Article by Peter Schouten.

We've seen them all: composite fillings that function present clinically, but are too ‘visible’ to be called aesthetic. The much-used term 'white filling' is probably quite appropriate here. In comparison to the tooth structure, these restorations are too opaque, or sometimes too transparent.

How much better would it be if the composite helped to create a seamless transition between tooth structure and composite? The so-called 'blending'.

But what enables this 'blending’ of composite and tooth structure to occur? The secret lies in utilizing the right mix of different filler particles and resins which give CLEARFIL MAJESTY™ ES-2 its light-diffusing properties. By varying the proportion of light-diffusing particles and the amount of pigment, it's possible to create composites with differing light-scattering properties and opacities. The most opaque variants contain more light-diffusing particles and more pigment. The more translucent ones contain obviously less.

All CLEARFIL MAJESTY™ ES-2 variants have the same filler content. This is important, as it means that the mechanical properties of all the CLEARFIL MAJESTY™ ES-2 variants are the same. The more translucent variants contain more barium glass than the more opaque variants. A higher barium glass content can lead to a less workable composite. With CLEARFIL MAJESTY™ ES-2, this is not the case. Kuraray has mastered the silanization process to such an extent that all variants, whether translucent or opaque, have the same filler amount, without compromising on workability.

Light diffusion test

Light diffusion properties are easy to see if the thin composite slices are placed on a black and white paper background and then held a few millimeters above the paper. Composites with high diffusion properties make the black strip virtually invisible. They blend in more readily with their surroundings.

Since 2010, thanks to its increased translucency, KATANA™ HT has become paramount in fully meeting the ever more demanding aesthetics in restorations where a zirconia frame is used in combination with new generation ceramics CZR. Such ceramics feature an enhanced leucite balancing, which makes them stronger and more durable.

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Since 2013, ML-Multi Layer technology has made it possible to skip the infiltration phase through multi-layered dentine/enamel millable discs. Such Multi-layered discs allow CUT-BACK solutions that definitely improve the function-related result as the palatal part of the restoration can be manufactured by using KATANA™ ML Zirconia only. Thus, without limiting the aesthetic results (which are reached by enamel-ceramic LUSTER porcelain with “MICRO LAYERING technique”, the restoration benefits of the low abrasiveness of the functional-occlusal areas which is reached through simple and effective mechanical polishing without either surface staining or glasuring.

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New generation KATANA™ UTML and STML introduced in 2015 can be used for anterior restoration thanks to the cubic zirconia based products that have been made available to make it possible to conceive a bi-layer to mono-layer transition in most clinical situations.

Cubic zirconia features superior optical behavior. Although mechanically inferior in performance to conventional zirconia, KATANA™ UTML and STML are aging-resistant, while UTML offers the same translucency as lithium disilicate based solution.

“ZERO-CUTBACK technique” is one of the ideal techniques that can be achieved with cubic zirconia solution. They can perfectly replicate digital projects without any need for subsequent layering and can be easily painted and mechanically polished in the palatal area.

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Kuraray Noritake Dental has also developed CZR FC Paste Stain with a wide range of coloring pastes specially designed for full anatomical solution of multi-layered zirconia. Their effectiveness is proven to be enhanced when used with “ULTRA MICRO LAYERING technique” on thin glasure or thin transparent ceramic mass.

Another advantage with STML and UTML products is the lower thickness, respectful of the latest micro-invasive dentistry standards and current market requests.

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Excellent flexural strengths higer than 550/750 MPa allow restoration to feature micro-invasive thicknesses from 0.4 mm on, p.e. on laminates. Unlike PFZ, zirconia lower thicknesses ensure better results.

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Above all, new generation zirconia makes the digital work-flow more efficient and performing, from the intra-oral impression to the final product which can be manufactured “model-free”.

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Thus a new procedure standard is introduced, where simplified adhesive cementation through composite cements opens the the way to zirconia-based adhesive restoration techniques. Regarding adhesion, unlike glass-ceramic, zirconia is not etchable, yet it can be fixed through phosphate monomer MDP, i.e. Panavia™ V5

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Dentist:

DANIELE RONDONI, MDT

• Graduating in 1979, Daniele Rondoni opened a laboratory in 1982, which is also the home of the AAT Community College he founded.
• Teacher and counsellor for the “Italian School for Dental Technicians”at the University of Chieti, University of Sienna and University of Rome Tor Vergata.
• EAED and IAED Active Member and a SICED Associate and O.L.
• International Instructor for Kuraray Noritake Dental products.
• Author of “Tecnica della Multistratificazione in ceramica” (Ceramic Multilayering Technique) and a lab manual about the use of composite materials, introducing his own method – the “Inverted Hardness Layering System”.

By Univ.-Prof. Dr. Florian Beuer MME

There is still some confusion among dental practitioners about how to cement zirconia restorations. In general, all types of cements – adhesive or self-adhesive resin cements and conventional cements – are compatible with all types of zirconia. The actual choice should be based on the restoration design (retentive or non-retentive), the translucency of the zirconia and the clinical situation (feasibility of working field isolation).

When to use which type of cement

The use of adhesive resin cements is mandatory whenever the highest possible bond strength is required. This is the case with one-wing Maryland bridges and other types of restorations lacking micromechanical retention, and with two-piece implant abutments.

In some other situations where retention is not an issue, adhesive or self-adhesive resin cements may have a beneficial effect. The major reason is their more esthetic appearance compared to conventional cements, which offers advantages whenever a highly translucent restorative material is used (e.g. KATANA Zirconia UTML). An important precondition for adhesive luting, however, is a dry working field. Consequently, conventional cements are preferable in the context of placing crowns, bridges and other types of restorations with retentive designs whenever opaque zirconia framework materials are used and / or it is difficult to ensure a dry working field.

How to pre-treat the tooth and the restoration

The highest bond strength of adhesive resin cements to zirconia is obtained after sandblasting with alumina (particle size max. 50 µm, pressure approx. 1 bar). Hence, this procedure is highly recommended. Subsequent steps may be different depending on the cement system employed and should be carried out according to the manufacturer’s instructions for use. On the side of the tooth, enamel etching is important independent of the products used.

Which products to use

In each of the cement classes, there are many different products to choose from. My recommendation is to select a proven and easy-to-use luting material. Among those products achieving the same high bond strength, the solution requiring the fewest application steps seems preferable as it reduces the risk of application errors. At Charité – University Medicine Berlin, we count on PANAVIA cements, which are based on many years of expertise in developing products for adhesive luting of zirconia.

Dentist:

PROF. DR. FLORIAN BEUER

Professor and Chair, Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité – Universitätsmedizin Berlin, Germany.

With CLEARFIL MAJESTY™ ES-2, the shade transition from composite to tooth is virtually invisible. The secret to this lies in light diffusion technology. How does this work?

Before we discuss the technology in detail, here are some more information about our CLEARFIL MAJESTY™ ES-2 composites. All CLEARFIL MAJESTY™ ES-2 composites are suitable for both anterior and posterior applications. The different variants within the ES-2 family are characterized by supreme handling and a long working time, and the fact that they do not slump during modeling. A key feature of these composites is the ease with which restorations blend into their surroundings. This results in durable and aesthetic restorations.

In CLEARFIL MAJESTY™ ES-2 composites, two types of fillers are used. Barium glass particles form the basis of the filler. Alongside this, advanced prepolymerized filler particles are added. The latter type is called light diffusion filler, since it is primarily these filler particles that achieve a light-scattering effect within the composite.

The way in which a restoration 'adjusts itself', to the shade of the tooth to be restored, is not the same for all composites. Most composite manufacturers make use of the so-called 'chameleon effect'. A composite that is sufficiently translucent allows light to pass through. Light is reflected off the walls of the cavity, whereby the composite restoration assumes the shade of the adjacent tooth structure.

In cavities that aren't too large with a sufficient amount of surrounding tooth structure, this chameleon effect works well enough. However, with larger cavities or in the absence of underlying tooth structure, as is often the case with anterior restorations, the aesthetic blending effect is limited. The brightness is far from satisfactory, and the restoration looks gray.

At Kuraray Noritake Dental Inc., we do things differently.

Besides the optimized translucency in CLEARFIL MAJESTY™ ES-2 composites, it's the light diffusion technology that makes the restoration blend seamlessly with the adjacent tooth structure. Thanks to the combination of these two parameters — translucency and light diffusion — the capabilities are far more extensive than with just translucency.

The different dental tissues have different opacities. Enamel is more translucent than dentin. However, the degree of translucency/opacity of both tissues is not always the same. Age, thickness of the structure and various intrinsic and extrinsic factors all play a role.

Depending on the desired end result, the most appropriate member(s) of the CLEARFIL MAJESTY™ ES-2 family is/are selected for the restoration.

In aesthetic restorations in which opacity differences need to be considered, a layering system is necessary. More uniform restorations are easily constructed with a composite that has broad shade and opacity coverage.

CLEARFIL MAJESTY™ ES-2 Premium for highly esthetic restorations.

CLEARFIL MAJESTY™ ES-2 Universal for routine aesthetic restorations involving few or no opacity differences.

By Kazunobu Yamada, RDT

With the new KATANA™ Zirconia YML it is extraordinarily easy to produce beautiful restorations. Brilliance and vitality may be added simply by applying CERABIEN™ ZR FC Paste Stain to the monolithic restoration after surface preparation.

A possible technique is demonstrated by Kazunobu Yamada, RDT, in this video.

What if Kuraray Noritake Dental had not developed the MDP monomer?

What would the quality of adhesive dentistry be if Kuraray Noritake had not developed the MDP monomer? MDP has proved to be a very effective functional monomer for creating durable bonding to enamel, dentine and metals. The best-known products containing MDP are CLEARFIL™ SE BOND and PANAVIA™.

Structure of Adhesive monomer MDP

Adhesion to various substrates is possible Thanks to MDP (methacryloyloxydecyl dihydrogen phosphate), which has been shown to create a long term, durable and stable bond to both dental tissue and metal oxides. Research conducted over the past few decades has demonstrated the effectiveness of MDP. The first Kuraray Noritake Dental product to contain MDP was PANAVIA EX. Various other adhesive and cementation systems followed. Our latest products, PANAVIA™ V5 and CLEARFIL™ Universal Bond, also rely to a large extent on the performance of the original MDP monomer. MDP has the following structure:

1. terminal double bond group for polymerisation
2. hydrophobic alkylene group to maintain a delicate balance between hydrophobic and hydrophilic properties and
3. hydrophilic phosphate group for performance of the acid demineralisation and chemical bonding to tooth structure.

Fig. 1. The chemical structure of adhesive monomer (MDP).

History

In the years between 1978 and the late 1990s, it became possible to increase the bond strength to dentine to more than the intrinsic strength of the dentine itself. MDP played a major role in these developments. The solid ionic bond with calcium from the HAp in dental tissue means that such failures as occur are cohesive in the dentine rather than being failures of the adhesive. Apart from in vitro studies confirming this bond strength, the long term clinical durability recorded over 13 years is also impressive.

Research

Research from Yaun et al., 2007, shows that defects along the interface are largely responsible for degradation of the hybrid layer. CLEARFIL™ SE BOND exhibited no such defects. So it was expected that SE BOND would also prove to have a stable connection to dental tissue. Recently, Peumans et al. From Leuven University, Belgium found CLEARFIL™ SE BOND to still have excellent clinical effectiveness after 13 years.

In their publication in the Journal of Dental Research 83, 2004, Yoshida et al. concluded that the choice of the adhesive monomer played a significant role in the effectiveness of the adhesive. They found MDP to be the best and fastest in tests for chemical adhesion (ionic bonding) and stability in a moist environment (insoluble) – better and more stable than 4-MET and Phenyl-P, in that order.

After 35 years, MDP is still in a class of its own. To date, no manufacturer has been able to develop an adhesive monomer with better adhesion properties combined with durable bond strength. Many attempts have been made, but none have succeeded. In the meantime, Kuraray’s patent on MDP has expired. This has opened up the market for other manufacturers to synthesise their own MDP. Only a few non-dental chemical companies are supplying MDP to other manufacturers of adhesive systems, and the synthesis of high-purity MDP remains extremely difficult.

More recently, Kumiko Yoshihara et al. published ‘Functional monomer impurity affects adhesive performance’, in Dental Materials 31 (2015) 1493-1501. They concluded that the three MDP’s they studied exhibited different levels of purity. Differences in the resultant hybrid layers were observed in all three MDP versions: both impurities and the presence of dimers had an effect on the etching efficacy of the HAp, and also on the intensity of nano-layer presence and the immediate bond strength.

μTBS of MDP’s from different origin

Yoshihara Ket al. Functional monomer impurity affects adhesive performance Dent Mater 31, 1493-1501, 2015.

Fig. 2.

Explanation

The three 10-MDP’s studied in this study clearly revealed a different purity. Differences in the ultrastructure of the resultant hybrid layers were observed for the three 10-MDP versions. Both the impurities and the presence of dimers affected the etching efficacy of HAp, the intensity of nano layering and the ïmmediate’ bond strength.

“The purity of 10-MDP present in commercial dental primers, adhesives and cements can be expected to influence bonding performance.”

By Kazunobu Yamada, RDT

Are you looking for a convenient finishing technique that allows you to successfully start using KATANA™ Zirconia YML for the production of life-like restorations?

In this video, Kazunobu Yamada, RDT, demonstrates how texturing and polishing of the lingual surface and texturing, pre-polishing and glazing of the labial surface of an anterior crown will deliver impressive outcomes.

The introduction of universal composites, which are not only universal in terms of application range but also in terms of shade adaptation, effectively marks the dawn of a new type of composite. This prompts a reinterpretation of the term "universal composite."

CLEARFIL MAJESTY™ ES-2 is a nanohybrid composite family. Nowadays, nanohybrid composites are commonly used as universal composites. They have a high filler content, they are strong, and they have exceptionally good polishability characteristics¹.

The newest variant in the CLEARFIL MAJESTY™ ES-2 range is CLEARFIL MAJESTY™ ES-2 Universal shade concept. For this composite; we expand the definition of universal and include shade coverage.

Posteriorly, a single material in a single shade is sufficient to cover the entire VITA™ range. This means that no shade determination is required. For the anterior zone, we offer two shade variants: a lighter and a darker variant (UL and UD). The lighter variant is used in the A1-A2 range and the darker for shades from A3 onwards. There is sufficient overlap between UL and UD ensuring no specific shade determination is necessary.

Finally, for situations that require extra lightness and brightness, an additional UW shade is available.

What makes CLEARFIL MAJESTY™ ES-2 Universal unique in comparison to other universal or single-shade composites?
The difference with CLEARFIL MAJESTY™ ES-2 Universal, is that without using an additional opaque composite, sometimes called a blocker, a successful, superbly matching restoration can be constructed. Not only with smaller cavities, but also with larger class I and II restorations. And, when used anteriorly, even an extensive Class IV restoration can be successfully constructed using CLEARFIL MAJESTY™ ES-2 Universal. So, it is not only for those small class III or V lesions.

Why Kuraray Noritake Dental Inc. can do this where others cannot, is to a large extent, thanks to optimized light diffusion technology (LDT). By using this technology in composites with the right translucency, the light is scattered and reflected in such a way that the composite blends in with the surrounding tooth structure.

Where others use the widely-employed chameleon effect, Kuraray Noritake Dental Inc. adds an extra dimension in the form of LDT. With the chameleon effect, light passes through the material and is reflected off the walls of the cavity. The perceived shade of the restoration is therefore the shade of the cavity walls. If the cavity is too large, thus requiring a larger amount of filling material, the light has to travel further and a large proportion of the light is absorbed. With this, the brightness of the restoration is reduced and the shade of the cavity walls no longer accurately reflected.

Our LDT allows light to be scattered within the composite itself, in addition to being reflected off the cavity walls. As a result, CLEARFIL MAJESTYTM ES-2 Universal is a particularly forgiving composite. This feature will be familiar to those who have used CLEARFIL MAJESTY™ ES-2 family products before.

CLEARFIL MAJESTY™ ES-2 Universal is the result of sophisticated filler, matrix and silane technology. It offers a solution for all your routine composite work. A consistently superb restoration where shade determination is a thing of the past.

Reference

¹ Ilie, N., & Hickel, R. (2011). Resin composite restorative materials. Aust Dent J, 56 Suppl 1, 59-66. doi:10.1111/j.1834-7819.2010.01296.x

We are pleased to share with you short training videos for CERABIEN™ ZR (CZR) porcelain.

Check out the below working steps and learn more about how to achieve outstanding aesthetics using this tried and proven material.

It is strong, it is pre-shaded like natural teeth, and it is reliable: KATANA™ Zirconia HTML, the highest strength version among KATANA™ multi-layered zirconia series. Now, Kuraray Noritake Dental Inc. has carefully optimized the product to further improve its optical properties and to harmonize the sintering schedules with all other materials of the KATANA™ Zirconia Multi-Layered Series.

The new KATANA™ Zirconia HTML Plus offers all popular properties of its predecessor, including the multi-layered colour structure and uniform strength distribution throughout the blank. It is suitable for a variety of indications including long-span bridges with a minimum wall thickness of just 0.4 mm in the anterior and 0.5 mm in the posterior region. This allows for minimally invasive preparations, while the user may choose between a monolithic, cut-back or framework design combined with the preferred finishing technique.

The PLUS refers to additional benefits like the material’s improved optical properties: KATANA™ Zirconia HTML Plus offers an increased translucency of 45 percent (compared to 43 percent KATANA™ Zirconia HTML) and an even more natural shade appearance of the manufactured restorations. “As the colour of the restorations appears deeper, more vivid and more saturated, and the translucency is closer to that of natural teeth, a great optical integration is achieved straight away. This leads to a reduced finishing effort”, says Mathias Fernandez Y Lombardi, EU Scientific Manager Dental Ceramics & CAD/CAM Materials at Kuraray Noritake Dental. At the same time, the high flexural strength (1,150 MPa) is maintained, providing for an unlimited range of indications.

Like its predecessor and all other materials of the KATANA™ Zirconia Multi-Layered Series, KATANA™ Zirconia HTML Plus is the result of an in-house development, powder compilation and blank production process that is able to control every detail. This enabled our specialists to achieve a precise alignment of the desired properties, while maintaining a high blank quality that leads to the accurate milling results with smooth surfaces and regular edges users of KATANA™ Zirconia HTML are familiar with.

The unique powder composition and specific in-house blank production procedure also allowed us to streamline the sintering protocols. For single-tooth restorations and bridges with up to three units, three different protocols are available: a 54-minute high-speed sintering programme specifically developed for remake and rush cases, a 90-minute schedule and the traditional seven-hour sintering programme. The latter is also suitable for long-span restorations.

These three options and identical schedules are available for KATANA™ Zirconia HTML Plus, KATANA™ Zirconia UTML, KATANA™ Zirconia STML and the new KATANA™ Zirconia YML with additional flexural strength and technical translucency gradation. With this feature, it becomes extraordinarily easy to standardize procedures despite an indication-specific selection of the best-suited KATANA™ Multi-Layered Zirconia.

Mathias Fernandez Y Lombardi concludes: “KATANA™ Zirconia HTML Plus is completely in line with our philosophy of developing products that support their users in streamlining and simplifying procedures without limiting choices. Users may choose from a whole range of highly specialized or universal zirconia solutions, may opt for their preferred design and finishing technique, and can select the sintering protocol that suits their individual needs. At the same time, the manual effort is reduced and the risk of starting the wrong sintering programme is eliminated.”