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 Dr. Florian Zwiener

The 85-year-old female patient presented after osteosynthesis of a multiple mandibular fracture she had sustained after a fall. During fixation, a massive nonocclusion had occurred in the left posterior region of the mandible (teeth 34 to 37; FDI notation). The patient desired to be able to chew properly again in this area. After endodontic treatment of the two avulsed central incisors, which had been replanted in the hospital, and periodontal therapy, a bite elevation was planned on the left side.

The idea was to restore the teeth and elevate the bite with three onlays and a crown made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent). During tooth preparation, however, a longitudinal root fracture was detected on the first molar. Therefore, only the first premolar was restored in this session. For this purpose, an onlay was produced chairside (with the CEREC system, Dentsply Sirona) and adhesively luted with PANAVIA™ V5 (Kuraray Noritake Dental Inc.). The first molar was extracted. One week later, the extraction socket, which was still healing, was modelled for the ovoid pontic using an electrotome loop. The second premolar and molar were prepared as abutment teeth for a bridge. The bridge was then milled from KATANA™ Zirconia Block for Bridge in the shade A3.5 and individualized with CERABIEN™ ZR FC Paste Stain (both Kuraray Noritake Dental inc.). After another week, the bridge was luted with the self-adhesive resin cement PANAVIA™ SA Cement Universal (Kuraray Noritake Dental Inc.) following sandblasting.

Fig. 1. Situation after multiple mandibular fracture on the left side.

Fig. 2. Clinical situation at the initial appointment in the dental practice.

Fig. 3. Open bite in the mandibular left posterior region.

Fig. 4. Bridge design …

Fig. 5. … using the CEREC Software.

Fig. 6. Due to the bright shade of the teeth in the cusp area, the restoration was positioned high in the KATANA™ Zirconia Multi-Layered Block.

Fig. 7. Surface texturing in the pre-sintered state (prior to the final sintering procedure).

Fig. 8. Bridge after a seven-hour sintering cycle.

Fig. 9. Appearance of the bridge after individualization with CERABIEN™ ZR FC Paste Stain …

Fig. 10. … and two glaze firings.

Fig. 11. Clinical situation after restoring the teeth with a lithium disilicate onlay and a zirconia bridge.

FINAL SITUATION

Fig. 12. Onlay and bridge in place (after adhesive luting with PANAVIA™ V5 and self-adhesive luting with PANAVIA™ SA Cement Universal).

Fig. 13. Final X-ray used to check for excess cement around the bridge.

Dentist:

DR. FLORIAN ZWIENER

Dr. Florian Zwiener is a distinguished dental professional known for his expertise in Endodontics, Prosthodontics, and CAD/CAM technology. Born in Cologne, Germany, he developed a passion for dentistry and pursued his education at the University of Cologne, where he obtained his degree in Dentistry. Currently, Dr. Florian Zwiener practices at the Dr. Frank Döring Dental Clinic in Hilden, Germany. Here, he continues to apply his specialized knowledge and skills, ensuring that his patients receive the highest quality of care. Follow Dr. Zwiener on Instagram: @dr.florian_zwiener.

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 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

Click here for the product page for more details

What can you expect to find online

- General information about:
- KATANA™ Zirconia YML
- CERABIEN™ ZR porcelains
- FC Paste Stain
- PANAVIA™ V5
- Full Product Assortment
- Safety Data Sheets
- Instructions For Use
- Technical Information

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.

Case report with Dr. José Ignacio Zorzin

Rationalizing clinical workflows: This is the main reason for the use of universal products in adhesive dentistry. They are suitable for a wide range of indications and different application techniques, fulfil their tasks with fewer components than conventional systems and often involve fewer steps in the clinical procedure. Universal adhesives are a prominent example.

How do universal adhesives contribute to a streamlining of workflows?

When restoring teeth with resin composite, the restorative material will undergo volumetric shrinkage upon curing. By bonding the restorative to the tooth structure with an adhesive, the negative consequences of this shrinkage – marginal gap formation, marginal leakage and staining, hypersensitivity issues and the development of secondary caries – are prevented. The first bonding systems available on the dental market were etch-and-rinse adhesives, which typically consisted of three components: an acid etchant, a primer and a separate adhesive. Later generations combined the primer and the adhesive in one bottle, or were two or one-bottle self-etch adhesives. Universal adhesives (also referred to as multi-mode adhesives) may be used with or without a separate phosphoric acid etchant.

Fig. 1. Volumetric shrinkage of resin composite restoratives and its clinical consequences.

Which technique to choose depends on the indication and the clinical situation. In most cases, the best outcomes are obtained after selective etching of the enamel¹. Bonding to enamel is generally found more effective when the enamel is etched with phosphoric acid, while the application of phosphoric acid on large areas of dentin involves the risk of etching deeper than the adhesive is able to hybridize. When the cavity is small, however, selective application of the phosphoric acid etchant to the enamel surface may not be possible, so that a total-etch approach is most appropriate. Finally, in the context of repair, the self-etch approach may be the first choice, as phosphoric acid might impair the bond strength of certain restorative materials by blocking the binding sites. By using a universal adhesive, all these cases may be treated appropriately, as the best suitable etching technique can be selected in every situation.

Apart from the differences related to the use or non-use of phosphoric acid etchant on the enamel or enamel-and-dentin bonding surface, the clinical procedure is always similar with the same universal adhesive. The following clinical case is used to illustrate how to proceed with CLEARFIL™ Universal Bond Quick (Kuraray Noritake Dental Inc.) in the selective enamel etch mode, and it includes some details about the underlying mechanism of adhesion.

How to proceed with selective enamel etching?

A clinical example.

This patient presented with a fractured maxillary lateral incisor, luckily bringing the fragment with him. Hence, it was decided to adhesively lute the fragment to the tooth with an aesthetic flowable resin composite.

Fig. 2. Patient with a fractured maxillary lateral incisor.

Fig. 3. Close-up of the fractured tooth.

Fig. 4. Working field isolated with rubber dam.

As proper isolation of the working field makes the dental practitioner’s life easier, a rubber dam was placed using the split-dam technique. It works well in the anterior region of the maxilla, as the risk of contamination with saliva from the palate is minimal. Once the rubber dam was placed, the bonding surfaces needed to be slightly roughened to refresh the dentin. As the surfaces were also slightly contaminated with blood and it is important to have a completely clean surface for bonding, KATANA™ Cleaner was subsequently applied to the tooth structure, rubbed into the surfaces for ten seconds and then rinsed off. The cleaning agent contains MDP salt with surface-active characteristics that remove all the organic substances from the substrate. The fragment was fixed on a ball-shaped plugger with (polymerised) composite and also cleaned with KATANA™ Cleaner.

Fig. 5. Cleaning of the tooth …

Fig. 6. … and the fragment with KATANA™ Cleaner.

What followed was selective etching of the enamel on the tooth and the fragment for 15 seconds. Whenever selective enamel etching is the aim, it is essential to select an etchant with a stable (non runny) consistency – a property that is offered by K-ETCHANT Syringe (Kuraray Noritake Dental Inc.). Both surfaces were thoroughly rinsed and lightly dried before applying CLEARFIL™ Universal Bond Quick with a rubbing motion. This adhesive is really quick: Study results show that the bond established immediately after application is as strong and durable as after extensive rubbing into the tooth structure for 20 seconds.^2,3 The adhesive layer was carefully air-dried to a very thin layer and finally polymerized on the tooth and on the fragment.

Fig. 7. Selective etching of the enamel of the tooth …

Fig. 8. … and the fragment with phosphoric acid etchant.

Fig. 9. Application …

Fig. 10. … of the universal bonding agent.

Fig. 11. Polymerization of the ultra-thin adhesive layer on the tooth …

Fig. 12. … and the fragment.

What happens to dentin in the selective enamel etch (or self-etch) mode?

After surface preparation or roughening, there is a smear layer on the dentin surface that occludes the dentinal tubules, forms smear plugs that protect the pulp and prevents liquor from affecting the bond. When self-etching the dentin with a universal adhesive, this smear layer is infiltrated and partially dissolved by the mild self-etch formulation (pH > 2) of the universal adhesive. At the same time, the adhesive infiltrates and demineralizes the peritubular dentin. The acid attacks the hydroxyapatite at the collagen fibrils, dissolves calcium and phosphate and hence enlarges the surface. Then, the 10-MDP contained in the formulation reacts with the positively loaded calcium (and phosphate) ions. This ionic interaction is responsible for linking the dentin with the methacrylate and thus for the formation of the hybrid layer.^4,5

In the total-etch mode, the phosphoric acid is responsible for dissolving the smear layer and demineralising the hydroxyapatite. This leads to a collapsing of the collagen fibrils, which need to be rehydrated by the universal adhesive that is applied in the next step. Whenever the acid penetrates deeper into the structures than the adhesive, the collagen fibrils will remain collapsed. This will most likely result in clinical issues including post-operative sensitivity⁶.

When applying the adhesive system, a dental practitioner rarely thinks about what is happening at the interface⁷. However, every user of a universal adhesive should be aware of the fact that a lot is happening there. This is why it is so important to use a high-performance material with well-balanced properties and strictly adhere to the recommended protocols.

Fig. 13. Schematic representation of dentin after tooth preparation: The smear layer on top with its smear plugs occluding the dentinal tubules protects the pulp and prevents liquor from being released into the cavity.

Fig. 14. Schematic representation of dentin after the application of a universal adhesive containing 10-MDP: The mild self-etch formulation partially dissolves and infiltrates the smear layer, while at the same time demineralizing and infiltrating the peritubular dentin5.

In the present case, the tooth and the fragment now needed to be reconnected. For this purpose, CLEARFIL MAJESTY™ ES-Flow (A2 Low) was applied to the tooth structure. The fragment was then repositioned with a silicone index, held in the right position with a plier and light cured. To obtain a smooth margin and glossy surface, the restoration was merely polished. The patient presented after 1.5 years for a recall and the restoration was still in a perfect condition.

Fig. 15. Reconnecting the fragment with the tooth structure.

Fig. 16. Treatment outcome.

Why is it important to adhere to the product-specific protocols?

Universal adhesives contain lots of different technologies in a single bottle. While this fact indeed allows users to rationalize their clinical procedures, it also requires some special attention. As every highly developed material, universal adhesives need to be used according to the protocols recommended by the manufacturer. In general, materials may only be expected to work well on absolutely clean surfaces, while contamination with blood and saliva is likely to decrease the bond strength significantly. Depending on the type of universal adhesive, active application is similarly important, as is proper air-drying and polymerization of the adhesive layer. In addition, care must be taken to use the material in its original state, which means that it needs to be applied directly from the bottle to avoid premature solvent evaporation or chemical reactions. When adhering to these rules, universal adhesives offer several benefits from streamlined procedures to simplified order management and increased sustainability, as fewer bottles are needed and likely to expire before use.

Dentist:

DR. JOSÉ IGNACIO ZORZIN

Dr. José Ignacio Zorzin graduated as dentist at the Friedrich-Alexander University of Erlangen-Nürnberg, Germany, in 2009. He obtained his Doctorate (Dr. med. dent.) in 2011 and 2019 his Habilitation and venia legendi in conservative dentistry, periodontology and pediatric dentistry (“Materials and Techniques in Modern Restorative Dentistry”). Dr. Zorzin works since 2009 at the Dental Clinic 1 for Operative Dentistry and Periodontology, University Hospital Erlangen. He lectures at the Friedrich-Alexander University of Erlangen-Nürnberg in the field of operative dentistry where he leads clinical and pre-clinical courses. His main fields of research are self-adhesive resin luting composites, dentin adhesives, resin composites and ceramics, publishing in international peer-reviewed journals.

References

1. Van Meerbeek, B.; Yoshihara, K.; Van Landuyt, K.; Yoshida, Y.; Peumans, M. From Buonocore‘s Pioneering Acid-Etch Technique to Self-Adhering Restoratives. A Status Perspective of Rapidly Advancing Dental Adhesive Technology. J Adhes Dent 2020, 22, 7-34.
2. Kuno Y, Hosaka K, Nakajima M, Ikeda M, Klein Junior CA, Foxton RM, Tagami J. Incorporation of a hydrophilic amide monomer into a one-step self-etch adhesive to increase dentin bond strength: Effect of application time. Dent Mater J. 2019 Dec 1;38(6):892-899.
3. Nagura Y, Tsujimoto A, Fischer NG, Baruth AG, Barkmeier WW, Takamizawa T, Latta MA, Miyazaki M. Effect of Reduced Universal Adhesive Application Time on Enamel Bond Fatigue and Surface Morphology. Oper Dent. 2019 Jan/Feb;44(1):42-53.
4. Fehrenbach, J., C.P. Isolan, and E.A. Münchow, Is the presence of 10-MDP associated to higher bonding performance for self-etching adhesive systems? A meta-analysis of in vitro studies. Dental Materials, 2021. 37(10): 1463-1485.
5. Van Meerbeek, B., et al., State of the art of self-etch adhesives. Dental Materials, 2011. 27(1): 17-28.
6. Pashley, D.H., et al., State of the art etchand-rinse adhesives. Dent Mater, 2011. 27(1): 1-16.
7. Vermelho, P.M., et al., Adhesion of multimode adhesives to enamel and dentin after one year of water storage. Clinical Oral Investigations, 21(5): 1707-1715.

Certaines entreprises utilisent principalement des technologies de base développées par d‘autres afin d‘améliorer leurs produits et d‘en introduire de nouveaux, alors que d‘autres sociétés mènent des recherches fondamentales et développent la technologie en interne. Cette différence est-elle importante pour ceux qui utilisent les produits en résultant au cabinet ou laboratoire dentaire au quotidien ? C‘est le cas - étant donné que les entreprises qui développent tout à partir de rien disposent généralement d‘une compréhension plus approfondie des produits et de leurs procédures de production, ce qui leur permet de modifier plus facilement certaines caractéristiques, de résoudre certains problèmes et de répondre aux besoins sur le marché. Cet article décrit l‘impact de plusieurs technologies de base développées par Kuraray Noritake Dental Inc. concernant le flux de travail associé à la création de restaurations composite directes.

Les restaurations directes - de la complexité à la simplicité

La dentisterie restaurative adhésive utilisant des adhésifs dentaires et résines composites haute performance est actuellement l‘un des plus populaires traitements des dents avec lésions carieuses. De nos jours, un flacon unique d‘adhésif universel et une ou deux nuances et opacités de composite universel suffisent généralement pour obtenir des résultats esthétiques et durables, à condition de sélectionner les bons matériaux. Toutefois, cela n‘a pas toujours été le cas. Pendant longtemps, les techniques utilisées pour créer des restaurations directes étaient assez complexes : les adhésifs étaient des flacons multiples sensibles à la technique appliquée et des systèmes à étapes multiples avec des temps d‘application longs. D‘un autre côté, les matériaux de charge composites ne produisaient des résultats naturels qu‘à grands renforts de nuances et opacités différentes et combinées correctement. Et, même lorsque les procédures complexes étaient mises en oeuvre correctement, le risque de microfuite, décoloration et caries secondaires au final était relativement élevé. Kuraray Noritake Dental Inc. a misé sur le solutionnement de ces problèmes à un stade relativement précoce, en commençant par l‘utilisation du monomère MDP original développé en 1981.

Optimiser la perfomance d'adhésion

Le monomère MDP original répondait au problème de durabilité limitée de la performance d‘adhésion des systèmes adhésifs. Le groupe hydrophile (phosphate) du MDP forme une liaison chimique particulièrement solide et durable avec le calcium de l‘hydroxyapatite, le principal composant de l‘émail et de la dentine. Le sel MDP-Ca formé procure la base pour une couche hybride stable, solide et durable. En combinaison avec la résine de l‘agent adhésif, le résultat est un scellement hermétique de la cavité après photopolymérisation. Jusqu‘à l‘heure actuelle, le MDP est un composant essentiel de tout produit adhésif de Kuraray Noritake Dental Inc., et c‘est le composant clé qui a fait de CLEARFIL™ SE Bond le système adhésif à auto-mordançage de référence absolue.

Cependant, convaincue que les adhésifs dentaires devaient apporter davantage qu‘une seule adhésion solide et durable, Kuraray Noritake Dental Inc. a commencé à se pencher sur un autre problème : le risque de déminéralisation et de cavitation causé par les bactéries restées dans la cavité. Sur la base de son expérience dans le développement d‘autres monomères adhésifs, Kuraray Noritake Dental Inc. a inventé le monomère MDPB qui a pour une action de nettoyage antibactérien de cavité. Différent d‘autres agents antibactériens qui pourraient nuire à la solidité de l‘adhésion d‘un adhésif appliqué ultérieurement, le monomère MDPB détruit les bactéries persistantes sans affecter la performance d‘adhésion. Il est contenu dans l‘apprêt de l‘adhésif à auto-mordançage en deux flacons CLEARFIL™ SE Protect et est immobilisé par polymérisation.

Le mécanisme bactéricide du MDPB est supposé similaire à celui de l‘agent antibactérien bien connu qu‘est le CCP (chlorure de cétylpyridinium), qui est contenu dans de nombreux dentifrices et bains de bouche.

Si l‘adhésif à auto-mordançage en deux flacons a simplifié la procédure d‘adhésion, la version en flacon unique a permis d‘aller encore plus loin. Réunir les ingrédients des systèmes en étapes multiples dans un seul flacon sans compromettre la stabilité du produit relève du défi. La technologie actuelle permet désormais cela. Pour sceller la surface le plus tôt possible après l‘application, la pénétration des monomères dans le tissu dentaire doit être rapide et efficace. En général, la pénétration est toutefois ralentie par les monomères qui ont besoin de temps pour pénétrer la structure dentaire - en particulièrement la dentine humide - et requièrent parfois même un mouvement de friction à cette fin. C‘est pourquoi Kuraray Noritake Dental Inc. s‘est concentrée sur le développement de la Rapid Bond Technology. Elle consiste dans le monomère MDP original associé aux monomères hydrophiles à réticulation d‘amide nouvellement développés et intégré à CLEARFIL™ Universal Bond Quick. Les monomères amides hydrophiles permettent une pénétration rapide, complète et profonde dans la dentine et forment avec la polymérisation un dense réseau polymère réticulé responsable d‘une adhésion solide et durable. Ainsi, les temps de friction et d‘attente sont supprimés et un scellement hermétique et durable de la cavité est réalisé après photopolymérisation.

En raison de leur hydrophilie (affinité avec l‘eau), les monomères amide de la Rapide Bond Technology pénètrent très bien la dentine. Après photopolymérisation, l‘adhésion présente une faible absorption d‘eau et donc une grande résistance dans le temps.

Optimiliser les restaurations directs

Combiner plusieurs couches, nuances et opacités : Heureusement, l‘utilisation de techniques de stratification très complexes pour créer des restaurations composite naturelles appartient au passé dans de nombreuses situations cliniques. En effet, les résines composites hautement développées se mélangent parfaitement à la structure dentaire adjacente. Pour fournir cette caractéristique favorable, Kuraray Noritake Dental Inc. a développé sa propre technologie de diffusion de la lumière (« Light Diffusion Technology », LDT). Cette technologie est incorporée dans des charges spécialement pré-polymérisées qui agissent comme des millions de micro-prismes transmettant et réfractant la lumière et la couleur depuis la structure dentaire alentour. Optimisés en taille, distribution et indice de réfraction par rapport à la matrice, les charges offrent un mélange naturel incomparable. L‘ensemble de la gamme de composites CLEARFIL MAJESTY™ contient cette technologie de charge maison. CLEARFIL MAJESTY™ ES-2 Universal, le dernier produit dans lequel Kuraray Noritake Dental Inc. fait usage du niveau supérieur de LDT permet une technique à nuance unique avec simplification de la sélection de nuance : il est disponible en deux nuances pour la zone antérieure et en une nuance unique pour la zone postérieure, mais se mélange si bien qu‘une couverture de quasiment chaque nuance du nuancier VITA classique A1-D4 est obtenue.

La réfraction et la transmission de la lumière sont le moyen d‘obtenir une excellente intégration optique : les charges de diffusion de la lumière de CLEARFIL MAJESTY™ ES-2 de Kuraray Noritake Dental Inc.

Étant donné qu‘un excellent aspect ne dépend pas seulement de l‘intégration optique et de marges de restauration indétectables, Kuraray Noritake Dental Inc. a également développé des charges qui assurent le reste, à savoir une brillance de surface naturelle et une rétention de polissage durable. La solution intégrée dans CLEARFIL MAJESTY™ ES Flow avec ses trois niveaux de fluidité est appelée « Submicron Filler Technology », consistant en des charges brillantes de taille submicronique. Ces charges sont si petites que les réflexions lumineuses offrent un effet naturel, même après usure. L‘exceptionnelle technologie silane de Kuraray Noritake Dental Inc. est utilisée pour rassembler des millions de ces charges submicroniques et les maintenir ensemble dans la durée. Elle permet des charges élevées dans les composites de faible viscosité et limite l‘absorption d‘eau qui entraînerait autrement une dégradation du composite polymérisé. L‘équilibre parfait entre les charges submicroniques brillantes, les charges de diffusion de la lumière, la matrice de résine et la propre technologie silane offre une combinaison équilibrée de propriétés mécaniqueset optiques.

Exemple d‘une restauration « single-shade » avec CLEARFIL MAJESTY™ ES-2 Universal.

Conclusion

Monomères adhésifs, technologies de charge et technologie silane procurent une solide combinaison de charges, clusters et matrice résine : Clairement, Kuraray Noritake Dental Inc. est un expert de confiance dans le domaine des restaurations adhésives. Ses propres technologies développées au cours des dernières décennies ont incontestablement contribué à améliorer (à long terme) la performance des restaurations directes et à faciliter l‘obtention de résultats fiables et esthétiques.

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!

Certaines entreprises utilisent principalement des technologies de base développées par d‘autres afin d‘améliorer leurs produits et d‘en introduire de nouveaux, alors que d‘autres sociétés mènent des recherches fondamentales et développent la technologie en interne. Cette différence est-elle importante pour ceux qui utilisent les produits en résultant au cabinet ou laboratoire dentaire au quotidien ? C‘est le cas - étant donné que les entreprises qui disposent d‘une compréhension plus approfondie des composants, mécanismes chimiques et technologies sous-jacentes sont en mesure de résoudre certains problèmes et de répondre aux besoins du marché rapidement et avec flexibilité. Cet article décrit l‘impact de plusieurs technologies de base développées par Kuraray Noritake Dental Inc. sur le collage de restaurations indirectes.

Le collage adhesif d‘Hier et d‘Aujourd‘hui

L‘usinage de restaurations dentaires de différents types de céramiques a fait émerger de nouvelles opportunités en prosthodontie : la production et la pose de restaurations hautement esthétiques sont désormais possibles. Dans ce contexte, on sous-estime souvent le rôle des systèmes de collage adhésif qui soutiennent non seulement l‘aspect esthétique des restaurations translucides en couleur de dent, mais ouvrent aussi la voie à des conceptions préparatoires et restauratives moins invasives. Les systèmes précoces qui assuraient l‘adhésion chimique entre les dents et les restaurations indirectes présentaient malheureusement un comportement compromis sur le long terme et une grande sensibilité technique alors que la procédure d‘application était extrêmement complexe. Le développement technologique chez Kuraray Noritake Dental Inc. a considérablement contribué à l‘amélioration de la performance d‘adhésion des systèmes à long terme et à la simplification de la manipulation.

Optimiser la performance d‘adhésion à long terme

Afin d‘atteindre une adhésion durable des systèmes de collage rapide à la structure dentaire (en particulier la dentine), Kuraray, société affiliée à Kuraray Noritake Dental Inc., a décidé dans les années 1970 de se concentrer sur le développement d‘un monomère adhésif plus puissant. Sur ce chemin vers l‘excellence, une première étape a été franchie avec l‘introduction du monomère phosphate Phenyl-P en 1976. Cinq ans plus tard, les efforts soutenus pour améliorer et affiner sa structure moléculaire conduisaient à l‘introduction du fameux monomère MDP qui est capable d‘établir une adhésion particulièrement solide et durable à l‘émail, la dentine, le métal et la zircone.

Le fait qu‘il fasse toujours partie de chaque produit adhésif et chaque système de collage adhésif de Kuraray Noritake Dental Inc. et qu‘il soit aujourd‘hui également utilisé par d‘autres fabricants pour optimiser la force d‘adhésion et la durabilité de l‘adhésion de leurs produits souligne l‘ingéniosité de cette invention. Comparé au MDP synthétisé ailleurs, le monomère MDP original de Kuraray Noritake Dental Inc. se démarque par son degré de pureté inégalé. Des études indépendantes montrent que ce degré de pureté a un effet positif sur son comportement d‘adhésion*. En offrant de la stabilité dans un environnement humide, le monomère MDP a contribué à une performance plus constante des produits qui en contiennent.

Les différents monomères MDP offrent différents niveaux de pureté et de performances d’adhésion. 

Trois apprêts à auto-mordançage expérimentaux ont été préparés avec 15 % en poids de 10-MDP fourni par différentes sources : KN (Kuraray Noritake Dental), PCM (Allemagne) ou DMI (Designer molecules Inc., USA). Crédits des données Dr Kumiko Yoshihara.

Pour que les systèmes de colle-résine adhésives fournissent une solide liaison avec un excellent joint marginal, le simple fait de contenir un monomère adhésif n‘est toutefois pas suffisant. Une polymérisation efficace de ce monomère est également nécessaire, mais n‘est pas toujours la plus facile à réaliser. Afin de fournir une bonne performance de photopolymérisation et de polymérisation en obscurité (« dark-cure ») de PANAVIA™ V5, Kuraray Noritake Dental Inc. a développé la technologie « Touch-Cure ». L‘élément clé de cette technologie est un nouvel accélérateur de polymérisation hautement actif dans PANAVIA™ V5 Tooth Primer qui est capable de coexister avec le monomère MDP acide et stimule la polymérisation à partir de l‘interface entre la dent et la colle dès que PANAVIA™ V5 Paste est appliqué à la surface de la dent déjà préparée. L‘accélérateur de polymérisation dans PANAVIA™ V5 Tooth Primer montre le même mécanisme d‘action dans PANAVIA™ Veneer LC, un système photopolymérisable de colle-résine qui fonctionne avec les mêmes primer. Il contribue à la polymérisation
de l‘interface adhésive, alors que PANAVIA™ Veneer LC Paste offre une excellente stabilité à la lumière ambiante et est polymérisé par photopolymérisation.

Pour l‘exemple, ce phénomène a été évalué pour PANAVIA™ F2.0, le prédécesseur de PANAVIA™ V5. Résultat de l‘étude : PANAVIA™ F2.0 a démontré des propriétés de collage marginal bien meilleures que d‘autres systèmes de colle-résine évalués**. Ce collage fiable et documenté de l‘interface conduit à une plus faible incidence de fuite marginale, à un ratio de polymérisation très élevé, même en mode auto-polymérisation (sans photopolymérisation ou à chaque fois que la lumière est bloquée par le matériau restoratif), et donc à une adhésion particulièrement forte.

Un avantage supplémentaire résultant de l‘incorporation de l‘accélérateur de polymérisation est sa fonction de puissant réducteur. Il neutralise l‘hypochlorite de sodium, couramment utilisé en tant que solution d‘irrigation dans le traitement endodontique, et élimine donc son effet négatif sur la force d‘adhésion de la pâte de colle appliquée ultérieurement.

A highly active polymerisation accelerator in PANAVIA™ V5 Tooth Primer promotes effective polymerisation of the cement at the adhesive interface.

Simpliflier le collage vitrocéramique

Moins de flacons, moins d‘étapes et des procédures de collage rationnalisées : c‘est la raison pour laquelle les collesrésine auto-adhésives ont été développés et commercialisés au début des années 2000. Toutefois, ces produits ont pour la plupart un champ d‘indication limité. Ils fonctionnent bien sur la zircone, le métal, l‘émail et la dentine, mais ne sont pas recommandés ou requièrent un primer silane supplémentaire pour l‘adhésion vitrocéramique. Contenant le MDP, PANAVIA™ SA Cement Universal est différent en raison d‘une autre technologie appartenant à Kuraray Noritake Dental Inc. : le monomère LCSi, un agent combinant le silane à longue chaîne carbonée. Ce monomère forme une solide liaison chimique avec la résine composite, la porcelaine et les céramiques de type silice (comme le disilicate de lithium), éliminant ainsi le besoin d‘un composant silane séparé (primer ou adhésif). En tirant parti des avantages de cette technologie, PANAVIA™ SA Cement Universal se démarque clairement d‘autres colles-résine auto-adhésives en tant que véritable système de collage monocomposant, même pour les restaurations en vitrocéramique.

Au besoin, la force d‘adhésion du produit à la structure dentaire peut être augmentée par l‘utilisation du fameux adhésif universel CLEARFIL™ Universal Bond Quick qui est doté de la technologie d‘adhésion rapide. Cette technologie a été développée par Kuraray Noritake Dental Inc. afin de résoudre les problèmes liés à la lenteur de la pénétration dans la structure dentaire, notamment dans la dentine humide, qui est le propre des adhésifs universels. Pour une pénétration adéquate, ces adhésifs doivent être activement et longuement frictionnés sur la structure dentaire ou les utilisateurs doivent attendre un certain temps avant de photopolymériser la couche. Composé du monomère original MDP combiné à des monomères amides hydrophiles, la „Rapid Bond Technology » du fabricant présente une affinité élevée avec l‘eau, entraînant une pénétration rapide et profonde dans la dentine humide. Par conséquent, les temps d‘application sont raccourcis et la manipulation est simplifiée sans affecter négativement la performance d‘adhésion.

Transformer la dentisterie avec des technologies d‘avant-garde

Les technologies développées par Kuraray Noritake Dental Inc. ont fortement contribué à améliorer la performance d‘adhésion des systèmes de colle adhésives et à universaliser réellement l‘utilisation des colles-résine auto-adhésives. Ainsi, l‘entreprise propose une gamme alignée de colles-résines haute-performance pour chaque utilisateur, pour les situations cliniques typiques. Moins de composants et moins d‘étapes sont nécessaires et les procédures sont simplifiées - pour moins d‘erreurs et des restaurations esthétiques qui durent. Mis à part les bénéfices d‘ordre technologique, les produits mentionnés offrent de nombreuses caractéristiques avantageuses supplémentaires. Vous en trouverez une description détaillée en ligne sure kuraraynoritake.eu.

Références

*) Functional monomer impurity affects adhesive performance.; Yoshihara K, Nagaoka N, Okihara T, Kuroboshi M, Hayakawa S, Maruo Y, Nishigawa G, De Munck J,
Yoshida Y, Van Meerbeek B. Dent Mater. 2015 Dec;31(12):1493-501.
**) Touch-Cure Polymerization at the Composite Cement-Dentin Interface.; Yoshihara K, Nagaoka N, Benino Y, Nakamura A, Hara T, Maruo Y, Yoshida Y, Van Meerbeek
B.J Dent Res. 2021 Aug;100(9):935-94

Interview with Mitsunobu Kawashima
Manager, Technology Division of Kuraray Noritake Dental Inc.

In 1983 – exactly 40 years ago – PANAVIA™ EX was introduced in Japan as the first product of the PANAVIA™ family and the first product containing the original MDP monomer. Since then, the PANAVIA™ family of resin cements has been continuously expanded by developing new resin-cement materials that are precisely adjusted to the contemporary demands of dental practitioners. The current line-up of easy-to-use, high-performance adhesive luting materials is globally available and used by dental practitioners with high quality standards.

We had a conversation with Mr. Mitsunobu Kawashima about PANAVIA™ EX as a ground-breaking innovation in the field of dental resin cements and subsequent steps toward the current well-balanced resin cement portfolio. He is currently responsible for the development of chair-side materials in the Technology Division of Kuraray Noritake Dental Inc. (Kuraray Noritake Dental) and has been part of the team developing the many products of the PANAVIA™ family for more than 30 years.

The resin cements developed by the company before the introduction of PANAVIA™ EX contained the adhesive monomer Phenyl-P. Why did you decide not to use Phenyl-P in the new formulation?

At the time we decided to develop PANAVIA™ EX, we were engaged in the development of new adhesive monomers to replace Phenyl-P. The main aim of this project was an improvement of our products’ bond strength to metal alloys and dentin. Among the new adhesive monomers being developed, we decided to use the MDP monomer, because it features excellent bonding to tooth structure and metal alloys used in dentistry, as well as superb resistance to water. Incidentally, our first products to contain the original MDP monomer were the resin cement PANAVIA™ EX and the bonding agent CLEARFIL™ NEW BOND.

Where did the name PANAVIA™ come from?

The name “PANAVIA™” is a compound word consisting of “PAN” and “VIA”. The former is of Greek origin, and the latter is of Latin origin. “PAN” means “everything” and “VIA” means “way” or “method”. Consequently, the name “PANAVIA” describes a “method for bonding everything”; it represents our desire to have products launched under the umbrella of the PANAVIA™ brand recognized as dental materials that can bond to all types of restoration and tooth structure.

Would you please tell us the story behind the development of PANAVIA™ EX?

Back in the early 1980s, it was indispensable for us to develop new adhesive monomers as a part of our project to develop a new resin cement with unprecedented adhesive properties. In this context, we conducted a comprehensive literature search for compounds thought to be involved in adhesion. At the same time, we carried out a variety of R&D activities, including basic research to quantitatively clarify the relationship between the molecular structures of monomers and their adhesive qualities, synthesis trials of various monomers and bond strength tests. Consequently, we succeeded in developing the MDP monomer that had the physical properties we were working to obtain. Following the development of that MDP adhesive monomer, we were finally able to create PANAVIA™ EX in our laboratory. In early 1982, we completed the first prototype of PANAVIA™ EX for external evaluation and asked a dental college in Japan to evaluate it. He found that the prototype cement might cure too quickly in clinical use. This was due to the fact that we had not taken into account the difference between room temperature and intraoral temperature, which has a huge impact on the curing time. This error led us to recognize how important clinical evaluations are during the development of dental materials. To this day, we continue to place great importance on the opinions of clinicians whenever a new material is being developed.

The name “PANAVIA™” is a compound word consisting of “PAN” and “VIA”. The former is of Greek origin, and the latter is of Latin origin. “PAN” means “everything” and “VIA” means “way” or “method”.

What were the key technological features of this new PANAVIA™ EX cementation system?

The system had five key features: Appropriate film thickness, appropriate flow properties of the paste, radiopacity, improved bond strength and improved surface-cure characteristics. At the time that PANAVIA™ EX was developed, a film thickness of 30 μm or less was desired for luting cements. The largest components we wanted to use in the formulation – the silica filler particles present in our composite resin – had a maximum particle diameter of 50 μm. We were able to achieve a film thickness of 30 μm or less by significantly extending the silica grinding time, which made the filler particles much finer. An appropriate paste consistency – a low level of viscosity and good flowability – was achieved by using low-viscosity monomers for PANAVIA™ EX. In order to make the cement radiopaque, we dispersed radiopaque filler within the powder component. In fact, we were convinced that it was essential to be able to check for the presence of excess cement under the gingival margins after a restoration was placed. The increase in bond strength was achieved by blending the MDP monomer into the liquid component.

What about the surface-cure characteristics of the cement?

Every dental practitioner knows that the surface of resin cements must be protected from oxygen in the air in order to cure properly. For this purpose, we developed OXYGUARD, a water-soluble gel material. It is applied to the restoration margins to cover the unpolymerized resin cement surface and protect it from exposure to oxygen. In this way, the formation of an oxygen inhibition layer – a layer of uncured resin on the surface that compromises the marginal integrity of the restoration – is prevented and an intact, fully polymerized cement surface can develop. In this way, the use of OXYGUARD has contributed greatly to improving the cure characteristics of cements.

What do today’s PANAVIA™ products and PANAVIA™ EX have in common?

The PANAVIA™ family of products, including PANAVIA™ EX, share the concept of “being a resin cement product that opens new dimensions in dentistry”. PANAVIA™ EX was our first resin cement, and it was conceived as a cement for a new era. It can bond to tooth structure and dental metals very well, thanks to the use of the MDP monomer. This important adhesive monomer is still used today in many of our products. Ever since the launch of PANAVIA™ EX, Kuraray Noritake Dental has continued to take on new challenges and has developed many new products in the growing PANAVIA™ family. These include PANAVIA™ 21, a cement in paste form that has a self-etching primer as an accessory; PANAVIA™ Fluoro Cement, a dual-cure cement paste that releases fluoride; and PANAVIA™ F2.0, which can be used with an LED curing unit. The current portfolio consists of PANAVIA™ V5, which features the substantially improved bonding performance that was achieved after a major review of the basic composition of the series, PANAVIA™ SA Cement Universal, which works as a standalone product without separate primers, and PANAVIA™ Veneer LC, PANAVIA™ family’s latest product. The latter is a light-curing resin cement with the specialized purpose of bonding laminate veneers.

In retrospect, what did the introduction of PANAVIA™ EX mean to Kuraray Noritake Dental?

In the development of new resin cements, it is important to quickly respond to the rapidly changing trends in the market. Whenever new prosthodontic treatment concepts appear – like adhesive bridges as a minimally invasive treatment option replacing a single tooth – or new restorative materials are introduced, such as different types of ceramics – we need to check if our resin cement systems are compatible with the tasks that come with these changes, as well as possibly developing new ones. Following the launch of PANAVIA™ EX, we received a wide range of feedback from experts working at dental clinics and laboratories. We leveraged this feedback in subsequent development projects, always striving to stick close to the clinical setting. After Kuraray Medical Inc. merged with Noritake Dental Supply Co., Limited, this ethos was embedded in the work ethic of all employees of Kuraray Noritake Dental.

Can you give us a brief history of the PANAVIA™ EX journey to the currently available PANAVIA™ family portfolio?

Since the launch of PANAVIA™ EX 40 years ago, six different PANAVIA™ products have been released. Each of them has received high acclaim for their unique features, both in the Japanese resin cement market and abroad. For 40 years, we have been improving PANAVIA™ in response to the demands of the times. We developed a product with increased adhesion when non-retentive preparation designs (adhesive bridges) and smaller bonding surfaces (due to less invasive preparations) became popular. And for users concerned about secondary caries, we developed a material with fluoride-releasing properties. At the same time, we focused strongly on making dental cementation easier by finding ways to make our resin cements bond well to various types of crown-restoration materials, including precious metals and ceramics. During these drives towards improvement, “achieving reliable general luting” has always been at the forefront of our goals. We believe that the successful evolution of the PANAVIA™ brand owes a great deal to our incessant efforts to obtain a high level of bond strength to dentin after chemical polymerisation”.

How did the R&D department evolve over the years?

Initially, our efforts in the development of dental materials had focused on bonding agents and restorative composite resins. PANAVIA™ EX was just one of our new development projects and only a few staff members were assigned to that product. After PANAVIA™ EX was launched in 1983 and it was accepted worldwide, our product line-up of resin cements was expanded considerably. Consequently, we have increased the number of development staff assigned to resin cements and set up a special development team responsible for the self-adhesive resin cement product line that includes PANAVIA™ SA Cement Universal. As a result, the size of the team assigned to resin cements has expanded substantially.

How did production change?

When PANAVIA™ EX was launched in 1983, the product was manufactured exclusively for the Japanese market in a relatively small facility. Today, in order to produce all products of the PANAVIA™ family for the global market, we have automated our production facilities and increased the production equipment and systems dedicated to producing the resin cement paste. To support our product quality, we have also set up a quality control system that assures we turn out safe and high-quality products, drawing on over 40 years of technical knowhow and experience in the production of resin cements.

For 40 years, we have been improving PANAVIA™ in response to the demands of the times.

When did external researchers start showing interest in PANAVIA™?

The development of PANAVIA™ EX was carried out with the active participation of researchers at a dental college in Japan, involving such activities as performing basic adhesion tests and experimenting with clinical applications using adhesive bridges. At that time, resin cements that provided a strong bond to tooth structure or metal alloys were not widely used. I believe that overseas researchers were interested in the development of PANAVIA™ EX at a relatively early stage, for this reason.

What current concept do you have in mind as you continue developing your adhesive cements?

We have two basic central concepts: “Achieving greater bond strength” and “Delivering easier handling characteristics”. I think that the shades of resin cements are also devised in each product in order to get the most of the characteristics of aesthetic restorative materials. At our company, we have embodied “achieving greater bond strength” in PANAVIA™ V5, and “delivering easier handling characteristics” in PANAVIA™ SA Cement Universal. We will continue to explore the development and introduction of various new technological applications, to bring even higher performance products to market.

What do you think is the strength of Kuraray Noritake Dental’s R&D team?

We conduct R&D activities continuously, focusing on the development of luting materials. In our product development department, the same person is often responsible for one product category over long period of time. For example, I have been engaged in the development of PANAVIA™ products for much of my time with the company. The result is that each person in the development department can be said to be an expert in a certain category of products. They leverage the technical knowledge acquired in the past for the development of new products, resulting in entirely new discoveries.

Do you have any ideas about what the future of PANAVIA™ will be?

We will continue to focus on the development of even simpler, easier-to-use resin cements suitable for a wide range of applications – products based on the concept of universality. This should allow users to focus more on the actual treatment than ever before, while of course delivering a strong and durable bond between the tooth structure and the restoration.

MITSUNOBU KAWASHIMA

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.