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2024 MARKS THE YEAR OF THE DRAGON

• Dragons, those mythical beings, embody innate courage, unyielding tenacity, and boundless intelligence. They fearlessly embrace challenges and eagerly venture into uncharted territories.
• The Year of the Dragon is hailed as a time of great power, auspicious beginnings, and transformative possibilities.
• This image, inspired by the traditional Japanese art of kirigami, combines age-old craftsmanship with cutting-edge AI technology. Just like the dragon, it represents a harmonious blend of ancient wisdom and modern innovation.

EMBRACE 2024 WITH OPEN ARMS –
IT BRINGS FORTH A YEAR OF NEW POSSIBILITIES

It is probably the best-known component of a dental product Kuraray Noritake Dental Inc. (Kuraray Noritake Dental) has ever developed: 10-Methacryloyloxydecyl Dihydrogen Phosphate, in short, the MDP monomer. Invented more than 40 years ago – the first product containing it was introduced in 1983 – MDP is still the leading functional monomer used to establish a long-term, durable and stable bond to hydroxyapatite in tooth structure and to metal oxides in restorative materials (oxide ceramics and metal alloys).

Nowadays, it is found in every dental adhesive and every component of a resin cement system with adhesive properties from Kuraray Noritake Dental. These include:

In addition, MDP has become an integral part of most universal adhesives and many adhesive cementation systems of other manufacturers as well. However, not all MDP is alike …

MDP: Chemical structure and mechanism of adhesion

The MDP monomer consists of three essential parts: A polymerizable group, a hydrophobic group and a hydrophilic group. The co-polymerizable methacrylate group has a terminal double bond enabling polymerisation. The large hydrophobic alkylene group – also referred to as the spacer – has the task to maintain a delicate balance between hydrophobic and hydrophilic properties of the monomer and offers great resistance to degradation. Finally, the hydrophilic phosphate group is responsible for acidic demineralisation, for chemical bonding with calcium in hydroxyapatite and for bonding with zirconia¹ (as well as with metal).

Bonding performance

Lots of in-vitro studies have been carried out to investigate the bonding behaviour of 10-MDP in the context of direct and indirect restorative procedures. No matter whether a cavity is to be filled with resin composite or an indirect restoration is to be placed, a strong and long-lasting bond to tooth structure needs to be established.Chemical structure of adhesive monomer 10-Methacryloyloxydecyl Dihydrogen Phosphate (MDP).

The critical substrate in this context is dentin, while bonding to enamel is found to be less challenging. That is why it is so important that (self-etch) adhesives containing 10-MDP show an extraordinarily high bond strength to tooth structure, particularly to dentin². In fact, 10-MDP also provides for a high bond stability over time by establishing an acid-base resistant zone on the adhesive interface³. This means that a great long-term performance may be expected. Fortunately, a great clinical long-term performance of products containing the MDP monomer has already been confirmed: A group from the University of Leuven (Belgium) has presented excellent results of a thirteen-year clinical trial involving the use of CLEARFIL™ SE Bond in 2015⁴.

When bonding to indirect restorations made of zirconia, the surface area of the ceramic should be increased by sandblasting⁵. Pre-treated in the recommended way, the bond strength to zirconia tends to be particularly high when MDP-based resin cement systems are used⁶. It is thus widely recommended by experts in the field of adhesive dentistry to employ MDP-containing primers or resin cements for the placement of zirconia-based restorations, especially those with a non- or less retentive preparation. The fact that products containing 10-MDP work well in this context has been confirmed in different clinical studies with observation periods of up to 10 years^7,8. The products used in these studies were PANAVIA™ 21, PANAVIA™ F2.0 and the latest version of the multi-component cementation system from Kuraray Noritake Dental, PANAVIA™ V5, which performed best.

Not all MDP is alike

Ever since the basic patent for MDP has expired, other manufacturers of dental adhesives and adhesive resin cements have started integrating the functional monomers in their own products. However, it has been revealed that there are differences in the purity of the MDP monomers synthesized and used, and that these differences have an impact on the long-term bonding performance of the products containing the MDP⁹. According to in-vitro test results, the Original MDP Monomer synthesized by Kuraray Noritake Dental stands out due to an unmatched level of purity. This purity has a positive effect on the microstructure and thickness of the hybrid layer formed on dentin, the intensity of nano-layering and the bond strength measured immediately as well as after artificial aging⁹.

Conclusion

The data summarized above reveals that after 40 years in clinical service, the Original MDP Monomer from Kuraray Noritake Dental is still a class of its own. It has everything needed to establish a strong and long-lasting bond to tooth structure, resin composite and metal oxides, and is therefore a valuable component in virtually every adhesive system. In order to provide for a high bond quality, however, it may be best to use an MDP monomer with a confirmed high purity – the Original MDP Monomer.

References

1. Nagaoka N, Yoshihara K, Feitosa VP, Tamada Y, Irie M, Yoshida Y, Van Meerbeek B, Hayakawa S. Chemical interaction mechanism of 10-MDP with zirconia. Sci Rep. 2017 Mar 30;7:45563.
2. Fehrenbach J, Isolan CP, Münchow EA. Is the presence of 10-MDP associated to higher bonding performance for self-etching adhesive systems? A meta-analysis of in vitro studies. Dent Mater. 2021 Oct;37(10):1463-1485.
3. Carrilho E, Cardoso M, Marques Ferreira M, Marto CM, Paula A, Coelho AS. 10-MDP Based Dental Adhesives: Adhesive Interface Characterization and Adhesive Stability-A Systematic Review.
4. Peumans M, De Munck J, Van Landuyt K, Van Meerbeek B. Thirteen-year randomized controlled clinical trial of a two-step self-etch adhesive in non-carious cervical lesions. Dent Mater. 2015 Mar;31(3):308-14.
5. Kern M, Barloi A, Yang B. Surface conditioning influences zirconia ceramic bonding. J Dent Res. 2009; 88: 817–822.
6. Özcan M, Bernasconi M. Adhesion to zirconia used for dental restorations: a systematic review and meta-analysis. J Adhes Dent. 2015 Feb;17(1):7-26.
7. Kern M, Passia N, Sasse M, Yazigi C. Ten-year outcome of zirconia ceramic cantilever resin-bonded fixed dental prostheses and the influence of the reasons for missing incisors. J Dent. 2017 Oct;65:51-55.
8. Bilir H, Yuzbasioglu E, Sayar G, Kilinc DD, Bag HGG, Özcan M. CAD/CAM single-retainer monolithic zirconia ceramic resin-bonded fixed partial dentures bonded with two different resin cements: Up to 40 months clinical results of a randomized-controlled pilot study. J Esthet Restor Dent. 2022 Oct;34(7):1122-1131.
9. Yoshihara K. et al. Functional monomer impurity affects adhesive performance. Dent Mater. 2015 Dec;31(12):1493–1501.

Is it safe to use the single-component PANAVIA™ SA Cement Universal to lute virtually all your indirect restorations?

Did you ever ask yourself how many components are really needed to safely cement your silicate-ceramic, zirconia or resin-based restorations? With PANAVIA™ SA Cement Universal, a single component is usually sufficient. Containing an unreacted silane coupling agent – the LCSi monomer – and the original MDP monomer, the dual-cure, self-adhesive resin cement adheres to tooth structure and to various restorative materials including the popular silica-based ceramics without the need for a separate primer.

For those wondering how it works and if it really works as well as desired, Kuraray Noritake Dental Inc. has created a scientific brochure. It contains in-depth information about the drivers of chemical adhesion contained in PANAVIA™ SA Cement Universal and its characteristic properties. The main part, however, focuses on the results of scientific studies – most of which have been conducted in external laboratories. With the aid of artificial aging, different testing devices and various experimental set-ups, the researchers have checked the resin cement thoroughly. The study results shed light on the behaviour of the material when used in the context of bonding to different restorative materials and different types of tooth structure. Self- and light-curing modes are compared, aging effects investigated and different moisture conditions taken into account.

As a whole, the collected data allows for a precise prediction of the clinical behaviour of PANAVIA™ SA Cement Universal. This valuation has already been confirmed by clinical experience of dental practitioners from all around the world. Moreover, the results of a first clinical study, which is also found in this compilation, are a proof of its exceptional performance.

Download the brochure to learn more about the properties and behaviour of the single-component universal resin cement!

ADHESIVE LUTING: A DRIVER OF INNOVATION

What would modern restorative treatments be like without the availability of high-performance (self-)adhesive resin cements? Tooth preparations would still be much more invasive due to the need for sufficient mechanical retention between the tooth and the restoration. At the same time, it would be impossible to restore teeth with many innovative, tooth-coloured materials such as low-strength ceramics and composite. In short, restorative dentistry would be much less developed than it is today.

When the first resin cements were introduced several decades ago, however, the achieved progress came at the expense of simplicity: Adhesive luting procedures were highly complex and the many different components quite technique sensitive. Luckily, this has changed over the years due to continued development efforts ultimately resulting in the products that are currently available. The resin cement line-up of Kuraray Noritake Dental Inc. consists of three main products: the dual-cure three-component system PANAVIA™ V5, the single-component dual-cure universal resin cement PANAVIA™ SA Cement Universal and the light-curing PANAVIA™ Veneer LC.

For those who would like to learn more about the three systems, this 10^th issue of the BOND Magazine is definitely worth reading. It reveals important details about the 40-year history of the PANAVIA™ brand, sheds light on the strengths of each resin cement to facilitate indication-specific cement selection and provides in-depth information about their clinical use. In addition, two articles are dedicated to hot topics around the luting of restorations made of zirconia, a popular restorative material that some still consider to be unsuitable for adhesive luting procedures. For everyone wondering how it is possible to successfully lute minimally invasive restorations made of zirconia, the article titled “Innovative resin cements forming the basis of minimally invasive prosthodontics” is highly recommended. Those unsure about how to proceed with 5Y-TZP should read the article “How to cement restorations made of high-translucency zirconia”. Interesting information about cleaning options prior to adhesive luting rounds out the content of this magazine.

Click here to read. Enjoy reading!

Start Reading: BOND | VOLUME 10 | 10/2023

Previous versions:

BOND | VOLUME 9 | 08/2022

BOND | VOLUME 8 | 12/2021

BOND | VOLUME 7 | 10/2020

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.

Om hun producten te verbeteren en nieuwe producten te introduceren, maken sommige bedrijven voornamelijk gebruik van basistechnologieën die zijn ontwikkeld door anderen; andere ondernemingen voeren fundamenteel onderzoek uit en ontwikkelen technologie in eigen huis. Is dat verschil relevant voor de professionals die de betreffende producten dagelijks gebruiken in tandarts- of tandtechnische praktijken? Dat is inderdaad relevant; bedrijven die alles vanaf het eerste begin ontwikkelen, hebben doorgaans namelijk een diepgaander begrip van de producten en hun productieprocedures. Zij kunnen dan ook gemakkelijker specifieke producteigenschappen aanpassen, bestaande problemen oplossen en inspelen op de behoeften van de markt. In dit artikel wordt ingegaan op de impact die verschillende door Kuraray Noritake Dental Inc. ontwikkelde basistechnologieën hebben op de workflow voor de vervaardiging van directe composietrestauraties.

Directe restauraties - van complex tot eenvoudig

Adhesieve restauratieve tandheelkunde met gebruikmaking van hoogwaardige tandheelkundige adhesieven en harscomposieten is momenteel een van de meest populaire methoden voor de behandeling van cariëslaesies.
Tegenwoordig zijn een single-bottle universeel adhesief plus één of twee kleuren en opaciteiten van een universele composiet meestal voldoende - mits de juiste materialen worden gekozen - om prachtige en duurzame resultaten te realiseren. Dat is echter niet altijd het geval geweest. De ingezette technieken voor de vervaardiging van directe restauraties waren lange tijd behoorlijk complex; de adhesieven bestonden uit technisch gevoelige multibottle- en meerstapssystemen met lange verwerkingstijden. Anderzijds werden met composietvulmaterialen alleen natuurgetrouwe resultaten bereikt als verschillende kleuren en opaciteiten op de juiste manier werden gecombineerd. En zelfs als de complexe procedures correct werden uitgevoerd, was er een relatief hoog risico van microlekkage, verkleuring en - uiteindelijk - secundaire cariës. Kuraray Noritake Dental Inc. heeft zich al in een vroeg stadium geconcentreerd op een oplossing voor deze problemen, te beginnen met de toepassing van het in 1981 ontwikkelde originele MDP-monomeer.

Optimalisatie van de hechtsterkte

Het originele MDP-monomeer loste het probleem op van de beperkte levensduur van de hechtsterkte van adhesieve systemen. De hydrofiele MDP-groep (fosfaat) vormt een uitzonderlijk sterke en duurzame en chemische hechting aan calcium, dat voorkomt in hydroxyapatiet, de basiscomponent van glazuur en dentine. Het gevormde MDP-Ca-zout biedt de basis voor een stabiele, sterke en duurzame hybridelaag. In combinatie met de hars van het hechtmiddel resulteert dit in een solide sealing van de caviteit na lichtuitharding. Tot op de dag van vandaag is MDP een essentiële component van alle adhesieve producten van Kuraray Noritake Dental Inc. en dankzij dit cruciale bestanddeel is CLEARFIL™ SE Bond het zelfetsende adhesieve systeem met de Gouden Standaard geworden.

Kuraray Noritake Dental Inc. was er echter van overtuigd dat tandheelkundige adhesieven méér dienden te bieden dan alleen een sterke en duurzame bevestiging en ging zich daarom richten op de oplossing van een ander probleem: het risico van demineralisatie en cavitatie, veroorzaakt door bacteriën die achterblijven in de caviteit. Op basis van ervaring in de ontwikkeling van andere adhesieve monomeren vond Kuraray Noritake Dental Inc. het MDPB-monomeer uit, met een antibacterieel reinigend effect voor de caviteit. Anders dan antibacteriële producten die de hechtsterkte van een opvolgend adhesief zouden kunnen aantasten, doodt het MDPB-monomeer de achterblijvende bacteriën zonder afbreuk te doen aan de hechtsterkte. Het monomeer is verwerkt in de primer van het two-bottle zelfetsende adhesief CLEARFIL™ SE Protect en wordt via polymerisatie geïmmobiliseerd.

Het bacteriologische mechanisme van MDPB wordt verondersteld gelijk te zijn aan de welbekende antibacteriële agens CPC (CetylPyridiniumChloride), die voorkomt in vele tandpasta‘s en mondspoelproducten.

Hoewel de adhesieve procedure al is vereenvoudigd door two-bottle zelfetsende adhesieven, gaan universele singlebottle adhesieven net nog een stapje verder. Het is een uitdaging om de ingrediënten die worden gedistribueerd binnen multi-stepsystemen samen te brengen in één flacon, zonder afbreuk te doen aan de stabiliteit van het product. Dankzij de huidige technologie is dit nu mogelijk. Om het oppervlak zo snel mogelijk na het aanbrengen te sealen, dienen de monomeren snel en efficiënt door te dringen in het tandweefsel. Die penetratie wordt doorgaans echter vertraagd door monomeren die tijd nodig hebben om door te dringen tot de tandstructuur - in het bijzonder vochtig dentine - en soms zelfs moeten worden ingewreven. Om die reden heeft Kuraray Noritake Dental Inc. zich geconcentreerd op de ontwikkeling van de Rapid Bond Technology. Deze technologie omvat het originele MDP-monomeer dat, in combinatie met nieuw ontwikkelde hydrofiele, gecrosslinkte amidemonomeren, is verwerkt in CLEARFIL™ Universal Bond Quick. De hydrofiele amidemonomeren zorgen voor een snelle, diepe en volledige penetratie in het dentine en vormen na lichtuitharding een dicht gecrosslinkt polymeernetwerk, dat garant staat voor een sterke en duurzame hechting. Zodoende gaat er geen tijd meer verloren met wachten en masseren; na lichtuitharding is de caviteit solide en langdurig geseald.

Vanwege hun hydrofiliciteit (wateraffiniteit) dringen de amidemonomeren van de Rapid Bond Technology goed door in het dentine. Na lichtuitharding heeft de bonding een lage waterabsorptie en daarmee een hoge verouderingsbestendigheid.

Optimalisatie van directe restauraties

Combineren van meerdere lagen, kleuren en opaciteiten; het gebruik van uiterst complexe layeringtechnieken voor de vervaardiging van natuurgetrouwe composietrestauraties behoort in vele klinische situaties gelukkig tot het verleden. Dat is te danken aan hoogwaardige harscomposieten die zich naadloos voegen naar de omliggende tandstructuur. Om deze gunstige producteigenschap te realiseren, heeft Kuraray Noritake Dental Inc. haar Light Diffusion Technology (LDT) ontwikkeld. Deze technologie is verwerkt in speciale geprepolymeriseerde vuldeeltjes die werken als miljoenen microprisma‘s, die licht en kleur van de omliggende tandstructuur overdragen en afbuigen. De vuldeeltjes zijngeoptimaliseerd qua afmeting, verdeling en refractie-index en bieden dan ook een ongeëvenaarde natuurlijke vermenging. Deze propriëtaire vultechnologie is verwerkt in het volledige composietaanbod CLEARFIL MAJESTY™ in het nieuwste product - CLEARFIL MAJESTY™ ES-2 Universal - maakt Kuraray Noritake Dental Inc. gebruik van geavanceerd LDT voor een monochrome techniek met vereenvoudigde kleurselectie; dit product is beschikbaar in twee kleuren voor het anterieure gebied en één kleur voor het posterieure gebied. Het harmonieert echter zo fraai dat vrijwel alle kleuren van de klassieke VITA A1-D4 kleurenkaart worden afgedekt.

Juiste refractie en transmissie van licht voor een geweldige optische integratie; de lichtdiffusievuldeeltjes van CLEARFIL MAJESTY™ ES-2 van Kuraray Noritake Dental Inc.

Een fantastische optische uitstraling hangt niet alleen samen met optische integratie en onzichtbare restauratieranden. Daarom heeft Kuraray Noritake Dental Inc. ook vuldeeltjes ontwikkeld die voor de rest zorgen: een natuurlijke oppervlakglans en langdurig behoud van glans. De oplossing die is verwerkt in CLEARFIL MAJESTY™ ES Flow met drie niveaus van vloeibaarheid, is genaamd Submicron Filler Technology en bestaat uit glanzende vuldeeltjes van submicronformaat. Deze vuldeeltjes zijn zo nietig dat lichtreflectie - zelfs na slijtage - een natuurlijk effect oplevert. De uitzonderlijke silaantechnologie van Kuraray Noritake Dental Inc. wordt gebruikt om miljoenen van die submicronvuldeeltjes bij elkaar te brengen en - door de tijd heen - te houden. Daardoor is de lading met vuldeeltjes in de laagviscose composieten hoger en wordt de wateropname beperkt die de kwaliteit van de uitgeharde composiet anders zou aantasten. De perfecte balans tussen de glanzende submicronvuldeeltjes, lichtdiffusievuldeeltjes, harsmatrix en propriëtaire silaantechnologie is verantwoordelijk voor een uitgebalanceerde combinatie van mechanische en optische eigenschappen.

Voorbeeld van een eenkleurige restauratie, vervaardigd van CLEARFIL MAJESTY™ ES-2 Universal.

Conclusie

Adhesieve monomeren en vuldeeltjes- en silaantechnologie staan garant voor een solide combinatie van vuldeeltjes, clusters en harsmatrix; Kuraray Noritake Dental Inc. is overduidelijk een erkende expert op het gebied van adhesieve restauraties. De propriëtaire technologieën die in de afgelopen decennia zijn ontwikkeld, hebben absoluut bijgedragen aan betere prestaties (op lange termijn) van directe restauraties, en aan een gemakkelijker weg naar betrouwbare en esthetische resultaten.

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!

Er zijn bedrijven die voornamelijk gebruikmaken van basistechnologieën die door anderen zijn ontwikkeld om hun producten te verbeteren en nieuwe producten te introduceren, terwijl andere bedrijven fundamenteel onderzoek doen en zelf technologieën ontwikkelen. Is dat verschil relevant voor de professionals die de betreffende producten dagelijks gebruiken in tandarts- of tandtechnische praktijken? Zeker wel. Bedrijven die een diepgaande kennis hebben van de onderliggende componenten, chemie en technologieën kunnen bestaande problemen effectief oplossen en snel en flexibel reageren op de behoeften van de markt. In dit artikel wordt ingegaan op de impact die verschillende, door Kuraray Noritake Dental Inc. ontwikkelde, basistechnologieën hebben op het cementeren van indirecte restauraties

Adhesief cementeren, vroeger en nu

Het gebruik van diverse soorten keramiek voor het frezen van tandheelkundige restauraties opent nieuwe mogelijkheden in de tandprothetiek, waardoor het nu gemakkelijker is om hoogesthetische restauraties te creëren en te plaatsen. Wat vaak onderschat wordt in deze context, is de rol van adhesieve cementeersystemen; deze ondersteunen niet alleen de esthetische uitstraling van de translucente, restauraties, maar bieden ook mogelijkheden voor minder invasieve preparaties en restauratieontwerpen. De eerste systemen die zorgden voor de chemische hechting tussen de elementen en indirecte restauraties, vertoonden verminderde prestaties op de lange termijn en met een hoge gevoeligheid voor techniek. Bovendien was de procedure uitzonderlijk complex. De technologische ontwikkeling bij Kuraray Noritake Dental Inc. leverde een belangrijke bijdrage aan een verbeterde hechtprestatie op lange termijn, terwijl de verwerking ook eenvoudiger werd.

Optimalisering van de hechtsterkte op lange termijn

Om een duurzame hechting van de eerste cementeersystemen aan tandstructuren (vooral dentine) te realiseren, besloot, Kuraray, de moederbedrijf van Kuraray Noritake Dental Inc., in de jaren zeventig zich te richten op de ontwikkeling van een sterker adhesief monomeer. Als eerste stap op weg naar succes introduceerde het bedrijf in 1976 het fosfaatmonomeer Phenyl-P. Vijf jaar later leidden voortdurende inspanningen om de moleculaire structuur te verbeteren en te verfijnen tot de lancering van het populaire MDP-monomeer, dat zorgt voor een bijzonder sterke en duurzame hechting aan glazuur, dentine, metaal en zirkonium.

Het inventiviteit van deze uitvinding wordt benadrukt doordat het nog steeds een essentieel onderdeel is van elk adhesief product en adhesief cementeersysteem van Kuraray Noritake Dental Inc., en inmiddels ook wordt gebruikt door andere fabrikanten om de sterkte en duurzaamheid van hun bevestigingen te optimaliseren. In vergelijking met elders gesynthetiseerd MDP, onderscheidt het Originele MDP-monomer van Kuraray Noritake Dental Inc. zich door een ongeëvenaard niveau van zuiverheid. Onafhankelijke onderzoeken tonen aan dat dit niveau van zuiverheid een positief effect heeft op de hechtingseigenschappen*. Het MDP-monomeer biedt stabiliteit binnen een vochtige omgeving en draagt zo bij aan meer consistente prestaties van het product waarin het is verwerkt.

Het niveau van zuiverheid en de hechtsterkte verschillen per MDP-monomeer.

Er werden drie experimentele zelfetsende primers geprepareerd, die bestonden uit 15 wt.% 10-MDP en afkomstig waren uit verschillende bronnen: KN (Kuraray Noritake Dental), PCM (Duitsland) of DMI (Designer molecules Inc., VS). Met dank aan Dr. Kumiko Yoshihara voor de gegevens.

Voor adhesieve cementsystemen die moeten zorgen voor een sterke hechting met een uitstekende marginale afdichting is het niet voldoende als ze simpelweg een adhesieve monomeer bevatten. Een efficiënte uitharding van dat monomeer is ook een vereiste en die laat zich niet altijd gemakkelijk realiseren. Om te zorgen voor een effectieve uitharding, zowel chemische als onder licht, van PANAVIA™ V5, heeft Kuraray Noritake Dental Inc. de Touch-Cure Technology ontwikkeld. De kern van deze technologie is een nieuw ontwikkelde, zeer actieve polymerisatieversneller in de PANAVIA™ V5 Tooth Primer. Deze werkt samen met het acidische MDP-monomeer en bevordert de polymerisatie vanaf de interface tussen element en cement zodra PANAVIA™ V5 Paste wordt aangebracht op het al geprimede tandoppervlak. In PANAVIA™ Veneer LC - een lichtuithardend cementsysteem met dezelfde primers worden gebruikt - werkt de polymerisatieversneller van PANAVIA™ V5 Tooth Primer volgens hetzelfde mechanisme. Deze draagt bij aan de uitharding van de adhesieve interface; PANAVIA™ Veneer LC Paste biedt een uitstekende stabiliteit in omgevingslicht en wordt door lichtuitharding gepolymeriseerd.

Bijvoorbeeld, dit verschijnsel werd geëvalueerd voor PANAVIA™ F2.0, de voorganger van PANAVIA™ V5. De uitkomst van de studie was dat de eigenschappen ten aanzien van marginale afdichting van PANAVIA™ F2.0 veel beter waren dan die van andere getoetste cementsystemen**. Deze gedocumenteerde, betrouwbare afdichting van de interface komt marginale lekkage minder voor en wordt een hoge graad van polymerisatie bereikt, zelfs in de zelfuithardende modus (zonder lichtuitharding of bij blokkering van het licht door het restauratieve materiaal); het eindresultaat is dus een bijzonder krachtige hechting.

Een bijkomend voordeel van de integratie van de polymerisatieversneller is dat deze functioneert als een sterke reductor. Het natriumhypochloriet, dat bij endodontische behandelingen vaak wordt gebruikt als irrigatieoplossing, wordt geneutraliseerd; op die manier wordt het negatieve effect op de hechtsterkte van de naderhand aangebrachte cementpasta opgeheven.

Cementeren van glaskeramiek vereenvoudigen

Minder flesjes, minder stappen en gestroomlijnde cementeerprocedures: dat is de reden waarom zelfhechtende composietcementen zijn ontwikkeld en geïntroduceerd in het begin van de jaren 2000. De meeste van die producten hebben echter een beperkt indicatiegebied. Ze presteren goed bij het hechten aan zirkonium, metaal, glazuur en dentine, maar worden niet aanbevolen voor hechten aan glaskeramiek, of hebben in dat geval een extra silaanprimer nodig. PANAVIA™ SA Cement Universal, dat MDP bevat, onderscheidt zicht vanwege een andere gepatenteerde technologie van Kuraray Noritake Dental Inc.: het LCSi-monomeer, Long Carbon-chain Silane Coupling agent. Dit monomeer vormt een sterke chemische hechting aan composiet, en glaskeramiek zoals; porselein, lithiumdisilicaat, etc.. Een aparte primer of voorbehandling is niet meer nodig. Dankzij de voordelen van deze technologie onderscheidt PANAVIA™ SA Cement Universal zich duidelijk van andere zelfhechtende composietcementen als een zelfhechtend eenstapscomposietcement, zelfs voor restauraties die van glaskeramiek worden vervaardigd.

De hechtsterkte van dit product aan de tandstructuur kan, indien gewenst, nog worden vergroot door gebruik van het universele adhesief CLEARFIL™ Universal Bond Quick met de Rapid Bond Technology. Deze innovatieve technologie is door Kuraray Noritake Dental Inc. ontwikkeld om problemen - specifiek voor universele adhesieven - op te lossen rondom de trage penetratie in tandstructuren, vooral vochtig dentine. Om een goede penetratie te garanderen, moeten deze adhesieven een lange tijd en actief in de tandstructuur worden gewreven of moeten gebruikers even wachten voordat de laag kan worden uitgehard met licht. De Rapid Bond Technology, samengesteld uit het originele MDP-monomeer en de hydrofiele amidemonomeren, zorgt voor een hoge wateraffiniteit, die leidt tot een snelle en diepe penetratie van vochtig dentine. Dankzij deze technologie kan er bij CLEARFIL™ Universal Bond Quick direct na aanbrengen worden verder gewerkt, zonder negatieve invloed op de hechtsterkte.

Tandheelkundige transformatie dankzij baanbrekende technologieën 

De door Kuraray Noritake Dental Inc. ontwikkelde technologieën hebben een grote bijdrage geleverd aan de verbeterde hechtkracht van adhesieve cementeersystemen en aan een werkelijk universeel gebruik van zelfhechtende composietcementen. Het bedrijf biedt dan ook een gestroomlijnde portfolio van hoogwaardige composietcementen voor elke gebruiker en voor verschillende klinische situaties. Er zijn minder componenten en minder stappen nodig en de procedures zijn vereenvoudigd; dus: minder fouten en duurzame restauraties. De genoemde producten bieden, nog afgezien van de technologiegerelateerde pluspunten, veel bijkomende productvoordelen. Meer informatie via kuraraynoritake.eu.   

Referenties

*) 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