so well-made that it has not needed any changes since.

This is showing their consistently high quality and creates unbroken succession in the valuable tradition of passing on techniques and knowledge.

Today, among different generations of dental technicians, we can use and share the same methods, vocabulary and abbreviations, powders, and temperature charts developed by our skilled teachers 30 to 40 years ago. This unique feature sets Noritake and Creation porcelains apart from all other brands and systems in the world.

The other Noritake porcelain I use quite frequently is CERABIEN™ ZR, which is also well-tried and tested and has even some more advantages than EX3.

Is there any final advice you would like to give?

To become a good professional, I suggest to developing in four parallel directions:

1. Practicing on phantoms - fabricating cases and ceramic samples. It helps to experiment and practice with varied materials and techniques.
2. Implementing the achieved techniques in clinical cases.
3. Working with case presentation PowerPoint or Keynote: documenting the working steps in pictures and videos from beginning to end.
4. Mastering the communication using e-mails. Constantly calibrate and adjust the information exchange process between the clinic and lab. Acquire deeper knowledge about the work of each other.

Good luck!

Interview with DT Giuliano Moustakis

The percentage of restorations made of zirconia in a full-contour (monolithic) design is steadily increasing. As an enabler of this development, companies like Kuraray Noritake Dental Inc. have introduced high-performance zirconia materials with well-balanced optical and mechanical properties along with innovative finishing solutions. A popular example is KATANA™ Zirconia YML with its multi-layered flexural strength, translucency and colour structure. Combined with Esthetic Colorant for KATANA™ Zirconia and CERABIEN™ ZR FC Paste Stain, it is very well suited for a simplified approach to zirconia aesthetics: The Zero-Bake Technique. We had a conversation with DT Giuliano Moustakis about its benefits and areas of application.

Giuliano Moustakis, why is there a need for a new technique related to the finishing of monolithic zirconia restorations?

Like many manufacturers of restorative materials, I truly believe that the trend towards monolithic zirconia restorations is here to stay. The reason is that there is a huge number of patients who place great value on high-quality dental treatments, but have a limited budget. Many of them are interested in metal-free restorations that blend in nicely with the surrounding dentition and are able to withstand the test of time. Reasonable cost is more important to them than highest-end aesthetics. The new materials available on the market allow us to produce restorations with the desired properties, but we need to think about how to combine them in the most effective way to be able to respond to all those demands including the financial one.

Please describe the Zero-Bake Technique.

This technique is based on a monolithic restoration design carried out in the preferred design software. In this step, it is already important to focus on a natural surface morphology – about 80 percent of the morphology are realized in the digital manufacturing procedure. After milling, some morphological details (the last 20 percent) are added with hand instruments. My personal set of instruments consists of two kinds of diamond discs used for the interproximal area of bridges (with virtually no pressure), a round-end straight carbide bur (fine), Panther stones and a zirconia-blade carving instrument. However, any set of instruments that feels comfortable in the hands of its user may be selected for this task. Taking into account the volumetric shrinkage during sintering and the final polishing and glazing, the structure created is ideally slightly over-contoured and clearly defined. It is definitely worth investing time in this preparatory step, as it will make our lives much easier later in the process. After surface texturing, selected colours of Esthetic Colorant for KATANA™ Zirconia – specific dyeing liquids designed for the imitation of natural optical effects – are applied to the surface.

Fig. 1. Working out the details in the interproximal area with rotating disc-shaped instruments.

Fig. 2.  Integration of the micro morphology with a round-end straight carbide bur.

Do you have any recommendations on how to proceed with this set of liquids?

Just follow the colour reproduction of the adjacent natural teeth. With Esthetic Colorant, we want to create beautiful illusions, and nature is our best source of inspiration. To be able to copy what we see, however, we need to understand the properties and behaviour of the materials we use. Consequently, I strongly recommend to test them extensively. For example, you may train on remnants of zirconia blanks before moving on to real patient cases. The duration of the testing period should depend on the outcomes produced, which should be highly predictable at the moment the first patient case is started. I experimented and practiced with Esthetic Colorant for about six months, and did use it on the first real case after one moth of practicing.

Nowadays, there are five effect liquids which I use on a daily basis in almost every case:

• A Plus: Used mainly in the vestibular cervical and palatal cervical and mamelon areas to increase the chroma of A dentin shades
• Blue: Used to reproduced the blueish enamel colour found in the area of the incisal edge and occlusal cusps
• Gray: Used (often in addition to Blue) to reproduce the grayish enamel colour found on the incisal edge and cusps
• Orange: Used to give an orange appearance to the cervical area and to intensify the contours of the mamelons
• Brown: Used to reproduce the dentin colour in the cervical area and to darken the colour in the main groove

In addition, there is a liquid with a special function I value highly: Opaque. This modifier liquid is applied on the intaglio of a restoration to mask discoloured or metal abutments. In order to intensify the effects of this and other liquids, they may be applied to a single spot up to three times.

Fig. 3.  Basic chromatic map for Individualization in the anterior region.

Fig. 4.  Restoration after sintering.

Fig. 5.  Frontal view of a complex restoration including gum parts with information on where to apply which type of Esthetic Colorant.

Fig. 6.  Basal view of the restoration with Opaque applied to mask the screws, and Violet and Pink to add colour to the gums.

Fig. 7.  Occlusal view with colour recommendations.

How do you apply Esthetic Colorant and what are the steps that follow once you have applied them?

For application, I use the dedicated Liquid Brush Pen for Esthetic Colorant. They allow for a controlled application of the desired amount of liquid and thus support predictable outcomes. Once all Esthetic Colorant liquids are applied, it is essential to dry the zirconia at a temperature between 80 and 200° C for a minimum of 30 minutes. During application of the liquids and drying, any contact with metal must be prevented. Therefore, the brushes used during application must be metal-free, and the same holds true for the tray. By adhering to this rule, discolouration is effectively prevented. The subsequently selected sintering protocols are not affected by the effect liquids – and the same for all types of zirconia from the KATANA™ Zirconia Multi-Layered series. Once sintered and cooled down, the surface of the restorations is finished with a set of polishing instruments. My tip in this context is to be careful not to destroy the micro morphology created in the pre-sintering step. To add the final gloss and natural fluorescence, the surface is treated by sandblasting for the application of CERABIEN™ ZR FC Paste Stain, fixed in a single glaze firing procedure.

Does the technique also work without glazing?

Yes, it is definitely possible to do without this step. In this case, however, the restoration will not offer a fluorescent effect. Whenever a restoration is finished without glazing, the surface must be perfectly polished. If completely smooth, the hardness of the material will not cause any harm to the opposing dentition.

What are the main indications for the Zero Bake Technique?

Personally, I use it most often in the context of complex reconstructions and in the posterior region, especially when the available space is limited. It allows for minimal wall thicknesses and the surface is – when well-polished – more antagonist-friendly than a lithium disilicate surface. In other cases, and depending on the financial budget, digitally produced dentin-core crowns are a great option. The dentin core is milled from KATANA™ Zirconia YML, the enamel added using CERABIEN™ ZR Luster Porcelains. Esthetic Colorant, internal stans and CERABIEN™ ZR FC Paste Stain may be added for individual effects. Compared to traditional full porcelain layering, this concept is quicker, involves a lower shrinkage, offers a high stability due to the specific framework design and requires a thinner wall thickness (e.g. 0.6 mm strength of the dentin core plus 0.6 mm porcelain).

Fig. 8.  Example of a dentin-core restoration. The surface morphology is refined with a Panther stone.

Why is it important to develop new design and finishing concepts nowadays?

To my mind, a lack of time is the greatest issue of modern dental technology. Due to a lack of skilled personnel and an expected decrease in the number of dental laboratories in many countries around the globe, we have to keep looking for concepts that help us reduce the time pressure and make our lives easier. While simplifying procedures, however, we need to provide for the same or even a higher quality of the outcomes. This is exactly what I wanted to achieve when starting to develop the Zero-Bake Technique. My personal gain is more free time.

Why do you share your ideas with others by working as an instructor and lecturer?

I simply enjoy interacting with colleagues, equipping them with knowledge and letting them benefit from good ideas.

Dentist:

DT GIULIANO MOUSTAKIS

Giuliano Moustakis has more than 30 years of expertise as dental technician. He was born in Greece but currently resides in Germany, where he has a lab in Falkensee. Giuliano studied at the School of Dental Technology (SBIE) in Athens, Greece. Over the years he completed several other studies in Germany and Japan, including: the maxillofacial prosthetic technician (IASPE), advanced education in functional diagnosis of the temporomandibular joint, Curriculum implant prosthetics for dental technicians (DGZI). He has been a global instructor at Kuraray Noritake Dental Inc. since 2019. Last but not least it is important to note that he is also a gifted and enthusiastic photographer.

As an instructor and consultant for Kuraray Noritake Italia, I received my first set of Esthetic Colorant dyeing liquids for testing purposes approximately one year ago. When the package arrived in the dental laboratory, it made me curious immediately and I simply could not wait to start using the colourful liquids on KATANA™ Zirconia.

I started with some simple test work, applied the basic liquids like A Plus to pre-sintered zirconia, played a little with Gray and Violet and put the structures into the sintering furnace to reveal the obtained effects. The outcome was so convincing that I was sure Esthetic Colorant would be a great addition to the range of materials used in my laboratory for the production of zirconia restorations. The liquids would support me ideally by giving more character to my restorations from the inside.

To my mind, the use of Esthetic Colorant is convenient for two reasons:

1. KATANA™ Zirconia is a very compact material, even in its green (pre-sintered) state. This property is not only responsible for a great performance in terms of milling accuracy, stability and surface quality, but also provides for a controlled penetration of the effect liquids into the structure. They neither diffuse too deep into the zirconia nor do they spread too much on the surface.
   
   
2. Esthetic Colorants are water-based infiltrating liquids with a very light colour effect. Hence, they do not create such marked characterization effects like liquids from other companies. This is a huge advantage in my eyes, because I can characterize my zirconia internally without exaggerating. This allows me to copy lightly to moderately intensive effects, while giving depth to some areas of the tooth. Great examples are the occlusal table of a posterior restoration or incisal effects in the anterior region. In addition, I am able to shield the grayish effect resulting from a metal post or discoloured abutment tooth with the Esthetic Colorant Opaque applied to the inner surface of a restoration.

In short: I think Esthetic Colorants are fantastic. Just try them out yourself, because seeing is believing!

DT FRANCESCO NAPOLITANO

Nola (NA) ITALY

Clinical Case by MDT Mathias Berger

Highly reliable implants, advanced surgical techniques and innovative restorative materials, designs and approaches: modern implant dentistry has evolved into a predictable discipline producing aesthetic and functional outcomes, which are successful in the long term. Asking patients what they expect from a complex implant-supported reconstruction in the maxilla, natural aesthetics and biocompatibility are often demanded apart from functional aspects. With modern zirconia materials that offer the flexural strength required and well-balanced aesthetics, these demands are easily met.

The following case example is used to demonstrate how to maximise the potential of the recently introduced KATANA™ Zirconia HTML PLUS (Kuraray Noritake Dental Inc.), a multi-layered zirconia and the successor of KATANA™ Zirconia HTML with further improved strength and aesthetics. A special cutback design refined with hand instruments, shading with Esthetic Colorant for KATANA™ Zirconia and micro-layering with CERABIEN™ ZR porcelains (both Kuraray Noritake Dental Inc.) led to a quite natural result.

Start now reading the clinical case of MDT Mathias Berger by clicking image below!