429 Too Many Requests

By Dr. Aleksandra Łyżwińska, Warsaw, Poland.

Every dentist aims to polish to a high gloss without damaging the freshly modeled occlusal surface. Firstly, use high-quality polishing rubbers. The plural form is not accidental (Fig. 1). In my opinion, a single rubber systems are not capable of achieving an impeccable gloss in a safe manner. Be patient and gentle. Polishing requires time and a delicate touch.

Fig. 1.

Immediately after polymerization the composite is covered with an oxygen inhibition layer (Fig. 2). It is imperative to remove it by a brush and any polishing paste or a prophylactic sandblaster. The next step is to remove excess composite using abrasive discs, burs and firm polishing rubber points.

Fig. 2.

During polishing without water cooling, the rubber leaves crumbling on the composite surface (Fig. 3). These fragments can be spread across the restoration surface using a fine nylon brush. This allows for the polishing of each fissure and pit (Fig. 4).

Fig. 3.

Fig. 4.

The key to long lasting shine is polishing with gradation. Time to change a rubber point to the dark blue TWIST DIA for Composite rubber, which is more abrasive than light blue one (Fig. 5). Remember to apply gentle pressure and maintain a maximum speed of 8000 revolutions per minute. This way, you will achieve fine particles without the risk of overheating the pulp. The particles were once again spread over the entire surface. The thinner the bristle, the better the polishing effect in the grooves (Fig. 6).

Fig. 5.

Fig. 6.

Third round: use the light blue TWIST DIA for Composite rubber for a mirror-like gloss (Fig. 7). A beautiful gloss emerges beneath the particles. An alternative to thin nylon brushes is brushes made from natural goat hair (Fig. 8).

Fig. 7.

Fig. 8.

Polishing is not only a matter of aesthetics but, above all, function. The adherence of bacterial biofilm to a polished composite is significantly lower than to a rough surface (Fig. 9). My recipe for achieving a mirror-like gloss polish: high-quality diamond rubber points with gradation, used with sensitivity over an extended period (Fig. 10).

Fig. 9.

Fig. 10.

Dentist:

DR. ALEKSANDRA ŁYŻWIŃSKA
Warsaw, Poland

Dr. Aleksandra Łyżwińska is a restorative dentist. She graduated from the Warsaw Medical University in 2017, where she was an assistant professor at the Department of Conservative Dentistry and Endodontics. Her focus lies in modern adhesive techniques, resin composites and biomaterials.

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

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

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

MDP: Chemical structure and mechanism of adhesion

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

Bonding performance

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

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

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

Not all MDP is alike

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

Conclusion

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

References

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

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

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

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

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

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

ADHESIVE LUTING: A DRIVER OF INNOVATION

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

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

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

Click here to read. Enjoy reading!

Start Reading: BOND | VOLUME 10 | 10/2023

Previous versions:

BOND | VOLUME 9 | 08/2022

BOND | VOLUME 8 | 12/2021

BOND | VOLUME 7 | 10/2020

Photo credits to Giuliano Moustakis

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

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

The reasons to choose KATANA™ quality

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

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

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

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

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

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

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

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

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

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

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

The origin of well-balanced properties

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

Daži uzņēmumi galvenokārt izmanto citu izstrādātās pamattehnoloģijas, lai uzlabotu savus produktus un ieviestu jaunus, savukārt citi uzņēmumi veic fundamentālus pētījumus un tehnoloģiju izstrādi paši. Vai šī atšķirība ir nozīmīga speciālistiem, kuri katru dienu izmanto iegūtos produktus zobārstniecības praksē vai zobu tehniskajā laboratorijā? Protams, ka ir, jo šādiem uzņēmumiem ir dziļa izpratne par pamatā esošajiem komponentiem, ķīmiju un tehnoloģijām, kā arī tās spēj atrisināt problēmas un elastīgi un ātri reaģēt uz tirgus vajadzībām. Šajā rakstā ir aprakstīta vairāku Kuraray Noritake Dental Inc. izstrādāto pamattehnoloģiju ietekme uz netiešo restaurāciju cementēšanu.

Adhezīvā cementēšana toreiz un tagad

Iespēja frēzēt zobu restaurācijas no dažāda veida keramikas ir pavērusi jaunas iespējas protezēšanai: ir iespējams izgatavot un cementēt ļoti estētiskas restaurācijas. Tas, kas šajā kontekstā bieži tiek novērtēts par zemu, ir adhezīvu cementēšanas sistēmu nozīme, kas ne tikai veicina zobu krāsas restaurāciju estētiski caurspīdīgo izskatu, bet arī paver ceļu mazāk invazīvai slīpēšanai un restaurācijām. Agrīnās sistēmas, kas nodrošināja ķīmisko saķeri starp zobu audiem un netiešām restaurācijām, diemžēl nespēja nodrošināt paredzamu ilgtermiņa rezultātu un tās bija saistītas ar augstu tehnikas jutīgumu, kā arī cementēšanas procedūra bija ārkārtīgi sarežģīta. Tehnoloģiju attīstība uzņēmumā Kuraray Noritake Dental Inc. sniedza būtisku ieguldījumu cementēšanas sistēmu ilgtermiņa adhēzijas veiktspējā un darbplūsmas vienkāršošanā.

Ilgtermiņa adhēzijas veiktspējas optimizēšana

Lai panāktu agrīno cementēšanas sistēmu ilglaicīgu adhēziju ar zoba struktūru (īpaši dentīnu), Kuraray (Kuraray Noritake Dental Inc. mātesuzņēmums) pagājušā gadsimta 70. gados nolēma pievērsties jaudīgāka adhezīvā monomēra izstrādei. Kā pirmo soli ceļā uz izcilību tas 1976. gadā ieviesa fosfāta monomēru Phenyl-P. Piecus gadus vēlāk, pēc nepārtrauktiem centieniem uzlabot un pilnveidot tā molekulāro struktūru, tika izveidots populārais MDP monomērs, kas spēj izveidot īpaši spēcīgu un ilgstošu saiti ar emalju, dentīnu, metālu un cirkoniju.

Šī izgudrojuma atjautību uzsver fakts, ka tas joprojām ir daļa no katras Kuraray Noritake Dental Inc. adhezīvās un adhezīvās cementēšanas sistēmas, un to izmanto arī citi ražotāji, lai optimizētu savu produktu adhēzijas stiprību un savienojuma izturību. Salīdzinot ar citur sintezēto MDP, Kuraray Noritake Dental Inc. oriģinālais MDP monomērs izceļas ar nepārspējamu produkta tīrības līmeni. Neatkarīgi pētījumi liecina, ka šādam tīrības līmenim ir pozitīva ietekme uz tā spēju veidot saiti1. Piedāvājot stabilitāti mitrā vidē, MDP monomērs ir veicinājis to saturošo produktu konsekventāku darbību.

Dažādi MDP monomēri piedāvā dažādus tīrības līmeņus un atšķirīgu adhezīvo veiktspēju.

Tika sagatavoti trīs eksperimentāli paškodinoši praimeri, kas sastāvēja no 15 masas % 10-MDP, no dažādiem produktiem: KN (Kuraray Noritake Dental), PCM (Vācija) vai DMI (Designer Molecules Inc., ASV). Datus sniedza Dr. Kumiko Yoshihara.

Tomēr, lai adhezīvās kompozīta cementa sistēmas nodrošinātu spēcīgu saiti ar izcilu restaurāciju malas blīvumu, nepietiek tikai ar adhezīvo monomēru. Nepieciešama arī efektīva šī monomēra polimerizācija – un ne vienmēr tā ir tik viegli paveicama. Lai nodrošinātu efektīvu PANAVIA™ V5 sacietēšanu gan gaismā, gan tumsā, Kuraray Noritake Dental Inc. izstrādāja Touch-Cure tehnoloģiju. Šīs tehnoloģijas galvenā sastāvdaļa ir jaunizstrādāts, ļoti aktīvs PANAVIA™ V5 Tooth Primer polimerizācijas paātrinātājs, kas spēj darboties MDP monomēra radītajā skābajā vidē. Tas veicina polimerizāciju, sākot jau no vietas, kur zobs saskaras ar cementu uzreiz kā PANAVIA™ V5 cementa pasta tiek uzklāta uz zoba virsmas, kura iepriekš ir apstrādāta ar praimeri. PANAVIA™ Veneer LC ir gaismā cietējoša kompozīta cementa sistēma, kas darbojas ar tiem pašiem praimeriem, un kuram PANAVIA™ V5 Tooth Primer polimerizācijas paātrinātājs nodrošina tādu pašu darbības mehānismu. Tas veicina adhezīvo virsmu polimerizāciju, savukārt PANAVIA™ Venner LC Paste nodrošina izcilu stabilitāti apkārtējā gaismā un tā polimerizācija notiek tikai gaismošanas laikā.

Piemēram, šī parādība tika novērtēta PANAVIA™ F2.0, kas ir PANAVIA™ V5 priekštecis. Pētījuma rezultāts: PANAVIA™ F2.0 uzrādīja daudz labākas restaurāciju malas blīvuma īpašības nekā citas novērtētās cementa sistēmas2. Šis dokumentētais drošais restaurāciju malu blīvums samazina malas sūces gadījumu skaitu, nodrošina ļoti augstu polimerizācijas pakāpi pat pašsacietēšanas režīmā (bez gaismošanas vai visur, kur gaismu bloķē restaurāciju materiāls) un līdz ar to panāk īpaši spēcīgu saiti.

Papildu ieguvums, kas rodas no polimerizācijas paātrinātāja iekļaušanas, ir tā spēcīga reducētāja funkcija. Tas neitralizē nātrija hipohlorītu, ko parasti izmanto kā skalošanas šķīdumu endodontiskās ārstēšanas laikā, un tādējādi novērš tā negatīvo ietekmi uz vēlāk uzklātās cementa pastas saites stiprību.

Vienkāršota stikla keramikas cementēšana

Mazāk pudeļu, mazāk soļu un racionalizētas cementēšanas procedūras – iemesli, kāpēc pašadhezīvie kompozīta cementi tika izstrādāti un ieviesti 2000. gadu sākumā. Tomēr lielākajai daļai šo produktu ir ierobežots indikāciju diapazons. Tie labi darbojas uz cirkonija, metāla, emaljas un dentīna, taču tie nav ieteicami, vai arī ir nepieciešams papildu silāna praimeris, lai veidotu saiti ar stikla keramiku. MDP saturošais PANAVIA™ SA Cement Universal atšķiras ar citu Kuraray Noritake Dental Inc. patentētu tehnoloģiju: LCSi monomēru, garās oglekļa ķēdes silāna savienojuma aģentu. Šis monomērs veido spēcīgu ķīmisko saiti ar kompozīta materiālu, porcelānu un silīcija keramiku (piemēram, litija disilikātu), tādējādi novēršot nepieciešamību pēc papildus silānu saturoša produkta (praimera vai adhezīva) lietošanas. Izmantojot šīs tehnoloģijas priekšrocības, PANAVIA™ SA Cement Universal nepārprotami izceļas no citiem pašadhezīvajiem kompozīta cementiem kā patiesa vienkomponenta cementēšanas sistēma pat restaurācijām, kas izgatavotas no stikla keramikas.

Ja vēlaties, produkta saites stiprību ar zoba audiem var palielināt, izmantojot populāro universālo adhezīvu CLEARFIL™ Universal Bond Quick ar Rapid Bond tehnoloģiju. Šo tehnoloģiju ir izstrādājusi Kuraray Noritake Dental Inc., lai atrisinātu problēmas, kas saistītas ar lēnu adhezīva nonākšanu dziļāk zoba struktūrā, īpaši mitrā dentīnā, kas raksturīga universālajiem adhezīviem. Lai nodrošinātu pietiekamu adhezīva iesūkšanos zoba struktūrā, tie ir ilgstoši un aktīvi jāierīvē zoba struktūrā vai arī ārstam ir jāgaida ilgāks laiks, pirms slānis tiek nogaismots. Patentētā Rapid Bond tehnoloģija, kas sastāv no oriģinālā MDP monomēra apvienojumā ar hidrofilajiem amīda monomēriem, nodrošina augstu afinitāti pret ūdeni, kas nodrošina ātru un dziļu saites iespiešanos mitrā dentīnā. Rezultātā tiek saīsināts uzklāšanas laiks un vienkāršota apstrāde, negatīvi neietekmējot adhezīva veiktspēju.

Secinājums

Kuraray Noritake Dental Inc. izstrādātās tehnoloģijas ir būtiski veicinājušas adhezīvo cementēšanas sistēmu saites veiktspēju un patiesi universālu pašlīmējošo kompozīta cementu izmantošanu. Tā rezultātā uzņēmums spēj piedāvāt modernizētu augstas veiktspējas kompozīta cementu klāstu katram ārstam tipiskām klīniskajām situācijām. Nepieciešams mazāk komponentu un mazāk darbību, un procedūras ir vienkāršotas – mazāk iespēju pieļaut kļūdas un vieglāk nodrošināt ilgtspējīgas estētiskās restaurācijas. Papildus ar tehnoloģiju saistītajām priekšrocībām, minētie produkti piedāvā vairākas citas noderīgas funkcijas. Detalizēts apraksts ir atrodams tiešsaistē vietnē kuraraynoritake.eu.   

Atsauces

*) 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

Daži uzņēmumi galvenokārt izmanto citu izstrādātās pamattehnoloģijas, lai uzlabotu savus produktus un ieviestu jaunus, savukārt citi uzņēmumi paši veic fundamentālus pētījumus un tehnoloģiju izstrādi. Vai šī atšķirība ir nozīmīga kādam, kurš katru dienu izmanto šos produktus zobārstniecības praksē vai laboratorijā? Tā ir – uzņēmumiem, kas visu izstrādā no nulles, parasti ir dziļāka izpratne par produktiem un to ražošanas procedūrām, un tas atvieglo specifisku īpašību modifikāciju, esošo problēmu risināšanu un tirgus vajadzību apmierināšanu. Šajā rakstā ir aprakstīta vairāku Kuraray Noritake Dental Inc. izstrādāto pamattehnoloģiju ietekme uz tiešo restaurāciju darba plūsmu.

Tiešās restaurācijas – no sarežģītām līdz vienkāršām

Adhezīvā restauratīvā zobārstniecība, izmantojot augstas veiktspējas zobu adhezīvus un kompozīta materiālus, šobrīd ir viens no populārākajiem veidiem, kā ārstēt zobus ar kariesa bojājumiem. Mūsdienās parasti pietiek ar vienas pudeles universālo adhezīvu un vienu vai diviem universālā kompozīta materiāla toņiem un opacitāti, lai radītu skaistu un izturīgu rezultātu, ja tiek izvēlēti pareizi materiāli. Tomēr ne vienmēr viss ir bijis tik vienkārši. Ilgu laiku tiešo restaurāciju process ir bijis diezgan sarežģīts: adhezīva aplicēšanai bija ļoti specifiska tehnika, vairāku pudeļu sistēmas un vairāku soļu sistēmas ar ilgu uzklāšanas laiku. No otras puses, kompozīta plombējamie materiāli radīja reālistiskus rezultātus tikai tad, ja tika pareizi apvienoti daudzi dažādi toņi un opacitātes. Un pat tad, ja sarežģītās procedūras tika veiktas pareizi, mikro sūces, krāsas maiņas un galu galā sekundāra kariesa risks bija salīdzinoši augsts. Kuraray Noritake Dental Inc. pievērsās šo problēmu risināšanai diezgan agri, sākot ar 1981. gadā izstrādātā oriģinālā MDP monomēra izmantošanu.

Adhēzijas kvalitātes optimizēšana

Oriģinālais MDP monomērs atrisināja jautājumu par adhezīvo sistēmu ierobežoto ilgtermiņa adhēzijas veiktspēju. MDP hidrofilā (fosfāta) grupa veido īpaši spēcīgu un ilgstošu ķīmisku saiti ar kalciju, kas atrodas hidroksilapatītā – galvenajā emaljas un dentīna sastāvdaļā. Rezultējošais MDP-Ca sāls nodrošina pamatu stabilam, spēcīgam un izturīgam hibrīda slānim. Kombinācijā ar sveķiem, saistvielā pēc sacietēšanas gaismā tiek panākts blīvs kavitātes pildījums. Līdz pat mūsdienām MDP ir būtiska jebkura Kuraray Noritake Dental Inc. adhezīvā produkta sastāvdaļa, un tā ir galvenā sastāvdaļa, kas ļāva CLEARFIL™ SE Bond kļūt par Zelta standarta pašlīmējošo līmēšanas sistēmu.

Tomēr, būdami pārliecināti, ka zobārstniecības adhezīvam ir jānodrošina vairāk nekā tikai spēcīga un ilgstoša saite, Kuraray Noritake Dental Inc. sāka pievērsties cita jautājuma risināšanai: demineralizācijas un tālāka kariesa riskam, ko izraisa kavitātē palikušās baktērijas. Pamatojoties uz savu pieredzi citu adhezīvu monomēru izstrādē, Kuraray Noritake Dental Inc. izgudroja MDPB monomēru, kam piemīt antibakteriāls kavitāti attīrošs efekts. Atšķirībā no antibakteriālajiem līdzekļiem, kas var pasliktināt pēc tam uzklātā adhezīva saķeres stiprību, MDPB monomērs nogalina atlikušās baktērijas, neietekmējot savienošanas veiktspēju. Tas ir iekļauts divu pudeļu sistēmas pašadhezīvajā CLEARFIL™ SE Protect praimerī un tas tiek imobilizēts polimerizācijas ceļā.

Tiek uzskatīts, ka MDPB baktericīdais mehānisms ir līdzīgs labi zināmajam antibakteriālajam līdzeklim CPC (cetilpiridīnija hlorīds), kas ir daudzās zobu pastās un mutes skalošanas līdzekļos.

Lai gan divu pudeļu sistēmas pašadhezīvās saites jau ir vienkāršojušas adhēzijas procedūru, vienas pudeles universālie adhezīvi spēj paveikt vēl vairāk. Tas ir izaicinājums apvienot sastāvdaļas, kas sadalītas daudzpakāpju sistēmās vienā pudelē, neapdraudot produkta stabilitāti. Pašreizējās tehnoloģijas tagad to padara iespējamu. Lai pēc iespējas ātrāk pēc uzklāšanas noslēgtu virsmu, monomēru iekļūšanai zobu audos jābūt ātrai un efektīvai. Tomēr, šo iekļūšanu parasti palēnina monomēri, kuriem nepieciešams laiks, lai iekļūtu zoba struktūrā – īpaši mitrā dentīnā – un dažreiz pat to ir nepieciešams ierīvēt. Tāpēc Kuraray Noritake Dental Inc. koncentrējās uz Rapid Bond tehnoloģijas izstrādi. Tas sastāv no oriģinālā MDP monomēra, kas apvienots ar nesen izstrādātiem hidrofiliem šķērssaistītiem amīda monomēriem un ir integrēts CLEARFIL™ Universal Bond Quick. Hidrofilie amīda monomēri nodrošina ātru, dziļu un pilnīgu iekļuvi dentīnā un pēc sacietēšanas veido blīvu, šķērssavienotu polimēru tīklu, kas ir atbildīgs par spēcīgu un izturīgu saiti. Tādējādi tiek novērsts gaidīšanas un ierīvēšanas laiks, un pēc sacietēšanas gaismā tiek izveidota cieši, blīvi un ilgstoši noslēgta kavitāte.

Pateicoties to hidrofilitātei (ūdens pievilcībai), Rapid Bond Technology amīdu monomēri ļoti labi iekļūst dentīnā. Pēc sacietēšanas gaismā saite uzrāda zemu ūdens absorbciju un tādējādi augstu novecošanās izturību.

Tiešo restaurāciju optimizēšana

Vairāku slāņu, toņu un opacitāšu apvienošana: ļoti sarežģītu slāņošanas paņēmienu izmantošana reālistisku kompozīta materiālu restaurāciju izveidei, par laimi, daudzās klīniskās situācijās ir pagātne. Iemesls: augsti attīstīti kompozīta materiāli, kas nemanāmi saplūst ar blakus esošo zobu struktūru. Lai nodrošinātu šo labvēlīgo efektu, Kuraray Noritake Dental Inc. ir izstrādājis savu patentēto gaismas difūzijas tehnoloģiju (LDT). Tehnoloģija ir iestrādāta īpašos iepriekš polimerizētos filleros, kas darbojas kā miljoniem mikroprizmu, kas pārraida un lauž gaismu un krāsu no apkārtējās zoba struktūras. Pildvielas ar optimizētu izmēru, sadalījumu un refrakcijas indeksu attiecībā pret matricu, piedāvānepārspējamu dabisko sajaukšanos. Visa CLEARFIL MAJESTY™ kompozītmateriālu sērija satur šo patentēto pildvielu tehnoloģiju. Tā jaunākais produkts – CLEARFIL MAJESTY™ ES-2 Universal –, kurā Kuraray Noritake Dental Inc. izmanto nākamā līmeņa LDT, ļauj izmantot vienas krāsas tehniku ar vienkāršotu toņu izvēli: tas ir pieejams divos toņos priekšzobiem un vienā tonī aizmugurējam zobu reģionam, taču tas saplūst tik labi, ka aptver gandrīz katru VITA klasisko toni no A1 līdz A4.

Gaismas laušana un caurlaidība pareizajā veidā lieliskai optiskai integrācijai: CLEARFIL MAJESTY™ ES-2 gaismas difūzijas pildvielas no Kuraray Noritake Dental Inc.

Tā kā lielisks optiskais izskats ir atkarīgs ne tikai no optiskās integrācijas un nenosakāmām plombes robežām, Kuraray Noritake Dental Inc. izstrādāja arī pildvielas, kas nodrošina pārējo – dabisku virsmas spīdumu un ilgstošu pulēšanas noturību. CLEARFIL MAJESTY™ ES Flow integrētais risinājums ar trīs plūstamības līmeņiem tiek saukts par submikronu pildvielu tehnoloģiju, kas sastāv no spīdīgām submikrona izmēra pildvielām. Šīs pildvielas ir tik mazas, ka gaismas atstarošanās uzrāda dabisku efektu pat pēc nodiluma. Uzņēmuma Kuraray Noritake Dental Inc. izcilā silāna tehnoloģija tiek izmantota, lai savienotu miljoniem šo submikronu pildvielu un laika gaitā saglabātu tās kopā. Tas pieļauj lielu pildvielu slodzi zemas viskozitātes kompozītmateriālos un ierobežo ūdens uzņemšanu, kas pretējā gadījumā izraisītu sacietējušā kompozīta materiāla degradāciju. Ideāls līdzsvars starp spīdīgajām submikronu pildvielām, gaismas difūzijas pildvielām, sveķu matricu un patentēto silāna tehnoloģiju ir atbildīgs par līdzsvarotu mehānisko un optisko
īpašību kombināciju.

Viena toņa restaurācijas piemērs, kas izgatavots no CLEARFIL MAJESTY™ ES-2 Universal.

Secinājums

Adhezīvie monomēri, pildvielu tehnoloģijas un silāna tehnoloģija nodrošina stabilu pildvielu, klasteru un sveķu matricas kombināciju: Kuraray Noritake Dental Inc. nepārprotami ir uzticams eksperts adhezīvo restaurāciju jomā. Pēdējo desmitgažu laikā izstrādātās patentētās tehnoloģijas noteikti ir veicinājušas tiešo restaurāciju labāku (ilgtermiņa) veiktspēju un vieglāk sasniedzamus uzticamus un estētiskus rezultātus.

Interview with Andreas Chatzimpatzakis

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

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

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

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

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

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

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

Please summarize the most important details of your presentation.

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

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

Fig. 2. Esthetic Colorant …

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

Fig. 4. Appearance after sintering.

Fig. 5. Final outcome.

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

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

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

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

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

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

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

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

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

Fig. 7. … and after crown placement.

Fig. 8. High aesthetics …

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

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

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

What drives you to share your knowledge with others?

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

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

Alexander (Alek) Aronin is a master dental technician who dedicated himself to the creation of high-end, handmade porcelain restorations. He runs a dental laboratory and morphology school in Spain, and travels the world as a lecturer and teacher.

The greatest source of inspiration in his professional life is the book Collection of Ceramic Works by Hitoshi Aoshima. Through reading it in 1996, he discovered superb outcomes of working with dental ceramics. Moreover, the book’s content made him realize that the creation of handmade porcelain work is a result of special education and manual skills. Those who want to become masters need a lot of commitment and a striving for continuous improvement, which Alek shows in his work and his classes. We talked to him about his philosophy and his enthusiasm for the creation of lifelike restorations. He shared with us his perspective on the future of dental technology and gave some practical tips on how to achieve a high level of professional satisfaction.

Photo courtesy of Dennis Debiase

Alek, many dental technicians decide to focus on CAD/CAM technology and automated processing of dental ceramics. Due to improvements on the material side, a handmade porcelain layer is no longer necessary in many clinical cases. In this context, the manual refinement process is reduced to a minimum. Why did you decide to take a completely different path and focus on fully manual dental craftsmanship?

The shift towards automated processing is not a matter of choice for dental technicians rather, it is a natural response to the evolution of technology. The high-end manual refinement process remains unchanged. The human element, from communication to hand crafting among skilled individuals and demanding clients, has been a constant so far throughout history. This traditional connection remains stable for centuries.

Digitalisation is not the revolution in the dental industry, and I do not see the benefit of it in our narrow specialization yet. In the area we are working, we do all steps of our case faster, incomparably more precise and more profitable. But we are keeping eye on machines and waiting for a suitable one.

Machines and automated processes widely serve mass production businesses focused on fast, affordable and uniform results in a highly competitive field. Our goal and workflow are different - we provide individual work and personal attention to each of our partners and patients.

So, we do not compete with the production labs and do not interrupt each other, we coexist in parallel worlds as always. A small number of dentists and their patients will always demand personal attention and valued restorations and service of the highest quality.

Many dental technicians admire your work. Yet, you continue to strive for improvement. Why is this the case?

On one side, we are limited by static ceramic material used to mimic dynamic natural teeth that keep changing for a lifetime. On the other side, we are limited by our manual skills. I am still far away from my teachers and Japanese colleagues. My target is to improve the fabrication process. My goal is to achieve the simplicity and imperfectness like Aoshima-sensei.

Alek lecturing at the IDS 2023 in Cologne.
Photo courtesy of Dennis Debiase

We are enjoying the outcome, but prefer to focusing on the improvement of the process, and move on to create a better one. This is what I am learning in Japan, and this is what I teach my students.

Talking about learning: What are the most important aspects a dental technician who wants to improve his skills should have in mind when looking for a good teacher?

Manual skills are very important, but not the only aspect that should be taken into account. Every individual should be motivated and guided and this is a teacher’s job.

I love the traditional Japanese way of teaching and learning: The teachers are passionate, leading the way by evoking emotions and manual skills to bring the best out of every single student. My personal advice for dental technicians who want to become masters in the creation of lifelike high-end dental restorations is to select their teachers carefully and go to a private school or courses whenever they have the chance.

What are the most important tools a dental technician needs to use when trying to create high-end lifelike restorations?

I suggest to focus on four aspects:

1. Documentary dental photography - required for documentation and communication with the dental office and patients using constant (once set and never changed) parameters of the photo equipment.
2. Focus to the biomimetic additive dentistry. This is a minimum machine invasive field. Dental technicians and dentists should be able to develop a deep knowledge about clinical and lab-side procedures to be able communicate with each other.
3. Mastering morphology and function (shape carving), and anatomy (internal staining), which comes with value control and mimicking fine tooth details for best integration in the mouth.
4. Written communication (stop phone calls) is very important, this is the way how to exchange the information between the patient, clinic and lab by strict protocols.

I teach these complex skills in my morphology school and in many of my trainings worldwide. Focusing on the four aspects, a dental technician has a great chance to become a good specialist in a relatively short period of time in a narrow field.

Is material selection important for achieving great results?

I’ve been using Noritake ceramic for most of my life, and the reason is simple: Noritake created their EX-3 porcelain over 40 years ago, and it was so well-made that it has not needed any changes since.

This is showing their consistently high quality and creates unbroken succession in the valuable tradition of passing on techniques and knowledge.

Today, among different generations of dental technicians, we can use and share the same methods, vocabulary and abbreviations, powders, and temperature charts developed by our skilled teachers 30 to 40 years ago. This unique feature sets Noritake and Creation porcelains apart from all other brands and systems in the world.

The other Noritake porcelain I use quite frequently is CERABIEN™ ZR, which is also well-tried and tested and has even some more advantages than EX3.

Is there any final advice you would like to give?

To become a good professional, I suggest to developing in four parallel directions:

1. Practicing on phantoms - fabricating cases and ceramic samples. It helps to experiment and practice with varied materials and techniques.
2. Implementing the achieved techniques in clinical cases.
3. Working with case presentation PowerPoint or Keynote: documenting the working steps in pictures and videos from beginning to end.
4. Mastering the communication using e-mails. Constantly calibrate and adjust the information exchange process between the clinic and lab. Acquire deeper knowledge about the work of each other.

Good luck!