Interview with Mathias Fernandez Y Lombardi

INTRODUCING CERABIEN™ MiLai LOW-FUSING PORCELAINS AND INTERNAL STAINS

Highly aesthetic lithium disilicate or zirconia-based framework materials combined with a micro-layer of porcelain are becoming the new standard for producing lifelike all-ceramic restorations. For those wondering why it’s worth adopting the new technique, how to start, how to improve and which materials to use, we had a conversation with a true expert in all things ceramic: Mathias Fernandez Y Lombardi, Head of Technical Marketing – Europe at Kuraray Europe GmbH.

Mathias Fernandez Y Lombardi, do you believe in micro-layering as a technique that is capable of streamlining procedures in the dental laboratory while fulfilling high aesthetic demands?

Yes, I truly believe that micro-layering is the next step in the evolution of indirect restorative techniques and materials. This evolution is driven by improvements in the area of framework materials, which are becoming more and more tooth-like in their appearance. We have moved from metal to opaque, high-strength zirconia and – more recently - high-translucency multi-layered zirconia and lithium disilicate, which no longer require thick porcelain layers to achieve lifelike outcomes. In this context, it’s only natural that a new technique has emerged.

Kuraray Noritake Dental Inc. is well-known as a pioneer in multi-layered zirconia technology and veneering porcelains. Are there any products particularly suitable or specifically developed for micro-layering?

We offer a series of high-translucency, multi-layered zirconia perfectly suited for micro-layering on the one hand and an aligned portfolio of internal stains and porcelains specifically developed for micro-layering on the other. The zirconia portfolio includes three different blank types with a multi-layered colour structure (KATANA™ Zirconia UTML, STML and HTML Plus), one variant with flexural strength, translucency and colour gradation (KATANA™ Zirconia YML), but also the timeless classic HT for the frameworks should be mentioned. While the first three offer a uniform strength and are chosen based on the indication, KATANA™ Zirconia YML with its multi-layered strength is a universal material suitable for an extremely wide range of applications.

The set of internal stains and porcelains specifically designed for the micro-layering technique that we just introduced is CERABIEN™ MiLai. With this addition to the CERABIEN™ family, we offer a perfect complement to the KATANA™ Zirconia Multi-Layered series, and with it, a revolutionary workflow that significantly deviates from traditional methods, enabling us to deliver greater efficiency, cost savings, and more flexibility. However, CERABIEN™ MiLai is not only compatible with KATANA™ Zirconia, but also with aesthetic zirconia from other manufacturers and reinforced silicate ceramics such as lithium disilicate with a CTE value within 9.5-11.0×10-⁶/K (50 °C – 500 °C).

Fig. 1. Overview of CERABIEN™ MiLai Low-Fusing Porcelains.

Fig. 2. Overview of CERABIEN™ MiLai Internal Stains.

Why should a dental technician start using the micro-layering technique and invest in a new set of porcelains for this purpose?

The reasons to start micro-layering are obvious: depending on the design, micro-layering can eliminate or minimize the chipping risk. Moreover, the technique is highly efficient, as the number of layers and bakes is drastically reduced. This results in a reduced thickness of the restoration facilitating minimally invasive preparations and a less complex layering procedure that even beginners are able to learn and implement very quickly. A new set of porcelains specifically developed for micro-layering like CERABIEN™ MiLai can further support the feasibility of the technique and the quality of the outcomes achieved even by beginners. Due to the shortage of skilled workers in dental laboratories, this aspect is becoming increasingly important.

How does CERABIEN™ MiLai support users in achieving aesthetic, high-quality outcomes right from the start?

With traditional porcelain systems, it can be challenging to create all the desired individual shade effects in a layer of only 0.03 mm to 0.6 mm thickness. With CERABIEN™ MiLai, this isn’t the case as the system is specifically designed for this purpose. The saturation and translucency of the porcelains are matched to the framework materials and adjusted to the volume of the porcelain layer. The compact line-up makes it quite easy to select and combine the right shades for satisfying results right from the start. More experienced users can mix the different components for additional effects, so that there are no limits to their creativity.

Images courtesy of MDT Daniele Rondoni.

Fig. 3. Virtually unlimited design options: crown with a full micro cut-back, crown with a vestibular cut-back and monolithic restoration.

Furthermore, the versatility of CERABIEN™ MiLai is a key feature that results in great outcomes. The system can be used on lithium disilicate and zirconia, a monolithic surface, a vestibular cut-back or a full micro cut-back. With this broad application spectrum, dental technicians are likely to use CERABIEN™ MiLai daily, which allows them to develop a true understanding of the components and to establish work routines very quickly. As a consequence, the outcomes become predictable and controllable. This is further supported by consistent handling and optical properties – all the result of a single core technology.

Please tell us more about this technology.

The core technology used in CERABIEN™ MiLai is synthetic feldspathic ceramic technology. Originally developed for Super Porcelain EX-3 and adjusted to the specific needs of CERABIEN™ ZR in the first step and CERABIEN™ MiLai more recently, this technology is responsible for consistent properties. This is because the formulation never needs to be aligned due to changing natural components. However, I believe that the greatest benefit of using feldspathic porcelain lies in the elimination of shadow effects. Everyone familiar with layering natural feldspathic porcelains on ceramics will know the typical greyish shadows appearing in restorations after several firing cycles. They originate from inhomogeneities in the material caused by micro-movements during firing. Showing no movements in this phase, synthetic felspathic porcelains from Kuraray Noritake Dental Inc. are the first and only porcelains preventing this effect. Finally, the further developed version of the technology allowed us to realize a low firing temperature of just 740 °C while maintaining the desired coefficient of thermal expansion. This is essential for the material’s compatibility with lithium disilicate.

Are there any other benefits arising from the low firing temperature?

The low firing temperature definitely offers an economic benefit, as the process consumes less energy and takes less time compared to high-temperature firing cycles. Moreover, the wear of the furnace is reduced. Finally, the low temperature is of interest for users of CERABIEN™ ZR in specific indications: Some ceramists like to combine the systems especially in cases with artificial gingiva. They create the porcelain work on the teeth with CERABIEN™ ZR first and then individualize the gingival area with CERABIEN™ MiLai. Due to the low firing temperature, the form, colour and surface of the previously applied veneering porcelain will remain stable.

Image courtesy of MDT Ioulianos Moustakis.

Fig. 4. Application of CERABIEN™ MiLai Tissue Porcelains on a complex restoration with the teeth already finalized.

Image courtesy of MDT Ioulianos Moustakis.

Fig. 5. Application of CERABIEN™ MiLai Internal Stains on a zirconia bridge.

Do you have any application technique recommendations for CERABIEN™ MiLai?

The best aesthetic outcomes are obtained by using the internal stain technique. By applying the stains first, it is possible to create natural depth effects despite the minimal thickness of the porcelain layer. The stains are easy to use and the outcomes are impressive. The micro-layer of porcelain applied on top acts like a window imitating the enamel, which contributes to a tooth-like appearance. Due to the compact line-up and easily manageable effects, this technique is even suitable for beginners.

Is the procedure different depending on the base material (lithium disilicate versus zirconia)?

Most of the steps are identical. However, surface conditioning may be different depending on the material used (as described in the material manufacturer’s instructions for use). Moreover, Value Liner 1 or Value Liner 2 is typically used on lithium disilicate for wash baking, whereas Translucent or Luster are recommended for this step on zirconia. When space is limited, internal stains may be applied directly. All following steps – the optional but highly recommended application of internal stains, the building-up of Translucent or Luster and baking, morphological corrections, the glaze bake and finishing – are identical.

What are the options for glazing?

CERABIEN™ MiLai porcelains offer a self-glaze effect obtained by fine-polishing (with PEARL Surface C) followed by glaze baking. This leads to a natural gloss, while maintaining the anatomical details. Alternatively, CERABIEN™ ZR FC Paste Stain Glaze or Clear Glaze can be applied and fixed by baking. These liquid ceramics allow users to add some structural details, while the surface appears glossier. However, the procedure is more time-consuming due to the additional application step.

Do you have any recommendations regarding the indication-specific selection of the framework or base material?

Traditionally, lithium disilicate has been the material of choice for aesthetic single anterior restorations, while zirconia was predominantly used for multi-unit restorations and restorations in the posterior area. With the availability of KATANA™ Zirconia STML / UTML and CERABIEN™ MiLai, zirconia is becoming increasingly attractive for the production of minimally invasive veneers, crowns and the like. A thin-walled restoration made of KATANA™ Zirconia, speed-sintered in just a few minutes and combined with a thin layer of CERABIEN™ MiLai, results in an incredibly strong restoration with several aspects that lithium disilicate simply cannot match. The preparation technique for zirconia is much more favourable for dentists - for example marginal adaptation and biocompatibility, especially regarding gingival healing, are superior. Aesthetically, there is no risk of a greyish effect when using zirconia with CERABIEN™ MiLai, while lithium disilicate needs to be treated with Value Liner to prevent this. Additionally, the ease of cementation with PANAVIA™ SA Cement Universal further enhances the quality of the restoration in the fastest possible timeframe, allowing for quick and flexible responses to dentists’ needs.

You mentioned speed sintering as a factor contributing to a streamlined workflow. Studies have shown, however, that this step might weaken the mechanical and aesthetic properties of zirconia. Do you recommend speed sintering despite this fact?

Indeed, speed sintering does affect the translucency and flexural strength of some zirconia variants. This is probably the reason why dental technicians have been reluctant to change their established practices of sintering overnight – despite the availability of high-speed furnaces. However, KATANA™ Zirconia is an exception: Due to our unique powder formulation, we are able to offer zirconia with a composition that is completely independent from other brands of dental zirconia. With this, we are able to fundamentally change the traditional workflow of an end-user and offer more flexibility, speed and efficiency, resulting in less energy consumption, stress and costs. In a study conducted at the Division of Biomaterials at the University of Alabama at Birmingham¹, three different high-translucency zirconia materials including KATANA™ Zirconia Block (KATANA™ Zirconia STML) were sintered according to a traditional and a high-speed sintering schedule. Prior to sintering and afterwards, the three-point bending strength, translucency and grain structure were analysed. The material from Kuraray Noritake Dental Inc. was the only zirconia with properties that remained unaffected after speed sintering. Internal testing confirmed this finding for all variants of the KATANA™ Zirconia Multi-Layered series. As a result, we do recommend speed sintering of our materials, delivering true economic and time advantages.

With highly potent materials for micro-layering now available, do you think that full ceramic layering is going to be a thing of the past?

I am convinced that in the near future the great majority of dental restorations will be produced using aesthetic framework materials and simplified micro-layering techniques. However, full porcelain layering is here to last. There will always be a demand for a few highly-skilled ceramists serving the needs of individuals with the highest aesthetic demands. It is like tailor-made versus off-the-peg suits: the tailor-made ones are the best you can buy, but most people wear off-the-peg ones, which are perfectly adequate in virtually every environment.

Thank you very much!

Reference

1. Lawson NC, Maharishi A. Strength and translucency of zirconia after high-speed sintering. J Esthet Restor Dent. 2020 Mar;32(2):219-225. doi: 10.1111/jerd.12524. Epub 2019 Sep 13. PMID: 31515932.

Mathias Fernandez Y Lombardi

EU Scientific Manager
Dental Ceramics & CAD/CAM Materials
Kuraray Europe GmbH

2013
Successful completion of an apprenticeship as a dental technician at Seuthe dental laboratory in Plettenberg, Germany

2018
Successful completion of dental technology studies at the University of Osnabrück, Germany. Graduation as an engineer in dental technology

Since March 2018
Employee of Kuraray Europe GmbH

Interview with Tomohiro Emoto.

Kuraray Noritake Dental Inc. Launched its first porcelain for porcelain-fused-to-metal restorations – Noritake Super Porcelain AAA*, still available after more than 30 years under the name Noritake Super Porcelain EX-3* – in 1987. The knowledge acquired since then formed the basis for the development of CERABIEN™ ZR and the brand-new CERABIEN™ MiLai portfolio. How much of Noritake Super Porcelain is found in CERABIEN™ MiLai?

*Noritake Super Porcelain AAA and Noritake Super Porcelain EX-3 were designed and launched by Noritake Company Ltd., the predecessor of Kuraray Noritake Dental Inc.

Naturally, the knowledge we have acquired on developing porcelain products has been fully applied in the development of CERABIEN™ MiLai. The methods used to handle Synthetic Feldspar - such as low firing technologies, stable thermal expansion even with multiple baking, particle distribution control – are amongst the most important findings we have acquired since the development of Noritake Super Porcelain AAA. This expertise has been utilized to create both the design concept and development of CERABIEN™ MiLai.

WHAT ARE THE MOST DECISIVE DIFFERENCES FROM OTHERS?

The most decisive difference between CERABIEN™ MiLai and others is that we focus on micro-layering technique with this product. CERABIEN™ MiLai enables you to express life-like colours even with thin layers of porcelain. Also, this is the first porcelain we have launched which is compatible with lithium disilicate as well as zirconia.

Photo: MDT Andreas Chatzimpatzakis

WITH CERABIEN™ ZR BEING AVAILABLE AND CLINICALLY SUCCESSFUL, WHY DID YOU DECIDE TO DEVELOP A NEW LINE OF PORCELAINS AND INTERNAL STAINS?

The best way that we propose to create aesthetic restorations is Porcelain Fused to Zirconia (PFZ) with CERABIEN™ ZR. However, this method requires high levels of expertise and experience which is a lengthy learning curve for beginner dental technicians. As a result, Full Contour Zirconia (FCZ), which does not require such advanced skills and expertise, and which allows virtually anyone to create (albeit not perfect but nevertheless acceptable) restorations, is becoming increasingly popular. CERABIEN™ MiLai sits in the middle of these two methods. It enables technicians to create more aesthetic restorations with a simple, single micro-layering technique, making it ideal for those who wish to produce aesthetic restorations but without the high learning-curve associated with the traditional method, or those who use lithium disilicate materials.

CERABIEN™ MiLai enables you to express life-like colours even with thin layers of porcelain.

IS CERABIEN™ MILAI THE ANSWER TO THE NEW GENERATION OF MILLABLE CERAMIC MATERIALS THAT HAVE IMPROVED A LOT IN TERMS OF MECHANICAL BUT ALSO OPTICAL PROPERTIES IN RECENT YEARS, SUCH AS THE ENTIRE KATANA™ ZIRCONIA LINE-UP, TO OFFER FOR THIS KIND OF MATERIALS A FASTER AND ALSO HIGHLY AESTHETIC FINISHING OPTION?

Yes, it is. Formerly, zirconia materials were mono-coloured and not translucent. However, the improvement of zirconia materials, which began with KATANA™ Zirconia ML followed by KATANA™ Zirconia STML/UTML and KATANA™ Zirconia YML, has been an ongoing process and the aesthetics of the material itself is now very high thanks to improvements in translucency. This has led to the development of CERABIEN™ MiLai, a simple process that can achieve highly aesthetic restorations with thin layers, making the most of the high translucency of the zirconia materials.

WHAT ARE THE SPECIFIC NEEDS OF USERS FAVORING THE MICRO-LAYERING TECHNIQUE WITH RESPECT TO FEATURES OF THE VENEERING PORCELAIN?

When dental zirconia materials were first launched, chipping issues with porcelains for dental zirconia materials were a problem. At that time, dental porcelains were built up on a zirconia framework, the design of which failed to take into account the final shape. As a result, dental technicians were prone to building excessive thickness into porcelain layers which were unable to resist high occlusal pressure. Nowadays, it is standard for the final shape to be taken into account in the framework design resulting in reduced chipping issues. I must mention here that CERABIEN™ ZR, which was launched at that time, showed a higher endurance ratio than others in trials and was well accepted by the market.

What we want to offer with CERABIEN™ MiLai is a similar or developed version concept of this framework design. You can reduce the risk of problems post-installation of the restoration by minimizing the porcelain thickness while maximizing the area of dental zirconia which has such strong properties that almost no chipping issue can be expected.

As a result, the micro-layering technique, which can prevent post-installation problems, should prove ground-breaking for dental technicians.

Photo: MDT Giuliano Moustakis

WHAT DID YOU DO TO MEET THESE DEMANDS?

The thinking behind the development of CERABIEN™ MiLai has been to focus on delivering thin layering that replicates the enamel structure, thus allowing technicians to achieve desired shades regardless of the depth of a layer.

HOW DID YOU MANAGE TO DECREASE THE FIRING TEMPERATURES AND WHAT IS THE EFFECT OF THIS FEATURE?

Up to now, it has generally been tricky to achieve low firing temperature while maintaining a low coefficient of thermal expansion, because they contradict each other. However, thanks to the technologies and knowledge we have cultivated since the development of Noritake Super Porcelain AAA, we could finally be breaking through this obstacle. As a result, CERABIEN™ MiLai can even be used with lithium disilicate materials, which should be baked at low temperature to avoid damaging the material.

DUE TO THE FACT THAT CERABIEN™ MILAI CAN BE APPLIED NOT ONLY TO ZIRCONIA BUT ALSO TO LITHIUM DISILICATE MATERIALS, E.MAX FOR EXAMPLE, HAVE NEW SHADES/MASSES BEEN SPECIALLY DEVELOPED THAT HAVE BEEN PERFECTLY ADAPTED FOR LITHIUM DISILICATE MATERIALS?

The Value Liner has primarily been developed to achieve high aesthetics from lithium disilicate materials, even lithium disilicate which has high translucency compared to zirconia materials. Also, the key for adapting for lithium disilicate is the firing temperature which I mentioned earlier. To match the colour of restoration with the tooth, the selection of framework colour is important both for lithium disilicate materials and zirconia materials. We recommend selecting one shade brighter than the target shade taking into consideration the utilization of internal stain to express the detailed character of a tooth.

CERABIEN™ MiLai can even be used with lithium disilicate materials, which should be baked at low temperature to avoid damaging the material.

WHAT DID YOU DO TO ENABLE THE IMITATION OF VIRTUALLY EVERY TOOTH SHADE WITH JUST 16 PORCELAINS AND 15 INTERNAL STAINS?

We have prepared Value Liner porcelains, which can be utilized for adjusting the value of restorations. These Value Liner porcelains and internal stains are important to adjust colour and express detailed characters. As micro-layering does not require body porcelains, since it is expected that the framework material itself – either zirconia or lithium disilicate – would express the dentine structure, adjusting the colour and value respectively with internal stains and Value Liners is essential. To reproduce the enamel structure, users can use the 16 shades of porcelains as they are, or they can mix the shades to find the desired colour. These 16 porcelains and 15 internal stains have been through trials conducted with KOLs across the world, including Europe, so we want to reassure you that even the world’s most skilled KOLs have tested and confirmed quality and effectiveness of CERABIEN™ MiLai.

Photo: MDT Giuliano Moustakis

WHAT IS THE BENEFIT OF THIS SLIM LINE-UP?

The biggest benefit of CERABIEN™ MiLai is a simple procedure. Thanks to its simplicity, not only Kuraray Noritake Dental porcelain users but also new users and beginners can achieve excellent results with this porcelain series without struggling with complicated procedures.

HOW LONG DID IT TAKE YOU TO DEVELOP CERABIEN™ MILAI (FROM THE INITIAL IDEA TO THE AVAILABLE PRODUCT)?

We initially came up with the concept in 2015 when KATANA™ Zirconia STML and UTML were launched. The development project itself was started in 2019.

We created CERABIEN™ MiLai believing that the micro-layering technique would become the standard in porcelain restorations and that CERABIEN™ MiLai would become the material of choice for dental technicians.

DID YOU COME ACROSS ANY SPECIFIC CHALLENGES DURING THE DEVELOPMENT PROCESS?

The biggest challenge we faced was the development of a material which would be compatible with lithium disilicate. We had already produced porcelains which are compatible with zirconia or metal, but up to that point we had not created porcelains for lithium disilicate before CERABIEN™ MiLai. Not only did we have to develop the material within our R&D department, but also alter the production and inspection processes in collaboration with many other departments.

THE PRODUCT NAME CERABIEN™ MILAI IS DERIVED FROM THE WORD "MIRAI", WHICH MEANS AS MUCH AS "FUTURE" IN JAPANESE. HOW MUCH FUTURE IS THERE IN THIS MATERIAL OR, TO BE MORE PRECISE, IS THIS MATERIAL A PIONEER FOR THE FUTURE PRODUCTION OF HIGHLY AESTHETIC RESTORATIONS?

We created CERABIEN™ MiLai believing that the micro-layering technique would become the standard in porcelain restorations and that CERABIEN™ MiLai would become the material of choice for dental technicians.

Building up dental porcelains is not an easy process; it takes time to acquire the knowledge and master the technique. On top of this, dental technicians have long been plagued with post-installation problems such as chipping.

Micro-layering with CERABIEN™ MiLai enables every dental technician, from newcomers through to those with many years’ experience, to create better restorations. It is our hope that dental technicians everywhere will get to experience the ease at which aesthetic restorations can be realised with CERABIEN™ MiLai, just adding one step of micro-layering.

WHAT IS YOUR VISION WITH REGARD TO FUTURE DEVELOPMENTS IN THE AREA OF PORCELAIN FOR CERAMIC LAYERING?

Personally, I think the trend will continue to shift towards easier handling while maintaining good aesthetics, as can be seen by the recent increase in popularity of the micro-layering technique.

WHAT ABOUT THE POTENTIAL OF NEW CERAMIC CAD/CAM MATERIALS AND THEIR SUITABILITY FOR MONOLITHIC USE?

We believe that monolithic use will increase further, because the perception of aesthetics is changing among patients as well as dentists and dental technicians. Before, a "natural" restoration was considered acceptable; now it can also be "cosmetically" aesthetic. Formerly, it was said that monolithic use was not suitable as it could not reproduce life-like restorations. Now, we believe it will be increasingly embraced as patients show a demand for cosmetically aesthetic restorations.

Our KATANA™ Zirconia has mechanical advantages: high strength and high translucency, and high potential in longevity. Since dental zirconia appeared in dental material market, its aesthetics have been improved remarkably. And we, at Kuraray Noritake Dental Inc., have been developing outstanding CAD/CAM materials and will continue creating innovative materials from now on too.

We are convinced that developing better products for monolithic use is crucial for releasing dentists and dental technicians from complicated procedures while at the same time giving patients a sense of safety as well as aesthetic satisfaction.

WHY SHOULD A DENTAL TECHNICIAN TEST CERABIEN™ MILAI?

We are convinced that, once dental technicians who use either zirconia materials or lithium disilicate to make restorations, experience the ease at which they can achieve aesthetically-pleasing restorations with CERABIEN™ MiLai, demand will grow. We would therefore like to encourage all dental technicians to give it a go and see the results for themselves!

IS THERE ANYTHING ELSE YOU WOULD LIKE TO ADD FOR CUSTOMERS?

Thank you so much for reading this article to the end. I am very honoured to finally launch CERABIEN™ MiLai. This product is the result of many struggles. I am firmly convinced that it is the answer for any dental technician eager to realise high levels of aesthetics in a restoration in just a simple step. I would ask them to please try out CERABIEN™ MiLai for themselves and experience what will become standard practice in the future, right now.

TOMOHIRO EMOTO

R&D Department Technical Group Manager
Japan Academy of Esthetic Dentistry Executive Member
Academic Lecture Committee Member

With highly aesthetic ceramic materials available for the production of indirect restorations, it is no longer necessary to always design high strength frameworks and add multiple layers of porcelain. Nowadays, due to the rapid technological and optical improvements of zirconia and Lithium Disilicate (LiDiSi), a restoration may be manufactured with a monolithic design or minimal cut-back. Using appropriate materials, a less complex micro-layering technique will produce the desired outcomes, even if the aesthetic expectations are high. A new porcelain system specifically designed for this purpose is CERABIEN™ MiLai from Kuraray Noritake Dental Inc. The compact line-up of low-fusing porcelains and internal stains for micro-layering supports effiicient, economic finishing procedures leading to outstanding aesthetics at the first go.

The CERABIEN™ MiLai system consists of 16 base shades and 15 internal stains, which are easy to select and manage, and may even be mixed for additional shade effects. Due to the low firing temperature of all system components (740° C / 1,364° F), CERABIEN™ MiLai is not only compatible with zirconia, but also with silicate ceramic (such as IPS e.max) substructures. This means that fewer lines of porcelain are needed, the porcelain inventory is reduced once again, and fewer decisions need to be taken.

In order to provide for persistent handling properties and predictable outcomes, CERABIEN™ MiLai, like all other porcelains from Kuraray Noritake Dental Inc., are based on synthetic feldspathic porcelain technology. It is special in that its material structure and particle distribution resemble those of natural teeth, and its properties remain stable even after multiple firing cycles – giving dental technicians exactly what they expect. CERABIEN™ MiLai (tooth shades) are fluorescent, which adds to the vitality and life-like appearance of the restorations.

With these properties, CERABIEN™ MiLai is the outstandinig solution for every dental technician who would like to turn the finishing of zirconia and lithium disilicate restorations into a straightforward, efficient and economic procedure that produces predictably beautiful outcomes every time.

No matter whether you are a dental practitioner or dental technician, there is one thing you surely want to avoid: failure of indirect restorations. While it is clear that on both sides, the use of high-performance materials and appropriate techniques will contribute to achieving the desired outcomes, there is one aspect that should generally be given more attention: proper communication and exchange of information between the dental practice and laboratory.

As a dental professional: Are you aware of the information and details your case partners need to know in order to achieve the best possible result regarding fit, function and aesthetics?

For both, dental practitioner and dental technician, it is essential to know what precisely the respective partner does need to produce the desired outcomes. Hence, if it is not clear what information is needed and how it should be delivered, it is essential to sit down with your partner and find out. The goal of this personal or virtual meeting should be the establishing of a standardized flow of information between your companies. The necessary information might differ depending on the complexity of the case, but most details are always the same.

During the meeting, it is essential to focus on every step in the procedure that benefits from interaction between the practice and laboratory. It starts after the patient’s initial appointment and ends when the restoration is in place. In the following sections, the required information for indirect restoration planning, possible ways of communication to provide for a healthy flow of required information and important details are listed.

Teamwork starts before the actual treatment

Most dental technicians know a lot about the different restorative materials available and their suitability for specific clinical situations. Leverage this knowledge by involving your partner early – ideally before tooth preparation. This is most important for complex reconstructions, but also relevant when a single tooth needs to be restored: The restorative material and restoration design (monolithic, cutback, framework) have an impact on the space required and hence on the amount of tooth structure that needs to be removed. Aiming to opt for the least invasive treatment possible, it is essential that tooth preparation is limited to the necessary minimum.

The better the records, the better the fit of the final restoration

When it comes to taking records of the initial situation and the situation after tooth preparation, dental practitioners are often confronted with challenges. Limited mouth opening, a lack of time, or difficult moisture conditions are only some of the numerous factors that might prevent a clinician from taking a precise impression and bite registration. Nevertheless, it is decisive for the work in the dental laboratory to receive accurate records with all the necessary details such as the preparation margin. Understanding what exactly a dental technician needs to deliver a precisely fitting restoration will surely have a positive impact on the motivation to get the records right from the start, independent of the challenges.

Personally seeing the patient provides valuable additional information on a patient’s facial characteristics, on the status and appearance of the teeth and on their internal colour structure. These details can support a dental technician optimally in producing true-to-life dental restorations.

Structured try-in feedback facilitates targeted adjustments

Whenever try-in reveals that adjustments are required, well-structured feedback is important. It helps modify the restorations exactly as desired, hence avoiding additional appointments and wasting time in the practice and laboratory.

“Digitalization has made physical distance irrelevant, and we are able to deliver high-quality restorations even if the patient is hundreds of miles away”
- Dr Efe Celebi -

How to standardize

There are many possible ways to standardize the flow of information between the dental practice and laboratory. Depending on the individual preferences and established workflows, a personal or digital approach may be selected. Those preferring a personal approach will possibly want to develop paper forms for some steps, while relying on personal interaction for others. The digital approach uses a combination of digital imaging technologies, case management software and communication platforms to exchange relevant information.

A personal approach

At the Laboratorio odontotecnico Castellano in Bologna, Italy, the team around Vincenzo Castellano pursues the approach of personally seeing almost every patient prior to treatment planning. The laboratory technicians’ opinion is determinant for the treatment plan to be developed. Their partner practitioners value their expertise in restorative materials and digital technologies, which are evolving very quickly. The team is simply able to tell which material to choose in a specific situation to best manage the expectations of the patient and the functional needs. “Determining the restorative material in this early phase is very important, as its mechanical parameters (minimum wall thickness etc.) have an impact on the preparation design and depth. In fact, patients are always happy if they are able to meet the dental technician who produces their restorations, and – already well-informed by their dentist and the internet – often seize the opportunity to gather additional information about their planned treatment”, Vincenzo Castellano states.

Also, during subsequent appointments like try-in, the responsible dental technician is present to evaluate the situation and gather feedback from the patient directly. In his laboratory, online meetings conducted with patients substitute personal meetings only when this is the only way to enable personal interaction, as – in his opinion – personal meetings always deliver more details important for a great outcome. He says: “The most important approach to the patient is the human one. When using advanced digital technologies, we risk standardizing protocols to the extent that we forget there is an individual in front of us, with their own unique characteristics and wishes, entrusting us with their most precious asset: their smile.”

A digital approach

A perfect example of a laboratory with a purely digital approach is DentLab, a Turkish dental laboratory founded in 2015 by Dentgroup, Turkey’s largest Dental Service Organization (DSO). Its founder Dr Efe Celebi and his team have developed a special lab module for the group’s own practice management software, DentSoft. The module allows dental professionals to submit their orders electronically by using online forms and adding digital image data such as X-rays, intraoral scans, face scans and photographs. Users are able to see at a glance which data and information is strictly required. If desired, a user even receives procedural guidance: Specific devices like intraoral scanners, procedures and materials are recommended.

Once an order is submitted, the software sends a delivery date notification, so that the next appointment can be scheduled right away. Then, the incoming order is checked. Whenever some details are missing, the practice is contacted via a chat function in the software. Orders with incomplete or inaccurate data are rejected. A feedback function allows the technician to specify what needs to be repeated, improved or modified. Once accepted, the ordered items are produced and shipped to the office in a trackable box. It arrives with pre-treatment and cementation recommendations. Whenever necessary, patient feedback at try-in can be recorded on video or discussed live in a virtual meeting. “Digitalization has made physical distance irrelevant, and we are able to deliver high-quality restorations even if the patient is hundreds of miles away,” says Dr Efe Celebi. To facilitate improvement in the dental laboratory, the software has a case evaluation function that allows dental practitioners to evaluate the fit, function and look of every restoration.

“The most important approach to the patient is the human one. When using advanced digital technologies, we risk standardizing protocols to the extent that we forget there is an individual in front of us, with their own unique characteristics and wishes, entrusting us with their most precious asset: their smile.”
- MDT Vincenzo Castellano -

Conclusion

By establishing a well-structured, standardized and bidirectional flow of information between the dental office and laboratory, it is possible to improve the overall quality of prosthodontic treatments. It can be implemented with the aid of existing workflow management software, or set up according to individual demands using paper forms and personal meetings.

Anyway, sitting down together to discuss the topic of communication in a personal or virtual meeting has additional advantages, as it will help everyone involved develop a better understanding of the procedures carried out and challenges faced by their respective partner in the busy work environment. With this knowledge, it becomes easier to build a strong relationship that grows from mutual feedback and advice promoting common strategies for improvement. The result will be more streamlined work processes with less stress, higher-quality outcomes and happier patients.

We would like to express our gratitude to MDT Vincenzo Castellano and Dr Efe Celebi for sharing their individual approaches and the thinking behind them.

This year, the Kuraray Noritake Dental stand will be packed with news from the world of dentistry, so we offer not just one reason to visit, but a whole range: new chairside products, new labside products, inspiring lectures, enlightening hands-on demonstrations… And the best thing? You don´t have to choose just one thing, come and see them all at the Kuraray Noritake Dental booth in Hall 11.3 | Stand E010!

Chairside – smart streamlined solutions

When it comes to a dental practice, our vision is clear: a world where your materials and tools work seamlessly in your hands, where complexity is minimized, and where you are given enough time to focus on what matters most: the individual desires and needs of every single patient. This is the future of dentistry - and we are leading the way. Come discover our new additions to the UNIVERSAL EXCELLENCE family: a flowable universal composite and a new generation of a universal bond!

Labside – speed and aesthetics hand in hand

No matter whether a minimally invasive procedure or the best aesthetic outcomes are desired: Kuraray Noritake Dental has the products for you. New in the portfolio: CERABIEN™ MiLai - low-fusing porcelains and internal stains. Come and see for yourself its ultra-thin layering, exceptional mechanical properties and consistent handling for both zirconia and lithium disilicate. And while you're there, have a coffee while speed-sintering with our KATANA™ Zirconia discs takes place in real time.

Get inspired by 12 expert speakers on 2 stages

Are you a user of or interested in one of Kuraray Noritake Dental’s products or solutions, but eager to learn more about their practical use from proven experts in your field? From Wednesday until Saturday, we offer a programme of exciting lectures and live demonstrations - this time simultaneously on two stages: one dedicated to chairside and the other one to labside topics!

Warm welcome

Everyone, from sales person to scientific marketeer, looks forward to giving you a warm welcome, answering your questions and introducing you to the world of innovative Kuraray Noritake Dental products, solutions and workflows. And while you are already in Cologne anyway, why not enjoy the breathtaking beauty of the old town? Have you ever seen its famous Gothic Cathedral? Or its Old Town inviting you to stroll through its narrow alleys, finding traces of history around every corner? This year's IDS offers so many reasons to attend that it's hard not to accept the invitation.

Additional information and the full programme of lectures and hands-on courses at the IDS is available online.

Article by Peter Schouten

Ceramic primers vary widely in composition and effectiveness, despite what their name might suggest. Most common primers include silane, but silane alone is insufficient for pre-treating all materials commonly used in indirect restorations before bonding.

Silane—typically in the form of γ-MPS—has a strong affinity for silica- or glass-based materials. While certain metals and their oxides can chemically react with silane, other components provide a stronger and more reliable bond to metals and metal oxides and should be seriously considered.

For metal(oxide) pretreatment in bonding, the MDP monomer is far more reactive than silane. The original MDP monomer, developed by Kuraray Co., Ltd. in 1981, remains the highest-quality MDP available, as confirmed by research.¹

CLEARFIL™ CERAMIC PRIMER PLUS is a single-component adhesive primer that forms strong bonds with a wide range of restorative materials. This two-in-one primer incorporates the original MDP monomer, which establishes a robust bond with metals and zirconia. Simultaneously, the silane coupling agent (γ-MPS) ensures excellent adhesion to resin composites, hybrid ceramics, and glass-based ceramics such as lithium disilicate and porcelain.

ENHANCED BOTTLE DESIGN

The primer bottle is designed for effortless one-handed operation. Its unique nozzle ensures precise dispensing, minimizing the risk of contamination and spills.

PROVEN EFFECTIVENESS OF MDP-CONTAINING PRIMERS

To enhance the bonding of prosthetic materials, use a primer containing both MDP and silane. Numerous studies have demonstrated the effectiveness of this combination.

OPTIMAL PRIMING FOR ADHESIVE CEMENTING

These studies underscore the critical role of MDP-containing primers in achieving reliable and durable adhesion for prosthetic materials. Products containing only silane, such as RelyX™ Ceramic Primer (3M ESPE), are less effective at creating a durable bond between resin cements or composites and ceramic- or metal-based prosthetic materials.

Image from clinical case by MDT Rondoni and Dr. Attanasio

STRAIGHTFORWARD AND EFFICIENT

The use of CLEARFIL™ CERAMIC PRIMER PLUS is straightforward: just apply it to the bonding surface, dry it, and proceed with the following treatment step. Incorporated into your process to streamline adhesion preparation and achieve reliable results!

JUST APPLY AND DRY

CLEARFIL™ CERAMIC PRIMER PLUS may be applied to any restoration surface after the required pretreatment. Pretreat the adherent surface of the restoration as indicated:

* If your laboratory already treated with a hydrofluoric acid, cleaning and activating with K-ETCHANT Syringe just before applying CLEARFIL™ CERAMIC PRIMER PLUS is recommended.

**When using with PANAVIA™ V5 or CLEARFIL™ DC CORE PLUS

Universal prosthetic primer designed for a strong bond and procedural simplicity

Author:

PETER SCHOUTEN

References

1. Yoshihara K., et al.(2015) Functional monomer impurity affects adhesive performance, Dental Materials, Volume 31, Issue 12, https://doi.org/10.1016/j.dental.2015.09.019. Pilo, R., et al. (2018). “Effect of tribochemical treatments and silane reactivity on resin bonding to zirconia.” Dent Mater 34(2): 306-316.
2. Cao, Y., et al. (2021). The effects of four primers and two cement types on the bonding strength of zirconia. Annals of Translational Medicine. 10. 10.21037/atm-21-4909.
3. Reymus, M., et al. (2019). “Bonding to new CAD/CAM resin composites: influence of air abrasion and conditioning agents as pretreatment strategy.” Clin Oral Investig 23(2): 529-538.
4. Uğur, M., et al. (2023). Effect of ceramic primers with different chemical contents on the shear bond strength of CAD/CAM ceramics with resin cement after thermal ageing. BMC Oral Health. 23. 10.1186/s12903-023-02909-z.
5. Pilo, R., et al. (2018). “Effect of tribochemical treatments and silane reactivity on resin bonding to zirconia.” Dent Mater 34(2): 306-316.
6. Inokoshi, M., et al. (2014). “Bonding effectiveness to different chemically pre-treated dental zirconia.” Clin Oral Investig 18(7): 1803-1812.

Interview with Dr. Efe Celebi

In March 2024, Dr Ahmad Al-Hassiny, Director of the Institute of Digital Dentistry, shared his observations from LMT Lab Day 2024 in Chicago, noting that over 90 percent of U.S. dental laboratories and nearly 50 percent of dental practices have already adopted digital technologies and workflows. These advancements streamline the production of dental models, restorations across various materials, and much more.

Our company Kuraray Noritake Dental Inc. is dedicated not only to developing high-quality products and constantly adapting them to the needs of dentistry, but also to streamlining procedures in the dental laboratory and practice. Aiming to understand the current needs of dental technicians and dental practitioners around the world to provide what would really make a difference, we are in close dialogue with experts in the field. We love to listen to their stories, learn how digital technologies and artificial intelligence are already transforming dental procedures and see how we can contribute to a smooth transition – e.g. with products that support efficient workflows and great outcomes.

Lately, we had the chance to sit down with a leading figure in Turkey’s digital dentistry transformation, Dr Efe Celebi, to discuss the current landscape and future of digital innovation in dentistry. Being convinced that his experience is worth being shared with a broader audience, we have summarized the conversation.

Dr. Celebi, you’re known as a pioneer in digital dentistry. What drove you to establish companies with a strong digital focus?

As the founder of Dentgroup, Turkey’s largest Dental Service Organization (DSO), I have always believed in the power of digital dentistry. My goal was to establish digital workflows for producing indirect restorations, beginning with intraoral scanning at our practices. Initially, we sought laboratory partners in Turkey willing to make this transition with us. But at that time, none of our partner labs were prepared to take the leap, so we decided to build our own. Digitalization, after all, is simplifying work in almost every field, and dentistry is no exception. So, in 2015, we founded DentLab to provide cutting-edge digital laboratory services.

How did you go about implementing digital workflows?

From the very beginning, we aimed to digitize every aspect of our work—from production to data management and communication. Our practices already used our own practice management software, DentSoft, successfully. To connect our clinics with the lab, we developed a specialized lab module. This allowed our dental practitioners to submit every order electronically. It was a huge improvement over the old process, where forms with sketches were mailed physically, just as it had been in in the old days. Now, practitioners can select the teeth in need of treatment, specify restoration colour and design, and upload radiographs, photos, and intraoral scans with just a few clicks. Over time, we have continuously enhanced communication features between clinics and labs, adding things like delivery date notifications for orders, so patients can book their next appointment before they even leave the clinic. These tools have greatly improved coordination between our dentists and lab technicians.

How is communication organized in the software?

We created a chat-style communication area where different team members can talk, with all records saved and accessible to anyone involved in a treatment. This setup is a major improvement over phone calls, as every detail—from treatment notes to radiographs and photos—is stored and easy to reference. We even enabled practitioners to rate the products they receive, and every necessary remake is documented along with the responsible technician. This feedback system has allowed us to maintain high-quality standards, identify issues, and provide targeted training where needed.

Modern digital technologies used at DentLab to provide cutting-edge digital laboratory services.

Have you made other improvements in workflow and communication between clinics and laboratories?

DentLab initially served Dentgroup practices exclusively, but we eventually opened its services to other clinics. In this context, we set standards for incoming orders—from the required data to impression quality. If an order does not meet these standards, we reserve the right to reject it, explaining why, so the submitter can improve. We also implemented a loyalty programme and developed a special, trackable package with a QR code to prevent loss of items in transit. This innovation lets both the team in the lab and the clinic track each package’s location in real time, solving a common logistical challenge. We have even patented this unique packaging system.

Unique patented delivery box used at DentLab to prevent loss of items.

Do you provide guidance on materials and tools for clinics?

Yes, as part of our commitment to quality, we recommend specific intraoral scanners and even distribute them to customers outside our network. We also advise clinics on material choices, pre-treatment needs, and compatible resin cements for permanent placement of the produced restorations. Our protocols cover the entire restorative procedure. For aesthetic cases, we recommend starting with a smile design and using mock-ups. The mock-up evaluation lets practitioners and patients provide feedback, so the responsible lab technician can produce the final restoration with precision.

With digital workflows so well-established, do you think technicians still benefit from meeting patients face-to-face?

Not necessarily. Occasionally, a dentist may request a patient visit the lab, and we accommodate this. However, digitalization has made physical distance irrelevant, as clinics and labs can now work seamlessly from anywhere. In fact, we serve offices in Europe without any face-to-face interactions between patients and lab technicians. For patients, especially in a city like Istanbul, avoiding long travel times is a big plus, while we can still ensure high-quality outcomes.

Would you say digitalization has improved treatment quality overall?

Absolutely. There is a learning curve to digital processes, but once practitioners adjust, the quality is noticeably higher. In traditional workflows, practitioners might bend the rules, asking technicians to work with suboptimal impressions, for example. Digital systems do not allow for such shortcuts; preparation quality is clear from the scan, and impression errors can be corrected instantly before submitting to the lab. Additionally, digital scans will never shrink, distort, or tear during production, unlike physical impressions.

What are the main challenges associated with digital dentistry today?

The biggest challenge is simply taking the first step. Dentistry has been hesitant to change after decades of doing things the same way. Going digital requires an investment in both time and money. But those who make the switch find the rewards—better outcomes and more efficient procedures—well worth it.

What is next for digital dentistry?

With AI advancing quickly, the field is evolving in exciting ways. Today, we can combine digital impressions, facial scans, photographs, and 3D imaging to create a “virtual patient”. Some clinics are already using software to analyze digital data, like dental X-rays, and I predict that robot-assisted or even autonomous clinical procedures are on the horizon. Imagine robot arms taking impressions or patients scanning their own teeth with smartphones. Impression-taking procedures carried out at home already support aligner treatments in some cases. As these technologies advance, the need for dental assistants will likely decrease. The digital future for dentistry is incredibly promising, filled with tools that can transform patient care and practice efficiency on a global scale.

Example of beautiful, precisely fitting all-ceramic restorations produced at DentLab.

Article by Dr. Clarence Tam HBSc, DDS, FIADFE, AAACD

A NOVEL MDP-BASED SURFACTANT SOLUTION

The everyday practice of adhesive restorative dentistry, whether utilizing direct or indirect restorations, is fraught with the need for ideal environmental conditions to generate an optimal prognosis. The bonding of composite resin is the foundation of direct and indirect restoratives, as it provides the link between restoration and tooth. As dentistry strives to be minimally invasive, the treatment of the bonding interface is reflected in this philosophy by the use of self-etching multi-substrate acidic monomers such as 10-methacryloyloxyldecyl dihydrogen phosphate (10-MDP). There are myriad opportunities for both intaglio and fitting surfaces to be contaminated with varying agents to the detriment of restoration prognosis.

Some of the contaminants to be considered are of course, moisture from exhalation, ambient humidity in the oral cavity, blood, saliva and artificial sources such as provisional cement during a two-stage indirect delivery technique. Moisture is an agent which is only welcomed via a controlled approach during the dentin penetration phase of priming the substrate for adhesion, however if excessive in quantity will compromise the hybridization of the interface. Blood and saliva are ubiquitous in restorative dentistry, and best controlled via the application of rubber dam as part of an absolute isolation philosophy. Contamination of the prepared surface can also occur through artificial cements or lubrication agents. Hemostatic agents such as ferric sulfate and aluminum chloride have the ability to deposit insoluble precipitates on the surface of the tooth in a manner that 33% orthophosphoric acid can only partially remove. Also considered is the particulate deposition of dentin and enamel as part of standard tooth preparation. This smear layer is residual on the dentin surface, often occludes dentinal tubules, and is an obstacle that must be overcome in order to bond to the hydroxyapatite and collagen fibrils of the surface.

Overall, the risks to adhesive compromise and at worst, adhesive failure are high. This report details the use of a novel solution for debriding both indirect restorative and tooth intaglio with a 10-MDP salt-based solution that has the flexibility to be used both extraorally and intraorally.

ENDEMIC CONTAMINANTS: MOISTURE, BLOOD AND SALIVA

Moisture is a critical component to maximize the adhesive bond strength of certain modern universal adhesives. The presence of moisture allows for increased penetration of bonding solutions into dentinal tubules and between collagen fibrils, ultimately bolstering the resilience of the hybrid layer¹. During the cementation of an indirect restoration, both salivary and blood contamination of the mating surfaces have been shown to have a deleterious effect on bond strengths, with blood contamination faring the worst in all conditions². Van Meerbeck et al reported on technique sensitivity with one-step contemporary universal adhesives³. The basis of his findings note that these adhesives require water as an ionization medium for the self-etching reaction, with the need to evaporate water from the interfacial surfaces in order to maximize bond strengths. Despite this, these interfaces are considered semi-permeable which predisposes the hybrid layer to an increased risk of hydrolytic degradation in adhesive solutions that are not 2-hydroxyethyl methacrylate-free (HEMA-free), which has a greater affinity for water.

Periera et al tested varying degrees of wetness of dentin substrate controlled with variables such as short vs. long air blasts, wet vs. dry cotton pellets, microbrush use and an intentionally over-wet surface. In all groups, the “wettest” dentin intaglio surface resulted in the lowest shear bond strength⁴.

The influence of saliva and blood contamination is clearly negative in situations where the bonding interface was contaminated before or after adhesive application. For saliva, this reduction is due to the deposition of salivary glycoprotein on the surface, and relative to blood, macromolecules such as fibrinogen and platelets block access to the tubules for effective bonding. Blood contamination was found consistently to be more profoundly deleterious on bond strength relative to saliva².

In general, on smear layer-affected dentin, chlorhexidine was consistently superior to other agents such as ethanol, EDTA, aloe vera in establishing the highest shear bond strength to dentin. On dentin that had previously been etched and contaminated with blood and saliva, the agent subsequently applied that showed the highest recovery of shear bond strength was 37.5% phosphoric acid⁵. A study on the nanomechanical and nanoroughness of etched dentin and self-etching adhesive treated dentin both contaminated with saliva revealed that KATANA™ Cleaner was capable of restoring control values of complex modulus and nanoroughness relative to control⁶.

SYNTHETIC WORKFLOW CONTAMINANTS: DENTAL STONE, HEMOSTATIC AGENTS, ROOT CANAL SEALERS AND PROVISIONAL CEMENTS

A 2020 study by Marfenko et al demonstrated that salivary contamination showed significantly lower bond strengths relative to intaglio contamination by dental stone from laboratory processes. The application of a silane coupling agent to the intaglio surface has a protective effect on the bond strength⁷. The caveat is that lithium disilicate-based restorations are often requested pre-etched with hydrofluoric acid from the laboratory. Often, the case is returned to the clinician on the secondary or primary model. If already treated with hydrofluoric acid, the surface can now be considered recontaminated with the stone or resin model or simply skin oils from handling. The unprotected surface needs to be decontaminated in any case following the try-in procedure, which now may feature elements of dental stone, blood and saliva, not to mention hemostatic agents such as aluminum chloride and ferric sulphate. If silane coupling agents are applied prior to try-in, the question of whether the intaglio surface was truly contaminant-free after removal from the model.

Aluminum chloride is a hemostatic agent that leaves an insoluble precipitate on the surface of the dentin, that is only partially removed when treated with phosphoric acid, resulting only in a partial recovery of shear bond strength relative to control. The application of ethylene diacetyl tetrasodium acetate (EDTA) returned the bond strengths to the level of normal dentin⁸. The bonding of polycrystalline ceramic restorations and metal alloys is contaminated with saliva upon try-in. This can be removed via steam cleaning and air particle abrasion set at 2.5 bar for 15 seconds⁹. Phosphoric acid is often mistakenly applied as a cleaning agent to the intaglio surface. In polycrystalline ceramics such as tetragonal zirconia polycrystal, this is disastrous, as phosphates will bond firmly to the free sites that the 10-MDP monomer normally bonds to as part of the APC protocol of zirconia bonding, significantly compromising bond strength (Blatz, 2016)¹⁰. A study of modern surface cleaners demonstrated successful debridement of the surface using KATANA™ Cleaner for both blood and saliva-contaminated substrates^{11, 12}.

Provisional cements are thought to have a deleterious effect on the shear bond strength of adhesively-bonded indirect ceramic restorations. Ding et al (2022) uncovered that resin-based and non-eugenol cement use in the provisional phase decreased the bond strength relative to control, whilst the use of calcium hydroxide and polycarboxylate cements exhibited acceptable metrics. Debridement of the prepared surface with air particle abrasion (APA) resulted in recovery of decreased bond values to that of control¹³. Equally useful was the application of Immediate Dentin Sealing (IDS)¹⁴, a technique characterized ideally by APA before adhesive bonding and the application of a resin coat, occluding both the dentin tubules as well as the oxygen inhibition layer, allowing the resin-dentin bond to mature and strengthen in the absence of stresses. This approach is effective in minimizing post-operative hypersensitivity and bacterial ingress, as well as optimizing the shear bond strength particularly when indirect ceramics are concerned¹⁵. Hardan et al found that the shear bond strength was highest when IDS was completed using a three-step etch and rinse adhesive protocol¹⁴.

Hemostatic agents used in clinical dentistry exhibit a pH of 1.1 to 3.0 and are as acidic as self-etching primers¹⁶. Chaibutyr and Kois found that dentin when contaminated with 25% aluminum chloride or 13% ferric sulphate demonstrated a significantly lower shear bond strength to dentin, which was significantly recovered using the etch-and-rinse approach¹⁷. This approach albeit successful was only able to achieve partial reversal of shear bond strength deficits relative to control, with a pre-etching application of EDTA required in order for full recovery⁸. KATANA™ Cleaner was found to have a positive effect on the cleaning of dentin contaminated with both aluminum chloride and ferric sulphate.

The bonding of dentin substrate contaminated with root canal sealers is a concern for the integrity of core buildups post-endodontic treatment. The use of  KATANA™ Cleaner was found to be generally superior to the ethanol test subgroup in the removal of zinc-oxide eugenol-based sealer with equal performance to 70% ethanol for the epoxy resin-based sealer¹⁸.

CLINICAL CASE DEMONSTRATION

A 35 year old ASA 1 female patient presented to the practice with multiple failing composite restorations in the second quadrant that were planned for replacement. Prior to the delivery of topical and local anaesthesia, it is common procedure in the practice to ascertain shade specifics of planned restoratives before potential dehydration can affect the optical properties of the natural tooth. Smart monochromatic composites (Fig. 1) are a class of direct restoratives that leverages the ability of its nanofiller composition and refractive index to mimic the structural color of the surrounding enamel and dentin¹⁹. This typically enables a clinician to have a simplified selection of shades on hand.

Two carpules of 2% Lignocaine with 1:100,000 epinephrine were delivered via buccal infiltration before absolute isolation was achieved using a non-latex rubber dam (Isodam HD Heavy, 4D Rubber, UK) (Fig. 2). The old restorations were excavated along with caries (Fig. 3), and the dentin structure assessed for residual decay with a detector dye (Caries Detector, Kuraray Noritake Dental Inc.). The preparation cavosurface margins were gently bevelled before surface treatment with air particle abrasion (30psi, 29 micron aluminum oxide in a 17.5% ethanol carrier, Aquacare UK) (Fig. 4). The enamel margins were etched with 33% orthophosphoric acid and rinsed (Fig. 5). The preparation surfaces were decontaminated further of any residual smear or powder residue using a MDP-based surfactant (KATANA™ Cleaner, Kuraray Noritake Dental Inc.) (Fig. 6). A single step self-etching universal adhesive was applied to the preparation as per manufacturer instructions and air thinned before light curing (Fig. 7).

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

A matrix-in-matrix approach was utilized for the second bicuspid as the first step to allow for simultaneous anatomic construction of the mesial and distal marginal ridges. This technique does not require the use of a wedge as the outer circumferential Tofflemire matrix (Omnimatrix, Ultradent Products) tightens cervically around the inner anatomically-curved sectional matrix (Garrison Firm Band, Garrison Dental Solutions) allowing for a hermetic gingival seal (Fig. 8). If required, the setup may be further modified by the use of Teflon inserted between the two matrices to provide better proximofaciolingual adaptation. As a result, finishing and contour creation post-band removal is kept to a minimum. Following this, a traditional sectional matrix system may be employed to close contacts and build marginal ridges in the conventional manner (Fig. 9).

Following marginal ridge construction, the matrix assembly was removed and with the Class II lesions converted into a Class I situation, microlayering proceeded with a high flexural strength flowable liner (CLEARFIL MAJESTY™ Flow, Kuraray Noritake Dental Inc.) prior to the application of a monochromatic composite resin (CLEARFIL MAJESTY™ ES-2 Universal U shade, Kuraray Noritake Dental Inc.). The buccal cusps were constructed first as the author considers this essential to establishing restoration lobe proportions (Fig. 10). Subsequent layers were completed in a lobe-by-lobe approach to finish the occlusal anatomy (Fig. 11 and 12). The restoration was checked for occlusal functional conformativity, finished and polished to high shine (Fig. 13).

Fig. 8

Fig. 9

Fig. 10

Fig. 11

Fig. 12

Fig. 13

DISCUSSION

Dental substrates are often contaminated in both direct and indirect restorative processes. Historically, etch-and-rinse approaches have been successful for at least the partial recovery of bond strength however it is not practical in situations where selective or self-etching is the adhesive strategy. The restorative dentist in these cases can use the 10-MDP monomer in self-etching systems to target non-demineralized dentin such as CLEARFIL™ Universal Bond Quick to establish an acid base resistance zone (ABRZ) otherwise known as Super Dentin²⁰. The presence of the operative smear layer impedes full access of the self-etching primer to the dentin substrate in some cases. In such cases, without KATANA™ Cleaner, APA is required to transform the substrate back to control bonding potential. APA as a modality is only utilized by a subset of dental practitioners often due to financial constraints or lack of technique experience. KATANA™ Cleaner thus represents a versatile tool for the decontamination and  optimization of substrate surfaces for adhesive bonding both in intraoral and extraoral applications. Its ability to re-establish ideal bonding values in areas that are not effectively reached by APA such as endodontic canal anatomy in a non-invasive manner literally cements it as a truly indispensable tool for the modern restorative dentist.

Disclaimer: Some indications are not described in the product’s Instructions for Use and are based on published research and/or the author’s experience. Before using each product, read carefully the Instructions for Use supplied with the product for full details and workflows.

Dentist:

CLARENCE TAM

References

1. Sugimura R, Tsujimoto A, Hosoya Y, Fischer NG, Barkmeier WW, Takamizawa T, Latta MA, Miyazaki M. Surface moisture influence on etch-and-rinse universal adhesive bonding. Am J Dent. 2019 Feb;32(1):33-38. PMID: 30834729.
2. Taneja S, Kumari M, Bansal S. Effect of saliva and blood contamination on the shear bond strength of fifth-, seventh-, and eighth-generation bonding agents: An in vitro study. J Conserv Dent. 2017 May-Jun;20(3):157-160. doi: 10.4103/0972-0707.218310. PMID: 29279617; PMCID: PMC5706314.
3. Van Meerbeek B, Van Landuyt K, De Munck J, Hashimoto M, Peumans M, Lambrechts P, Yoshida Y, Inoue S, Suzuki K. Technique-sensitivity of contemporary adhesives. Dent Mater J. 2005 Mar;24(1):1-13. doi: 10.4012/dmj.24.1. PMID: 15881200.
4. Pereira GD, Paulillo LA, De Goes MF, Dias CT. How wet should dentin be? Comparison of methods to remove excess water during moist bonding. J Adhes Dent. 2001 Fall;3(3):257-64. PMID: 11803713.
5. Haralur SB, Alharthi SM, Abohasel SA, Alqahtani KM. Effect of Decontamination Treatments on Micro-Shear Bond Strength between Blood-Saliva-Contaminated Post-Etched Dentin Substrate and Composite Resin. Healthcare (Basel). 2019 Nov 1;7(4):128. doi: 10.3390/healthcare7040128. PMID: 31683858; PMCID: PMC6956069.
6. Toledano M, Osorio E, Espigares J, González-Fernández JF, Osorio R. Effects of an MDP-based surface cleaner on dentin structure, morphology and nanomechanical properties. J Dent. 2023 Nov;138:104734. doi: 10.1016/ j.jdent.2023.104734. Epub 2023 Oct 2. PMID: 37793561.
7. Marfenko S, Özcan M, Attin T, Tauböck TT. Treatment of surface contamination of lithium disilicate ceramic before adhesive luting. Am J Dent. 2020 Feb;33(1):33-38. PMID: 32056413.
8. Ajami AA, Kahnamoii MA, Kimyai S, Oskoee SS, Pournaghi-Azar F, Bahari M, Firouzmandi M. Effect of three different contamination removal methods on bond strength of a self-etching adhesive to dentin contaminated with an aluminum chloride hemostatic agent. J Contemp Dent Pract. 2013 Jan 1;14(1):26-33. doi: 10.5005/jp-journals-10024-1264. PMID: 23579888.
9. Yang B, Lange-Jansen HC, Scharnberg M, Wolfart S, Ludwig K, Adelung R, Kern M. Influence of saliva contamination on zirconia ceramic bonding. Dent Mater. 2008 Apr;24(4):508-13. doi: 10.1016/j.dental.2007.04.013. Epub 2007 Aug 6. PMID: 17675146.
10. Blatz MB, Alvarez M, Sawyer K, Brindis M. How to Bond Zirconia: The APC Concept. Compend Contin Educ Dent. 2016 Oct;37(9):611-617; quiz 618. PMID: 27700128. (7)
11. Awad MM, Alhalabi F, Alzahrani KM, Almutiri M, Alqanawi F, Albdiri L, Alshehri A, Alrahlah A, Ahmed MH. 10-Methacryloyloxydecyl Dihydrogen Phosphate (10-MDP)-Containing Cleaner Improves Bond Strength to Contaminated Monolithic Zirconia: An In-Vitro Study. Materials (Basel). 2022 Jan 28;15(3):1023. doi: 10.3390/ma15031023. PMID: 35160968; PMCID: PMC8838745.
12. Tian F, Londono J, Villalobos V, Pan Y, Ho HX, Eshera R, Sidow SJ, Bergeron BE, Wang X, Tay FR. Effectiveness of different cleaning measures on the bonding of resin cement to saliva-contaminated or blood-contaminated zirconia. J Dent. 2022 May;120:104084. doi: 10.1016/j.jdent.2022.104084. Epub 2022 Mar 3. PMID: 35248674.
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Article by Dr. Clarence Tam HBSc, DDS, FIADFE, AAACD

A CHAMELEON SUPERCOMPOSITE

INTRODUCTION

The name of the game in modern-day esthetic and restorative dentistry is that of Responsible Esthetics. The goal of treatment typically strives to correct any structural and cosmetic shortfalls in both biologically-driven and trauma-affected teeth with the precise, artistic placement of various replacement layers, all whilst respecting and retaining a maximal volume of residual tooth structure. Anterior teeth can be affected by enamel and dentin dysplasia, caries and sclerotic conditions and are characterized by a laundry list of genetically-derived and environmentally-acquired conditions with an esthetic deficit that often threaten an individual’s functional and psychosocial integrity if not restored to the seamless picture of health.

Missing and defective tooth structure must be categorized into its attendant enamel and dentin components. Both substrates are distinctly different in composition, with enamel being highly inorganic in nature and dentin proportionately more collagenous in nature. The latter stratum is responsible for the refraction of light, the expression of the true color of the tooth, namely the hue and the endowment of fracture toughness or resilience in functional performance. The value and chroma are the other elements of color and are modified by the thickness of enamel. The replacement of enamel has been found to be best substituted from a biomechanical perspective by adhesively-bonded indirect porcelain restorations, and dentin using both composite resin and short fiber reinforced composite (SFRC), the latter imparting increased fracture toughness in large volume replacement restorations, especially those with pericervical structural deficits.

In adolescent patients, the gold standard of treatment involves direct composite resin, as often zero to minimal tooth structure preparation is required as a foundation to the bonded restorative. It would be impractical to use bonded indirect restorations when the development of the dentition in puberty is continuous, especially with the retraction of gingiva as one progresses to young adulthood. Resin composite allows prescience in the opportunity to predictably modify and/or add to the existing restoration if dental bleaching for the other teeth is desired or if a further traumatic incident is encountered. The ability to modify bonded porcelain is not predictable and frequent marginal failures occur due to a lower shear bond strength to bonded composite, especially after thermocycling. This is despite our ability to establish a chemical linkage via silane coupling agents from silicate ceramics to resin composite especially at a blended interface.

STATEMENT OF PROBLEM

Dental shades in clinical dentistry have long been classified using the VITA^* Classical A1 – D4 shade guide. Despite being ubiquitous in dental practices, composite resin systems with corresponding shade systems do not satisfactorily match to their purported shade¹. Floriani et al found that various mixtures of different shades in one system was required to achieve an acceptable color match with the VITA^* Classical shades using the CIEDE2000 formula. Testing another composite resin, they found that none of the A1, A2 or A3 shades matched acceptably to the standard shade guide². Indeed, even with indirect ceramic layering systems, a wide range of unacceptable discrepancy was noted between VITA^* labeled porcelain shades and the actual shade guide³. The VITA^* Classical shade guide became the standard in dental shade classification with the release of its A1-D4 shade guide in 1985. The majority of human-tested dental shades has been found to be in the A-family (78.5%), followed by C (13.2%), D (5.2%) and B (3.1%)¹. As such, the shade accuracy of a given composite system must be important if they are to be visually naturomimetic.

CHAMELEON EFFECT DEVELOPMENT

There are myriad composite resin systems featuring a simplified shade Universal system that have acceptable chameleon effects due to their balance of translucency, light transmission, diffusion and refractive index properties. There is a concern over how these optical properties may change after both thermocycling and wet storage, potentially compromising the excellent initial esthetic blend⁴. Refractive index (RI) is best optimized when the RI of the inorganic fillers match closely with the RI of the cured organic matrix, typically in a range between 1.47 and 1.52⁵. If the match is dissimilar, this drives up the opacity of the restoration due to heightened refraction and reflection at the filler/matrix interface⁶.

Layering of composite to mask an intraoral defect is complicated by the need to mask any linear defects such as fracture lines superimposed over the shadowing of the dark intraoral cavity in addition to regional color variations. It is confounded by the requirement to recreate natural maverick and translucent effects particularly in the incisal window region of upper and lower incisors and canines, giving the illusion of a virgin, healthy tooth. This has been historically difficult to accomplish in anterior teeth given the need to block out restorative interfaces with natural tooth structure and recreate a seamless internal structure and details. This detailed layer belies a well contoured enamel layer with realistic translucency, polishability and accurate primary and secondary anatomy.

Adding to the complexities described above, the histoanatomical approach to composite layering dictates that missing enamel is replaced by enamel shades, and dentin by the corresponding dentin shade in the appropriate shade. This shade must be selected at the very start of the appointment, as often even a minute of dehydration has a negative effect on both the perceptibility threshold and acceptability threshold of teeth⁷, resulting in the incorrect shade.

DEVELOPMENT

CLEARFIL MAJESTY™ ES-2 is a value-based super-nanofilled composite system that covers 15 VITA^* shades in just 4 shade options with its Universal series. This Universal series provides a chameleon effect and has 4 variants: Universal (U), Universal Light (UL), Universal Dark (UD) and Universal White (UW). It is the VITA^*-approved shading concept relative to color accuracy. Incorporating nano-fillers that consist of silanated barium glass fillers and slanted silica nanoclusters, its wear resistance is high and features minimal abrasiveness against the functional antagonist. The RI of both inorganic filler and organic matrix are well-matched, and the high refractive index of the composite mimics and is extremely similar to natural enamel (1.613) and dentin (1.540), thanks to an innovation labeled Light Diffusion Technology (LDT), which distorts light in a similar way dental tissue does⁸. There is comfort that the stability of refractive index and other optical transmission properties remains statistically stable even after artificial thermocycling and water-storage aging studies⁴. The color stability of CLEARFIL MAJESTY™ ES-2 has been proven over time, where a direct comparison to Filtek Ultimate showed CLEARFIL MAJESTY™ ES-2 to feature significantly less color variation from baseline and marginal functional wear over a three to four year period in teeth featuring amelogenesis imperfecta⁹. This color substantivity is important as dietary and environmental stressors applied over time should have as minimal effect on the restoration to ensure continued esthetic integration.

CLINICAL PROTOCOL

CLEARFIL MAJESTY™ ES-2 Universal is a monochromatic solution that covers the five key shades featured in the CLEARFIL MAJESTY™ ES-2 Premium. As such, it exhibits the most significant LDT relative to all five shades, as its ability is equal when blending to higher value translucent shades as it does to cervical chromatic shades. In a Class IV restoration with a defined fracture line, the challenge is to restore the tooth in a minimal volume of available space. The alchemy requires a complete visual occlusion of the fracture line position, and recreation of internal and external opaque and translucent anatomy along with maverick staining, craze lines and effects. In anterior teeth, the idiom of “the less you see, the less you notice” is not true, especially due to the presence of incisal edge window effects as above, however, materials with the best light diffusion and structure transference properties should be utilized to ensure the highest probability of success.

A 15 year old ASA I female presented to the practice exhibiting aged, chromatic composite restorations with poor marginal integration and gross axial overhangs; essentially a gross failure of primary anatomy and esthetics. She had been involved in a bike accident where she high-sided off braking sharply in a face-meets-concrete scenario, resulting in an uncomplicated moderate enamel-dentin fracture with blushing, affecting both the facial and palatal aspects of tooth 1.1 and a mild uncomplicated enamel dentin fracture affecting the distoincisobuccolingual aspect of tooth 2.1. The restoration overhangs were significant, extending into the proximal contour zone, thus obviating effective interdental cleaning. Vitality tests were confirmed along with radiographs to exclude the presence of apical pathology. The patient accepted the option of pre-prosthetic whitening, to improve the value characteristics of the adjacent teeth, allowing the selection of a brighter value shade combination. Intraoral digital scans were acquired and custom bleaching trays with a no reservoir, cervical seal-priority design were fabricated. The patient was instructed to bleach overnight for a 2 week period using a 10% carbamide peroxide solution (Opalesence, Ultradent Products, UT) until her maximal value was reached. Her baseline shade of the incisors was a 1M1/2M1 combination in the upper incisors and a 2M1 in the lower incisors. On final post-bleach assessment she exhibited a lightened shade of VITA^* 0M3 in all incisors. The patient was instructed to use a fluoride-containing, amorphous calcium phosphate complex (ToothMousse Plus, GC America) during the following 2 weeks after cessation of whitening whilst the residual oxygen radical species dissipated from the teeth.

Fig. 1. Pre-operative unrestricted smile 1:2 ratio view, teeth 1.1 and 2.1 with old, defective composite restorations with excessive chroma.

On the day of the procedure, the pre-dehydrated shade was assessed using the supplied “real composite” shade guide tabs featured in the CLEARFIL MAJESTY™ ES-2 Premium system, with the enamel shade being WE (White Enamel) and the dentin shade WD (White Dentin). It was assessed that both white maverick effects as well as a moderate halo effect was desired along with moderate to strong translucency in the incisal window.

The patient was anesthetized using 1.5 carpules of 2% Lignocaine with 1:100,000 epinephrine (Septodont) before a rubber affixed with individual ties for the central incisors (NicTone Medium). Excavation of the old restorative material was undertaken, and the residual natural incisal edge was found to be undermined by a through-and-through fracture. Thus, the preparation was converted into a true Class IV design, with the facioincisal cavosurface margin subjected to an infinity bevel. The maxillary central incisors were isolated from the lateral incisors by way of a serrated metal strip (Komet) and the prepared surfaces subjected to micro particle abrasion using a 29 micron aluminum oxide powder in 17.5% ethanol carrier (Aquacare). The surfaces were subsequently treated with a calcium sodium phosphosilicate powder (Sylc, Aquacare) to increase the inorganic content of the prepared surface especially extending into the exposed tubules. The teeth were etched using a 33% orthophosphoric acid before a 1 minute 2% chlorhexidine scrub (Vista Products). The surface was reduced to a moist dentin surface before the bond applied, air thinned and cured.

A Mylar strip was pre-crimped in the palatoproximal line angles and positioned on the linguoaxial surface of both teeth 1.1 and 2.1. There is no shade guide for the CLEARFIL MAJESTY™ ES-2 Universal U shade, as it bears a significant chameleon effect however it does come in a light (L) and dark (D) variant. The UL shade was deemed the most suitable for the palatal or lingual shelf, with an average thickness of 0.3mm. This layer was applied in a freehand fashion with a focus on establishing the desired outline form of the tooth relative to the contralateral 2.1. The Mylar matrix setup was removed and a precurved metal matrix (Garrison Slickband, Garrison Dental) was oriented in a position perpendicular to its normal placement interproximally, and the end of the curved band tucked into the sulcus before being secured by a wedge. In this way, there is light separation of the central incisors and an intimate contact between the matrix band and the mesial edge of the freshly applied lingual shelf. A 0.5mm frame extending more than halfway through the contact point was created and cured. The process was repeated on tooth 2.1 with the goal of recreating both lingual and proximal walls of the restoration, leaving only the facial volume to be replaced.

Fig. 2. Pre-crimped Mylar matrix repeated on the DIBP aspect of tooth 2.1 to close the available space. CLEARFIL MAJESTY™ ES-2 Universal UL is used here.

Block-out of the composite extensions against the natural tooth structure was achieved by opacification using an opaque composite resin (WD, CLEARFIL MAJESTY™ ES-2 Premium, Kuraray Noritake Dental Inc.) layered in both horizontal and vertical increments. It is noted that the restorative join line must be completely obscured at the end of layering the dentin volume, otherwise the case will have almost certain esthetic failure. The internal dentin anatomy and its inherent variation was created to mirror that of the 2.1, which had minimal compromise of its incisal window with details intact. A super translucent composite resin (Clear, CLEARFIL MAJESTY™ ES-2 Premium, Kuraray Noritake Dental Inc.) was placed between the lobes of the dentin layers and cured. A 9:1 ratio of white: orange tint was mixed and placed on the incisal edge and proximoincisal corners to recreate the halo effect. A pure white tint was placed in gentle dentin mamelon-connecting spider legs up to the incisal edge to impart the realism. This was layered in a manner consistent with the appearance of the 2.1.

Fig. 3. Both horizontal and vertical dentin composite increments are demonstrated mimicking the contralateral tooth.

Fig. 4 & 5. Final immediate post-operative result after finishing and polishing.

DISCUSSION

The esthetic merit of this case is foundationally supported by composite resin technology on multiple levels. The color and physical stability over time needs to be proven in order for the clinician to have faith in its prognostication. Specifically, the material needs to have an excellent and well-matched refractive index, and one that is unaffected by both water and thermocycling stressors.

The palatal shelf was fabricated using a new-generation super nano-filled universal composite system that boasts a strong chameleon effect. If it is our intention to fool the eye, to obscure, then this first layer works well to start the blockout process of the darkness of the mouth behind the fracture line of the restored tooth. Following this, the chroma and value of the tooth are corrected using the dentin, simultaneous to its continued opacification of the fracture line and intraoral darkness. Both dentin and enamel layers are applied histoanatomically, that is, in a manner respecting the various thickness zones observed in nature.

Ultimately, esthetic success in direct composite resin is not dictated on the first day post-operatively. Factors are in play, from dehydration to occlusal wrinkles that need to be ironed out and corrected. The win depends on what material is used, along with how that material was developed to what standards, and why shade accuracy is so important in a world of variety. In a dental world with myriad composite options, we are looking for precision. Precision in technology leads to efficiency and physicoesthetic maintenance in clinical results. This ultimately results in a boost to clinician-patient confidence and an optimal prognosis.

Dentist:

CLARENCE TAM

*VITA is a trademark of VITA Zahnfabrik, Bad Sackingen, Germany

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2025 MARKS THE YEAR OF THE SNAKE