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

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

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

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

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

ADHESIVE LUTING: A DRIVER OF INNOVATION

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

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

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

Click here to read. Enjoy reading!

Start Reading: BOND | VOLUME 10 | 10/2023

Previous versions:

BOND | VOLUME 9 | 08/2022

BOND | VOLUME 8 | 12/2021

BOND | VOLUME 7 | 10/2020

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.

Mõned ettevõtted kasutavad enda toodete parendamiseks ja uute toodete turule toomiseks peamiselt teiste ettevõtete arendatud tehnoloogiaid. Leidub aga ka ettevõtteid, mis viivad põhiuuringuid ise läbi ja arendavad tehnoloogiaid ettevõttesiseselt. Kas see lähenemise erinevus peaks olema oluline neile, kes kasutavad lõpptoodet igapäevaselt enda hambaravipraksises või -laboris? Jah, kuna need ettevõtted, millel on sügav arusaam tehnoloogia aluseks olevatest materjalidest, keemiast ja tehnikatest, on suutelised lahendama olemasolevaid ja tekkivaid probleeme ning reageerima turu vajadustele paindlikult ja kiiresti. See artikkel kirjeldab mitme Kuraray Noritake Dental Inc.-i välja töötatud tehnoloogia mõju indirektsete restauratsioonide tsementimisele.

Adhesiivse tsementimise ajalugu ja tänapäev

Erinevat tüüpi keraamikatest hambarestauratsioonide freesimise võimalus on avanud hambaproteetikas uusi horisonte: võimalik on luua ja paigaldada väga esteetilisi restauratsioone. Tihti alahinnatakse selles kontekstis adhesiivsete tsementsüsteemide, mis ainult ei toeta läbipaistvate hambavärvi restauratsioonide esteetilist väljanägemist, vaid võimaldavad ka vähem invasiivset preparatsiooni ja restauratsiooni mudeleid. Varased süsteemid, millega loodi hammaste ja indirektsete restauratsioonide vahel keemiline adhesioon, ei taganud pikaajalist toimivust ja olid väga tundlikud tehnika suhtes ning ühtlasi oli pealekandmise protseduur väga keerukas. Kuraray Noritake Dental Inc.-i tootearendus soodustas oluliselt süsteemide pikaajalist toimivust ja lihtsustas käsitsemist.

Pikaajalise sidususe optimeerimine

Selleks, et varajased tsementimissüsteemid kinnituks pikaajaliselt hambastruktuuridele (eriti dentiinile), otsustas Kuraray (Kuraray Noritake emaettevõte) 1970ndatel keskenduda võimsama adhesiivse monomeeri arendamisele. Selle eduka teekonna esimene samm oli fosfaatmonomeeri fenüül-P loomine 1976. aastal. Viis aastat hiljem viisid pidevad jõupingutused parandada selle molekulaarstruktuuri populaarse MDP-monomeeri loomiseni, millega suudeti luua eriti tugev ja pikaajaline side emailiga, dentiiniga, metalliga ja tsirkooniumiga.

Asjaolu, et see aine on endiselt igas Kuraray Noritake Dental Inc.-i adhesiivis ja adhesiivses tsementimissüsteemis, ja ka kasutusel teiste tootjate toodetes, et optimeerida sidustugevust ja kinnituse kestvust, on märk selle leiutise geniaalsusest. Võrreldes mujal sünteesitud MDP-ga paistab Kuraray Noritake Dental Inc.-i originaalne MDP-monomeer silma oma ületamatu puhtuse poolest. Sõltumatud uuringud näitavad, et sellel puhtuse tasemel on kinnitumise toimivusnäitajatele positiivne mõju.1 Säilitades toimivusnäitajate stabiilsuse ka niiskes keskkonnas, on MDP-monomeer muutnud ka seda sisaldavate toodete toimivuse stabiilsemaks.

Erinevatel MDP-monomeeridel on erinev puhtuse aste ja sidumisvõime.

Ette valmistati kolm eksperimentaalset isesöövituvat praimerit, mis koosnesid 15 massiprotsendi osas 10-MDP-st, mis pärinesid eri allikatest: KN (Kuraray Noritake Dental), PCM (Saksamaa) või DMI (Designer Molecules Inc., USA). Andmed pärinevad dr Kumiko Yoshiharalt.

Ainuüksi adhesiivse monomeeri sisaldusest aga ei piisa, et adhesiivsed vaiktsemendisüsteemid saaksid luua tugeva sideme ja ääresulu. Vaja on ka see monomeer tõhusalt polümeriseerida. Seda ei ole samas alati lihtne saavutada. PANAVIA™ V5 tõhusaks valgusja nakkekõvastamiseks lõi Kuraray Noritake Dental Inc. Touch-Cure tehnoloogia. Selle tehnoloogia olulisem osa on praimeris PANAVIA™ V5 Tooth Primer sisalduvja äsja välja töötatud väga aktiivne polümerisatsiooni katalüsaator, mille omadused ei kao happelise MDPga kokkupuutel. See soodustab polümerisatsiooni algamist hamba ja tsemendi liitekohas niipea, kui pastat PANAVIA™ V5 Paste lisatakse juba praimeriga töödeldud hambapinnale. Valguskõvastuvas vaiktsemendisüsteemis PANAVIA™ Veneer LC, mida kasutatakse samade praimeritega, on praimeris PANAVIA™ V5 Tooth Primer sisalduva polümerisatsiooni katalüsaatori toimemehhanism sama. See soodustab adhesiivi liitekoha polümerisatsiooni, samal ajal kui valguskõvastatav PANAVIA™ Veneer LC Paste säilitab stabiilsuse ümbritseva valguse suhtes.

Seda fenomeni hinnati näiteks PANAVIA™ V5 eelkäija PANAVIA™ F2.0 puhul. Uuringu tulemus: PANAVIA™ F2.0-l oli palju paremad äärte sulgemise omadused kui teistel hinnatud tsemendisüsteemidel.2 See liitekoha dokumenteeritud sulgemisvõime vähendab servade lekkimise esinemissagedust, suurendab polümerisatsiooni suhet isegi isekõvastuvas režiimis (valguskõvastumiseta või kui restauratiivmaterjal blokeerib valguset) ja toob kaasa eriti tugeva sideme.

Polümerisatsiooni katalüsaatori täiendav eelis on see, et see on tugev redutseerija. See neutraliseerib naatriumhüpokloriti, mida kasutatakse enamasti endodontilise ravi ajal loputuslahusena, ja eemaldab seeläbi pärast seda peale kantud tsemendipasta sidustugevusele avalduvad negatiivsed mõjud.

Lihtsustame klaaskeraamilist tsementimist

Vähem pudeleid ja protseduurietappe ning sujuvam tsementimine: selle pärast isesidustuvad vaiktsemendid 2000ndate alguses välja töötati ja turule toodigi. Enamikel neist toodetest on aga piiratud kasutusnäidustuste ulatus. Need töötavad hästi tsirkooniumil, emailil ja dentiinil, kuid neid ei soovitata kasutata või vajavad täiendava silaanpraimeri kasutamist klaaskeraamika puhul. MDP-d sisaldav PANAVIA™ SA Cement Universal erineb selle poolest, et sisaldab veel üht Kuraray Noritake Dental Inc.-i patenteeritud tehnoloogiat: pika süsinikuahelaga silaanist sidusainet LCSi Monomer. See monomeer moodustab tugeva keemilise sideme vaikkomposiidiga, portselaniga ja ränidioksiidi tüüpi keraamikatega (nt liitiumdisilikaat), mistõttu ei ole eraldi silaanikomponenti (praimerit või adhesiivi) vaja. Selle tehnoloogia eeliseid ära kasutades eristab PANAVIA™ SA Cement Universal end selgelt teistest isenakkuvatest vaiktsementidest kui ühekomponentne tsemendisüsteem, mida saab kasutada isegi klaaskeraamikast restauratsioonidel.

Vajadusel saab suurendada toote sidustugevust hambastruktuuriga, kasutades Rapid Bond tehnoloogiat hõlmavat populaarset universaalset adhesiivi CLEARFIL™ Universal Bond Quick. Kuraray Noritake Dental Inc. töötas selle tehnoloogia välja, et lahendada universaalsete adhesiivide puhul levinud hambastruktuuri (eriti dentiini) aeglase läbitungimisega seotud probleeme. Hea läbitungimise saavutamiseks tuleb neid adhesiive hambastruktuuri pikalt hõõruda, sest vastasel korral peavad kasutajad ootama pikalt, enne kui kihti valguskõvastada saavad. Koosnedes originaalsest MDP-monomeerist ja hüdrofiilsetest amiidmonomeeridest, võimaldab Rapid Bond tehnoloogiat suurt afiinsust veega, tungides seeläbi kiirelt märja dentiini sügavatesse kihtidesse. Selle tõttu on aplitseerimisaeg lühem ja käsitsemine lihtsam, ilma et sidumisvõime väheneks.

Järeldus

Kuraray Noritake Dental Inc.-i välja töötatud tehnoloogiad on kõvasti suurendanud adhesiivsete tsemendisüsteemide sidusustugevust ja isesidustuvate vaiktsementide kasutusnäidustuste ulatust. Seetõttu suudab ettevõtte pakkuda vaiktsemente igale kasutajale kõikide tavapäraste kliiniliste olukordade puhul. Väiksem arv komponente ja vähem protseduuri etappe väldivad vigade tekkimist ja suurendavad restauratsioonide esteetikat ja püsivust. Lisaks tehnoloogiaga seotud kasuteguritele on mainitud toodetel veel nii mõndagi muud pakkuda. Täpse kirjelduse leiab veebist aadressil kuraraynoritake.eu.   

Viited

*) 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

Mõned ettevõtted kasutavad enda toodete parendamiseks ja uute toodete turule toomiseks peamiselt teiste ettevõtete arendatud tehnoloogiaid. Leidub aga ka ettevõtteid, mis viivad põhiuuringuid ise läbi ja arendavad tehnoloogiaid ettevõttesiseselt. Kas see lähenemise erinevus peaks olema oluline neile, kes kasutavad lõpptoodet igapäevaselt enda hambaravipraksises või -laboris? Jah, sest kõik nullist välja töötavatel ettevõtetel on enamasti sügavam arusaam toodetest ja nende tootmisprotseduuridest, mis teeb lihtsamaks muuta spetsiifilisi omadusi, lahendada probleeme ja reageerida turu vajadustele. See artikkel kirjeldab mitme Kuraray Noritake Dental Inc.-i välja töötatud tehnoloogia mõju indirektsete restauratsioonide valmistamise töövoole.

DIREKTSED RESTAURATSIOONID – KEERULISEST LIHTSAKS

Hambaadhesiive ja vaikkomposiite kasutav adhesiivne restauratiivne hambaravi on kõige populaarsem viis ravimaks karioossete kolletega hambaid. Tänapäeval piisab enamasti ühest universaalse adhesiivi pudelist ja universaalse komposiidi ühest või kahest värvitoonist ja opaaksusest, et luua kestvaid tulemusi, st kui valitud on õiged materjalid. See ei pruugi alati nii olla. Direktsete restauratsioonide valmistamise tehnikad on pikalt olnud üsna keerulised: adhesiivid olid tehnikatundlikud mitme pudeli ja etapiga süsteemid ja neil oli pikk pealekandmise aeg. Komposiidist täitematerjalidega saab elutruusid tulemusi aga vaid mitme erineva värvitooni ja opaaksuse õigel viisil kombineerimisel. Isegi kui need komplekssed protseduurid õigel viisil läbi viia, on mikrolekke, värvimuutuse ja lõpuks ka teisese kaariese risk võrdlemisi suur. Kuraray Noritake Dental Inc. hakkas nendele probleemidele üsna varakult tähelepanu pöörama, alustades 1981. aastal välja töötatud MDP-monomeeri kasutusele võtmisega.

SIDUSUSTUGEVUSE OPTIMEERIMINE

Originaalne MDP-monomeer lahendas adhesiivsüsteemide pikaajalise toimivuse piirangutega seotud küsimusi. MDP hüdrofiilne (fosfaadi-) rühm moodustab emaili ja dentiini alusaines hüdroksüapatiidis leiduva kaltsiumiga
eriti tugeva ja kauakestva keemilise sideme. Tekkinud MDP-Ca sool moodustab põhja stabiilsele, tugevale ja kestvale hübriidkihile. Koostoimes sidusaines sisalduva vaiguga tekib kaviteedile pärast valguskõvastamist
tihke täide. MDP on tänaseni oluline osa kõigist Kuraray Noritake Dental Inc.-i adhesiividest ja on peamine põhjus, mis tegi sidusainest CLEARFIL™ SE Bond isesöövitavate adhesiivide kullastandardi.

Veendunud, et hambaadhesiivid peaksid olema võimelised rohkemaks kui kestvaks sidemeks, hakkas Kuraray Noritake Dental Inc. keskenduma teise probleemi lahendamisele: kaviteeti jäänud bakterite põhjustatud demineralisatsioonile ja kavitatsioonile. Teiste adhesiivsete monomeeride arendamise kogemusele toetudes leiutas Kuraray Noritake Dental Inc. MDPB-monomeeri, millel on antibakteriaalne kaviteeti puhastav toime. Erinedes antibakteriaalsetest ainetest, mis võivad vähendada järgmistes etappides aplitseeritud adhesiivi sidustugevust, tapab MDPB-monomeer allesjäänud bakterid sidustugevust mõjutamata. See sisaldub kahepudelise isesöövitava adhesiivi CLEARFIL™ SE Protect praimeris ja immobiliseerub polümerisatsiooni toimel.

MDPB bakteritsiidne mehhanism on eeldatavast sarnane tuntud antibakteriaalsele ainele CPC (tsetüülpüridiinkloriid), mida leidub paljudes hambapastades ja loputusvedelikes. 

Kuigi kahepudelilised isesöövitavad adhesiivid on juba lihtsustanud adhesiivi kasutamise protseduuri, lähevad ühepudelilised universaalsed adhesiivid veel kaugemale. Tuua kokku mitmeetapiliste süsteemide erinevad komponendid ühte pudelisse vähendamata seejuures toote stabiilsust, on paras väljakutse. Tänase tehnoloogiaga on see saanud võimalikuks. Pinna sulgemiseks esimesel võimalusel pärast aplitseerimist peab monomeeride läbitungimine hambakoesse olema kiire ja tõhus. Läbitungimist aeglustavad aga enamasti monomeerid, millel kulub hambastruktuuri – eriti märja dentiini – läbimiseks kauem, ja vahel tuleb neid isegi selle sisse hõõruda. See on ka põhjus, miks Kuraray Noritake Dental Inc. keskendus Rapid Bond tehnoloogia arendamisele. See sisaldab originaalset MDP-monomeeri ja hiljuti välja töötatud hüdrofiilseid ristseonduvaid amiidimonomeere ning on integreeritud sidusainesse CLEARFIL™ Universal Bond Quick. Hüdrofiilsed amiidimonomeerid tagavad kiire, sügava ja täieliku läbitungimise dentiini ja
moodustavad kõvastumisel tihedalt ristseondunud polümeeri võrgustiku ja seega tugeva ja kestva sideme. Seeläbi kaob vajadus ootamise ja hõõrumise järele ning kaviteet sulgub valguskõvastamisel tihkelt ja kestvalt.

Hüdrofiilsuse (afiinsus vee suhtes) tõttu tungivad Rapid Bond tehnoloogia amiidimonomeerid hästi dentiinist läbi. Pärast valguskõvastumist ei ima side enam vett ja peab seetõttu kaua vastu.

DIREKTSETE RESTAURATIIVIDE OPTIMEERIMINE

Mitme kihi, värvitooni ja opaaksuse kombineerimine Õnneks ei ole enam paljude kliiniliste juhtumite puhul vaja kasutada keerukaid kihistamistehnikaid, et luua elutruusid komposiitrestauratsioone. Selle põhjuseks on uudsed vaikkomposiidid, mis sulanduvad märkamatult kokku kõrvalhamba struktuuriga. Seda omadust võimaldas Kuraray Noritake Dental Inc.-i välja töötatud Light Diffusion Technology (LDT). See tehnoloogiat kätkevad spetsiaalsed eelpolümeriseeritud täiteained, mis toimivad miljonite mikroprismadena, mis edastavad ja painutavad ümbritsevalt hambastruktuurilt pärit valgust. Matriitsi suhtes optimeeritud suuruse, hajuvuse ja murdumisnäitajaga täiteaine sulab kõrvalhammastega eristamatult kokku. Kogu CLEARFIL MAJESTY™ komposiidiseeria sisaldab seda patenteeritud täiteainetehnoloogiat. Kuraray Noritake Dental Inc.-i kõige viimasem toode CLEARFIL MAJESTY™ ES-2 Universal, milles on kasutusel LDT, on kasutatav ainult ühe värvitooniga: kaks tooni esihammastele ja üks tagahammastele. See sulandub nii hästi kokku, et katab põhimõtteliselt kogu VITA A1-D4 värvispektri.

Valgusmurdumine ja -hajuvus tagavad hea optilise kattuvuse: CLEARFIL MAJESTY™ ES-2 valgust hajutavad täiteained Kuraray Noritake Dental Inc.-lt.

Hea väljanägemine ei sõltu alati sulandumisest ümbritsevaga ja restauratsiooni märkamatutest servadest, mistõttu arendas Kuraray Noritake välja täiteained, mis hoolitsevad ka ülejäänu eest: loomulik pinnaläige ja poleerimise kestvus. Kolme voolavuse astmega CLEARFIL MAJESTY™ ES Flow sisaldab Submicron Filler tehnoloogiat, mis koosneb läikivatest mikronist väiksematest täiteosakestest. Need täiteosakesed on nii väikesed, et valgus peegeldub loomulik viisil isegi pärast kulumist. Miljonite nende imepisikeste täiteosakeste ühendamiseks ja koos hoidmiseks kasutatakse Kuraray Noritake Dental Inc.-i erakordset silaanitehnoloogiat. See võimaldab kasutada suuremaid täiteaine koguseid vähese viskoossusega komposiitides ja piirab veeimavust, mis tooks kaasa kõvastunud komposiidi lagunemise. Mikronist väikesemate läikivate täiteosakeste, valgust hajuvate täiteainete, vaikmatriitsi ja silaanitehnoloogia vaheline tasakaal on võtmetähtsusega mehaaniliste ja optiliste omaduste optimeerimisel.

Näide ühetoonilisest restauratsioonist CLEARFIL MAJESTY™ ES-2 Universaliga.

JÄRELDUS

Adhesiivsed monomeerid, täiteosakeste ja silaanitehnoloogiad pakuvad tugeva täiteainete, klastrite ja vaigumatriitsidevaliku: Kuraray Noritake Dental Inc. on ilmselgelt usaldusväärne partner adhesiivsete restauratsioonide valdkonnas.Viimaste aastakümnete jooksul välja töötatud patenteeritud tehnoloogiad aitavad kaasa direktsete restauratsioonide (pikaajalisele) toimele ja võimaldavad lihtsamalt saavutada töökindlaid ja esteetilisi tulemusi.

Interview with Andreas Chatzimpatzakis

Fewer bakes, fewer ceramic powders - there is clearly a trend toward simplification in the production of zirconia-based prosthetic work. This is also true for implant-based restorations, which often involve gum parts. DT Andreas Chatzimpatzakis, international trainer for Kuraray Noritake Dental Inc., and the owner of ACH Dental Laboratory in Athens, Greece, shares his approach to high aesthetics in implant prosthodontics in the following conversation.

You are a user of the CERABIEN™ ZR portfolio from the outset. When did you test the products for the first time and why?

Well, it was many years ago when I finished my very first zirconia-based restoration. The reason to test CERABIEN™ ZR was that when I asked the dental technician who had milled the framework which porcelain system to use. He suggested to use CERABIEN™ ZR, which I did. I was immediately impressed by the system and by the outcome I was able to achieve on the first attempt.

Did you ever test any other porcelain systems for ceramic layering?

Yes. Before I becoming an international trainer for Kuraray Noritake Dental Inc., I had the opportunity to test many other porcelain systems for layering on zirconia. Based on this experience, I can say that CERABIEN™ ZR is unique and the best system I have ever used. The reason is that its translucency and chroma are extremely close to natural teeth. In addition, due to a controlled firing shrinkage, a One-Bake Technique may be employed even in long-span restorations.

Your hands-on demonstration at the Kuraray Noritake Dental booth during the IDS 2023 in Cologne focused on White and Pink Aesthetics achieved with CERABIEN™ ZR. Is there a specific concept you use?

Nowadays, everyone producing dental restorations – no matter whether based on natural teeth or on implants – is confronted with increasing aesthetic demands of patients and dental practitioners. The high demands are developed because life-like restorations and cosmetic dental treatment outcomes are presented everywhere in the web and on social media. The showcased quality of outcomes is simply expected, even if the financial budget is limited. To be able to fulfil these demands in the field of implant-based prosthodontics, I have developed an approach that allows me to achieve high aesthetics with little effort. My concept is based on using not too many ceramic powders. For extra chroma and special characterization, I rely on the power of the internal live stain technique, first introduced by Hitoshi Aoshima-sensei.

Please summarize the most important details of your presentation.

The first important detail is the design and characterization of the framework. Before sintering, I apply Esthetic Colorant for KATANA™ Zirconia. After the sintering process, shade base stain and internal stains are mixed and applied. In this way, I create a nice canvas that helps me to achieve a life-like result with only a few selected ceramic powders. In most cases, three to five powders are enough to produce a great result. Among the powders used most frequently are Opacious Body, Body, LTX, Mamelon and CCV. After the first bake and a little grinding, I make use of internal stains again. They offer support in the controlling of the chroma and the integration of special characteristics. When this step is completed, the final build-up is done with one or two ceramic powders, most of the times LT1 and Enamel or LT0. Pink aesthetics are usually created with Tissue 1, 3 and 5. For the free gingiva, LT Coral is my go-to solution. The major goal is always to obtain maximum quality in a minimum of time. To achieve this, a good knowledge of the materials and of course practicing – on both, porcelain build-up and morphology – are strictly required.

Fig. 1. Complex implant-based restoration: Framework design.

Fig. 2. Esthetic Colorant …

Fig. 3.  … applied prior to the final sintering procedure.

Fig. 4. Appearance after sintering.

Fig. 5. Final outcome.

Are there any concrete tips and tricks you would like to share?

For the characterization of the framework, I mix the internal stains with shade base stain powders; mostly with SS Fluoro. For the first bake, especially when the restoration is large and the amount of ceramic to be applied huge, I reduce the heating rate up to 38 degrees per minute. I also increase the drying process up to 17 or even 20 minutes depending to the restoration. Experience shows that these measures optimize the aesthetic outcomes.

You often mention that it is extraordinarily important to understand the morphology of natural teeth to be able to produce beautiful restorations. Why is this the case?

A successful prosthetic restoration needs to offer proper function and aesthetics. Function means a precise fit, perfect contact points and occlusion, a proper emergence profile and interproximal embrasures for self-cleaning etc. All this is described by the term morphology. Aesthetics, on the other hand, is guided by shape and colour. The effort required to establish a proper morphology is much higher (about 70 percent of the total work) than the effort involved in obtaining the right translucency, opalescence and chroma.

What instruments do you use to imitate the morphology of natural teeth and how do you do it?

I usually make use of the Optimum™ Spring Ceramic Brush Size 8 (MPF Brush Co.), stones and diamond burs for detailed grinding and carving after the final bake. I studied morphology at the Osaka Ceramic Training Centre in Japan with Shigeo Kataoka-sensei. According to him, a key factor in creating a perfect macro and micro morphology lies in the shadows. To be able to take into account the interference of light and shadow during grinding, a light source is placed on one side of the restoration.

How many bakes do you need to produce highly aesthetic restorations?

It depends on the case, although in many situations, I nowadays opt for some kind of micro-layering. Lately, I have used micro-layering a lot with internal stain directly on the zirconia framework. In other cases, I do a quick first bake, then the internal staining, a final bake and glazing. For small or single-unit restorations in the posterior region, a One-Bake Technique is often sufficient. Even a Zero-Bake approach using Esthetic Colorant on a monolithic zirconia restoration may be appropriate here, and it is very convenient. If there is a restoration with high aesthetic demands – these are typically single anterior restorations – the technique I select depends on the shade. In some cases, using only the internal stain technique is enough to reach a high aesthetic level, while in other cases, additional steps need to be taken. To my mind, there is no single technique that fits all cases. As mentioned before, I try to achieve high aesthetics in a minimum of time.

Fig. 6. Clinical example of achieving high aesthetics in a minimum of time: Before …

Fig. 7. … and after crown placement.

Fig. 8. High aesthetics …

Fig. 9. … achieved in a minimum of time.

Did your approach change due to the availability of high-translucency zirconia materials with colour (and flexural strength) gradation?

Well, yes! My overall approach changed more to micro-layering. Several years ago, we needed to consider how to mask the framework and how to achieve translucency in areas with limited space. The problem was solved for single-unit and small anterior bridge restorations with the availability of KATANA™ Zirconia UTML and STML. With the introduction of KATANA™ Zirconia YML, a high-translucency material became available for long-span or implant-based restorations as well. We have strength and translucency all in one disc. In most of my cases, the framework material replaces the dentin with regard to morphology and shade. Hence, I need to focus on adding the enamel by applying the transparent and translucent powders. The powders of the internal stain technique are used to characterize the framework, and with a micro-layer of porcelain, the goal of creating an aesthetic restoration in the minimum of time is achieved. This is exactly why I am sure that micro-layering is the future.

What drives you to share your knowledge with others?

My passion! I love my work! And I love to see technicians become better and better. Dental technology is an exciting journey, a journey that begins when the first impression arrives in the dental laboratory, and it ends when the final restoration is cemented into the patient’s mouth. And this journey is so exciting because we change lives. We change people’s personalities, we give them back their smile, we give them back their self-respect. Consider that every day, every single moment working on our bench trying to imitate nature… there is nothing more exciting than that!!!

My approach as an instructor is to lead dental technicians to master the art of observing natural teeth. This is the way every individual will understand morphology and shade. You need no special talent to be a very good dental technician. You need to observe! Your eyes see, your mind understands, and your hands will follow.