2023 DENTAL ADVISOR Top Product is an everyday cement that eliminates the need for a separate primer

PANAVIA™ SA Cement Universal adheres to virtually all substrates, including lithium disilicate, in a single procedure without the need for a separate primer or silane, and it also offers easy, gingival-friendly removal of excess cement and requires no refrigeration. Therefore it is no wonder that this year DENTAL ADVISOR gave PANAVIA™ SA Cement Universal Top Product award in the category of Indirect Restoratives.

What makes its strong and durable bond possible without the added step of applying a separate substrate is that PANAVIA™ SA Cement Universal combines two innovative technologies in a single product. The silane coupling agent, LCSi monomer, establishes a durable, chemical bond with porcelain, lithium disilicate, and composite resin; and the original MDP monomer provides for chemical reactiveness with zirconia, dentin and enamel.

The result is a convenient, versatile, and efficacious single solution to practitioners’ everyday cementation needs for a wide variety of indications, including cementation of crowns/bridges, inlays/onlays, posts, splints, and even adhesion bridges.

The significant benefits and quality of PANAVIA™ SA Cement Universal are reflected in the study findings and feedback of the 31 DENTAL ADVISOR clinical evaluators who used the cement in 516 applications and gave it an overall clinical rating of 96 percent. Their comments on its ease of use, handling characteristics, and aesthetics included: “Good flow and film thickness;” “Amazing viscosity, tack cure-ability, and very easy cleanup;” and “Great color match, and I liked the universal ability to work with so many substrates.”

The Top Product or Preferred Product Awards conferred by US-based DENTAL ADVISOR were introduced to help busy practitioners make sense of the numerous new solutions indicated for less invasive techniques, standardized or simplified procedures, and better outcomes on a regular basis. DENTAL ADVISOR conducts its practice-based clinical evaluations and product performance tests shortly after product launch, and publishes results annually online to help potential users identify high-quality new dental materials and determine which among them are best suited to fulfill their individual requirements.

For more information visit the website of DENTAL ADVISOR: www.dentaladvisor.com.

Five-time DENTAL ADVISOR Top Product delivers more than a reliable bond

For the fifth time CLEARFIL™ SE Protect has made DENTAL ADVISOR’S list of Top Products for 2023, placing it among dental materials and equipment deemed to deliver the best practice-based performance based on the publication’s annual review of such products.

Featured in the Bonding Agent Self-etch category, CLEARFIL™ SE Protect is a self-etch adhesive that offers more than just a reliable bond. It is:

• Antibacterial (self-etch) primer thanks to containing MDPB monomer
• Built on the same system of the gold standard adhesive CLEARFIL™ SE BOND
• Possible to use it for extended indications of core build-up and indirect restoration with CLEARIFL™ DC Activator.

All in all - surely a great addon to your dental toolbox.

Application of CLEARFIL SE Protect is also truly versatile – you can use it for any direct restorations, but in particular when treating hypersensitive teeth. It is also widely used for core build-up with self- or dual-cured resin materials and for cementation with composite resin cement in combination with CLEARFIL™ DC Activator.

CLEARFIL™ SE Protect offers you following features:

• Virtually no post-operative sensitivity
• Excellent bond strength for enamel and dentin
• Fast and simple procedure with low technique sensitivity

These attributes are reflected in the study findings and comments of the 13 DENTAL ADVISOR editors and consultants—seven of whom had previously used CLEARFIL™ SE BOND in their practices. After CLEARFIL™ SE Protect was assessed over a six-week period during which over 150 restorations were placed, it received a 98% clinical rating by consultants using a 1-5 rating scale,

The practitioners evaluating the product found no post-operative sensitivity. Among their observations mentioned in the online DENTAL ADVISOR report were the fact that the primer and bond wet the tooth evenly. They also mentioned that CLEARFIL™ SE BOND is effective in the reduction of sensitivity when placed on areas of recession or similar areas of sensitive tooth structure.

The Top Product or Preferred Product Awards conferred by US-based DENTAL ADVISOR were introduced to help busy practitioners make sense of the numerous new solutions indicated for less invasive techniques, standardized or simplified procedures, and better outcomes on a regular basis. DENTAL ADVISOR conducts its practice-based clinical evaluations and product performance tests shortly after product launch, and publishes results annually online to help potential users identify high-quality new dental materials and determine which among them are best suited to fulfill their individual requirements.

For more information visit the website of DENTAL ADVISOR: www.dentaladvisor.com

DENTAL ADVISOR Top Product to address everyday dental challenges

For the 8^th straight year, CLEARFIL MAJESTY™ ES Flow has been included among DENTAL ADVISOR’S Top Products, which is made up of dental materials and equipment deemed to deliver the best practice-based performance based on the publication’s annual review of such products.

Featured in the Direct Restorative category, CLEARFIL MAJESTY™ ES Flow comes in three different levels of flowability designed to cover a range of flowable composite indications that cannot be addressed with a single viscosity. Whether the practitioner needs the product to be firm enough to stay put where applied, malleable enough to create a specific shape, or runny enough to flow into every corner or undercut, one of the three versions is appropriate for the job. For example, the high flowability variant is the perfect choice for cavity linings and as a resin coat in immediate dentin sealing (IDS) procedures, while the super low flowability option is suitable for direct veneer procedures and for build-up of posterior cusps etc.

Equipped with Kuraray Noritake Dental Inc.’s Light Diffusion Technology, the universal flowable composite integrates seamlessly with the surrounding tooth structure. If no recontouring required, then a glossy surface can be obtained simply by wiping with a cotton roll soaked in alcohol.

The version tested by the 29 DENTAL ADVISOR consultants in more than 900 applications in their dental practices was the medium flowability variant (Low) of CLEARFIL MAJESTY™ ES Flow. They evaluated properties including placement/handling, aesthetics, viscosity, and polishability and rated all to be “excellent,” with no running during placement and a good adaptation to the cavity walls and when flowed into narrow areas. This led to a recommendation rate of 100 percent and a 98 percent overall clinical rating.

Among their comments were: “The material blended so well with the tooth structure that you had to look hard to find the interface;” “Syringe design prevents oozing from the tip;” and “Readily apparent on radiographs.”

The Top Product or Preferred Product Awards conferred by US-based DENTAL ADVISOR were introduced to help busy practitioners make sense of the numerous new solutions indicated for less invasive techniques, standardized or simplified procedures, and better outcomes on a regular basis. DENTAL ADVISOR conducts its practice-based clinical evaluations and product performance tests shortly after product launch. It publishes results annually online in its January/February issue to help potential users identify high-quality new dental materials and determine which among them are best suited to fulfill their individual requirements.

For more information visit the website of DENTAL ADVISOR: www.dentaladvisor.com.

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

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

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

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

Fig. 2. Possible cutback design.

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

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

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

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

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

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

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

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

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

Photo credits to MDT Giuliano Moustakis.

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

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

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

Photo credits to MDT Daniele Rondoni.

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

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

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

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

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

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

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

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

Photo credits to MDT Roberto Rossi.

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

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

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

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

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

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

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

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

KATANA™ Zirconia YML, finished with CERABIEN™ ZR.

Photo credits to MDT Giuliano Moustakis.

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

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

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

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

Dentist:

YOSHIHISA YAMADA

“Very nice handling properties”

PAVANIA™ Veneer LC receives 4.6 rating in REALITY’s Five Star Award

After a FirstLook evaluation published in May 2022, a team of evaluators from REALITY RATINGS & REVIEWS has thoroughly tested PANAVIA™ Veneer LC in the clinical practice environment – with great outcomes. The purely light-cured resin cement received 4.6 out of 5 stars in the Five Star Award, the most convincing features being its handling and viscosity.

While most of the evaluators used PANAVIA™ Veneer LC for the permanent cementation of veneers, some also tested the onlay indication (restricted to high-translucency materials of a material-specific maximum thickness). Those who decided to polish the margins (43 %) found that the resin cement is very well polishable with little effort. Among the handling properties highlighted were easy seating with virtually no drifting, non-stickiness and easy excess removal – both after tack curing and in the cement’s uncured state. In addition, the evaluators praised the minimal film thickness and favourable viscosity, which has a considerable impact on the ease of seating. The working time was sufficient for all evaluators, independent of their way of working (filtering/blocking dental unit light or not, placing multiple veneers simultaneously or one veneer at a time).

The shade offering – PANAVIA™ Veneer LC is available in the four shades Clear, Universal/A2, Brown/A4 and White – was regarded adequate by most evaluators (79 %), the most popular shade being Clear. One evaluator stated that “I think the “clear” shade is my new favorite. It seems to have a brightness to it compared to other clear or translucent cements.”. Being the only shade with a high opacity, White was found to have a decisive impact on the appearance of the final restoration. The try-in pastes were well-received for their handling and easy rinse-off ability.

The PANAVIA™ Veneer LC kit available in Europe consists of PANAVIA™ Veneer LC Paste, PANAVIA™ V5 Tooth Primer and CLEARFIL™ CERAMIC PRIMER PLUS. Hence, it builds confidence by sharing primers with the proven PANAVIA™ V5, while its long working time and specific handling properties add extra benefits that are extremely valuable during veneer cementation. Click here to read the full evaluation!

Interview with Dr. Karim Nasr

Zirconia is a popular restorative material with highly beneficial mechanical and meanwhile also optical properties. Due to long processing times, especially sintering, the material was initially not suitable for single-visit dentistry. This changed with the availability of zirconia variants with shortened sintering times and special high-speed sintering furnaces.

We discussed with Dr. Karim Nasr, who is senior lecturer at the University of Toulouse in France and head of CAD/CAM postgraduate training, about his actual practice. His passion for CAD/CAM leads him to use CEREC since 2006 (former CEREC trainer) and to found also iAcademy, a training academy about digital dentistry. He shared his experience with us and we talked about his workflow and indication-specific material preferences as well as specific recommendations regarding the use of KATANA™ Zirconia Block in single-visit dentistry.

Dr. Nasr, which chairside CAD/CAM system do you currently use?

Karim Nasr: I am currently using a chairside CEREC Primescan AC system (Dentsply Sirona) combined with a MCXL milling machine (Dentsply Sirona) in my private practice. In my hospital practice and in the specialized esthetic dentistry consultation that I manage, we use a CEREC Primescan AC system combined with a CEREC Primemill milling machine (Dentsply Sirona).

Why did you opt for those components?

Karim Nasr: The choice of this entire system was guided by several criteria. Working on a proprietary chain certainly locks the possibilities of mixing the equipment, but brings real simplicity and fluidity of use. Moreover, the CEREC Software is certainly the most successful CAD software for a chairside use. It offers personalized and easily modifiable restorations in just a few steps. The simultaneous milling of the top (extrados) and bottom (intrados) surfaces without changing the burs ensures a very short milling time. Finally, a large number of materials are available and can be used with this system.

When did you start working with a chairside CAD/CAM system?

Karim Nasr: I discovered and started working with my first chairside system (CEREC 3) in 2005, shortly after graduating. At that time, everything was new in this field. The intraoral scanner, CAD software, milling unit and ceramic materials had just been introduced. All those components allowed us to deliver aesthetic dental treatments within a single treatment session for the first time.

How did the chairside CAD/CAM systems evolve over time?

Karim Nasr: Of course, with the advances in computer technology, the systems have become more efficient. While it was still necessary to powder the surfaces and possible to record one or two teeth in 2005, powder is no longer required in 2022 and complete arches can be scanned in less than two minutes with an accuracy of less than 20 μm. The design process is highly automated and very well assisted – artificial intelligence is used at all stages, making the work easier.

For what purposes do you use your system today?

Karim Nasr: In more than 15 years, the use of my system has evolved a lot. Nowadays, I reserve it for procedures that can be performed in a single session. This is of the greatest utility for my patients and it allows me to optimize my treatment time. For this reason, not only the milling time, but also the time needed for post-processing is crucial for the decision whether to use my chairside CAD/CAM system or to collaborate with a dental laboratory.

What kinds of materials do you process chairside?

Karim Nasr: I think I have tested all the materials available (at least in France), to be able to select the most suitable ones for daily procedures. Currently, I use different kinds of materials depending on the indications encountered: PMMA for temporary restorations, composites for inlays and onlays, glass-ceramics for onlays, overlays and crowns, and finally zirconia for crowns and bridges.

How do chairside CAD/CAM and zirconia go together?

Karim Nasr: In fact, quite simply. For me, a chairside equipment must be able to produce restorations in the same treatment session. Otherwise, it is a labside workflow. Thus, to use zirconia in chairside systems, the milling procedure must be fast and efficient, but above all, the post-processing (especially sintering) process must be fast. For short processing times, dry milling is recommended, as well as the use of a fast-sintering furnace (such as the CEREC SpeedFire from Dentsply Sirona).

What are the benefits of zirconia compared to other ceramic materials?

Karim Nasr: There are many of them. From a biomechanical point of view, the high mechanical strength of zirconia allows us to work with reduced wall thicknesses, which enables us to be more conservative in dental tissues or to choose any placement method (cementation or bonding). From a biological point of view, perfectly polished, zirconia is the most tolerant ceramic, as it is kind to antagonistic teeth and incredibly well tolerated by periodontal tissues. I prefer zirconia for my crowns on implants for this reason.

What was your first impression when you heard about KATANA™ Zirconia Block?

Karim Nasr: I caught a first glimpse of the new material during an event in 2018. KATANA™ Zirconia STML already existed in discs for laboratories and was well known for its aesthetic qualities. Its block version was highly anticipated. But the most amazing feature was the short sintering times announced (with the CEREC SpeedFire in particular). Testing it, I was immediately amazed by the quality of the ceramic and impressed that it is possible to obtain such an aesthetic result (translucency and shade gradation) within such a short time. This is aesthetic zirconia for everyone!

For which indications would you employ KATANA™ Zirconia Block?

Karim Nasr: I reserve the use of KATANA™ Zirconia Block for crowns and for 3-unit bridges. In some cases, I also use it to produce cantilever bridges with a single-retainer design to replace missing incisors (as described by M. Kern). I particularly like it in my cases where I employ a Biologically Oriented Preparation Technique (BOPT) or Vertiprep.

Are there any material features which are particularly interesting for you?

Karim Nasr: Its biomechanical qualities (which are those of zirconia, already mentioned above) already allow me to extend the indications of my chairside restorations. But, in my opinion, the most interesting property is the degree of translucency. Although it is translucent, KATANA™ Zirconia Block is slightly more opaque than glass-ceramics in their lowest degree of translucency. This allows me to use it on discoloured substrates with higher confidence and to avoid the gray effect without having to use an opaque resin cement.

Do you have any recommendations for an ideal processing of KATANA™ Zirconia Block?

Karim Nasr: The use of zirconia in chairside procedures requires certain precautions to be taken in order to achieve the expected results. I have carried out many tests to identify the mistakes not to be made.

First, dry milling is strongly recommended. Nevertheless, it is quite possible to mill in wet environment. However, in this case, it is fundamental to reserve a tank only for the milling of zirconia, never use any lubricant in water (ideally demineralized water), and to have the filters always clean, which means that they need to be cleaned after each milling procedure. After milling, it is important to remove all the powder of zirconia that may have remained on the surface. After dry milling, the restoration must be sprayed with air. The same is the case after the use of burs or polishers to finish the surface. After wet milling, a demineralized water and ultrasound bath may be indicated but is not mandatory.

(Very) fast sintering with CEREC SpeedFire, for example, gives very satisfactory results comparable to conventional slow sintering, which has also been confirmed by scientific literature. Without an appropriate furnace, it is impossible to perform restorations in the same treatment session. However, I do not use CEREC SpeedFire for staining, glazing or micro-layering, but rather a furnace that can be parameterized. Finally, I advise users to finish and glaze only what is necessary (occlusal grooves, vestibular surfaces if visible) and to polish the rest.

Do you have any tips on how to achieve optimal outcomes with KATANA™ Zirconia Block?

Karim Nasr: In anterior cases, I always recommend to perform shading and staining steps in the mouth because there is no better model than the patient himself. Micro-layering in anterior cases makes it possible to improve the aesthetic result with few steps. The 4.4.1. system, which has been specifically developed for KATANA™ Zirconia, makes micro-layering easy to achieve. For polishing, the use of “twist” polishers is recommended. They make it easier to polish all surfaces, especially the occlusal surfaces, both extra-orally and in the mouth. Just like their counterparts for composite, TWIST™ DIA for Zirconia for Zirconia polishers prove to be very effective.

Dr. Nasr, thank you very much.

DR. KARIM NASR

KATANA™ Zirconia STML is a highly popular material used in many dental laboratories around the world. Compared to traditional zirconia framework materials with a mainly tetragonal polycrystalline structure, the material has a higher yttria content, leading to a different material structure with an impact on the optical and physical properties (the translucency is increased, the flexural strength reduced). As a consequence, the indication range is limited to single-tooth restorations and two to three-unit bridges in the anterior and posterior regions. The greatest benefit lies in a much higher aesthetic potential, which is responsible for the fact that the material is predominantly used for the production of monolithic restorations or those with a micro cut-back individualized with a micro-layer of porcelain.

While the indications and technical procedure are wellknown, there seem to be some obscurities regarding the handling in the dental office. Is conventional cementation possible and recommended or is an adhesive luting procedure preferable? Is the surface pre-treatment the same as for tetragonal zirconia or is a different procedure required? And what may be expected regarding the longterm behaviour of KATANA™ Zirconia STML restorations? A close look into the available scientific literature provides some guidance.

DEFINITIVE PLACEMENT OF RESTORATIONS MADE OF KATANA™ ZIRCONIA STML

Conventional cementation or adhesive luting? In principle, both procedures are possible when the restoration to be placed has a retentive design. It is generally accepted that a full coverage crown provides sufficient retention for conventional cementation when the abutment tooth is at least 4 mm high and the convergence angle of the axial walls ranges between 6 and 12 or maximally 15 degrees (1,2). The reason is that the flexural strength of the material is higher than 350 MPa (3), the critical value for conventional cementation. As conventional cements are opaque and available in a single shade, however, the use of a (self-) adhesive resin cement may be preferable with all hightranslucency restorative materials for aesthetic reasons. Anyway, these products are mandatory whenever a macroretentive preparation design is not feasible or wanted. To sum up, the use of a self-adhesive or adhesive resin cement is preferable in many situations. An argument in favour of self-adhesive resin cements is the lower effort involved in their use. But what about the pre-treatment of the zirconia? No matter what type of dental zirconia is used, etching with hydrofluoric acid is ineffective due to the lack of glass matrix in the material. However, it is clear that surface modification is necessary to establish a strong and durable bond to any resin cement system4,5. The method generally recommended for high-strength zirconia is sandblasting with aluminium oxide particles or tribochemical silica coating4. The particle size should be small (≤ 50 μm) and the pressure low (about 1 bar) to avoid a weakening of the material’s mechanical properties (3,4). For lower-strength material variants, this risk of weakening the material seems to be higher (5), so that it becomes even more important to work with a low pressure and particle size (5-8). In the case of KATANA™ Zirconia, however, it was reported that “alumina-sandblasting significantly increased the biaxial flexural strength of KATANA™ STML.” (9) This means that proper sandblasting of restorations made of KATANA™ Zirconia STML did not affect the flexural strength of the material, which was even increased because of the specific properties of zirconia from Kuraray Noritake Dental.

Based on these findings, the following procedures are recommended for high-translucency zirconia:

OPTION 1
Aluminium oxide air-abrasion followed by the use of a selfadhesive resin cement containing 10-MDP (6)

OPTION 2
Tribochemical silica coating followed by silanization of the bonding surface (6)

As the dual-cure self-adhesive resin cement PANAVIA™ SA Cement Universal contains the Original MDP monomer and the long carbon-chain silane coupling agent (LCSi Monomer), it is suited for both procedures. PANAVIA™ SA Cement Universal is available in an automix syringe and a handmix system, which consist of a pastepaste formulation. One paste contains the Original MDP monomer in a hydrophilic monomer environment and the other contains the inactive LCSi Monomer in an environment of hydrophobic monomers. When extruding the pastes, they are mixed in the syringe’s mixing tip (automix) or dispensed on a mixing pad and mixed by hand (handmix). Afterwards, the material is simply applied to the intaglio of the restoration and the restoration is placed. Cleanup of excess cement is easiest after tack-curing (2 to 5 seconds).

DOES THIS WORK WELL IN THE CLINICAL ENVIRONMENT?

The best way to check whether the described procedure is successful in the clinical environment is by conducting a clinical study. This is exactly what a group of researchers from the University Complutense of Madrid, Spain, has done with the material combination KATANA™ Zirconia STML and PANAVIA™ SA Cement Universal (10). Within the framework of the prospective clinical trial, 30 posterior crowns made of KATANA™ Zirconia STML were placed in 24 individuals in need of posterior tooth restorations. The teeth were prepared as recommended for all-ceramic restorations, allowing for a wall thickness of approximately 1 mm (recommended minimum wall thickness of KATANA™ Zirconia STML for crowns in the posterior region: 1.0 mm). The restorations were sintered, characterized and glazed as recommended by the material manufacturer and subsequently tried in. Prior to cementation, the intaglio of the restorations was pre-treated with aluminium oxide particles (50 μm, 1 bar pressure) followed by ultrasonic cleaning. The use of PANAVIA™ SA Cement Universal also was in line with the manufacturer’s recommendations. A clinical evaluation of the crowns was performed after 6, 12 and 24 months using the California Dental Association (CDA) quality evaluation system. The parameters evaluated in this system are the surface and colour of the restorations, their anatomical form and the marginal integrity of the crowns. After 24 months, the success and survival rates were 100 percent. Regarding all three parameters, the crowns received a “satisfactory” (Score 3 or 4) rating, marginal integrity (the key parameter to judge the performance of the resin cement) received an “excellent (the highest possible Score 4) in all 30 cases.

CONCLUSION

The researchers concluded that “the excellent results obtained in this study suggest that the third-generation tooth-supported monolithic zirconia crowns in posterior regions seem to be a good alternative to metal-ceramic crowns, second-generation monolithic zirconia crowns, and veneered zirconia crowns. A long-term study is necessary to confirm this short-period study.” Hence, it seems that KATANA™ Zirconia STML and PANAVIA™ SA Cement Universal are a promising team, and that adhering to the recommended abovementioned protocols is likely to produce excellent results that are stable over many years.

References:
1 Edelhoff D, Özcan M. To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials: cementation. Clin Oral Implants Res. 2007;18 Suppl3:193-204. 2 Güth JF, Stawarczyk B, Edelhoff D, Liebermann A. Zirconia and its novel compositions: What do clinicians need to know? Quintessence Int. 2019;50(7):512-20. 3 Kern M, Beuer F, Frankenberger R, Kohal RJ, Kunzelmann KH, Mehl A, Pospiech P, Reis B. All-ceramics at a glance. An introduction to the indications, material selection, preparation and insertion techniques for all-ceramic restorations. Arbeitsgemeinschaft für Keramik in der Zahnheilkunde. 3rd English edition, January 2017. 4 Comino-Garayoa R, Peláez J, Tobar C, Rodríguez V, Suárez MJ. Adhesion to Zirconia: A Systematic Review of Surface Pretreatments and Resin Cements. Materials (Basel). 2021 May 22;14(11):2751. 5 Mehari K, Parke AS, Gallardo FF, Vandewalle KS. Assessing the Effects of Air Abrasion with Aluminum Oxide or Glass Beads to Zirconia on the Bond Strength of Cement. J Contemp Dent Pract. 2020 Jul 1;21(7):713-717. 6 Chen B, Yan Y, Xie H, Meng H, Zhang H, Chen C. Effects of Tribochemical Silica Coating and Alumina-Particle Air Abrasion on 3Y-TZP and 5Y-TZP: Evaluation of Surface Hardness, Roughness, Bonding, and Phase Transformation. J Adhes Dent. 2020;22(4):373-382. 7 Alammar A, Blatz MB. The resin bond to high-translucent zirconia-A systematic review. J Esthet Restor Dent. 2022 Jan;34(1):117-135. 8 Soto-Montero J, Missiato AV, dos Santos Dias CT, Giannini M. Effect of airborne particle abrasion and primer application on the surface wettability and bond strength of resin cements to translucent zirconia. J Adhes Sci Technol, Online publication May 2022. 9 Inokoshi M, Shimizubata M, Nozaki K, Takagaki T, Yoshihara K, Minakuchi S, Vleugels J, Van Meerbeek B, Zhang F. Impact of sandblasting on the flexural strength of highly translucent zirconia. J Mech Behav Biomed Mater. 2021 Mar;115:104268. 10 Gseibat M, Sevilla P, Lopez-Suarez C, Rodríguez V, Peláez J, Suárez MJ. Prospective Clinical Evaluation of Posterior Third-Generation Monolithic Zirconia Crowns Fabricated with Complete Digital Workflow: Two-Year Follow-Up. Materials (Basel). 2022 Jan 17;15(2):672. (https://pubmed.ncbi.nlm.nih.gov/35057389/)

Article by Peter Schouten.

I am frequently asked questions about the intraoral repair of porcelain chippings. To achieve success in repairs, it is essential to consider several important issues.

Perhaps the single most crucial issue to recognise is why the chipping occurred in the first place. For example, if loading stress is the leading cause, this should be considered during the repair.

Other issues to consider are removal of contamination, optimal roughening and chemical activation of the surface, and the prevention of contamination during the repair. Also, a rubber dam should be used to isolate the working field.

FUNDAMENTALS OF ADHESION

Adhesive procedures can be only successful by using the proper substances and methods. Different kinds of surfaces often need different treatments for success. However, the three basic fundamentals of adhesion must be respected to achieve the best results.

1) Mechanical retention through a roughened surface.

2) Chemical activation through chemically active substances.

3) High energetic bonding surface allowing for optimal interaction (wetting capacity) between the surface and the applied medium. Contamination will lower the bonding capacities and must be avoided or removed in any case.

TYPES OF FRACTURE

The most frequent fractures are porcelain only and those that include exposure of the substructure in PFZ or PFM prosthesis.

Many cases present with only limited chipping to the porcelain, for example, at the incisal edge. To achieve a durable repair in this instance, start by increasing the bonding/repair area using a fine diamond burr to create a large bevel. A fine grit burr is preferable over a medium or coarse version because a higher number of shallow grooves deliver a more optimal bonding surface than lesser deeper ones do. Additional roughening of the adherent surface by sandblasting with alumina (50 µm grain size, 2 bar pressure) is highly recommended to increase the surface area further.

When repairing porcelain chippings where the substructure is exposed, it is essential to be aware that multiple substrates are dealt with, indicating a need to adjust the repair protocol accordingly.

Clean the roughened fractured surface thoroughly. KATANA™ Cleaner is the product of choice. It is a safe and easy to use product with high cleaning power. It can be used both intra and extra orally on all kinds of dental substrates. After rinsing and thorough drying, the surface is ready for the next step, chemical activation.

CLEARFIL™ CERAMIC PRIMER PLUS contains both silane and MDP and effectively treats both silica-containing ceramics and metal oxides (zirconia) and metals. After application and thorough drying, the composite restoration can be carried out immediately without an extra bonding step. The composite of choice is a durable flowable, CLEARFIL MAJESTY™ ES Flow. It has high flexural strength, even higher than most paste-type composites. Besides that, it adapts to the surface better and easier. Quick and easy polishing and gloss retention are other highly valuated qualities of CLEARFIL MAJESTY™ ES Flow.

HINTS AND TIPS

• Isolate the working field by using rubber dam
• Bevel the chipping extensively using a fine diamond burr
• Roughen the adherent surface, preferably by sandblasting
• Clean the bonding area with KATANA™ Cleaner
• Apply CLEARFIL™ CERAMIC PRIMER PLUS to the entire bonding area (including exposed zirconia or metal) and dry thoroughly
• Cover exposed metal with a thin layer of CLEARFIL™ ST OPAQUER and light cure
• Repair with a strong flowable composite, such as CLEARFIL MAJESTY™ ES Flow

REPAIR OF PORCELAIN CHIPPINGS VIDEO

A discoloured abutment tooth, a metal post or tooth-coloured gum areas: It is not always possible to meet the target tooth or gum shade with a pre-shaded zirconia framework. Porcelain layering on a differently coloured base, however, is likely to deliver unexpected outcomes. The “CERABIEN™ ZR” Shade Base line-up has been developed and recently extended by Kuraray Noritake Dental Inc. for those who would like to avoid surprises and provide for a favourable framework colour, right from the start of porcelain layering. The five new opaque shades deliver approximately five times higher opacity than conventional “CERABIEN™ ZR” Shade Base porcelains, and can mask the base colour much more effectively for even more lifelike restorations.

The “CERABIEN™ ZR” Shade Base opaque shade line-up consists of three shades that reproduce tooth colour: Opaque White as a bleaching shade, Opaque Light as an A2 shade, and Opaque Dark as an A3.5 shade. They may be mixed or applied as delivered to the zirconia framework in thin layers to mask severely discoloured or metal areas. In most situations with a severely discoloured base, a precise matching of the target shade is achieved by applying an opaque shade as a first layer and a target-coloured “CERABIEN™ ZR” Shade Base as a second layer.

The other two new opaque shades – “CERABIEN™ ZR” Opaque Light Tissue and Opaque Dark Tissue – are used in a similar way to create a pink-opaque base in the gum areas of tooth-coloured zirconia frameworks (e.g. made of KATANA™ Zirconia Multi-Layered discs), which is perfect for reproducing gingival colour. Applied as a thin coating, the opaque tissue shades neutralise the tooth colour and their moderate reflection improves the colour effect of the subsequently applied tissue porcelains.

With their high masking ability, the new opaque shades make it even easier to adjust zirconia framework colours for highly aesthetic porcelain layering – no matter whether the base colour of a tissue or tooth area needs to be optimized.