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

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

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

MDP: Chemical structure and mechanism of adhesion

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

Bonding performance

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

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

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

Not all MDP is alike

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

Conclusion

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

References

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

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

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

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

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

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

ADHESIVE LUTING: A DRIVER OF INNOVATION

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

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

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

Click here to read. Enjoy reading!

Start Reading: BOND | VOLUME 10 | 10/2023

Previous versions:

BOND | VOLUME 9 | 08/2022

BOND | VOLUME 8 | 12/2021

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Case by Kanstantsin Vyshamirski

A male patient (47 years of age) presented to his dentist with severe damage to his teeth. His main request was to increase aesthetics, to achieve a more pleasing envisaged aesthetic area. A side request was to achieve a ‘whitening but natural look’. This was achieved by using a lighter colour palette of zirconia and porcelain materials.

The final result was achieved through the creation of a wax-up, followed by a mock-up, provisional restoration and finally adhesive bonding of the zirconia crowns.

INITIAL SITUATION

Fig. 1. Initial situation. Male patient (47 years of age).

Fig. 2. Planning the new smile according to patient’s aesthetic and functional parameters.

Fig. 3. Mock-up in place to check the new look in the patient’s mouth.

Fig. 4. KATANA™ Zirconia YML shade A1 crowns with labial cutback after milling.

Fig. 5. Crowns after sintering on the plaster model.

Fig. 6. Noritake CERABIEN™ ZR porcelain layering map.

Fig. 7. Finishing the labial surface using both polishing and selfglaze. On the palatal side of the crowns only CERABIEN™ FC Paste Stain stains and glaze were used for finishing. To aid in optimisation of the soft tissue condition the palato-cervical and near proximal areas were polished.

Fig. 8. Finished crowns on the plaster model.

Fig. 9. Try-in using PANAVIA™ V5 White try-in paste, to confirm the proper appearance. For the final adhesive cementation PANAVIA™ V5 White has been used.

FINAL SITUATION

Fig. 10. Situation after seven months. The result is aesthetically pleasing and the gingival condition excellent.

Fig. 11. Recall after 1.5 years.

Dentist:

KANSTANTSIN VYSHAMIRSKI

Kanstantsin started his dental technician career in 2014. His speciality is aesthetic prosthetic porcelain works. Kanstantsin is an experienced user of KATANA™ Zirconia and Noritake porcelains. He owns his lab in Riga, Latvia.

Photo credits to Giuliano Moustakis

Can you imagine a world without multi-layered zirconia? The invention of a zirconia material with natural colour gradation and well-balanced translucency and strength led to fundamental changes in the way zirconia-based restorations are produced. When the first product of its kind – KATANA™ Zirconia ML – was introduced to the dental market exactly ten years ago, dental technicians all over the world suddenly started rethinking their manufacturing concepts.

Since then, the trend towards a decreased thickness of the porcelain layer, a limiting of this layer to the vestibular area and the production of monolithic restorations is clearly perceivable. Technicians have developed their own concepts of micro-layering, which allow for more patient-centred approaches. This is also due to the fact that the total wall thicknesses of the restorations may be decreased without compromising the aesthetics. The line-up of multi-layered zirconia currently available from Kuraray Noritake Dental Inc. (KATANA™ Zirconia UTML, STML, HTML Plus and KATANA™ Zirconia YML with additional translucency and strength gradation) enables users to make indication-related material choices for the production of restorations that are precisely aligned to the individual demands of each case.

The reasons to choose KATANA™ quality

But why choose KATANA™ Zirconia instead of any other multi-layered zirconia disc? According to experienced users of the KATANA™ Zirconia Multi-Layered series, there are many reasons to opt for KATANA™.

For Jean Chiha, owner at North Star Dental Laboratories and Milling Center in Santa Ana, California, it is the combination of optical and mechanical properties that makes the difference: 

“KATANA™ Zirconia is the game changing material with well-balanced esthetics and strength!”. 

Naoki Hayashi, president of Ultimate Styles Dental Laboratory in Irvine, California, aesthetics is the most decisive argument to opt for the discs from Kuraray Noritake Dental Inc. He states:

“KATANA™ Zirconia discs offer trusted esthetics which gives me confidence in my clinical cases”.

Naoto Yuasa, chief ceramist at Otani Dental Clinic in Tokyo, adds predictability as an important factor:

“KATANA™ sustains my passions for aesthetic restorations and those of a predictable future in the long run”, whereas dependability is the key element.

For Hiroki Goto, the laboratory manager at Sheets and Paquette Dental Practice in Newport Beach, California reports:

“Without KATANA™ there is no pride. Haven’t experienced it yet? You have to see how reliable it is!”

Finally, we have asked Kazunobu Yamada, a pioneer in making porcelain laminate veneers using complementary color techniques and a first-hour user of KATANA™ Zirconia, what comes to his mind when thinking about KATANA™ Zirconia. According to the president of CUSP Dental Laboratory in Nagoya City, there is a clear link between the product name and its characteristics:

“Did you know that the word "KATANA" also means "protection against misfortune and evil"? Katana zirconia, the culmination of many years of research and development by Kuraray Noritake, has an unparalleled quality. KATANA™, for me, is truly "Protection for all technicians".”

The origin of well-balanced properties

It seems that the KATANA™ Zirconia Multi-Layered line-up stands out due to set of valuable properties enabling a dental technician to produce beautiful, high-quality restorations every time. The secret of success lies in meticulous raw material selection and controlled processing from the powder to the pre- sintered blank carried out at the production facilities of Kuraray Noritake Dental Inc. in Japan. They provide for the high product quality that is responsible for the materials’ outstanding behaviour supporting the best possible outcomes.

Clinical case by Dr. Florian Zwiener

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

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

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

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

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

Fig. 4. Bridge design …

Fig. 5. … using the CEREC Software.

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

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

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

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

Fig. 10. … and two glaze firings.

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

FINAL SITUATION

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

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

Dentist:

DR. FLORIAN ZWIENER

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

Case by Kanstantsin Vyshamirski

A male patient (47 years of age) presented to his dentist with severe damage to his teeth. His main request was to increase aesthetics, to achieve a more pleasing envisaged aesthetic area. A side request was to achieve a ‘whitening but natural look’. This was achieved by using a lighter colour palette of zirconia and porcelain materials. The final result was achieved through the creation of a wax-up, followed by a mock-up, provisional restoration and finally adhesive bonding of the zirconia crowns.

Initial situation

Fig. 1. Initial situation. Male patient (47 years of age)

Fig. 2. Planning the new smile according to patient’s aesthetic and functional parameters.

Fig. 3. Mock-up in place to check the new look in the patient’s mouth.

Fig. 4. KATANA™ Zirconia YML shade A1 crowns with labial cutback after milling.

Fig. 5. Crowns after sintering on on the plaster model.

Fig. 6. Noritake CERABIEN™ ZR porcelain layering map.

Fig. 7. Finishing the labial surface using both polishing and selfglaze. On the palatal side of the crowns only CERABIEN™ FC Paste Stain stains and glaze were used for finishing. To aid in optimisation of the soft tissue condition the palato-cervical and near proximal areas were polished.

Fig. 8. Finished crowns on the plaster model.

Fig. 9. Try-in using PANAVIA™ V5 White try-in paste, to confirm the proper appearance. For the final adhesive cementation PANAVIA™ V5 White has been used.

Final situation

Fig. 10. Situation after seven months. The result is aesthetically pleasing and the gingival condition excellent.

Fig. 11. Recall after 1.5 years

Click here for the product page for more details

What can you expect to find online

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

Kanstantsin started his dental technician career in 2014. His speciality is aesthetic prosthetic porcelain works. Kanstantsin is an experienced user of KATANA™ Zirconia and Noritake porcelains. He owns his lab in Riga, Latvia.

Case report with Dr. José Ignacio Zorzin

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

How do universal adhesives contribute to a streamlining of workflows?

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

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

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

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

How to proceed with selective enamel etching?

A clinical example.

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

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

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

Fig. 4. Working field isolated with rubber dam.

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

Fig. 5. Cleaning of the tooth …

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

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

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

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

Fig. 9. Application …

Fig. 10. … of the universal bonding agent.

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

Fig. 12. … and the fragment.

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

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

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

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

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

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

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

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

Fig. 16. Treatment outcome.

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

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

Dentist:

DR. JOSÉ IGNACIO ZORZIN

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

References

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

Nogle virksomheder bruger hovedsageligt grundlæggende teknologier, som andre har udviklet, til at forbedre deres produkter og indføre nye produkter, mens andre virksomheder udfører grundlæggende forskning og teknologiudvikling internt. Er denne forskel relevant for en person, som til dagligt bruger de heraf følgende produkter i en tandlægepraksis eller på et laboratorium? Det er den, fordi virksomheder med en dyb forståelse for de underliggende komponenter, kemi og teknologier er i stand til at løse eksisterende problemer og reagere fleksibelt og hurtigt på markedets behov. Denne artikel beskriver virkningen af flere grundlæggende teknologier, der er udviklet af Kuraray Noritake Dental Inc. til cementering af indirekte restaureringer.

Adhæsive cementer før og nu

Fræsning af forskellige typer keramiske tandrestaureringer har åbnet op for nye muligheder inden for protetik. Man kan producere og placere meget æstetiske restaureringer. Det, der ofte undervurderes i denne sammenhæng, er den rolle adhæsive cementer spiller, da de ikke kun understøtter de gennemsigtige, tandfarvede restaureringers æstetiske udseende, men også baner vejen for mindre invasive præparations- og restaureringsdesign. Tidlige produkter, der sikrede kemisk adhæsion mellem tænder og indirekte restaureringer, havde desværre en tvivlsom adfærd og en høj teknisk følsomhed på lang sigt, samtidig med at appliceringsproceduren var ekstremt kompleks. Teknologiudviklingen hos Kuraray Noritake Dental Inc. har bidraget væsentligt til en forbedret, langtidsholdbar bindingsevne og en forenklet applicering.

Optimering af den langtidsholdbare bindingsevne

For at opnå en langtidsholdbar binding af tidlige cementeringssystemer til tandstrukturen (især dentin) besluttede Kuraray, et moderselskab til Kuraray Noritake Dental Inc., i 1970‘erne at fokusere på udviklingen af en mere kraftig adhæsiv monomer. Det første skridt på vejen mod ”excellence” var at indføre fosfatmonomeren Phenyl-P i 1976. Fem år senere førte fortsatte bestræbelser på at forbedre og forfine dens molekylære struktur til indførslen af den populære
MDP-monomer, der er i stand til at skabe en særlig kraftig og langtidsholdbar binding til emalje, dentin, metal og zirkonia.

Det, at den stadig er en del af alle Kuraray Noritake Dental Inc.’s adhæsiver og adhæsive cementer og samtidig også bruges af andre producenter til at optimere deres produkters bindingsstyrke og -holdbarhed, understreger opfindelsens genialitet. Sammenlignet med MDP, der er syntetiseret andre steder, skiller Kuraray Noritake Dental Inc.’s originale MDP-monomer sig ud for sit uovertrufne renhedsniveau. Uafhængige undersøgelser viser, at dette renhedsniveau har en positiv effekt på bindingsadfærden1. MDP-monomeren har, ved at tilbyde stabilitet i et fugtigt miljø, bidraget til en mere ensartet ydeevne for de produkter, der indeholder den.

Forskellige MDP-monomerer tilbyder forskellige renhedsniveauer og forskellige bindingsevner.

Der blev klargjort tre eksperimentelle, selvætsende primere bestående af 15 wt % 10-MDP fra forskellige kilder: KN (Kuraray Noritake Dental), PCM (Tyskland) eller DMI (Designer molecules Inc., USA). Data venligst udlånt af Dr. Kumiko Yoshihara.

For at adhæsive resincementer skal kunne give en kraftig binding med en enestående marginal forsegling, er det dog ikke nok at indeholde en adhæsiv monomer. En effektiv polymerisering af denne monomer er ligeledes nødvendig - men det er ikke altid så let at opnå. For at kunne sikre en effektiv lys- og mørkhærdning af PANAVIA™ V5 har Kuraray Noritake Dental Inc. udviklet sin Touch-Cure Technology. Denne teknologis vigtigste del er en nyudviklet, meget aktiv polymeriseringsaccelerator i PANAVIA™ V5 Tooth Primer, som kan eksistere sammen med den sure MDP-monomer, der fremmer polymerisering ved grænsefladen mellem tanden og cementen, så snart PANAVIA™ V5 Paste påføres på den forbehandlede tandoverflade. I PANAVIA™ Veneer LC - en lyshærdende resincement, der fungerer med de samme primere - viser polymeriseringsacceleratoren i PANAVIA™ V5 Tooth Primer den samme virkningsmekanisme. Det bidrager til polymeriseringen af den adhæsive grænseflade, mens PANAVIA™ Veneer LC Paste har en fremragende omgivende lysstabilitet og polymeriseres ved lyshærdning.

Dette eksempel blev for eksempel evalueret for PANAVIA™ F2.0, forgængeren til PANAVIA™ V5. Resultatet af forsøget: PANAVIA™ F2.0 viste meget bedre marginale forseglingsegenskaber end de andre evaluerede cementer2. Denne dokumenterede sikre forsegling af grænsefladen giver en lavere forekomst af marginal lækage, en meget høj polymeriseringsratio, selv i selvhærdende tilstand (uden lyshærdning eller hvor lyset måtte være blokeret af restaureringsmaterialet) og dermed en særlig kraftig binding.

En ekstra fordel ved indføjelsen af polymeriseringsacceleratoren er, at den fungerer som et kraftigt reduktionsmiddel. Den neutraliserer natriumhypochlorit, som ofte bruges som skylleopløsning under endodontisk behandling, og eliminerer dermed dens negative effekt på bindingsstyrken af den efterfølgende cementpasta.

Forenkling af glaskeramisk cementering

Færre flasker, færre trin og strømlinede cementeringsprocedurer. Det er derfor de selv-adhæsive resincementer blev udviklet og indført i starten af 00’erne. De fleste af disse produkter har dog et begrænset indikationsområde. De fungerer godt på zirkonia, metal, emalje og dentin, men anbefales enten ikke eller kræver en ekstra silanprimer til glaskeramisk binding. PANAVIA™ SA Cement Universal med MDP er anderledes, fordi det er en anden patentbeskyttet teknologi fra Kuraray Noritake Dental Inc.: LCSi-monomer er et silankoblingsmiddel med en lang kulstofkæde. Denne monomer danner en kraftig kemisk binding med resinkomposit, porcelæn og silica-keramik (såsom lithiumdisilikat), hvilket fjerner behovet for en separat silankomponent (en primer eller et adhæsiv). PANAVIA™ SA Cement Universal skiller sig klart ud fra andre selv-adhæsive resincementer som en ægte enkomponentscement, ved at udnytte fordelene ved denne teknologi, selv til restaureringer af glaskeramik.

Hvis det ønskes, kan produktets bindingsstyrke til tandstrukturen øges ved at bruge det populære universaladhæsiv CLEARFIL™ Universal Bond Quick med Rapid Bond Technology. Denne teknologi er udviklet af Kuraray Noritake Dental Inc. for at løse problemer med langsom indtrængning af tandstrukturen, især våd dentin, som er typisk for universaladhæsiver. For at sikre korrekt indtrængning skal disse adhæsiver gnides aktivt ind i tandstrukturen i lang tid, eller brugerne skal vente i et stykke tid, før produktet er lyshærdet. Den patenterede Rapid Bond Technology, der består af den originale MDP-monomer, kombineret med hydrofile amidmonomerer, giver en høj affinitet til vand, hvilket giver en hurtig og dyb indtrængen af våd dentin. Som følge heraf forkortes appliceringstiden, og håndteringen forenkles, uden at det påvirker bindingens ydeevne negativt.

Konklusion

Teknologier, der er udviklet af Kuraray Noritake Dental Inc., har i høj grad bidraget til en forbedret bindingsevne for adhæsive cementer og en meget universel brug af selv-adhæsive resincementer. Som følge heraf tilbyder virksomheden en strømlinet portefølje af højtydende resincementer til alle brugere og til typiske kliniske situationer. Der er behov for færre komponenter og færre trin og procedurerne forenkles - hvilket giver færre fejl og æstetiske restaureringer, der holder. Udover de teknologirelaterede fordele tilbyder de nævnte produkter mange andre fordelagtige funktioner. En detaljeret beskrivelse findes online på kuraraynoritake.eu.   

Referencer

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

Nogle virksomheder bruger hovedsageligt grundlæggende teknologier, som andre har udviklet, til at forbedre deres produkter og indføre nye produkter, mens andre virksomheder udfører grundlæggende forskning og teknologiudvikling internt. Er denne forskel relevant for en person, som til dagligt bruger de heraf følgende produkter i en tandlægepraksis eller på et laboratorium? Det er den, fordi virksomheder, der udvikler alt fra bunden, som regel kender produkterne og fremstillingsprocedurerne bedre, hvilket gør det lettere for dem at ændre specifikke funktioner, løse eksisterende problemer og reagere på markedets behov. Denne artikel beskriver virkningen af flere grundlæggende teknologier, der er udviklet af Kuraray Noritake Dental Inc., på arbejdsprocessen med at skabe direkte restaureringer i komposit.

Direkte restaureringer - fra komplekst til simpelt

Adhæsiv genopbyggende tandpleje, der anvender højtydende dentaladhæsiver og resinkompositter er lige nu en af de mest populære måder at behandle tænder med kariesangreb på. I dag er en enkelt flaske universaladhæsiv og en eller to nuancer og opaciteter af universalkomposit normalt nok til at skabe smukke og holdbare resultater, forudsat at de rigtige materialer er valgt. Dette har dog ikke altid været tilfældet. De teknikker, der blev brugt til at lave direkte restaureringer, har i lang tid været ret komplekse: Adhæsiver var teknisk krævende og krævede flere flasker og flere trin med lange appliceringstider. Omvendt giver kompositfillere kun naturtro resultater, når mange forskellige nuancer og opaciteter kombineres på den rigtige måde. Og selvom de komplekse procedurer blev udført korrekt, var risikoen for mikrolækage, misfarvning og i sidste ende sekundær caries forholdsvis høj. Kuraray Noritake Dental Inc. fokuserede ret tidligt på at løse disse problemer og startede med at bruge den originale MDP-monomer, der blev udviklet i 1981.

Optimer af bindingsevnen

Den originale MDP-monomer var i stand til at løse problemet med adhæsivernes begrænsede langtidsholdbare bindingsevne. MDPs hydrofile (fosfat) gruppe danner en særlig kraftig og holdbar kemisk binding med calcium, der findes i hydroxyapatit, som er hovedbestanddelen i emaljeog dentin. Det MDP-Ca-salt, der dannes, danner grundlaget for et stabilt, kraftigt og holdbart hybridlag. Sammen med resin i bindemidlet opnås en tæt forsegling af kaviteten efter lyshærdning. MDP har hidtil været en vigtig komponent i enhver adhæsiv fra Kuraray Noritake Dental Inc. og det er den nøglekomponent, der har gjort CLEARFIL™ SE Bond til den gyldne standard for selvætsende adhæsivsystemer.

Kuraray Noritake Dental Inc. var dog overbevist om, at dentale adhæsiver burde give mere end blot en kraftig og langvarig binding, og begyndte derfor at fokusere på at løse et andet problem: risikoen for demineralisering og kavitation forårsaget af resterende bakterier i kaviteten. På baggrund af sin erfaring med at udvikle andre adhæsive monomerer opfandt Kuraray Noritake Dental Inc. MDPB-monomeren, der har en antibakteriel kavitetsudrensende effekt. I modsætning til antibakterielle midler, der kan forringe bindingsstyrken af et efterfølgende appliceret adhæsiv, dræber MDPB-monomeren de resterende bakterier uden at påvirke bindingsevnen. Den følger med primeren til det 2-trins selvætsende adhæsiv CLEARFIL™ SE Protect og immobiliseres ved polymerisering.

MDPBs bakteriedræbende mekanisme formodes at være den samme som det velkendte antibakterielle stof CPC (Cetylpyridiniumchlorid), der findes i mange typer tandpasta og mundskyl.

Selvom de 2-trins selvætsende adhæsiver allerede har forenklet klæbeproceduren, går 1-trins universaladhæsiver lige skridtet videre. Det er en udfordring at samle ingredienser, fordelt på flere trin, i én flaske uden at gå på kompromis med produktets stabilitet. Takket være moderne teknologi er dette nu muligt. For hurtigst muligt at forsegle overfladen efter appliceringen skal gennemtrængningen af monomererne i tandvævet være hurtig og effektiv. Men gennemtrængningen bremses normalt af monomerer, der har brug for tid til at trænge ind i tandstrukturen - især våd dentin - og sommetider endda skal gnides ind. Derfor fokuserede Kuraray Noritake Dental Inc. på at udvikle Rapid Bond Technology. Den går ud på kombinere den originale MDP-monomer med nyudviklede hydrofile tværbindende amid-monomerer og er integreret i CLEARFIL™ Universal Bond Quick. De hydrofile amid-monomerer giver en hurtig, dyb og fuldstændig gennemtrængning af dentinen og danner ved hærdning et tæt tværbundet polymernetværk, der er ansvarligt for en kraftig og holdbar binding. Tiden der går med at vente og gnide fjernes derfor, og der skabes en tæt og langvarig forsegling af kaviteten efter lyshærdning.

Deres hydrofilicitet (evnen til at blande sig med vand) betyder, at Rapid Bond-teknologiens amidmonomerer trænger meget godt gennem dentinen. Efter lyshærdning har bindingen en lav vandoptagelse og derfor en høj
modstandsdygtighed over for aldring.

Optimering af direkte restaurering

Kombination af flere lag, nuancer og opaciteter: Brugen af meget komplekse layeringteknikker til at skabe naturtro kompositrestaureringer hører heldigvis fortiden til i mange kliniske situationer. Dette skyldes højt udviklede resinkompositter, der blender perfekt sammen med den omkringliggende tandstruktur. For at opnå denne gode egenskab har Kuraray Noritake Dental Inc. udviklet sin egen Light Diffusion Technology (LDT). Denne teknologi bruges i særlige præpolymeriserede fillers, der fungerer som millioner af mikroprismer, der transmitterer og bryder lys og farve fra den omkringliggende tandstruktur. Fillerne er optimeret i størrelse, fordeling og brydningsindeks i forhold til matrixen og giver en uovertruffen naturlig blending. Hele CLEARFIL MAJESTY™ kompositdelen indeholder den patenterede fillerteknologi. Det nyeste produkt – CLEARFIL
MAJESTY™ ES-2 Universal – hvor Kuraray Noritake Dental Inc. gør brug af den næste generation af LDT, giver mulighed for at benytte en enfarvet teknik med et forenklet farvevalg. Produktet fås i to nuancer til den forreste del og i én nuance til den bagerste del, men blender så godt ind at det dækker stort set alle nuancer i VITA classical A1-D4-farveguiden.

Korrekt brydning og transmission af lys for at opnå en god optiskintegration: lysdiffusionsfillere i CLEARFIL MAJESTY™ ES-2 fra Kuraray Noritake Dental Inc.

Da en smuk optisk fremtoning ikke kun afhænger af optisk integration og usynlige restaureringsmarginer, har Kuraray Noritake Dental Inc. også udviklet fillers, der sørger for resten - en naturlig overfladeglans og holdbar polering. Løsningen, der er integreret i CLEARFIL MAJESTY™ ES Flow med dens tre flydeevnegrader, kaldes Submicron Filler Technology, som består af blanke submikrone fillers. Disse fillers er så små, at lysets refleksion virker naturlig også efter nogen tid. Kuraray Noritake Dental Inc.’s exceptionelle silanteknologi bruges til at samle millioner af disse submikrone fillers og sørge for at holde dem sammen over tid. Det giver mulighed for høje fillermængder i kompositter med lav viskositet og begrænser vandoptagelsen, som ellers ville føre til nedbrydning af den hærdede komposit. Den perfekte balance mellem de blanke submikrone fillers, lysdiffusionsfillers, resinmatrix og patenteret silanteknologi sikrer en balanceret kombination af mekaniske og optiske egenskaber.

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

Konklusion

Adhæsive monomerer, fillerteknologier og silanteknologi, der giver en solid kombination af fillers, clusters og resinmatrix: Kuraray Noritake Dental Inc. er uden tvivl en pålidelig ekspert inden for adhæsive restaureringer. De patenterede teknologier, der er udviklet inden for de seneste årtier, har i høj grad bidraget til at skabe en bedre (og mere holdbar) ydeevne af direkte restaureringer, hvor pålidelige og æstetiske resultater er meget nemmere at opnå.