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Interview with Dr Imad Ghandour

In recent years, zirconia has emerged as the preferred choice for dentists who wish to perform restorative procedures with a reliable and metal-free material. With the recent development of multi-layered aesthetic high-translucency options, zirconia’s popularity has further increased. In comparison to the opaque whiteness of older generations of zirconia, these newer versions have an enhanced appearance and functionality that makes them suitable for natural-looking anterior restorations.

Kuraray Noritake Dental’s KATANA Zirconia disc range is made with a proprietary zirconia powder - processed in-house - that gives it its natural appearance. Suitable for zirconia prostheses, from single crown to full arch, it is an ideal option for restorations in both the anterior and posterior regions. We spoke with Dr Imad Ghandour, a prosthodontist with a strong scientific background and a private practice in Le Cannet in France, about his experiences with the KATANA Zirconia range in restorative procedures.

Dr Ghandour, when did you first start using zirconia as a material for your restorations?

In 1998, when I was still sintering manually, I began using zirconia alumina. It was nice to have an alternative to metal alloys that was much more aesthetic. From 2003, however, I started with VITA blocks, but only for frameworks - I would still build up with ceramics. Now, with so much of dentistry being digitally focused, there is a need for a material that can be milled without changing anything in the morphology of the teeth. Why? Because we need to be able to reproduce the treatment plan as accurately as possible. Simply put, the KATANA Zirconia range solves this need for me.

With respect to dentistry being digitally focused, how has this changed the role of the dentist regarding performing restorative procedures?

Well, it is clear that we have entered the age of digital dentistry. Around 80 per cent of restorations are conducted via CAD/CAM systems and without dentists even touching the materials themselves. There are great advances being made in the technologies that are available for everyday use in dental practices worldwide, and many of them can be used to assist dentists performing restorative procedures. It is important, though, to keep in mind that these technological advancements alone will not lead to better results - they should supplement the requisite hands-on skills and techniques that all dentists must first learn. With this base of fundamentals, we can then use digital dentistry to make restorative procedures more predictable and reproducible. Of course, to ensure the best results in restorative procedures, dentists also need to use the materials that have the best aesthetic and mechanical properties.

For how long have you been using Kuraray Noritake Dental’s KATANA Zirconia range, and what has your experience been?

I have been using KATANA Zirconia for a little bit more than one year. In that time, I have primarily used the KATANA Zirconia STML (Super Translucent Multi Layered) line and have been pleasantly surprised by how natural-looking the restorations I have made with the material are. For example, when I sinter a crown made of Katana Zirconia STML, I am amazed at how much the sintered material is reminiscent of a pearl - it truly brings to mind the idea of one’s teeth being one’s pearly whites.

When using KATANA, how do you ensure that you select the correct shade to achieve a natural look?

Firstly, no one - not a dentist nor a dental technician - can be absolutely certain that the shade and chroma of the restoration that is in one’s hand will be the same once it is in position in the oral cavity. This is due to the complexities of the oral environment - the pinkness of the gingivae, for one, can have a large impact on how the restoration appears, often making it seem far duller than it does in the light of a dental laboratory. This can cause dental practitioners to compensate and make prostheses that appear far brighter than they will when they are in place.

With a product like KATANA and its related glazing materials, however, I can create crowns and other restorations that have an optimal fluorescence and translucency and are able to maintain their shading better than any other ceramic material I have used. I am able to select a shade with the confidence that it will look exactly the same once placed inside the mouth, with its chroma remaining unabsorbed by the gingiva. Achieving a natural look, then, depends on choosing a shade that is as close to that of the surrounding dentition as possible. Since KATANA Zirconia UTML (Ultra Translucent Multi Layered) is available in 16 standard shades and a further four enamel shades, there is no shortage of options in this regard.

How does the multi-layered technology of KATANA Zirconia help you to achieve optimal and natural-looking aesthetic results?

Well, firstly, the layering of the material is designed to replicate the colour and translucency progression of natural teeth, which allows for restorations to blend in as much as possible. This multi-layered technology has also proved itself to be very handy when I am sintering crowns made of KATANA Zirconia. Simply put, if one sinters a crown quickly, it will be a little more opaque. If one sinters it at a higher temperature and quite slowly, it will be much more translucent. The multi-layered aspect of KATANA Zirconia is excellent in that it gives me the ability to make restorations more or less translucent depending on what is required.

With 40 years of success in the commercial dental products market, Kuraray Noritake Dental has firmly established its commitment to providing leading-edge solutions for adhesive dentistry. The 1983 introduction of the PANAVIA™ EX resin cement, which utilized Kuraray’s original MDP monomer technology, set the industry standard for adhesion and has continued to do so for over 30 years since. With PANAVIA™ V5, and PANAVIA™ SA Cement Universal which is the latest addition to PANAVIA™ family, Kuraray Noritake Dental presents a pair of resin cements designed for strong, durable bonding for zirconia-based and other restorations.

PANAVIA™ V5

PANAVIA™ V5 is a resin cement with exceptional procedural simplicity and predictability. It sets a new standard for adhesion to the KATANA™ Zirconia Block or other zirconia, allowing for self-cure dentine bond strengths equal to our gold-standard light-cure bonding agent, CLEARFIL™ SE BOND. PANAVIA™ V5 offers natural aesthetic stability in shading through its amine-free paste, which is available in five shades and has been scientifically proven to demonstrate a lower level of post-curing colour variance than other cements.

PANAVIA™ SA Cement Universal

PANAVIA™ SA Cement Universal is a forerunner in self-adhesive resin cements that adheres virtually to all materials including glass ceramics. The original silane coupling agent, LCSi monomer, incorporated in the paste creates a strong chemical bond to porcelain, lithium disilicate and composite resin. Available in an automix or handmix option, its high concentration of MDP monomer allows for increased chemical reactiveness with zirconia, which, combined with mechanical retention created by sandblasting, has been demonstrated as crucial for durable bonding to this material. Building upon the success of our PANAVIA™ SA Cement Plus, it offers a wide range of indications for adhesion and is suitable for crowns/bridges, inlays/onlays, posts, and even adhesion bridges.

By Peter Schouten, Technical Manager Kuraray Europe Benelux

Kuraray Noritake’s self-adhesive cement series, PANAVIA™ SA Cement Universal, has evolved through several stages of development since it was first introduced as “CLEARFIL™ SA Cement”. Over time, various improvements have been implemented, bringing us to our latest product: PANAVIA™ SA Cement Universal. Improvements include: strengthening of the bonding power to dental tissue, increasing the storage temperature to room temperature and extending the shelf life to three years. What remained the same - the easy removal of any excess cement, the moisture tolerance and the integration of the original MDP monomer.

The original MDP enables PANAVIA™ SA Cement Universal to be bonded to dental tissue as well as to metals and zirconia ceramics. Until recently, the chemical bonding of glass-based materials such as porcelain, glass ceramics, including lithium disilicate, and composite, was only possible with an additional silane-based primer.

With the introduction of PANAVIA™ SA Cement Universal the silanisation step has become redundant. Instead, the silane has been incorporated into the PANAVIA™ SA Cement Universal paste. As a result, there is only one single universal procedure, without the need for separate primers.

LCSi

Adding silane to the paste sounds easy. However, there are some limiting factors. For example, keeping silane in the form of γ-MPS (γ-methacryloxypropyltrimethoxysilane) active for a long time is a challenge. This is partly due to γ-MPS’ hydrophilic nature. Contact with water under acidic condition results in hydrolysis of alkoxy groups of silane. Therefore, it is best to use a more hydrophobic and thus stable silane and to avoid bringing it into contact with water and acid prematurely.

We have been using a long-chain silane (LCSi) for some time in a number of our superior composites, such as CLEARFIL™ MAJESTY™ Posterior and CLEARFIL™ MAJESTY™ ES Flow. However it’s the first time we have used it in a cement.

This unique silane has long hydrocarbon spacer (the hydrocarbon chain between the silanol group and the methacrylate group) which makes it more hydrophobic and stable than the small γ-MPS molecule. The reaction with the silica particles in the glass-based materials is expected to be also more orderly and faster. The result is a more optimally bonded surface with a greater resistance to hydrolysis.

A great deal of thought has gone into combatting the degradation of silanes in PANAVIA™ SA Cement Universal. It was decided to separate the more hydrophilic components from the hydrophobic ones so they only come together when the paste is mixed. This is why we are able to achieve a three-year shelf life, even when stored at room temperature.

Research

It’s not only in-house data that show comparable or even better bonding of PANAVIA™ SA Cement Universal to glass-based materials, than with its previous version, PANAVIA™ SA Cement Plus, in combination with CLEARFIL™ CERAMIC PRIMER PLUS. The first results from independent research are also strongly supporting this.

With PANAVIA™ SA Cement Universal, there is now a self-adhesive resin cement on the market that allows virtually all indirect materials to be bonded directly without the intervention of primers or bonding.

Case by Aleksandra Łyżwińska, DMD

This clinical case concerns a patient with a lesion on the occluso-distal aspect of the mandibular left first premolar. We opted for a direct treatment approach with a combination of flowable and high-viscosity composite resin (CLEARFIL MAJESTY™ ES Flow - Super Low A2, CLEARFIL MAJESTY™ ES-2 Classic A2). In order to establish a strong bond between the tooth structure and the restorative material, we decided to selectively etch the enamel and then apply a clinically proven self-etch adhesive (CLEARFIL™ SE BOND 2).

Fig. 1. Initial clinical situation.

Fig. 2. Appearance of the premolar after caries removal.

Fig. 3. Placement of a sectional matrix for anatomical shaping, the establishing of tight interproximal contacts and protection of the adjacent tooth.

Fig. 4. Appearance of the tooth structure after selective enamel etching.

Fig. 5. Interproximal wall built up with CLEARFIL MAJESTY™ ES-2 Classic (A2 shade) and cavity filled with CLEARFIL MAJESTY™ ES Flow - Super Low A2.

Fig. 6. After initial polishing.

FINAL SITUATION

Fig. 7. Occlusal view of the treatment outcome after finishing and polishing.

Fig. 8. Follow up after 1 week.

Dentist:

ALEKSANDRA ŁYŻWIŃSKA
Warsaw, Poland

Aleksandra Łyżwińska, DMD, is a passionate aesthetic and adhesive dentist. Driven by Evidence Based Dentistry, her goal includes using modern composite materials and bonding agents in her clinical practise. In addition to her primary job, she worked as a lecturer and an assistant professor at the Department of Conservative Dentistry and Endodontics of Medical University of Warsaw, her alma mater.

Case by Dr. Michał Pokojski

Universal resin composites with a simplified shade concept are popular as they streamline direct restoration procedures. Unfortunately, many of the available products that claim to blend in well with the surrounding tooth structure independent of its shade need a blocker or opaquer to mask dark areas. According to Kuraray Noritake Dental, CLEARFIL MAJESTY™ ES-2 Universal is different. This is why I decided to test its Universal shade (U) designed for all kinds of restorations in the posterior region in the context of replacing an amalgam restoration.

The restoration that needed to be replaced due to secondary caries was located in the maxillary molar region of a male patient. As usual under amalgam restorations, the remaining healthy tooth structure showed some discolouration. The cavity was prepared, the enamel etched and the whole bonding surface treated with CLEARFIL™ SE Bond. Subsequently, the restoration was built up using CLEARFIL MAJESTY™ ES-2 Universal in several layers. For a natural appearance, some brown tint was added to the fissures before finishing and polishing. The restoration shows a natural integration into the surrounding structure and is able to mask the discolouration on the cavity floor.

Fig. 1. Pre-operative image showing the amalgam restorations to be replaced.

Fig. 2. Appearance of the tooth after removal of the amalgam, caries excavation and cavity preparation.

Fig. 3. Tooth built up with CLEARFIL MAJESTY™ ES-2 Universal (U shade).

FINAL SITUATION

Fig. 4. Immediate treatment outcome.

Dentist:

DR. MICHAŁ POKOJSKI

Dr. Michał Pokojski is a graduate of the Medical University of Łódź, Poland. He maintains his private practice in Starachowice, Świętokrzyskie Voivodeship. His passion is endodontics and esthetic conservative dentistry. In his everyday duties microscope and camera are his main tools to provide his patients with professional and precise procedures and to ensure proper level of communication and understanding. His practice was guided by EBD from the very beginning, because in his opinion knowledge, scientific facts and dedication for what you do are the fundamentals of medicine and dentistry as well. His goal is to treat patients at the highest level of quality using the best available materials, instruments and procedures. His cases are well-known in the world thanks to modern ways of communication like Facebook and Instagram.

Clinical case by Dr Salvatore Scolavino

This video illustrates the recontouring treatment with dental light-cured restorative composite CLEARFIL MAJESTY ES-2.

Dentist:

DR SALVATORE SCOLAVINO

• Specialist in Asthetic Dentistry from Naples, Italy
• Member of the Styleitaliano group which focuses on minimally invasive dentistry techniques
• Private practice in Nola (NA)
• Active member SIDOC (Italian Society of Conservative Dentistry), IAED (Italian Academy of Esthetic Dentistry)
• Author and co-author of scientific publications on national and international journals
• Lecturer in national and international congresses and events

Case by Dr Adrien Lavenant

Introduction

The patient consulted for a follow-up examination and presented with recurrent caries at the maxillary right first molar. A direct treatment with composite needed to be performed. We decided to use Kuraray Noritake Dental Inc.´s CLEARFIL MAJESTY™ ES-2 Universal composite for several reasons: the efficiency of the treatment, favourable handling properties and ease of use.

The clinical case illustrations below show the step-by-step approach carried out during a 30-minute treatment session.

Fig. 1. Initial situation showing an occlusal caries lesion on the maxillary right first molar.

Fig. 2. Pre-operative X-ray.

Fig. 3. Isolation of the working field with rubber dam.

Fig. 4. Situation after caries excavation and tissue preparation.

Fig. 5. Cavity ready for the application of the universal composite: CLEARFIL™ Universal Bond Quick is visible on dentin and enamel and the cavity floor is covered by a thin layer of CLEARFIL MAJESTY™ ES Flow Low.

Fig. 6. Appearance of the tooth after buildup of the restoration with several layers of CLEARFIL MAJESTY™ ES-2 Universal composite (in the shade U developed for the posterior area).

Fig. 7. Stains applied in the occlusal fissures ensure an even more natural appearance.

Fig. 8. Final result after polishing with CLEARFIL™ Twist DIA and checking of the occlusion.

Fig. 9. Final result immediately after rubber dam removal.

Fig. 10. Post-operative X-ray.

FINAL SITUATION

Fig. 11. Check-up after 15 days with rehydrated dental tissues.

Dentist:

DR ADRIEN LAVENANT

Dr Adrien Lavenant obtained his DDS degree at the University of Aix-Marseille in 2010. He pursued his post-graduate education in the field of periodontology, restorative and aesthetic dentistry (University Aix-Marseille and Paris).

Dr Lavenant is a former member of the teaching staff of the University of Aix-Marseille since 2011 and he continues to teach in the postgraduate program in restorative and aesthetic dentistry.

Since 2010, he owns a private practice in Aix-en-Provence specialised in restorative, prosthetic and aesthetic implant dentistry. He has been part of the international Bio-emulation group since 2019 and shares his philosophy of patient care in accordance with the principles of biomimetic dentistry.

By Peter Schouten, Technical Manager Kuraray Europe Benelux

CLEARFIL MAJESTY™ ES-2 is the composite that allows intuitive creation of natural-looking restorations. The combination of its self-adaptive capacity, thanks to the use of light diffusion technology, its natural fluorescence, high filler content, fine workability and exceptional polishability provide outstanding aesthetic results.

CLEARFIL MAJESTY™ ES-2 is a forgiving composite. It blends seamlessly with the adjacent tooth structure. This is because CLEARFIL MAJESTY™ ES-2 incorporates light diffusing technology. This makes it possible to cover the entire VITA range using only VITA A shades.

In our endeavors to reproduce nature, we need to step away from the notion that artificial materials do all the work for us. Especially enamel is a difficult kind of tissue to replace with artificial materials like composite. When you replace natural enamel with translucent composite you almost never reach the desired goal! Why is this? The most determinant factor is the difference in value. Natural enamel increases in value in proportion to its thickness, while for (translucent) composite the value decreases.

In certain situations, for instance for the reproduction of the incisal edge of a central incisor, where a translucent zone is naturally present, the use of a more or less translucent composite is needed. However, it is often the opacity of a composite that we wish to harness in order to cover up underlying (irregular) discoloration. To do this, the use of a translucent composite is clearly not desirable. In this situation, the most opaque variant is your first choice of composite.

You've probably been there: applying anatomical layering techniques with a composite system, only to arrive at a somewhat disappointing result that looks too gray. This can be explained by the fact that, as a manufacturer - and we're certainly not alone here - we have created some confusion by giving composites names such as Dentin and, worse still, Enamel. These names suggest that these materials can be used as a replacement for natural dental tissue. Due to the totally different optical properties of each dental tissue and composite, this can only be achieved within a frequently too narrow spectrum. Therefore, when it comes to the use of the more translucent composite variants, I recommend a cautious approach. Only use such variants where transparency is required.

...it is often the opacity of a composite that we wish to harness in order to cover up underlying (irregular) discoloration. To do this, the use of a translucent composite is clearly not desirable. In this situation, the most opaque variant is your first choice of composite.

Kuraray Noritake Dental offers three basic opacities within the CLEARFIL MAJESTY™ family. These three variants enable you to create transparency where necessary, or indeed to avoid it in zones where greater coverage is required. The most opaque variant within the CLEARFIL MAJESTY™ ES-2 family is Premium Dentin. The semi-opaque variant Classic and the semi-translucent variant Premium Enamel.

The challenging class IV restoration as an example. The tendency exists to use dentin composite up to the dentin-enamel junction. Don't do this, but instead apply it right up to the outermost edge of the restoration. This means also covering the beveled enamel. Depending on the desired end result, you should only use the more translucent variants, Classic or Premium Enamel, in the incisal third.

Working with different variants of CLEARFIL MAJESTY™ ES-2 in one restoration where more than one variant end at the surface the transition from one type to the other is totally seamless. Since all three variants have virtually the same high filler percentages and filler type. During finishing you won't even notice the transition between the different variants. The polishability of all the variants is also identical.

All these qualities make CLEARFIL MAJESTY™ ES-2 your aesthetic composite for the effortless creation of natural-looking restorations. Both anterior and posterior.

Case by Dr. Max Andrup

This patient presented with a fractured amalgam restoration in the occlusal aspect of the mandibular right first molar. The cavity was shallow resulting in a very favourable C-factor. The C-factor describes the relationship between bonded and unbonded restorative material surfaces and is used as an indicator for polymerization shrinkage stress development in a cavity. Hence, it is essential to manage this factor when working with resin composites.

Fig. 1. Initial situation with the fractured amalgam restoration. In the distal aspect of the restoration, some recurrent decay is also visible.

Fig. 2. First molar ready for a new restoration after removal of the amalgam and bevelling of the enamel.

Fig. 3. Selective etching of the enamel prior to the application of CLEARFIL™ SE Protect into the cavity. Selective etching is performed in order to maximize the bond strength to enamel (by etching) and to dentin (without etching).

FINAL SITUATION

Fig. 4. Final situation after restoration of the cavity with CLEARFIL MAJESTY™ ES-2 Universal in the shade U developed for posterior restorations. The favourable C-factor and the fact that the polymerization shrinkage stress produced by the selected material is very low provide the conditions for a good long-term behaviour of the new restoration.

Dentist:

Dr. Max Andrup graduated from the University of Umeå in 2010 and today runs his private practice in the city of Hudiksvall, Sweden. He has a passion for restorative dentistry with a biomimetic approach.

Case by Dr. Michał Pokojski

When restoring primary carious lesions in the posterior area with composite, I wish to use a material that allows me to produce high-quality outcomes in an efficient procedure. The most important qualities of the restoration are its perfect marginal integrity and reliable long-term behaviour, which set the stage for a long and healthy life of the otherwise healthy tooth.

Reliability paired with ease of use is what I expected from the selected material combination: CLEARFIL™ SE Bond 2, a popular self-etch adhesive containing the original MDP monomer, and CLEARFIL MAJESTY™ ES-2 Universal. According to Kuraray Noritake Dental, the innovative resin composite comes with a universal shade concept and mechanical properties such as shrinkage, wear resistance and colour stability similar to those of proven CLEARFIL MAJESTY™ products. As a single shade is available for the posterior region, the need for shade determination is eliminated, which allows the dental practitioner to focus on the clinical work steps. In this case, a small primary defect in a third molar was restored. The outcome speaks for itself.

Fig. 1. Situation during cavity preparation revealing the carious lesion.

Fig. 2. Prepared cavity after the application of the bonding agent.

FINAL SITUATION

Fig. 3. Treatment outcome with the composite harmoniously integrated into the surrounding structure.

Dentist:

DR. MICHAŁ POKOJSKI

Dr. Michał Pokojski is a graduate of the Medical University of Łódź, Poland. He maintains his private practice in Starachowice, Świętokrzyskie Voivodeship. His passion is endodontics and esthetic conservative dentistry. In his everyday duties microscope and camera are his main tools to provide his patients with professional and precise procedures and to ensure proper level of communication and understanding. His practice was guided by EBD from the very beginning, because in his opinion knowledge, scientific facts and dedication for what you do are the fundamentals of medicine and dentistry as well. His goal is to treat patients at the highest level of quality using the best available materials, instruments and procedures. His cases are well-known in the world thanks to modern ways of communication like Facebook and Instagram.