Case by Vasiliki Tsertsidou

What kind of resin composite is recommended for core build-up procedures? While there are specific dual-cure core build-up resin composites available on the market, it is not mandatory to use them. Light curing is advisable to be applied even for materials with dual-cure polymerization. Some conventional resin composites demonstrate more favourable properties for a core build-up compared to specific core build-up resin composites itself.¹ Hence, it is possible to utilize a composite generally used in the dental office, provided it is indicated to and it is not applied deep within the root canal, where proper light curing would be impossible. The critical material properties for core build-ups are high filler load, sufficient flexural modulus and flexural strength.

CLEARFIL MAJESTY™ ES-2 composite series (Kuraray Noritake Dental Inc.) are suitable option for this case. With a filler load weight percentage of 78 and a flexural strength of 118 MPa (according to manufacturer), CLEARFIL MAJESTY™ ES-2 Classic corresponds to core build-up prerequisites*. The following case is illustrating the clinical procedure.

*The indication range of CLEARFIL MAJESTY™ ES-2 composite does not cover core build-up. In the specific case it is used for creating a large Class II filling where all conditions from the IFU, such as curing depth, are met.

Fig. 1. Endodontically treated tooth with a vertical fracture of palatal wall on maxillary right second premolar.

Fig. 2. Buccal view of the tooth.

Fig. 3. Clinical image, directly after removal of fragment.

Fig. 4. Fragment of the maxillary right second premolar.

Fig. 5. Circumferential matrix band for build-up to assist endodontic retreatment.

Fig. 6. Build-up of the missing walls (margin relocation) with CLEARFIL MAJESTY™ ES-2 Classic (A3).

Fig. 7. Temporary filling of the cavity.

Fig. 8. Replacement of the temporary filling material with CLEARFIL MAJESTY™ ES-2 Classic.

Fig. 9. Crown preparation.

Fig. 10. Proximal carious lesion present on the adjacent fist premolar.

Fig. 11. Situation after rubber dam placement and caries removal.

Fig. 12. Cavity restored with CLEARFIL MAJESTY™ ES-2 Classic.

Fig. 13. Prepared crown.

Fig. 14. Crown after sandblasting of the intaglio.

Fig. 15. Mechanically cleaned abutment tooth ready for pre-treatment.

Fig. 16. Intaglio of the crown treated with CLEARFIL™ CERAMIC PRIMER PLUS.

Fig. 17. Etching of the composite surface with phosphoric acid gel.

Fig. 18. Air-drying of PANAVIA™ V5 Tooth Primer on the abutment tooth.

Fig. 19. Crown in place after cementation with PANAVIA™ V5 Paste and excess removal.

A GOOD CHOICE

Dual-cure core build-up resin composites are two-component materials that need to be mixed homogeneously, which obstracts composition from containing high filler load. However, to prevent deformation of the core, a highly filled composite is advisable. This better simulates the flexural modulus of natural tissues compared to materials with low filler load. Consequently, a light-curing material like CLEARFIL MAJESTY™ ES-2 might be a better option. Applied in 2-mm increments in the core area (and not in the root canal), it performs well and provides the desired outcomes. Additionaly, the option of utilising the same material as for any other type of direct restorations is simplifying the stock management and supporting dental practitioners striving for a simplification of clinical procedures.

References

1. Spinhayer L, Bui ATB, Leprince JG, Hardy CMF. Core build-up resin composites: an in-vitro comparative study. Biomater Investig Dent. 2020 Nov 3;7(1):159-166. doi: 10.1080/26415275.2020.1838283. PMID: 33210097; PMCID: PMC7646551.

Dentist:

VASILIKI TSERTSIDOU

Door dr. Clarence Tam, HBSC, DDS, AAACD, FIADFE

Het gebruik van porseleinveneers voor het verbeteren van de vorm, kleur en visuele stand van anterieure tanden is een gebruikelijke techniek binnen de esthetische tandheelkunde. Het biomimetische doel van de restauratie van tanden raakt niet alleen het cosmetische domein; functionele afwegingen spelen ook een rol. Het is essentieel om in acht te nemen dat de intacte omhulsels van de palatale en faciale wanden met betrekking tot anterieure tanden verantwoordelijk zijn voor de intrinsieke buigsterkte. Als de tandheelkundige structuur is aangetast door endodontische invloeden, cariës en/of trauma, moet al het mogelijke worden gedaan om de residuele structuur te behouden en moet er naar worden gestreefd om basisprestaties van een onaangetaste tand te herstellen of overstijgen.

ACHTERGROND

Een vrouwelijke 55-jarige ASA II-patiënt meldde zich bij de praktijk voor een whitening-behandeling. Naar verwachting zou de whitening geen effect hebben op de kleur van een reeds bestaande porseleinen facing op tand 1.2. Deze zou binnen de procedure moeten worden verwijderd, vooral als de kleurveranderingen significant zouden zijn. De patiënt begon met de basiskleur VITA* 1M1:2M1; verhouding 50:50 in het bovenste anterieure gedeelte en 1M1 in het onderste anterieure gedeelte. Na een nightguard-bleekprotocol met 10% carbamideperoxide, 3 tot 4 weken lang gedurende de nacht, werd bij de patiënt een VITA* 0M3-kleur bereikt in de bovenste en onderste tandbogen. Als gevolg daarvan was er een aanzienlijk verschil in value tussen tand 1.2 met facing en de omringende tanden; tevens werd een toegenomen chroma vastgesteld bij de contralaterale tand 2.2 vanwege een faciaal-gerelateerde Klasse III-composietrestauratie. Laatstgenoemde tand stemde qua formaat niet overeen met de contralaterale tand en daarom werd besloten om beide laterale snijtanden te behandelen met geprepareerde laminaatveneers van lithiumdisilicaat. De aangrenzende hoektand (2.3) vertoonde lokale milde tot matige slijtage van de cusps, maar de patiënt wilde hieraan niets laten doen totdat de nieuwe facings zouden zijn geplaatst. Het doel van smile design in deze fase is om uiteindelijk te zorgen voor tweezijdige harmonie met het oog op de plaatsing van een aanvullende indirecte restauratie waarmee het faciale volume en het gebrek van de cusp op tand 2.3 op korte termijn worden hersteld.

PROCEDURE

Een protocol voor een digitaal smile design was niet nodig voor de aanvankelijke opzet, namelijk de individuele behandeling van de laterale snijtanden. Een lichte variatie is toegestaan bij dit tanden van dit type, aangezien deze de lach van de patiënt karakteriseren qua sekse en persoonlijkheid. Voorafgaand aan de verdoving was de doelkleur geselecteerd aan de hand van close-upfoto's die zowel gepolariseerde als ongepolariseerde selecties toonden. De foto's waren geprepareerd voor digitale kleurkalibratie door middel van referentieopnamen met een neutrale 18% grijswit-balanskaart (Afb. 1).

Afb. 1. Referentieopname met neutrale 18% grijskaart.

De basisbodykleur was VITA* 0M2 met een perspiltint BL2. De patiënt werd verdoofd met 1,5 ampul met een 2% lidocaïne-oplossing met epinefrine (verhouding 1:100.000); daarna werd een cofferdam volgens de split-damtechniek geplaatst. De facing op tand 1.2 werd gesectioneerd en verwijderd van tand 1.2; vervolgens werd op tand 2.2. een minimaal invasieve veneerpreparatie uitgevoerd (Afb. 2). De gedeeltelijke vervanging van de oude composietharsrestauratie werd uitgevoerd op het mesioincisobuccopalatale aspect van tand 12, waarbij het intacte segment werd behouden. De adhesie aan de oude composiet werd bereikt door middel van abrasie met microdeeltjes en een silaankoppelproduct (CLEARFIL™ CERAMIC PRIMER PLUS). De randen werden bijgewerkt en de retractiedraden gedrenkt in een aluminiumchloride-oplossing en vastgezet. De kleuren van preparatiestompen werden vastgelegd. Er werden definitieve afdrukken gemaakt met behulp van licht en zwaar polyvinylsiloxaan in een metalen tray. De patiënt verliet de praktijk met een noodvoorziening en instructies om de kleur in het laboratorium in het bisquebake-stadium te controleren. De door het tandtechnische laboratorium vervaardigde modellen bevestigen het minimaal invasieve karakter van deze casus.

Afb. 2. Veneerpreparatie bij tanden 1.2 en 2.2.

Na ontvangst van de modellen werd de patiënt verdoofd en werden de noodvoorzieningen verwijderd. De preparaties werden gereinigd en geprepareerd voor bevestiging door abrasie van de oppervlakken met behulp van aluminiumoxidepoeder (27 micron) bij een druk van 30 tot 40 psi. De facings werden getoetst door middel van een heldere glycerinepasta (PANAVIA™ V5 Try-in Paste Clear, Kuraray Noritake Dental Inc.). De retractiedraden werden vastgezet en de intaglio-oppervlakken van de restauraties werden 20 seconden lang behandeld met een 5% hydrofluoridezuur, waarna een silaankoppelproduct met 10-MDP (CLEARFIL™ CERAMIC PRIMER PLUS) werd aangebracht (Afb. 3). Het tandoppervlak werd gedurende 20 seconden geëtst met een 33% orthofosforzuur en vervolgens gespoeld. Daarna werd een primer met 10-MDP (PANAVIA™ V5 Tooth Primer) op de tand aangebracht (Afb. 4) en conform de instructies van de fabrikant drooggeblazen.

Afb. 3. Aanbrengen van CLEARFIL™ CERAMIC PRIMER PLUS op de intaglio-oppervlakken van de facings.

Afb. 4. Applicatie van PANAVIA™ V5 Tooth Primer op de geëtste tandoppervlakken.

Na het aanbrengen van veneercement (PANAVIA™ Veneer LC Paste Clear) (Afb. 5) werd de facing vastgezet. De cementovermaat had een relatief vaste consistentie en hield de facing goed in positie tijdens alle handelingen om de rand in orde te brengen vóór een tack-cure van 1 seconde (Afb. 6).

Afb. 5. Aanbrengen van PANAVIA™ Veneer LC Paste Clear op de geprepareerde intaglio-oppervlakken van de facings.

Afb. 6. PANAVIA™ Veneer LC Paste meteen na bevestiging. Let op de stroperige, relatief vaste consistentie van het cement, waardoor het gemakkelijk kan worden verwijderd onder vochtige omstandigheden én in de gelfase.

Het cement ging over in een geltoestand, waardoor de cementovermaat kon worden verwijderd bij een minimale reiniging (Afb. 7). Voor de definitieve uitharding werden de randen gecoat met een heldere glycerinegel om de zuurstofinhibitielaag te verwijderen (Afb. 8).

Afb 7. Verwijdering van cementovermaat na tack-cure van 1 seconde.

Afb. 8. Definitieve uitharding van de facings, gelijktijdig vanuit het palatale en faciale aspect.

De randen werden afgewerkt en op hoogglans gepolijst, en de occlusie van de restauraties werd positief bevonden. De postoperatieve opnamen laten een voortreffelijke randintegratie zien (Afb. 9).

Afb. 9. Postoperatieve esthetische verwerking van facings op de tanden 1.2 en 2.2.

Na de behandeling laten gepolariseerde opnames zien dat de restauraties esthetisch en functioneel goed zijn opgenomen in de nieuwe lach (Afb. 10), in afwachting van de esthetische verbetering van tand 2.3 om te harmoniëren met de contralaterale hoektand.

EINDRESULTAAT

Afb. 10. Eindresultaat via een gepolariseerde opname na de behandeling.

Tandarts:

CLARENCE TAM

References

1. Magne P, Douglas WH. Rationalization of esthetic restorative dentistry based on biomimetics. J Esthet Dent. 1999;11(1):5-15. doi: 10.1111/j.1708-8240.1999.tb00371.x. PMID: 10337285.
2. Magne P, Douglas WH. Porcelain veneers: dentin bonding optimization and biomimetic recovery of the crown. Int J Prosthodont. 1999 Mar-Apr;12(2):111-21. PMID: 10371912.
3. Pongprueksa P, Kuphasuk W, Senawongse P. The elastic moduli across various types of resin/dentin interfaces. Dent Mater. 2008 Aug;24(8):1102-6. doi: 10.1016/j.dental.2007.12.008. Epub 2008 Mar 4. PMID: 18304626.
4. Source: Kuraray Noritake Dental Inc. Samples (beam shape; 25 x 2 x 2 mm): The solvents of each material were removed by blowing mild air prior to the test.

Artikel van Dr. Michał Jaczewski

Composietrestoraties in de tandheelkunde

Composietrestauraties zijn de meest voorkomende behandelingen die tandartsen uitvoeren. Binnen de tandheelkunde worden diverse restauratieve technieken toegepast en allerlei restauratiematerialen gebruikt. Luchtbelletjes in of bij het oppervlak van composietlagen vormen - ongeacht het type materiaal, de restauratiemethode en de locatie - een veel voorkomend probleem. De composietrestauratie dient homogeen te zijn om de dichtheid van de vulling en de duurzaamheid daarvan te waarborgen. De reparatie van defecten vanwege luchtbelletjes is omslachtig en vergt soms een gehele of gedeeltelijke vervanging van de vulling. Het aantal defecten kan - afhankelijk van het type composiet (flowable of pasta) en/of de plaatsingstechniek - variëren, maar verschillende factoren spelen een rol.

Materiaalkeuze

Bij de Flowable Injection Technique gebruiken we vloeibare composieten, die uiteraard soepel vloeien, maar óók gevoelig zijn voor onjuiste applicatie. De eerste oorzaak van de vorming van luchtbelletjes is gelegen in de homogeniteit van het materiaal zelf. De spuit kan al in de productiefase of tijdens gebruik luchtbelletjes bevatten. Door gebruik van hoogwaardige producten kunnen we ons verzekeren van de hoogste kwaliteit en mogen we rekenen op een correcte werking dankzij de structuur en het ontwerp van de spuit, zodat de vorming van luchtbelletjes in het materiaal wordt teruggedrongen.

Belang van spuitontwerp 

De composiet CLEARFIL MAJESTY™ ES Flow is ontwikkeld om de vorming van luchtbelletjes tijdens dosering te voorkomen. Dankzij het speciale ontwerp van de spuit en plunjer wordt de mogelijkheid van morsen beperkt, evenals het terugvloeien van materiaal tijdens of na het doseren.

Een unieke veiligheidsvoorziening in de spuit is de speciale O-ringconstructie, die voorkomt dat het materiaal vloeit nadat de druk wordt vrijgegeven en tegelijkertijd zorgt voor minimale retractie, overigens zonder overmatige retractie van de plunjer.

Terugtrekken van de plunjer

Nog een oorzaak van luchtbelletjes is luchtinsluiting in de spuit doordat de plunjer doelbewust wordt teruggetrokken. Als de praktijkbeoefenaar of een medewerker gewoon is om de plunjer na het aanbrengen van de composiet in te trekken, kan er lucht in de spuit ontstaan. Het is dan heel aannemelijk dat die lucht als een holte in de restauratie terugkomt.

Belang van druk op de index

Binnen de Flowable Injection Technique gebruiken we een silicone index, waarin we het materiaal voor de tandopbouw opnemen. Deze index moet strak op de tand passen en mag niet bewegen - of worden bewogen - tijdens het injecteren. Als dat wél gebeurt, kunnen er luchtbelletjes optreden. Het aandrukken en weer loslaten van de index veroorzaakt een zuigend effect, waardoor de composiet wordt weggetrokken van de tand én index. Om defecten te voorkomen, dient er constant druk op de index te worden gehouden vanaf het moment dat het materiaal wordt geïnjecteerd tot aan het uitharden.

De siliconenindex kan op meerdere manieren worden aangepast om de mobiliteit te beperken en het risico van ongecontroleerde druk op de tand te verminderen. Een voorbeeld is het creëren van de index volgens het 'interlipmodel' (één wel, één niet); hiermee wordt - naast bedrijfszekerheid - een heel hoge mate van stabiliteit gerealiseerd.

Breedte van het injectiegat

De breedte van de injectieopening kan ook een oorzaak zijn van de vorming van luchtbelletjes. Als die opening te nauw is, kan de index door de applicatiepunt worden verplaatst tijdens het inbrengen of appliceren. Om dit probleem te voorkomen, dient de opening te worden verwijd, zodat de punt goed kan worden ingebracht en gemanipuleerd tijdens het injecteren. Bovendien kan eventuele lucht dankzij een bredere opening ontsnappen tijdens het appliceren. Het belangrijkste is echter dat het materiaal onder een constante druk wordt aangebracht en dat de punt niet uit de index wordt getrokken en opnieuw ingebracht. Dat kan namelijk leiden tot een niet uniforme composietlaag.

Wilt u meer weten over Flowable Injection Technique? Lees het inzichtelijke en inspirerende interview met Dr. Michal Jachzewski.

Tandarts:

MICHAL JACZEWSKI

Michał Jaczewski studeerde in 2006 af aan de Wroclaw Medical University en momenteel runt hij zijn eigen praktijk in de Poolse stad Legnica. Hij is gespecialiseerd in minimaal invasieve en digitale tandheelkunde, en is de oprichter van de Biofunctional School of Occlusion. Op deze school is hij docent en organiseert hij workshops die zijn gericht op een allesomvattende behandeling van patiënten.

Case by Martin Laurik, MDT

There are so many different restorative materials out there and so many design and finishing concepts available that it often seems difficult to select the best option for a specific case. Using an allrounder like KATANA™ Zirconia YML can facilitate decision making: It is a great choice for single- to multi-unit restorations, works on teeth and implants alike, and can be adapted to individual needs by selecting a suitable design concept and adequate finishing technique. In this way, it is even possible to solve aesthetically challenging cases as the one illustrated below.

Initial situation and temporization

This patient was in need for treatment after the loss of her maxillary right central incisor and the placement of an implant in this region. As a replacement of the restorations on the other three maxillary incisors was necessary as well, it was decided to produce four crowns made of the same material – KATANA™ Zirconia YML. For aesthetic evaluation of the restorations’ length, angulations and shape in the mouth and a functional test drive, the crowns were digitally designed in full contour and milled from PMMA in the determined tooth shade A2 (Fig. 1).

Fig. 1. Full-contour PMMA crowns on the master cast.

Design, milling and effect dyeing of the zirconia crowns

Once the appearance and functional aspects of the temporary restorations were approved by the patient and the restorative team, the definitive crowns were produced. Their design was based on the full-contour design of the temporaries; however, a facial reduction of 0.6 mm was carried out by the software to create space for individualization with a small layer of veneering porcelain. The crowns were then milled from a KATANA™ Zirconia YML disc in the shade A1 – approximately one shade lighter than the determined tooth shade. To mask the uneven colour from the tooth stumps and the implant abutment, the intaglio of the crowns was treated with Esthetic Colorant in the shade Opaque. Some individual and intensified colour effects on the vestibular surface were also created with Esthetic Colorant.

Internal staining and porcelain layering

To slightly adjust the chroma and lightness, a first layer of CERABIEN™ ZR Internal Stains was added, followed by a wash bake. After the application of a first layer of CERABIEN™ ZR porcelains (Body, Enamel and Translucent) and baking (Fig. 2) – the central incisors received a layer of A1B, the lateral incisors a mixture of A1B and A2B (slightly darker to provide for a better match with the canines) with LT1, LT Natural completing the picture – additional internal staining was carried out (Fig. 3). The final layer of CERABIEN™ ZR luster porcelains (LT1, ELT2 used on the convex line angles to achieve an external reflection) was added and fixed in a fourth bake (Fig. 4).

After adjustments and very rough polishing, a self-glaze firing programme was selected (firing temperature 915 °C, holding time 5 seconds). On the highly polished incisal and palatal parts of the crowns and for contact point adjustment, CERABIEN™ ZR FC Paste Stain Glaze was applied and fixed with the same bake. The finished crowns on the model are shown in Figure 5, while Figure 6 displays the final treatment outcome.

Fig. 2. Crowns milled from KATANA™ Zirconia YML with a facial cutback of 0.6 mm after individualization with Esthetic Colorant, sintering, internal staining and the application of a first layer of porcelain.

Fig. 3. This picture shows the subtle internal stain adjustment to the ceramic mostly on the incisal part.

Fig. 4. Crowns prior to final shape adjustments and polishing.

Fig. 5. Finished crowns on the model.

FINAL SITUATION

Fig. 6. Treatment outcome.

Easy approach to beautiful restorations

The presented approach is a relatively easy way of producing highly aesthetic anterior restorations. Using an allrounder zirconia combined with a few selected effect liquids, internal stains and luster porcelains, it is possible to achieve a great optical integration even in a situation where teeth and implants need to be restored. The natural shape and surface texture of the restorations plays an important role in this context, as does the base material – a naturally shaded, highly translucent zirconia.

Dentist:

MARTIN LAURIK, MDT

Martin started working as a dental technician in 2014. In the time since, he never stopped training and learning from renowned colleagues. Continuing education courses focused on dental ceramics and occlusion in the functional concept of Slavicek. Fascinated by the beauty of natural teeth, developing an understanding of their complexity and learning how to mimic nature’s design as closely as possible has always been his primary goal, while he is well aware that there is still a lot to be learned and explored on the road to excellence.

Abrasion and shape correction was also the major reason for this 58-year-old female patient to ask for cosmetic dental treatment. She was unhappy with the appearance of the anterior teeth in the maxilla, which showed signs of tooth wear and discolouration. The selected treatment approach was composite veneering with CLEARFIL MAJESTY™ ES-2 Universal in the shade UD. The shade was selected based on the indication and the somewhat darker shade of the patient’s natural teeth.

Fig. 1. Initial clinical situation.

Fig. 2. Treatment outcome.

Reasons for selecting universal dark:

- For older patients (tooth shades A3 and darker)

- Situations in which light easily passes through the composite (e.g., Class III, Class IV)

Universal dark properties:

- High light scattering effect

- Well-balanced translucency

Dentist:

JUSUF LUKARCANIN

Dr. Jusuf Lukarcanin is a Certified Dental Technician (DCT) and a Doctor of Dental Science (DDS). He studied dentistry at the Ege University Dental Faculty in Izmir, Turkey, where he obtained a Master‘s degree in 2011. In 2017, he received a Ph.D. degree from the Department of Restorative Dentistry of the same university. Between 2012 and 2019, Dr. Lukarcanin was the head doctor and general manager at a private clinic in Izmir.

Between 2019 and 2020, he worked at Tinaztepe GALEN Hospital as a Restorative Dentistry specialist, between 2020-2022 he worked at MEDICANA International Hospital Izmir as a Restorative Dentistry specialist. Currently he is an owner of a private clinic for aesthetics and cosmetics in Izmir.

Case by MDT Daniele Rondoni and Dr. Enzo Attanasio.

Veneers made of zirconia? In some cases, like the one presented below, monolithic zirconia veneers may be an option. Reasons for selecting a latest-generation zirconia such as “KATANA™ Zirconia” YML include its very high translucency and a wall thickness of only 0.3 to 0.4 mm supporting minimally invasive tooth preparation. Due to a highly automated production procedure, the manual effort involved may be reduced, while highly aesthetic outcomes are possible.

Fig. 1. Initial situation: Young female patient with misshaped and misaligned maxillary incisors. Digital smile design is used to reveal the ideal proportions and positions of the anterior teeth.

Fig. 2. Ideal tooth proportions and positions displayed over a picture of the teeth after orthodontic treatment and the creation of a mock-up. The positions are ideal and the tooth shapes obtained with the mock-up only need some minor adjustments.

Fig. 3. Facial view of the patient with the planned veneers blended in.

Fig. 4. Guided tooth structure removal with the aid of a silicone index. The minimum wall thickness of the selected material – “KATANA™ Zirconia” YML – is 0.4 mm.

Fig. 5. Matched digital impressions of the maxilla and mandible taken after tooth preparation.

Fig. 6. Monolithic restoration made of “KATANA™ Zirconia” YML placed on the resin model after the 7-hour final sintering.

Fig. 7. Lateral view of the master cast with the six veneers individualized with the liquid ceramic system CERABIEN™ FC Paste Stain.

Fig. 8. Tooth-like translucency of the veneers on the model.

Fig. 9. Intra-oral try-in with two different shades of the PANAVIA™ V5 Try-in Paste: A2 is used in the right and Clear in the left quadrant. It was decided by the dentist to use A2 shade.

Fig. 10. Lateral view of the cemented veneers. The result is a natural surface texture, which contributes to a natural appearance of the restorations.

Fig. 11. Frontal view of the veneers in place.

Fig. 12. Treatment outcome immediately after rubber dam removal.

FINAL SITUATION

Fig. 13. Treatment outcome with healthy soft tissues two weeks after treatment.

Fig. 14. Gums are healthy and the restorations show a great optical integration with the adjacent posterior teeth.

Dentists:

Presented by Kuraray Noritake Dental Inc.

Highly translucent multi-layered zirconia developed by a proprietary material and manufacturing method from Japan

CURRENT STATUS AND FUTURE PROSPECTS OF ZIRCONIA RESTORATIONS

In this issue, we asked Markus B. Blatz, Professor at the University of Pennsylvania, USA, Aki Yoshida (Gnathos Dental Studio) and Naoki Hayashi (Ultimate Styles Dental Laboratory), both dental technicians active in the USA and international instructors for Kuraray Noritake Dental Inc., to give their views on zirconia restorations and their outlook for the future.

WITH THE INTRODUCTION OF ZIRCONIA, THE MAINSTREAM OF PROSTHETIC TREATMENT HAS SHIFTED FROM METAL CERAMICS¹ TO ZIRCONIA CERAMICS². WHAT CHANGES HAVE OCCURRED WITH THE INTRODUCTION OF ZIRCONIA?

Blatz: My mentor for my first Ph.D. in dental materials was in the group that developed lithium disilicate and glass-infiltrated alumina. Therefore, I have seen the evolution of dental ceramic materials, including zirconia, which is the subject of this presentation, up close and personal.

Early zirconia was white, opaque, and not as esthetic as today. However, there is no doubt that zirconia ceramics were much more esthetic than metal ceramics. At the same time, however, we often heard the opinion that bilayer zirconia ceramic restorations were problematic, and this provoked much discussion. We conducted a large study in collaboration with a Boston laboratory to compare more than 1,000 posterior porcelain-fused-to-metal crowns and 1,100 posterior porcelain-fused-to-zirconia crowns and found no difference in chipping or fracture rates after about seven years. This proves that bilayer zirconia ceramics are safe when used with the proper veneering materials and the proper sintering and cooling protocols. The fact that zirconia became established as it is today is a major change for dentistry in general.

Yoshida: I also switched from metal ceramics to zirconia ceramics, and now I don't use metal anymore. It used to take a lot of time and effort to invest and cast metal, observe it with a microscope, and fit it. Considering the recent rise in metal prices, it has also become more cost-effective. In addition, I am allergic to metal and have a skin rash every time I have a prosthetic processed, so the shift to zirconia ceramics as the mainstream prosthetic is a welcome change. Of course, the use of zirconia has also improved esthetics. The translucency of zirconia is the greatest advantage that metal does not have.

Hayashi: Yes, that's right. The big advantage of zirconia is that if the abutment is not strongly discolored, it no longer needs to be treated with an opaquer. It was not easy to control the reflection of light from the operative tooth when fabricating metal ceramics. In addition to the esthetic advantage, the prosthetic space can be thinner than that of metal ceramics.

1. Metal ceramics: Prosthetic made of metal frame with porcelain.
2. Zirconia ceramics: Prosthetic made of zirconia frame with porcelain.

THE YEAR 2023 MARKED THE 10^TH ANNIVERSARY OF THE FIRST MULTI-LAYERED ZIRCONIA – KATANA™ ZIRCONIA ML. SINCE THEN, HOW DO YOU THINK HIGHLY TRANSLUCENT MULTI-LAYERED ZIRCONIA HAS REVOLUTIONIZED PROSTHETIC DEVICE MANUFACTURING?

Yoshida: I feel the ability to extend the zirconia frame to the occlusal surface and the incisal edge is the greatest advantage of using highly translucent multilayered zirconia. This allows us to provide crowns of both esthetics and strength, even for patients with para function. I have also made a zirconia Maryland bridge using highly translucent multi-layered zirconia, and it is doing very well. There are some cases where it is not possible to use zirconia, but still, it is wonderful to have a wider range of options.

Blatz: Many people still have the impression that zirconia cannot be bonded to tooth structure, but resin cement can be used to bond zirconia to tooth structure after proper pretreatment. Clinical studies of resin-bonded zirconia bridges have shown very high success after 10 or 15 years. Currently, resin bonding is recommended for very thin, highly translucent zirconia, rather than cementation. However, it should be added that this requires the dentist and technician to understand the proper bonding technique for zirconia.

In addition, Kuraray Noritake Dental's multi-layered zirconia has revolutionized monolithic zirconia without the need for veneering porcelain. However, this has also resulted in the need for dental technicians to shift to a different approach: instead of building up the restoration as with veneering ceramics, esthetic features are created on the outer surface in each case.

Maxillary 6 anterior monolithic crowns (Markus B. Blatz)

Fig. 1a and b: Initial examination.

Fig. 1c: Simulation of final prosthetic restoration.

Fig. 1d: Completed prosthetic on model (monolithic crown using KATANA™ Zirconia STML).

Fig. 1e and f: Final restoration (Dr. Julian Conejo and Sean Han, CDT).

Two cases of Maryland bridge and laminate veneers and a mandibular canine single crown implant superstructure (Aki Yoshida)

Fig. 2a and b: Case 1: A case of a congenital defect of a lateral incisor was restored with a Maryland bridge. Since the proximal and distal width of the defect was greater than the central incisor, a non-prep veneer was fabricated on the central incisor to balance the proportions. KATANA™ Zirconia STML was used for the Maryland bridge. Note the harmony between the zirconia frame extended to the incisal edge and the transparency of the laminate veneers made of Super Porcelain EX-3™ on the central incisors. This case demonstrates the characteristics of zirconia, which combines strength and esthetics.

Fig. 3a to c: Case 2: A case of a screw-retained crown restoration of an implant placed in a mandibular canine tooth. Extension of the zirconia frame from the entire lingual side to the incisal margin prevents fracture of the porcelain by the screw access hole edges and canine guides. KATANA™ Zirconia STML provides natural transparency even when zirconia is exposed at the incisal edge.

Maxillary 4 Anterior teeth implant bridge (Naoki Hayashi)

Fig. 4a to f: Implant bridge of maxillary four anterior teeth using implants placed in the maxillary bilaterallateral incisors as abutments and maxillary bilateral central incisorsaspontics. The lingual side is fully backed with zirconia and the labial side is minimally layered with CERABIEN™ ZR.

Hayashi: Indeed, the highly translucent multilayered zirconia has expanded the possibilities of monolithic crowns. For patients with high occlusal forces, monolithic crowns are suitable in terms of strength, and with the use of highly translucent multilayered zirconia, it is possible to achieve a certain level of esthetics with monolithic crowns. In fact, some patients are happy with it. However, at least in the current situation, we believe that if patients and dentists want high-end esthetics, then porcelain buildup is necessary, and monolithic crowns are only an option.

Blatz: The variety of options available is the advantage of zirconia. The dentist and the technician can work together to provide the best possible outcome for the patient.

Yoshida: In terms of options, Kuraray Noritake Dental's zirconia can be sintered in a short time (approximately 90 minutes) in addition to the normal sintering time (7 hours) using a zirconia raw material and manufacturing method developed by Kuraray Noritake Dental, which is an advantage in that it can be used for immediate restorations, remanufacturing and other unexpected situations.

FINALLY, DO YOU HAVE A MESSAGE FOR THE NEW GENERATION OF DENTISTS AND DENTAL TECHNICIANS?

Blatz: I encourage my students and colleagues to always do their best. This leads to good results, makes you happy, and makes you feel satisfied with your life. Some people only try to get rich, but just accumulating wealth is never happiness. The second is to keep an open mind. Nowadays, we are inundated with information through social media.

Some of it is very stimulating and wonderful, but there is also a lot of it that is wrong. On the other hand, there are those who believe that everything one leader says must be done. I would like to tell them, "Make sure you get your information from reliable sources, and then choose reliable information for yourself. Dentistry is changing, so let's keep an open mind. The most important thing is that the patient is ultimately satisfied with the results.

Hayashi: I would like the future generation to learn more about tooth morphology, occlusion, and fit. Color is the essence of the quality of the final prosthetic device, but we need to learn tooth morphology, occlusion, and fit before we learn color. We are all about creating a prosthetic device that will function in the patient's mouth for the long term, and that is our goal. There will be new technologies and materials in the future, but their essence will never change. I hope that you will always remember what is important in your clinical practice. This is why basic knowledge of anatomy and function is necessary.

Yoshida: New technologies and materials will continue to emerge. But human teeth will not change. The most important thing is to provide the best possible care to the patient. I hope that you will accumulate such experiences, and that when you reach the end of your life, you will be able to say that you are glad you chose this profession.

Thank you very much for the meaningful discussion today.

Source: QDT Vol.49/2024 April
The magazine may not be printed from the web and may not be forwarded
No reproduction or reprinting allowed

Dentists:

KATANA™ Zirconia YML offers an unmatched blend of aesthetics and mechanical properties, but also provides for cost and time efficiencies.

Recognised for its strength and density at point of manufacture, the material delivers incredible hardness in its green state. This offers the fully validated opportunity to make adjustments in morphology directly after milling.

These qualities, along with its strength and translucency once sintered, deliver the possibility to produce a wide range of high aesthetic indications. KATANA™ Zirconia YML has set a new benchmark in prosthetic dentistry.

It provides dental technicians with a material that is truly universal with no compromises required.

KATANA Zirconia YML in a Nutshell

KATANA Zirconia YML represents a pinnacle of zirconia technology. With its multi-layered structure, it offers a seamless gradation of colour, strength and translucency that mimics natural teeth, making it an ideal choice for the entire indication spectrum.

The material's unique composition allows for high-speed sintering (up to 3-unit bridges), which significantly reduces production time without sacrificing optical or mechanical properties.

Colour Gradation and Physical Properties

The colour gradation of KATANA Zirconia YML is designed to replicate the natural colour transition of human teeth, from the dentin core to the translucent enamel surface.

This combined with the material's impressive flexural strength of up to 1,100 MPa and translucency of up to 49%, enables the production of restorations that are virtually indistinguishable from natural dentition.

Applications and Advantages of KATANA Zirconia YML

KATANA™ Zirconia YML's versatility extends to a wide range of indications, including crowns, veneers, inlays, onlays, and bridges of all sizes. With its strong body and highly translucent enamel layer, it offers exactly the properties required for an unlimited indication range.

Positioning of restorations in KATANA™ Zirconia YML discs is extraordinarily easy. The reason is that the gap between the lowest flexural strength found in the enamel area and the highest flexural strength found in the lowest body layer is comparatively small. Moreover, the Body Layer 1 that is found adjacent to the enamel layer already offers a flexural strength that is higher than the 800 MPa requested for bridges with four or more units. Consequently, the material is classified as a Class 5 zirconia and users are on the safe side whenever they place their long-span restorations in the middle of the blank.

Positioning of long-span restorations in the middle of the disc.

Revolutionizing Sintering with High-Speed Capabilities

One of the groundbreaking aspects of KATANA Zirconia YML is its compatibility with high-speed sintering protocols. This capability allows dental laboratories to expedite the production process, delivering high-quality restorations in a fraction of the time traditionally required. Sintered during normal working hours at daytime, small restorations can be finished within hours, while the sintering load at night is reduced automatically. Great option not only for rush cases!

The high-speed sintering process does not compromise the material's optical or mechanical properties, maintaining its aesthetics and strength.

Recommended Finishing Techniques for Optimal Results

KATANA Zirconia YML is a beautiful and aesthetic material in its own. Therefore, when it comes to finishing, CERABIEN™ ZR FC Paste Stain is a great option.

KATANA Zirconia YML: A Testament to Innovation in Dental Materials

KATANA Zirconia YML stands at the forefront of dental material technology, offering outstanding aesthetics, strength, and efficiency. Its introduction has marked a significant advancement in the capabilities of dental technicians, allowing for the creation of restorations that truly mimic the beauty of natural teeth in a fraction of time.

As the dental industry continues to evolve, KATANA Zirconia YML remains a testament to the relentless pursuit of excellence in restorative dentistry.

For more detailed information on KATANA Zirconia YML, including technical guide, FAQs and Clinical cases, visit Kuraray Noritake Dental's YML dedicated page.

Interested in articles, user experience or clinical cases using KATANA Zirconia YML? Check the blog section of our website! 

Mathias Fernandez Y Lombardi

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

With PANAVIA™ SA Cement Universal and KATANA™ Zirconia

By using PANAVIA™ SA Cement Universal and its proprietary dual-monomer technology, you can now simplify the bonding of restoration to implant abutments without the use of separate primers or silane. Independent research has confirmed this new dual-monomer technology does not sacrifice adhesion or durability on glass-based ceramics or zirconia. The technique, in this case study, is for custom fabricated abutment & KATANA™ Zirconia YML crown, however, the basic technique on the treatment of the abutment and restoration may be used with any implant restoration combination as long as the proper surface treatments for type of material is followed.

INITIAL FIT OF ABUTMENT & RESTORATION

Basic technique on the treatment of the abutment and restoration.

Fig. 1. Check Initial Fit of Abutment & Restoration: abutment & crown margins should be checked to ensure proper fit.

Fig. 2. Protect base of implant with putty or light-cure block-out resin. The base of the implant should be covered so that it is not air abraded accidentally.

Fig. 3. Abrade titanium abutment with 50 μm alumina oxide powder.

Fig. 4. Clean abutment with KATANA™ Cleaner: Apply KATANA™ Cleaner by rubbing each area for 10 seconds.

KATANA™ Cleaner is a universal cleaner that is indicated to clean metal, zirconia & glass-based restorations. It is also an intra oral cleaner that may be used on dentin and enamel.

TREATMENT OF KATANA™ Zirconia RESTORATION WORKFLOW

Bonding to zirconia has been proven to be durable in research going back to the 1990’s with the original MDP adhesive monomer in the PANAVIA™ resin cements. The three requirements to bonding zirconia are:

1. Air abrade zirconia with 50 μm alumina oxide powder.
2. Clean zirconia
3. Apply an MDP-Based Primer or resin cement. PANAVIA™ SA Cement Universal contains the original MDP that was developed & patented in 1981 by Kuraray Dental.

Fig. 1. Air abrade KATANA™ Zirconia at 14-58 psi.

Fig. 2. Dispense & mix PANAVIA™ SA Cement Universal (it is available in automix or handmix formulations).

Fig. 3. Apply PANAVIA™ SA Cement Universal to the abutment or inside the crown.

Fig. 4. Seat restoration on abutment.

Fig. 5. Remove excess resin with a dry micro-applicator or brush.

Fig. 6. You may light-cure the margins after cleaning up all excess resin. If you fully cure excess resin, It can be difficult to remove. If difficult to remove, change curing time or distance with your light.

Fig. 7. Leave restoration on abutment to self-cure fully for approximately 10 minutes at room temperature.

Fig. 8. Final check of custom abutment KATANA™ Zirconia YML crown on model.

Dentist:

JEAN CHIHA

Technician Jean Chiha CDT, Santa Ana, CA USA

Mr. Chiha is the owner of North Star Dental Laboratory and Milling Center, Santa Ana, CA, and has served as President of the Dental Lab Owners Association of California since 2013. He is a 1985 graduate of Institut Dento Technic, a private dental technology school in France. Mr. Chiha lectures internationally on dental communication and case planning. Jean lectures around the world on a variety of topics and has carved out a niche with his extensive knowledge of zirconia. Affectionately referred to as “Mr. Katana” due to his involvement in the creation of the material.

Case by Dr. Jusuf Lukarcanin

This young patient aged 35 with microdontia presented in the dental office with the desire to have more beautifully shaped teeth. His teeth were almost free of dental caries, but with deficiencies in oral hygiene and signs of gingival inflammation. A deep bite was also evident. After professional tooth cleaning and oral hygiene advice, the teeth were restored with CLEARFIL MAJESTY™ ES-2 Universal in the shade UL.

Fig. 1. Initial situation.

Fig. 2. Initial situation: Deep bite.

Fig. 3. Teeth restored with composite in the single-shade technique.

Fig. 4. Immediate treatment outcome.

Reasons for selecting universal light:

- For younger patients (tooth shades A2 and lighter)

- Situations in which light easily passes through the composite (e.g., Class III, Class IV)

Universal light properties:

- High light scattering effect

- Well-balanced translucency

Dentist:

JUSUF LUKARCANIN

Dr. Jusuf Lukarcanin is a Certified Dental Technician (DCT) and a Doctor of Dental Science (DDS). He studied dentistry at the Ege University Dental Faculty in Izmir, Turkey, where he obtained a Master‘s degree in 2011. In 2017, he received a Ph.D. degree from the Department of Restorative Dentistry of the same university. Between 2012 and 2019, Dr. Lukarcanin was the head doctor and general manager at a private clinic in Izmir.

Between 2019 and 2020, he worked at Tinaztepe GALEN Hospital as a Restorative Dentistry specialist, between 2020-2022 he worked at MEDICANA International Hospital Izmir as a Restorative Dentistry specialist. Currently he is an owner of a private clinic for aesthetics and cosmetics in Izmir.