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Quantas cores são necessárias?

Caso apresentado por Gasparatos Spyros, estudante de pós-graduação do programa de Dentisteria Restauradora, Faculdade de Medicina Dentária, Universidade Nacional e de Kapodistrian de Atenas, Grécia

Restaurar dentes anteriores com grandes defeitos utilizando compósito pode ser um grande desafio. No entanto, com materiais de alto desempenho à mão e um conceito sistematizado de estratificação em mente, é possível produzir resultados altamente estéticos de maneira reproduzível. O caso clínico aqui apresentado é utilizado para ilustrar uma técnica de estratificação de duas cores com o CLEARFIL MAJESTY™ ES-2 Premium, um sistema de compósito com combinações de cores predefinidas.

Caso clínico

O paciente, um jovem do sexo masculino, estava insatisfeito com a aparência dos seus dentes anteriores superiores. Há vários anos, os seus incisivos centrais tinham sido restaurados com compósito. Estas restaurações tinham margens defeituosas e muito descoloridas, e a sua cor não correspondia à estrutura dentária natural adjacente. Os incisivos laterais superiores tinham forma conoide (microdontia). As considerações económicas e o desejo de salvar o máximo possível de estrutura dentária natural fizeram com que a equipa decidisse restaurar os quatro incisivos superiores com compósito. O CLEARFIL MAJESTY™ ES-2 Premium tornou-se o material de eleição, uma vez que elimina a necessidade de fórmulas complicadas de combinação de cores e permite resultados previsíveis.

Fig. 1. Sorriso inicial do paciente.

Fig. 2. Imagem intraoral da situação inicial com restaurações de compósito defeituosas e microdontia. Dois botões de compósito no incisivo lateral direito são utilizados para verificar a combinação de cores escolhida.

Restauração dos incisivos centrais

Decidimos restaurar primeiro os incisivos centrais e depois concentramo-nos nos incisivos laterais. A cor do dente foi determinada utilizando a guia de cores VITA™ clássica A1-D4, e os botões de compósito foram aplicados nos dentes para verificar a combinação de cores escolhida. Para simplificar o procedimento de restauração, foi produzida uma chave de silicone palatina antes de remover as restaurações existentes. Durante a preparação minimamente invasiva dos dentes foram criados biséis nas margens para proporcionar uma transição óptica suave da estrutura natural do dente para o compósito.

Foi aplicado um adesivo (CLEARFIL™ Universal Bond Quick) após o condicionamento seletivo do esmalte para obter uma adesão forte. Com a ajuda da chave de silicone, foi fácil criar as paredes palatinas das restaurações com CLEARFIL MAJESTY™ ES-2 Premium na cor A3E (esmalte), que corresponde à cor A3 do dente. O núcleo de dentina foi construído com o mesmo compósito na cor recomendada A3D (dentina), os mamelões foram modelados e foi adicionado um pouco de CLEARFIL MAJESTY™ ES-2 Premium na cor WD para o halo incisal. Alguns efeitos individuais (como fissuras no esmalte) foram imitados com corante castanho. A restauração foi finalizada nas áreas interproximais e vestibulares com compósito na cor A3E. Entre os incisivos centrais, foi utilizada uma cunha para retrair a papila e facilitar o desenho da área de contacto interproximal. As restaurações acabadas e pré-polidas já apresentavam um aspeto natural.

Fig. 3. Incisivos centrais após a remoção das restaurações antigas e do biselamento do esmalte.

Fig. 4. Paredes palatinas fotopolimerizadas realizadas com CLEARFIL MAJESTY™ ES-2 Premium na cor A3E.

Fig. 5. Construção do núcleo de dentina com mamelões individualizados utilizando a cor WD e o corante castanho.

Fig. 6. Situação após a finalização das restaurações dos incisivos centrais com compósito na opacidade do esmalte.

Fig. 7. Restaurações dos incisivos centrais após acabamento e polimento inicial.

Restauração dos incisivos laterais

Não foi necessária preparação dentária nos incisivos laterais. Em vez disso, foram apenas limpos após um ligeiro desgaste para aumentar a rugosidade da superfície de esmalte. O procedimento de reconstrução foi semelhante ao utilizado para os incisivos centrais. O dente adjacente foi protegido com fita de PTFE, e a parede palatina foi criada com a ajuda de um dedo em vez da chave de silicone. A seguir, concentrámo-nos na construção das paredes interproximais, depois colocámos uma pequena quantidade de dentina e finalizámos a forma com a aplicação da camada de esmalte vestibular.

Fig. 8. Reconstrução do incisivo lateral esquerdo.

Fig. 9. Situação após o acabamento e polimento.

Situação final

Fig. 10. Sorriso final que responde às exigências do paciente.

Conclusão

Duas opacidades diferentes, uma única combinação de cor e uma cor branqueada, mais um corante para efeitos especiais. No caso deste paciente, uma fórmula simples permitiu-nos criar restaurações anteriores realistas. Com a utilização de uma pasta de esmalte e uma pasta de dentina, é possível reconstruir de forma simples a anatomia natural do dente, sem correr o risco de acabar com um núcleo volumoso que - uma vez reduzido - perderá a sua estrutura óptica especial. Também é fácil controlar a espessura da camada final de esmalte que tem um impacto enorme nas propriedades ópticas de toda a restauração. Para a maioria dos pacientes e de dentes com uma estrutura de cor interna simples ou média/complexa, o conceito selecionado é muito adequado e conduz a resultados agradáveis.

Clinical case by Dr. Florian Zwiener

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

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

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

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

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

Fig. 4. Bridge design …

Fig. 5. … using the CEREC Software.

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

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

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

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

Fig. 10. … and two glaze firings.

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

FINAL SITUATION

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

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

Dentist:

DR. FLORIAN ZWIENER

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

Case report with Dr. José Ignacio Zorzin

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

How do universal adhesives contribute to a streamlining of workflows?

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

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

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

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

How to proceed with selective enamel etching?

A clinical example.

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

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

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

Fig. 4. Working field isolated with rubber dam.

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

Fig. 5. Cleaning of the tooth …

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

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

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

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

Fig. 9. Application …

Fig. 10. … of the universal bonding agent.

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

Fig. 12. … and the fragment.

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

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

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

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

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

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

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

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

Fig. 16. Treatment outcome.

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

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

Dentist:

DR. JOSÉ IGNACIO ZORZIN

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

References

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

Em 1976, a Kuraray introduziu o seu primeiro monómero adesivo - o monómero de fosfato Fenil-P. Nos anos seguintes, o compromisso da empresa com a investigação e desenvolvimento levou a esforços contínuos para melhorar e aperfeiçoar a estrutura molecular deste monómero. A Kuraray acabou por atingir este objetivo ao criar uma molécula com maior capacidade de aderência à estrutura dentária, baixa solubilidade e eficácia na ligação ao metal: o monómero MDP.

Desenvolvido e patenteado pela Kuraray em 1981, o monómero MDP continua a ser, até hoje, o principal monómero funcional para uma adesão fiável a vários substratos, incluindo o esmalte e a dentina. A investigação tem demonstrado repetidamente que os produtos que utilizam este monómero criam adesões duradouras e estáveis a longo prazo aos tecidos dentários, metais não nobres e cerâmica de zircónia. Em suma, é difícil saber onde estaria a dentisteria dentária adesiva sem o monómero MDP.

Um nível de pureza inigualável

Um dos segredos subjacentes ao êxito do monómero MDP da Kuraray Noritake é a sua natureza única de alta qualidade. A patente que a Kuraray detinha sobre o monómero expirou, abrindo o mercado a outros fabricantes para sintetizarem o seu próprio MDP. No entanto, um estudo realizado por Yoshihara et al.¹ mostrou que, dos três monómeros MDP adesivos que examinaram, as diferenças nos níveis de pureza eram visíveis e afetavam a intensidade da nano-capa e a força de adesão resultante. Sem surpresa, a medida da força de adesão apresentada pelo MDP original e altamente purificado da Kuraray Noritake foi a mais elevada.

"É muito claro que o monómero MDP é um dos monómeros mais eficazes disponíveis, dado o seu potencial de ligação química primária à hidroxiapatite", afirmou o Prof. Bart Van Meerbeek, uma das principais autoridades em agentes de adesão dentária, numa entrevista ao Dental Tribune International.

"Essencialmente, um adesivo universal que contenha uma elevada concentração de monómero MDP muito puro deverá ter o melhor desempenho", acrescentou, quando questionado sobre os sistemas de adesão universais.

Um monómero com muitas aplicações

O primeiro produto da Kuraray a utilizar o monómero MDP foi o cimento de resina PANAVIA EX. Introduzido em 1983, o PANAVIA EX tornou-se rapidamente conhecido como um facilitador de uma adesão fiável. A família PANAVIA de cimentos resinosos adesivos, incluindo o PANAVIA V5 e o PANAVIA SA Cement Universal, continua a utilizar o monómero MDP para proporcionar uma adesão de primeira classe aos profissionais de medicina dentária em todo o mundo.

Naturalmente, o monómero MDP constitui a espinha dorsal de uma série de produtos da atual gama de sistemas de adesão CLEARFIL da Kuraray Noritake Dental, como o padrão de referência CLEARFIL SE BOND 2, um agente de união suave de dois passos, autocondicionante e fotopolimerizável. O CLEARFIL Universal Bond Quick, o agente de adesão dentária universal de um só passo da empresa, utiliza a tecnologia de adesão rápida. A combinação sinérgica do monómero MDP original e dos monómeros de amida hidrofílicos cria uma adesão duradoura mais rápida e mais fácil do que nunca.

Há mais de 40 anos que existem provas, e a conclusão é clara: o monómero MDP da Kuraray Noritake Dental mudou a adesão dentária para melhor.

Referências

1. Yoshihara K. et al. Functional monomer impurity affects adhesive performance. Dent Mater. 2015 Dec;31(12):1493–1501.

Atualmente, os utilizadores de zircónia dentária têm muito por onde escolher. Inúmeros fabricantes oferecem materiais de zircónia que diferem nas suas propriedades mecânicas e ópticas e na gama de indicações. O que não é evidente à primeira vista é que os produtos disponíveis também diferem no que respeita à qualidade da oferta dos materiais CAD/CAM em bruto. A qualidade dos materiais em bruto depende muito da qualidade das matérias-primas e é afetada por diferentes aspetos durante o processamento, prensagem e pré-sinterização. Isto tem um impacto enorme na qualidade da superfície, na estabilidade das margens, no ajuste e nos requisitos de processamento das restaurações fresadas.

Produção de matérias-primas

A zircónia dentária pré-colorida é normalmente constituída por óxidos metálicos, incluindo óxido de zircónio, óxido de ítrio e óxido de alumínio, e também aditivos como aglutinantes e pigmentos ou iões coloridos. A maioria dos fabricantes de zircónia dentária obtém o pó pré-fabricado a partir de um parceiro externo da indústria, sendo a opção mais popular a Tosoh Corporation. Ao contrário, a Kuraray Noritake Dental baseia‑se num processo interno do princípio ao fim. Isto inclui a produção e adição dos componentes que formam a inovadora tecnologia multicapa da empresa para uma obter uma estrutura policromática em bruto e - no caso da "KATANA™ Zirconia" YML - obter translucidez adicional e gradação da resistência à flexão.

Na Kuraray Noritake Dental, o pó é produzido internamente.

Uma vez que mais etapas de produção de pó são realizadas internamente, a empresa tem controlo total sobre a qualidade das matérias-primas, sobre o tamanho de grão e a pureza da formulação. Isto também permite um alinhamento exato das propriedades mecânicas e ópticas do produto para conseguir uma transição suave de uma capa para a seguinte. O resultado é uma estrutura de cores sem descontinuidades e uma excelente correspondência das cores dos discos policromáticos com as cores do guia de cores VITA clássico A1-D4.

Nos materiais que combinam diferentes concentrações de ítria numa única peça em bruto, podem ser tomadas medidas internas adicionais de alinhamento. No caso do "KATANA™ Zirconia" YML, foi desenvolvida uma matéria-prima completamente nova para proporcionar uma taxa de contração uniforme e coeficientes harmonizados de expansão térmica em toda a peça em bruto e, assim, levar à perfeição a gradação da resistência à flexão.

As propriedades das restaurações de zircónia que são afetadas pela qualidade e composição do pó incluem a translucidez e o aspeto da cor, a resistência à flexão, o comportamento de envelhecimento e o desempenho da sinterização.

Prensagem do material em bruto

Os discos e blocos de zircónia utilizados para o processamento CAD/CAM são normalmente produzidos por prensagem uniaxial e isostática. No processo de compactação uniaxial, a pressão é aplicada ao pó a partir de uma direção (uniaxial) ou de duas direções (biaxial), enquanto o processo de compactação isostática envolve uma pressão praticamente igual aplicada de todos os lados. Por conseguinte, a prensagem isostática resulta normalmente numa distribuição mais uniforme da densidade em toda a peça em bruto e numa maior homogeneidade do material. Estes fatores são pré-requisitos para um comportamento previsível de processamento e sinterização e afetam o ajuste da restauração final. Para obter propriedades mecânicas e ópticas ótimas do material de zircónia, é essencial evitar grandes porosidades, bolsas de ar e impurezas causadas por partículas transportadas pelo ar que ficam presas durante a prensagem.

Na Kuraray Noritake Dental, um processo de prensagem único e extremamente meticuloso consegue uma distribuição uniforme da pressão e um baixo risco de contaminação por partículas transportadas pelo ar. Este procedimento específico reduz as forças de gravitação e contribui para uma densidade tão elevada quanto possível do material de zircónia. Todos os processos de preparação de alto nível, desde a produção da matéria-prima até à prensagem, são responsáveis pela elevada estabilidade das margens e pela qualidade da superfície das restaurações fresadas a partir de "KATANA™ Zirconia".

Pré-sinterização

O procedimento de pré-sinterização é necessário na medida em que confere aos blocos prensados a estabilidade necessária para poderem ser maquinados com ferramentas de fresagem. O perfil de temperatura selecionado e a duração do ciclo de pré-sinterização determinam a resistência do material e as propriedades de processamento e têm impacto no processo de sinterização final.

O procedimento único de pré-sinterização efetuado nas unidades de produção da Kuraray Noritake Dental produz peças em bruto que são estáveis no seu estado pré-sinterizado. Embora mais estável, o "KATANA™ Zirconia" pré-sinterizado é maquinável com ferramentas de fresagem comuns com revestimento de diamante, sem qualquer risco acrescido de quebra ou maior desgaste da ferramenta.

Sinterização rápida no laboratório

O procedimento único tem um impacto positivo na suavidade da superfície após a fresagem e pode reduzir significativamente os tempos de sinterização. No laboratório de prótese dentária, os tempos de sinterização podem ser reduzidos para 54 minutos* para restaurações unitárias e pontes de até três elementos - uma opção interessante para casos urgentes e repetições.

*O material é retirado do forno a 800 °C.

O YML "KATANA™ Zirconia" foi sinterizado rapidamente (programa de sinterização de 90 minutos), enquanto os discos dos concorrentes foram sinterizados utilizando programas de sinterização típicos de um dia para o outro, adequados para o material específico. Mesmo com uma sinterização de 90 minutos, o KATANA™ Zirconia YML apresenta propriedades ópticas superiores em comparação com os principais concorrentes.

São oferecidos programas de sinterização uniformes para toda a série multicapas "KATANA™ Zirconia"

Visão geral dos protocolos de sinterização recomendados.

Sinterização rápida no consultório

Ao utilizar o bloco "KATANA™ Zirconia" com o sistema CEREC da Dentsply Sirona, é possível sinterizar coroas unitárias ou pontes de até três elementos em 18-30 minutos sem comprometer as propriedades mecânicas ou ópticas.

Os blocos "KATANA™ Zirconia" apresentam propriedades ópticas superiores após 18 minutos de sinterização em comparação com amostras de matérias-primas dos principais concorrentes após programas de sinterização de 30 e 60 minutos concebidos pela Kuraray Noritake Dental, com base nas recomendações do fabricante.

Propriedades únicas da "KATANA™ Zirconia"

Em conjunto, estes esforços realizados pela Kuraray Noritake Dental para produzir zircónia dentária de alta qualidade fazem toda a diferença. A série "KATANA™ Zirconia" - "KATANA™ Zirconia" Yttria Multi Layered (YML), Ultra Translucent Multi Layered (UTML), Super Translucent Multi Layered (STML), High Translucent Multi Layered Plus (HTML Plus) e KATANA™ Zirconia High Translucent Mono Layered (HT) - tem uma estrutura homogénea de alta densidade com baixa porosidade e um elevado nível de pureza. Além disso, o "KATANA™ Zirconia" YML oferece uma estrutura contínua, sem linhas de transição, apesar da gradação da resistência à flexão. Todas estas propriedades otimizam o desempenho das peças em bruto durante a maquinação.

Imagens MEV de "KATANA™ Zirconia" não polida e de um material da concorrência com uma ampliação de 33×. As quatro imagens de cada material mostram a estrutura da superfície em diferentes áreas de uma coroa de um molar. Em todas as áreas, a superfície da restauração feita com o material da concorrência é mais áspera e apresenta mais porosidade do que a superfície da coroa de "KATANA™ Zirconia" diretamente após a fresagem, de acordo com os resultados da investigação do Dr. Josef Kunkela. Um dos fatores que contribui para este resultado da "KATANA™ Zirconia" é o disco em bruto mais densamente prensado e com tamanhos de grão mais pequenos. (Cortesia da Academia de Investigação Kunkela pelo Dr. Josef Kunkela).

Rugosidade da superfície

Um comportamento otimizado durante o processamento produz margens de restauração regulares, superfícies lisas e um ajuste preciso das restaurações. Este último aspeto deve-se ao facto de o comportamento de fresagem e a contração volumétrica durante a sinterização final serem altamente previsíveis, de modo que um utilizador que projete um espaço para o cimento de 20 μm obterá exatamente o que deseja. Graças ao grande controlo das propriedades ópticas e à excelente correspondência com as cores VITA clássicas A1-D4, o "KATANA™ Zirconia" é considerado uma das opções de zircónia dentária mais estéticas disponíveis no mercado.

Excelente ajuste marginal

Imagens MEV que mostram o ajuste de restaurações realizadas com dois materiais diferentes (dissilicato de lítio e "KATANA™ Zirconia" Block STML) num pilar dentário. A restauração de "KATANA™ Zirconia" mostra uma margem mais regular e um ajuste mais preciso (com um espaço para o cimento de 19-21 μm) do que a coroa de dissilicato de lítio (espaço para o cimento 26-45 μm). (Cortesia da Academia de Investigação Kunkela pelo Dr. Josef Kunkela).

Margens extremamente regulares de uma coroa de "KATANA™ Zirconia" após a fresagem, o que também é um resultado da estrutura favorável do material.

Para garantir todas as propriedades desejadas do material, incluindo a estética e a resistência, uma coisa é essencial: a maquinação efetuada no laboratório de prótese dentária - fresagem e sinterização - tem de respeitar os protocolos recomendados. Isto significa que a máquina de fresagem e o forno devem ser limpos e calibrados regularmente, o que proporciona as condições para um processamento otimizado da zircónia desde o pó até à restauração dentária final, fiel à realidade.

Mathias Fernandez Y Lombardi

Gestor Científico da UE Cerâmica dentária e materiais CAD/CAM

Kuraray Europe GmbH

Clinical Case by DT Ghaith Alousi

What does it take to reconstruct teeth according to the patient’s individual sense of beauty? Experience shows that copying nature is the secret of success. To become a good duplicator, it is essential to develop an eye for detail with regard to tooth forms, surface morphology and the internal colour structure of the teeth to be copied. In addition, the duplicator needs to develop an understanding of the materials and tools used to copy those details. The last key success factor is taking pleasure in interacting with patients.

Read the clinical case created by Ghaith Alousi and published in the LabLine magazine’s Autumn edition now and learn about his approach to creating aesthetic restorations, mimicking nature and truly individualising restorative treatments.

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!

Interview with DT Giuliano Moustakis

The percentage of restorations made of zirconia in a full-contour (monolithic) design is steadily increasing. As an enabler of this development, companies like Kuraray Noritake Dental Inc. have introduced high-performance zirconia materials with well-balanced optical and mechanical properties along with innovative finishing solutions. A popular example is KATANA™ Zirconia YML with its multi-layered flexural strength, translucency and colour structure. Combined with Esthetic Colorant for KATANA™ Zirconia and CERABIEN™ ZR FC Paste Stain, it is very well suited for a simplified approach to zirconia aesthetics: The Zero-Bake Technique. We had a conversation with DT Giuliano Moustakis about its benefits and areas of application.

Giuliano Moustakis, why is there a need for a new technique related to the finishing of monolithic zirconia restorations?

Like many manufacturers of restorative materials, I truly believe that the trend towards monolithic zirconia restorations is here to stay. The reason is that there is a huge number of patients who place great value on high-quality dental treatments, but have a limited budget. Many of them are interested in metal-free restorations that blend in nicely with the surrounding dentition and are able to withstand the test of time. Reasonable cost is more important to them than highest-end aesthetics. The new materials available on the market allow us to produce restorations with the desired properties, but we need to think about how to combine them in the most effective way to be able to respond to all those demands including the financial one.

Please describe the Zero-Bake Technique.

This technique is based on a monolithic restoration design carried out in the preferred design software. In this step, it is already important to focus on a natural surface morphology – about 80 percent of the morphology are realized in the digital manufacturing procedure. After milling, some morphological details (the last 20 percent) are added with hand instruments. My personal set of instruments consists of two kinds of diamond discs used for the interproximal area of bridges (with virtually no pressure), a round-end straight carbide bur (fine), Panther stones and a zirconia-blade carving instrument. However, any set of instruments that feels comfortable in the hands of its user may be selected for this task. Taking into account the volumetric shrinkage during sintering and the final polishing and glazing, the structure created is ideally slightly over-contoured and clearly defined. It is definitely worth investing time in this preparatory step, as it will make our lives much easier later in the process. After surface texturing, selected colours of Esthetic Colorant for KATANA™ Zirconia – specific dyeing liquids designed for the imitation of natural optical effects – are applied to the surface.

Fig. 1. Working out the details in the interproximal area with rotating disc-shaped instruments.

Fig. 2.  Integration of the micro morphology with a round-end straight carbide bur.

Do you have any recommendations on how to proceed with this set of liquids?

Just follow the colour reproduction of the adjacent natural teeth. With Esthetic Colorant, we want to create beautiful illusions, and nature is our best source of inspiration. To be able to copy what we see, however, we need to understand the properties and behaviour of the materials we use. Consequently, I strongly recommend to test them extensively. For example, you may train on remnants of zirconia blanks before moving on to real patient cases. The duration of the testing period should depend on the outcomes produced, which should be highly predictable at the moment the first patient case is started. I experimented and practiced with Esthetic Colorant for about six months, and did use it on the first real case after one moth of practicing.

Nowadays, there are five effect liquids which I use on a daily basis in almost every case:

• A Plus: Used mainly in the vestibular cervical and palatal cervical and mamelon areas to increase the chroma of A dentin shades
• Blue: Used to reproduced the blueish enamel colour found in the area of the incisal edge and occlusal cusps
• Gray: Used (often in addition to Blue) to reproduce the grayish enamel colour found on the incisal edge and cusps
• Orange: Used to give an orange appearance to the cervical area and to intensify the contours of the mamelons
• Brown: Used to reproduce the dentin colour in the cervical area and to darken the colour in the main groove

In addition, there is a liquid with a special function I value highly: Opaque. This modifier liquid is applied on the intaglio of a restoration to mask discoloured or metal abutments. In order to intensify the effects of this and other liquids, they may be applied to a single spot up to three times.

Fig. 3.  Basic chromatic map for Individualization in the anterior region.

Fig. 4.  Restoration after sintering.

Fig. 5.  Frontal view of a complex restoration including gum parts with information on where to apply which type of Esthetic Colorant.

Fig. 6.  Basal view of the restoration with Opaque applied to mask the screws, and Violet and Pink to add colour to the gums.

Fig. 7.  Occlusal view with colour recommendations.

How do you apply Esthetic Colorant and what are the steps that follow once you have applied them?

For application, I use the dedicated Liquid Brush Pen for Esthetic Colorant. They allow for a controlled application of the desired amount of liquid and thus support predictable outcomes. Once all Esthetic Colorant liquids are applied, it is essential to dry the zirconia at a temperature between 80 and 200° C for a minimum of 30 minutes. During application of the liquids and drying, any contact with metal must be prevented. Therefore, the brushes used during application must be metal-free, and the same holds true for the tray. By adhering to this rule, discolouration is effectively prevented. The subsequently selected sintering protocols are not affected by the effect liquids – and the same for all types of zirconia from the KATANA™ Zirconia Multi-Layered series. Once sintered and cooled down, the surface of the restorations is finished with a set of polishing instruments. My tip in this context is to be careful not to destroy the micro morphology created in the pre-sintering step. To add the final gloss and natural fluorescence, the surface is treated by sandblasting for the application of CERABIEN™ ZR FC Paste Stain, fixed in a single glaze firing procedure.

Does the technique also work without glazing?

Yes, it is definitely possible to do without this step. In this case, however, the restoration will not offer a fluorescent effect. Whenever a restoration is finished without glazing, the surface must be perfectly polished. If completely smooth, the hardness of the material will not cause any harm to the opposing dentition.

What are the main indications for the Zero Bake Technique?

Personally, I use it most often in the context of complex reconstructions and in the posterior region, especially when the available space is limited. It allows for minimal wall thicknesses and the surface is – when well-polished – more antagonist-friendly than a lithium disilicate surface. In other cases, and depending on the financial budget, digitally produced dentin-core crowns are a great option. The dentin core is milled from KATANA™ Zirconia YML, the enamel added using CERABIEN™ ZR Luster Porcelains. Esthetic Colorant, internal stans and CERABIEN™ ZR FC Paste Stain may be added for individual effects. Compared to traditional full porcelain layering, this concept is quicker, involves a lower shrinkage, offers a high stability due to the specific framework design and requires a thinner wall thickness (e.g. 0.6 mm strength of the dentin core plus 0.6 mm porcelain).

Fig. 8.  Example of a dentin-core restoration. The surface morphology is refined with a Panther stone.

Why is it important to develop new design and finishing concepts nowadays?

To my mind, a lack of time is the greatest issue of modern dental technology. Due to a lack of skilled personnel and an expected decrease in the number of dental laboratories in many countries around the globe, we have to keep looking for concepts that help us reduce the time pressure and make our lives easier. While simplifying procedures, however, we need to provide for the same or even a higher quality of the outcomes. This is exactly what I wanted to achieve when starting to develop the Zero-Bake Technique. My personal gain is more free time.

Why do you share your ideas with others by working as an instructor and lecturer?

I simply enjoy interacting with colleagues, equipping them with knowledge and letting them benefit from good ideas.

Dentist:

DT GIULIANO MOUSTAKIS

Giuliano Moustakis has more than 30 years of expertise as dental technician. He was born in Greece but currently resides in Germany, where he has a lab in Falkensee. Giuliano studied at the School of Dental Technology (SBIE) in Athens, Greece. Over the years he completed several other studies in Germany and Japan, including: the maxillofacial prosthetic technician (IASPE), advanced education in functional diagnosis of the temporomandibular joint, Curriculum implant prosthetics for dental technicians (DGZI). He has been a global instructor at Kuraray Noritake Dental Inc. since 2019. Last but not least it is important to note that he is also a gifted and enthusiastic photographer.

As an instructor and consultant for Kuraray Noritake Italia, I received my first set of Esthetic Colorant dyeing liquids for testing purposes approximately one year ago. When the package arrived in the dental laboratory, it made me curious immediately and I simply could not wait to start using the colourful liquids on KATANA™ Zirconia.

I started with some simple test work, applied the basic liquids like A Plus to pre-sintered zirconia, played a little with Gray and Violet and put the structures into the sintering furnace to reveal the obtained effects. The outcome was so convincing that I was sure Esthetic Colorant would be a great addition to the range of materials used in my laboratory for the production of zirconia restorations. The liquids would support me ideally by giving more character to my restorations from the inside.

To my mind, the use of Esthetic Colorant is convenient for two reasons:

1. KATANA™ Zirconia is a very compact material, even in its green (pre-sintered) state. This property is not only responsible for a great performance in terms of milling accuracy, stability and surface quality, but also provides for a controlled penetration of the effect liquids into the structure. They neither diffuse too deep into the zirconia nor do they spread too much on the surface.
   
   
2. Esthetic Colorants are water-based infiltrating liquids with a very light colour effect. Hence, they do not create such marked characterization effects like liquids from other companies. This is a huge advantage in my eyes, because I can characterize my zirconia internally without exaggerating. This allows me to copy lightly to moderately intensive effects, while giving depth to some areas of the tooth. Great examples are the occlusal table of a posterior restoration or incisal effects in the anterior region. In addition, I am able to shield the grayish effect resulting from a metal post or discoloured abutment tooth with the Esthetic Colorant Opaque applied to the inner surface of a restoration.

In short: I think Esthetic Colorants are fantastic. Just try them out yourself, because seeing is believing!

DT FRANCESCO NAPOLITANO

Nola (NA) ITALY