ALAN RODRIGO MUNIZ PALIALOL
INFLUÊNCIA DO PROTOCOLO ADESIVO NAS PROPRIEDADES
FÍSICO-QUÍMICAS E RESISTÊNCIA DE UNIÃO À CERÂMICA DE CIMENTOS
RESINOSOS EXPERIMENTAIS CONTENDO SISTEMA FOTOINICIADOR
TERNÁRIO
INFLUENCE OF ADHESIVE PROTOCOL ON PHYSICOCHEMICAL
PROPERTIES AND CERAMIC BOND STRENGTH OF EXPERIMENTAL
RESIN CEMENTS CONTAINING TERNARY PHOTOINITIATOR SYSTEM
Piracicaba
2017
UNIVERSIDADE ESTADUAL DE CAMPINAS
FACULDADE DE ODONTOLOGIA DE PIRACICABA
INFLUÊNCIA DO PROTOCOLO ADESIVO NAS PROPRIEDADES
FÍSICO-QUÍMICAS E RESISTÊNCIA DE UNIÃO À CERÂMICA DE CIMENTOS
RESINOSOS EXPERIMENTAIS CONTENDO SISTEMA FOTOINICIADOR
TERNÁRIO
INFLUENCE OF ADHESIVE PROTOCOL ON PHYSICOCHEMICAL
PROPERTIES AND CERAMIC BOND STRENGTH OF EXPERIMENTAL
RESIN CEMENTS CONTAINING TERNARY PHOTOINITIATOR SYSTEM
Tese apresentada à Faculdade de Odontologia de Piracicaba, da Universidade Estadual de Campinas, como parte dos requisitos exigidos para obtenção do Título de Doutor em Clínica Odontológica, Área de Concentração em Dentística.
Thesis presented to the Piracicaba Dental School of the University of Campinas in partial fulfillment of the requirements for the degree of Doctor in Clinical Dentistry, in Restorative Dentistry area.
Orientador: Profa. Dra. Giselle Maria Marchi Baron
ESTE EXEMPLAR CORRESPONDE À VERSÃO FINAL DA TESE DE DOUTORADO DEFENDIDA PELO ALUNO ALAN RODRIGO MUNIZ PALIALOL, ORIENTADO PELA PROFA. DRA. GISELLE MARIA MARCHI BARON.
Piracicaba
2017
Agência(s) de fomento e nº(s) de processo(s): FAPESP, 2014/02898-7
Ficha catalográfica Universidade Estadual de Campinas Biblioteca da Faculdade de Odontologia de Piracicaba
Marilene Girello - CRB 8/6159 Palialol, Alan Rodrigo Muniz,
P176i PalInfluência do protocolo adesivo nas propriedades físico-químicas e resistência de união à cerâmica de cimentos resinosos experimentais contendo sistema fotoiniciador ternário / Alan Rodrigo Muniz Palialol. – Piracicaba, SP : [s.n.], 2017.
PalOrientador: Giselle Maria Marchi Baron.
PalTese (doutorado) – Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba.
Pal1. Cerâmica. 2. Cimentos de resina. 3. Adesivos. 4. Fotopolimerização. I. Marchi, Giselle Maria,1970-. II. Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba. III. Título.
Informações para Biblioteca Digital
Título em outro idioma: Influence of adhesive protocol on physicochemical properties and
ceramic bond strength of experimental resin cements containing ternary photoinitiator system Palavras-chave em inglês: Ceramic Resin cements Adhesives Photopolymerization
Área de concentração: Dentística Titulação: Doutor em Clínica Odontológica Banca examinadora:
Giselle Maria Marchi Baron [Orientador] Rafael Pino Vitti
William Cunha Brandt Vanessa Cavalli Gobbo Luis Roberto Marcondes Martins
Data de defesa: 23-02-2017
Programa de Pós-Graduação: Clínica Odontológica
DEDICATÓRIA
Dedico este trabalho ao meu pai Antônio, à minha mãe Rosimeiri, ao meu irmão Thiago e à toda minha família pelo apoio, amor e compreensão durante toda esta jornada.
AGRADECIMENTOS ESPECIAIS
A Deus, por estar sempre presente iluminando minha vida, guiando meus passos e me dando força para seguir em frente.
Aos meus avós João, Maria, Antônio e Yolanda pela torcida, apoio, amor e carinho mesmo estando ausente na maior parte do tempo.
A todos os familiares que sempre torceram e incentivaram minha caminhada nessa jornada. Obrigado pelo apoio!
Ao irmão crossfitero que Piracicaba me deu, Diogo Dressano e sua família. Só tenho a agradecer pela parceria e palavras de incentivo e apoio nos momentos bons e ruins. Meu muito obrigado! Tamo junto mlk!
Aos amigos e parceiros de pesquisa Adriano Lima e Luciano Gonçalves, pela parceria, paciência, ensinamentos e convivência que se estende até hoje! Muito obrigado!
À minha orientadora Profa. Giselle Maria Marchi Baron, exemplo de pessoa e profissional a ser seguido. Serei sempre grato pelas oportunidades, pela confiança no meu trabalho, pelos ensinamentos acadêmicos e conselhos na vida pessoal. Sinto orgulho de ter sido seu orientado! Muito obrigado!
AGRADECIMENTOS
À direção da Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas, na pessoa do Diretor Prof. Dr. Guilherme Elias Pessanha Henriques e do Diretor Associado Prof. Dr. Francisco Haiter Neto.
Ao Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), pelo auxílio financeiro na concessão de bolsa e à Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), pela concessão de bolsa de Doutorado (2014/02898-7) e de Estágio e Pesquisa no Exterior (2014/23317-2) que possibilitaram a realização desse trabalho.
À Coordenadoria Geral da Pós-Graduação da FOP/UNICAMP, em nome da Profa. Dra. Cinthia Correia Machado Tabchoury, do secretário Leandro Viganó e da secretária Alessandra Pinho Sinhoreti, por toda atenção.
À minha Supervisora durante estágio de pesquisa no exterior (2015) na Oregon Health and Science University, Profa. Dra. Carmem Silvia Pfeifer, uma pessoa ímpar, outro exemplo a ser seguido! Obrigado pelos desafios que me fizeram crescer, por toda atenção, paciência e ensinamentos transmitidos com a maior boa vontade e dedicação.
Aos professores da Oregon Health and Science University, Prof. Dr. Jack Ferracane e Prof. Dr. Luiz E. Bertassoni pelos ensinamentos e convivência durante o estágio de pesquisa no exterior.
Aos Profs. Flavio Henrique Baggio Aguiar, Fernanda Miori Pascon e Anderson Catelan pelas sugestões e idéias que colaboraram para o enriquecimento desse trabalho no exame de qualificação.
Aos Profs. Luis Roberto Marcondes Martins, Vanessa Cavalli, Rafael Pino Vitti e William Cunha Brandt pelas correções, sugestões e idéias que colaboraram para o enriquecimento desse trabalho na defesa de Tese.
Aos Profs. Luis Roberto Marcondes Martins, Flávio Henrique Baggio Aguiar, Larissa Sgarbosa de Araújo Matuda e Anderson Catelan pelo aceite do convite para membro suplente durante os exames de qualificação e defesa de tese.
Aos Profs. Da Área de Dentística, Profa. Dra. Giselle Maria Marchi Baron, Profa. Dra. Débora Alves Nunes Leite Lima, Profa. Dra. Vanessa Cavalli, Prof. Dr. Flávio Henrique Baggio Aguiar, Prof. Dr. Marcelo Giannini, Prof. Dr. Luis Alexandre Maffei Sartini Paulillo, Prof. Dr. Luis Roberto Marcondes Martins, Prof. Dr. José Roberto Lovadino, pelos conhecimentos transmitidos na área clínica e acadêmica que contribuíram para o meu crescimento profissional.
Aos amigos de pós-graduação Ailla Lancellotti, Maria Beatriz D’Arce, Maria Humel, Ciça, Hugo, Anderson Catelan, Livia Aguilera, Larissa Sgarbosa, Kamila Andrade, Juliana Públio, Felipe Nogueira Anacleto, Bruno Vilela Muniz, Thais Mageste, pela convivência e por tornar os dias mais agradáveis.
Aos amigos de República durante a graduação, Guilherme Ramos Costa, Vitor Hugo, Leonardo Filizzola, Anderson de Souza, Fernando Domingos, Rafael Kinouti, Fabrício Fonseca, pela convivência, parceria e amizade acima de tudo!
Aos amigos de República durante a pós-graduação, Adriano Lima, Lucas Moura, Armando Kaieda, Leonardo Santos e Anderson Catelan pela convivência nas horas boas e difíceis e por tornar mais fácil a vida longe da minha família. Muito obrigado pela parceria e amizade!
Aos amigos que a FOP me deu na graduação e continuam presentes até hoje Thatiana de Vicente Leite, Daniel Sunfeld e Diogo Silva. Obrigado pela convivência e amizade.
Aos colegas de mestrado e doutorado deste e de outros programas.
À funcionária da Área de Dentística Mônica, pela convivência e por se mostrar sempre solícitas e prestativa quando precisei.
Ao Engenheiro Mecânico Marcos Blanco Cangiani, sempre solícito e pronto para ajudar na hora do aperto.
Ao Biólogo e técnico do setor de Microscopia Eletrônica de Varredura Adriano Martins pela ajuda e auxílio quando precisei.
Ao protético Carlos Donato pela comprometimento e colaboração com este trabalho.
A todos os funcionários da limpeza por tornarem o ambiente de trabalho limpo e agradável para todos.
À Suha (in memoriam) pelo companheirismo, fidelidade e proteção, conquistados com muito esforço e persistência, devido o seu valor.
RESUMO
No presente estudo foi avaliado a influência do protocolo adesivo nas propriedades físico-químicas e resistência de união (RU) à cerâmica de cimentos resinosos experimentais (CREs) contendo um sistema fotoiniciador ternário. Foram preparados cinco formulações de CREs contendo como base os monômeros Bis-GMA e TEGDMA (na proporção 1:1 em massa). O sistema fotoiniciador foi composto por 1 mol% de canforoquinona, 2 mol% de amina terciária 2-(dimetilamino) etil metacrilato e diferentes concentrações do sal hexafluorofosfato de difeniliodôno (DFI): 0; 0,25; 0,5; 1 e 2 mol%, definindo assim, cinco formulações de CREs. Como inibidor, foi acrescido à mistura 0,1 mol% de hidroxitolueno butilado e 60% em peso de partículas silanizadas de vidro de bário-alumínio-silicato foram incorporadas como carga inorgânica. Diante disso, dez grupos foram estabelecidos de modo que metade foi confeccionado sem a mistura com adesivo Adper Scotchbond Multi-Purpose - bond (G1 – G5) e a outra metade com a mistura de 3 µl de adesivo (G6 - G10). A fotoativação, para todos os testes, foi realizada através de um bloco de cerâmica IPS e.max com LED Bluephase G2 a 1265.5 mW/cm2 por 60 segundos. Para o teste de RU foram confeccionados setenta espécimes de cerâmica IPS e.max (n=7; 10 mm x 10 mm x 3 mm). Os espécimes foram cimentados em blocos de resina fotopolimerizável Filtek Z250 (10 mm x 10 mm x 5 mm). Após armazenamento em estufa por 24 horas a 37oC, as amostras foram seccionadas para obtenção de palitos (25 a 30 por bloco). Metade dos palitos de cada bloco foram submetidos ao ensaio de microtração imediato em máquina de ensaio universal EMIC (velocidade de 0,5 mm/min). A outra metade foi separada para o teste de microtração após armazenamento em água destilada pelo período de um ano. Foi realizado análise do padrão de fratura em lupa estereoscópica (Leica MZ75). Adicionalmente, foi avaliado a resistência coesiva (RC) dos CREs (n=10), cinética de polimerização e grau de conversão (GC) em espectrômetro de infravermelho transformado de Fourier (FTIR) (n=5) e teste de sorção e solubilidade (SS) (n=5). Os dados foram analisados através do teste de análise de variância (medidas repetidas para RU e 2 fatores para os demais testes) e teste Tukey, a um nível de significância de 5%. Para os valores de RU, não houve diferença estatísitca entre os grupos, tanto no tempo imediato quanto após o armazenamento (p>0,05). Da mesma forma, não houve diferença estatística entre os tempos imediato e após armazenamento (p>0,05). O grupo 0 mol% DFI apresentou os maiores valores de solubilidade e os menores valores para GC e RC
(p<0,05). Os demais grupos apresentaram valores semelhantes entre si (p>0,05). A adição do adesivo aumentou os valores de GC apenas para o grupo 0 mol% DFI (p<0,05). A adição do sal DFI melhorou a reatividade e as propriedades físico-químicas dos CREs, porém, não foi capaz de aumentar a RU à cerâmica. O uso do adesivo não exerceu influência nas propriedades físico-químicas dos CREs contendo sal de DFI. O armazenamento em água destilada por um ano não reduziu a RU à cerâmica.
Palavras-chave: Cerâmica. Cimento resinoso. Adesivo. Hexafluorofosfato de difeniliodônio.
ABSTRACT
The present study evaluated the influence of an adhesive protocol on physicochemical properties and ceramic bond strength (BS) of experimental resin cements (ERCs) containing a ternary photoinitiator system. For this purpose, five ERCs were prepared using a Bis-GMA/TEGDMA (1:1 molar ratio) base compound. The photoinitiator system was composed by 1 mol% of camphorquinone, 2 mol% of dimethylaminoethil methacrylate and different diphenyliodonium hexafluorophosphate (DPI) salt different concentrations of 0, 0.25, 0.5, 1 or 2 mol%, resulting in five ERCs. As an inhibitor, 0.1mol% of hydroxyl butyl toluene was used and a 60% in weigth of silanated barium-aluminum-silicate glass for fillers particles. Thus, ten groups were established so that one half was performed without adhesive mixture (G1-G5) and the other half (G6-G10) with adhesive mixture of 3 µl of Adper Scotchbond Multi-Purpose – Bond. For all laboratory tests, the light curing was performed through an IPS e.max ceramic block with Bluephase G2 light source at 1265.5 mW/cm2 for 60 seconds. Seventy IPS e.max Press ceramic specimens (10 mm x 10 mm x 3 mm) were fabricated and randomly divided among the ten groups (n=7) previously established. The specimens were fixed to light curing composite resin Filtek Z250 blocks (10 mm x 10 mm x 5 mm). After storage for 24 hours at 37oC, the specimens were sectioned perpendicular to the bond interface (25 to 30 beams per block) and half of the beams of each block were submitted to immediate microtensile bond strength test. The other half was separated for the microtensile test after storage in distilled water for one year. The failure mode was analyzed by a stereomicroscope (Leica MZ75) at 40x magnification. Additionally, it was evaluated the ultimate tensile strength (UTS) of ERCs using hourglass shape specimens (n=10). Degree of conversion (DC) and real-time polymerization kinetics were measured in disc shape specimens (n=5) using near-infrared spectroscopy (NIRS). Water up take and solubility (WS) were assessed too using disc shape specimens (n=5). Data were analyzed using analysis of variance (repeated measures for BS test and two criteria for the other tests) and Tukey test at a significance level of 5%. For immediate and after water storage BS values, there was no statistical difference between groups (p>0,05). Similarly, there was no statistical difference between immediate and after one year of water storage (p>0,05). The 0 mol% DPI ERC showed the higher values of WS and the lower values for DC, maximum rate of polymerization and UTS (p<0,05). The others ERCs presented similar values and were
not statistically different from each other (p>0,05). The addition of adhesive led to higher DC values only for 0 mol% DPI ERC (p<0,05). The addition of DPI salt improve the reactivity and physicochemical properties of ERCs. The adhesive had no influence on the physicochemical properties of ERCs containing DPI salt. Addition of a DPI salt to light-activated ERCs increased its DC, but was not able to increase the BS between the ceramic and resin materials. For this study, one year of water storage was not capable of jeopardizing ceramic BS.
Keywords: Ceramics. Resin cement. Adhesive system. Diphenyliodonium hexafluorophosphate.
SUMÁRIO
1 INTRODUÇÃO 15
2 ARTIGO: Influence of adhesive protocol on physicochemical properties and ceramic bond strength of experimental resin cements containing ternary photoinitiator system 18 3 CONCLUSÃO 39
REFERÊNCIAS 40
APÊNDICE 1 – Detalhamento das metodologias 45
ANEXO 1 – Comprovante de submissão do artigo 52
15 1 INTRODUÇÃO
As cerâmicas são materiais utilizados rotineiramente em procedimentos restauradores estéticos na odontologia devido as suas excelentes propriedades como alta resistência à compressão, estabilidade química, baixa condutibilidade elétrica, difusibilidade térmica, alta translucidez, alta fluorescência, biocompatibilidade, estética favorável e coeficiente de expansão térmica similar ao da estrutura dental (Anusavice, 1996; Borges, et al., 2003). De acordo com sua composição química, tais cerâmicas podem ser classificadas em: cerâmicas com óxidos metálicos e cerâmicas vítreas (Tian et al., 2014). As cerâmicas com óxidos metálicos são constituídas em maior parte pela sua fase cristalina (cristais de alumina ou zircônia), não apresentando mais do que 15% de matriz vítrea, ou praticamente sem matriz vítrea (Kern, 2009). Já as cerâmicas vítreas (feldspática, leucita, dissilicato de lítio) são compostas por uma matriz de vidro reforçada por cristais dispersos na sua estrutura (Hölland, 2000; Conrad et al., 2007; Sundfeld Neto et al., 2015).
A alteração da superfície de cerâmicas vítreas pelo condicionamento com ácido fluorídrico, resulta no aumento da área de superfície de contato proporcionando melhor interação entre cerâmica e agente cimentante (Kukiattrakoon & Thammasitboon, 2007; Zogheib et al., 2011). Para melhor aproveitamento do aumento da área de superfície, o cimento deve apresentar uma capacidade de molhamento da superfície adequada que consiga infiltrar nas irregularidades promovidas pelo condicionamento ácido (Oh et al., 2002).Apesar do uso do silano na união à cerâmica ser bem consolidado na literatura (Guarda et al., 2013; Yavuz et al., 2012), ainda existem poucos estudos avaliando a necessidade de aplicação do adesivo antes do uso do cimento resinoso (Oh et al., 2002; Naves et al., 2010) e muitos fabricantes recomendam a aplicação do cimento resinoso diretamente sobre a superfície silanizada da cerâmica. No entanto, é questionável se a combinação entre apenas agente silano e cimento resinoso seria capaz de promover a melhor combinação entre o cimento e as irregularidades promovidas pelo condicionamento ácido da cerâmica.
16 técnica adesiva de cimentação. Cimentos resinosos são eleitos como primeira escolha no procedimento de cimentação de restaurações em cerâmica pura, pois proporcionam vantagens como maior qualidade do selamento marginal, boa retenção, menor solubilidade e aumento da resistência à fratura da cerâmica (Burke et al., 2002; Guazzato et al., 2004a). Quanto ao modo de ativação, os cimentos resinosos podem ser classificados como quimicamente ativados, fotoativados e de dupla ativação (Pedreira et al., 2009; Baena et al., 2012). Dentre as principais características, os cimentos fotoativados apresentam algumas vantagens frente aos cimentos com ativação química, como maior controle do tempo de trabalho e melhor estabilidade de cor (Hekimoglu et al., 2000; Good et al., 2008). Entretanto, diante do efeito de atenuação da luz ativadora promovido pela cerâmica (Moraes et al., 2008; Arrais et al., 2009; Pick et al., 2010), a polimerização adequada deste tipo de cimento torna-se mais difícil. Sabe-se que as propriedades mecânicas de um compósito dependem da estrutura polimérica formada (smussen & Peutzfeldt, 2001) e do grau de conversão (Lovell et al., 2001), que estão estritamente relacionados com uma polimerização eficaz (Elliott et al., 2001). Sendo assim, a polimerização inadequada do material de cimentação pode resultar em propriedades mecânicas deficientes, maior sorção de água, maior solubilidade e menor estabilidade de cor (Watts, 2005; Ferracane, 2006; Ruttermann, et al., 2010).
Outra opção para este tipo de procedimento seria a utilização de cimentos de dupla ativação, uma vez que possuem o auxílio da ativação química para obtenção de adequada conversão, mesmo com menor incidência de luz (Prieto et al., 2013). Porém, os sistemas de dupla ativação possuem maior quantidade de amina terciária, molécula que sofre oxidação ao longo do tempo acarretando em alteração da cor do cimento, fator que pode comprometer a estética obtida inicialmente em restaurações anteriores de cerâmica pura (Lu & Powers, 2004; Ghavam et al., 2010; Kilinc et al., 2011).
Encontra-se, na literatura, uma possibilidade para melhorar a polimerização de compósitos fotoativados através do aumento de sua reatividade por meio da utilização de sistemas fotoiniciadores mais eficazes. Ogliari e colaboradores (2007) observaram a efetividade da adição de diferentes concentrações de um sal de ônio (hexaflurfosfato de difeniliodônio) na cinética de polimerização de adesivos dentinários. O estudo
17 demonstrou que a utilização conjunta com canforquinona, o fotoiniciador mais comumente utilizado em compósitos odontológicos, pode promover a decomposição de sais de ônio, permitindo que o mesmo atue na geração de radicais livres e, consequentemente, no aumento da reatividade de polimerização de metacrilatos.
Baseado nos resultados obtidos, Gonçalves e colaboradores (2013), avaliaram a influência da incorporação do sal de hexafluorfosfato de difeniliodônio na reatividade de cimentos resinosos experimentais fotoativados. A adição do sal nos cimentos resinosos elevou os valores das propriedades mecânicas do material, além de aumentar a reatividade e melhorar os valores de conversão monomérica dos cimentos em questão.
Entretanto, sabe-se que durante o procedimento de cimentação de facetas ou laminados cerâmicos é comum a fotoativação da camada de adesivo (aplicada no dente e na peça) e cimento resinoso ao mesmo tempo (Gresnigt & Özcan, 2011; Rigolin et al., 2014) e não se sabe qual seria o efeito dessa combinação/mistura nas propriedades do compósito formado na interface dente/cerâmica.
Sendo assim, o objetivo do presente estudo foi analisar a resistência de união a longo prazo destes cimentos experimentais com e sem adesivo, sob desafio de degradação hidrolítica, bem como o estudo de suas propriedades físico-químicas nas condições de cimentação adesiva.
18 2 ARTIGO: Influence of adhesive protocol on physicochemical properties and ceramic bond strength of experimental resin cements containing ternary photoinitiator system
Artigo submetido ao periódico The Journal of Prosthetic Dentistry (Anexo)
Alan R. M. Palialol, Flávio H. B. Aguiar, Hugo F. do Vale, Diogo Dressano, Luciano S. Gonçalves, Adriano F. Lima, Giselle M. Marchi
Abstract
The aim of this study was to evaluate the effect of an adhesive on ceramic bond strength and physicochemical properties of experimental resin cements (ERCs) containing a ternary photoinitiator system. ERCs were prepared using a Bis-GMA/TEGDMA (1:1 molar ratio) base monomers with silanated glass fillers (60% wt). The photoinitiator system used was camphorquinone (CQ-1mol%), dimethylaminoethyl methacrylate (DMAEMA-2mol%) and different DPI concentrations (0, 0.25, 0.5, 1 or 2 mol%). Ten groups were established so that one half was performed with addition of 3 µl of adhesive (G6-G10) and the other half with no adhesive addition (G1-G5). Light curing was performed through an IPS e.max ceramic block with Bluephase G2 light source at 1200 mW/cm2 for 60 seconds. Seventy IPS e.max Press ceramic specimens (10 mm x 10 mm x 3 mm) were fabricated for the ceramic bond strength (BS) test. The specimens were fixed to light curing composite resin Filtek Z250 blocks (10 mm x 10 mm x 5 mm). Ultimate tensile strength (UTS) was performed using hourglass specimens (n=10). Degree of conversion (DC) and real-time polymerization kinetics were carried out using near-infrared (NIR) spectroscopy in disc shape specimens (n=5). Water sorption and
19 solubility (WS) test were performed using disc shape specimens (n=5). Data were analyzed using analysis of variance (two criteria and repeated measures) and Tukey test (α=0.05). All groups presented similar BS to the ceramic. Similarly, there was no statistical difference between immediate BS and after one year of water storage. The 0 mol% DPI ERC showed higher values of WS and lower values of DC, maximum rate of polymerization and UTS. The others ERCs presented similar values and were not statistically different from each other. The addition of adhesive led to higher DC values only for 0 mol% DPI ERC. The addition of DPI salt improves the reactivity and physicochemical properties of ERCs. The adhesive had no influence on the physicochemical properties of ERCs containing DPI salt. Addition of a DPI salt to light curing ERCs increased its DC, but was not able to increase the BS between the ceramic and resin composite materials. For this study, one year of water storage was not capable of jeopardizing ceramic BS.
Key Words: Diphenyliodonium hexafluorophosphate. Resin Cement. Ceramics. Dental Adhesive.
Introduction
Dental ceramics are used for aesthetic restorative procedures due to excellent properties, such as a similar coefficient of thermal expansion to the tooth structure, chemical stability, low electrical conductivity, high compressive strength, thermal diffusivity, translucence and fluorescence1. For effective adhesion, the surface of glassy dental ceramics must be effectively etched using a strong acid, e.g. hydrofluoric, which increases surface free energy and contact area, improving the interaction between the
20 resin cement and ceramic2, 3. However, resinous material must present suitable wettability to infiltrate the ceramic surface irregularities promoted by the etching procedure4. It has been questioned if only resin cement is sufficient to promote suitable adhesion, due to relatively high viscosity that restricts adequate flow properties, and previous studies have demonstrated the positive influence of resin cement to ceramic adhesion following the additional application of an adhesive layer4, 5.
Resin cements are the first choice for cementation of all-ceramic restorations due to good marginal sealing, retention and increase of fracture strength of ceramic6-10. Regarding the curing mode, resin cements can be classified as self curing, light curing, and dual curing11, 12. Light-cured resin cements exhibit more control of working and setting time and improved color stability compared with self-cured types13, 14.
Previous studies have reported the effect of thickness, crystalline structure, and general opacity on light absorption through ceramics15-17 and it is well known that non-optimal polymerization of the resin cement can result in inferior mechanical properties, reduced color stability and greater water sorption and solubility18-20. Therefore, dual curing cements are considered the most appropriate for all-ceramic restorations, since a maximum degree of conversion is more likely to be achieved, even under lower light exposure21. However, dual curing systems present high concentrations of tertiary amine compared with entirely photoactivated materials, since it must have sufficient quantity to react with the chemical initiator (usually, benzoyl peroxide). Nevertheless, the high amount and type of tertiary amine (aromatic) leads to oxidation of this molecule over time, resulting in color change of resin cement, compromising aesthetic quality, mainly in anterior full ceramic restorations22-24. Other negative aspects
21 presented by the dual resin cements are the requirement for mechanically mixing, which may increase air inclusions and decrease mechanical properties25, as well as reduced working time due and less temporal control of the setting reaction, critical for cementation procedures.
A possibility to improve cure and potentially the effectiveness of resin cement may be realized by the use of alternative, or modified photoinitiator systems that improve polymerization efficiency in low light situations. The use of iodonium salts in resinous materials containing camphorquinone (CQ) has been previously reported to improve degree of conversion, flexural strength and flexural modulus, due to increased reactivity of adhesive systems and resin cements26, 27. It follows that a more reactive system with higher quantum yield may assist in providing adequate degree of conversion in lower light conditions through opaque ceramics.
The use of iodonium salts such as diphenyliodonium hexafluorphosphate (DPI) in combination with conventional binary CQ-amine photoinitiator systems increases the degree and rate of polymerization of dental resins by facilitating an increased free radical concentration compared with the binary system alone26, 27. Despite the maximum absorption of DPI at ~200-250 nm, its interaction with the ketone radical formed by activation of CQ-amine system, generates additional active phenyl radicals improving the efficiency of the reaction. The influence of the DPI on mechanical properties of experimental resin cements were demonstrated in previous investigations 28-30.
22 common to light cure the adhesive layer (applied to the tooth and ceramic) and resin cement at the same time40,41. However, it is not known what would be the effect of this combination/mixture of adhesive and cement on the properties of the composite formed at the tooth/ceramic interface.
Therefore, the aim of this study was to evaluate the influence of an adhesive and different DPI concentrations on the long-term ceramic bond strength of light curing experimental cements under hydrolytic degradation challenge, as well as their physicochemical properties. Study hypotheses were: 1) Water storage will decrease ceramic bond strength. 2) Addition of an adhesive to experimental resin cement will not improve physicochemical properties of experimental resin cements. 3) DPI salt will improve ceramic bond strength and physicochemical properties of experimental resin cements.
Material and methods
Transmission of light through ceramic
In order to evaluate the attenuation of light transmitted through ceramic, the irradiance of the LED source (Bluephase G2, Ivoclar-Vivadent, Schaan, Liechtenstein) on ‘High Power’ mode was measured with the calibrated spectrometer (MARC® Resin Calibrator, BlueLight analytics Inc., Halifax, Canada). Three measurements were performed using the bottom surface sensor either without the ceramic at a distance of 0 mm or beneath the ceramic block (3 mm).
23 A monomer blend with 1:1 mass ratio of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl] propane (Bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) (Esstech Inc., Essington, PA, USA) was prepared. Camphorquinone (1mol%) (Esstech) and 2-(dimethylamino) ethyl methacrylate (2mol%) (Sigma–Aldrich, St. Louis, MO, USA) were added as the photoinitiator system. For the model blends, five experimental resin cement (ERC)s were prepared by incorporation of 0 (control), 0.25, 0.5, 1 or 2 mol% of a diphenyliodonium hexafluorophosphate (DPI) salt (Sigma– Aldrich). The monomers were mixed with 60% mass fraction of silanated barium-aluminum-silicate glass fillers (Esstech Inc., 0.7 µm average size). All the compounds were blended using a centrifugal mixing device (SpeedMixer, DAC 150.1 FVZ-K, Hauschild Engineer- ing, Hamm, North Rhine-Westphalia, Germany).
Microtensile bond strength and failure pattern analysis
For the bond strength test, 70 lithium disilicate reinforced ceramic blocks (10 mm length, 10 mm width, 3 mm thickness) (IPS E.max Press, Ivoclar Vivadent, Schaan, Liechtenstein) shade MO1 and 70 microhybrid composite resin blocks (Filtek Z250, 3M ESPE, St. Paul, MN, USA) shade A2 (10 mm length, 10 mm width, 5 mm thickness) were fabricated (n=7). Resin composite blocks were made with an elastomer mold (Express, 3M ESPE, St. Paul, MN, USA) filled with 2 layers, each one light cured for 20 s each using a third generation LED source (Bluephase G2, Ivoclar Vivadent, Schaan, Liechtenstein) with an irradiance of 1266 mW/cm2, measured using a calibrated spectrometer (MARC® Resin Calibrator, BlueLight analytics Inc., Halifax, Canada). Ceramic blocks were etched with 10% hydrofluoric acid (Dentsply, Petrópolis, Brazil) for 20 s, rinsed with air/water spray and air-dried. Then, a silane-coupling agent (RelyX
24 Ceramic Primer, 3M ESPE, St. Paul, MN, USA) was applied on the ceramic surface and
air-dried for 1 min. In groups G6 to G10, a coat of adhesive (Adper Scotchbond
Multi-Purpose -Bond, 3M ESPE, St. Paul, MN, USA) was applied after the silane and light cured together with the cement. A Microman 25 M pipette (Gilson, Villiers-le-Bel, France) was used to standardize the amount of cement (10 µl) and adhesive (3 µl). ERCs were applied on the ceramic surface, and bonded to the composite block. Light-curing was performed through the ceramic for 60 s using the LED source (Bluephase G2) with an irradiance of 1266 mW/cm2. After light curing procedure, the specimens were storage in distilled water at 37°C for 24 h. Following 24 h storage, the specimens were
cross-sectioned perpendicularly to the ceramic-composite interface with a low-speed saw (Isomet, Buehler Ltd., Lake Bluff, IL, USA) under water-cooling, to obtain beams (25 to 30 peer block). Half of beams of each block were submitted to immediate microtensile bond test performed in an universal testing machine (EMIC DL 2000, São José dos Pinhais, PR, Brazil) at a crosshead speed of 0.5 mm/min. The other half was submitted for the storage in distilled water (changed every 15 days) for one year and subsequent microtensile test.
After the microtensile bond-strength test, the fractured interfaces were analyzed under a stereomicroscope (Leica MZ75, Heerbrugg, Switzerland) at 40x magnification and the failure modes were classified into four types: adhesive failure, cohesive failure in ceramic, cohesive failure in composite and mixed failure involving ceramic, cement and composite.
25 Real-time polymerization was analyzed using a Fourier Transform near infrared spectroscopy (FT-NIRS; Nicolet 6700, Thermo Scientific, Hemel Hemstead, UK) monitoring the peak at 6164 cm-1, which corresponded with the vinyl bond -CH2 absorbance. Specimens (6 mm diameter x 0.8 mm thick, n=5) were prepared in a disc shape rubber mold using only the ERCs (G1-G5) or mixing the ERCs with 3 µl of adhesive (Adper Scotchbond Multipurpose Bond, 3M ESPE) (G6-G10). A Microman 25 M pipette (Gilson, Villiers-le-Bel, France) was used to standardize the amount of cement (10 µl) and adhesive (3 µl). Light curing of the ERC specimens was performed using the same LED unit and time of curing used for bond strength test, beneath a IPS E.max Press ceramic block, to simulate the attenuation of light during the cementation procedure. Rate of polymerization was obtained by taking the first derivative between time (s) and conversion (%).
Ultimate tensile strength
Hourglass shape specimens (3 mm base, 0.8 mm thick and constricted area of 1mm2, n=10) were prepared using an elastomer mold (Express, 3M ESPE, St. Paul, MN, USA). For standardize the cement (10 µl) and adhesive (3 µl) quantity, it was used a Microman 25 M pipette (Gilson, Villiers-le-Bel, France). Specimens were light cured using the same Bluephase G2 LED source (Ivoclar Vivadent, Schaan, Liechtenstein) for 60s through an IPS E.max Press ceramic block (Ivoclar Vivadent, Schaan, Liechtenstein) measuring 10 mm in length x10 mm in wide x 3 mm in thickness. After light curing, all specimens were storage in distilled water at 37°C for 24 h and submitted to ultimate tensile strength test in an universal testing machine (EMIC DL 2000) at a crosshead speed of 0.5 mm/min. The crosssectional area of the fractured zone of each specimen was measured
26 using a digital caliper (Mitutoyo Corporation, Tokyo, Japan) and the ultimate tensile strength (UTS, MPa) of each specimen was calculated as the maximum force at tensile failure, divided by the cross-sectional area of the specimen.
Water sorption and solubility
The water sorption and solubility test was carried out according to Gonçalves et al., 2013, but with changes in the specimens dimension of specimen and light curing process. Disc shape specimens (n=5) measuring 6 mm of diameter and 0,5 mm of thickness were made using an elastomer mold (Express, 3M ESPE, St. Paul, MN, USA). The light curing was performed using the same LED source Bluephase G2 (Ivoclar vivadent, Lichtenstein) for 60 s and through an IPS E.max Press ceramic block (10 mm in length x10 mm in wide x 3 mm in thickness), as described before. Afterward, the specimens were dry-stored at 37°C for 24h and repeatedly weighed using an analytical
balance (Discovery DV215CD; Ohaus Corporation, Pine Brook, NJ, USA) accurate to 0.01mg until achieving a constant mass (m1). Specimens were then individually placed in sealed vials, immersed in distilled water (changed every period of 7 days), and stored at 37°C. After 21 days, the surface water of the specimens was removed by blotting with absorbent paper, and the weighing process was repeated to obtain a new mass (m2). The specimens were then dry-stored again at 37°C and reweighed after 24h intervals until the obtainment of a constant final dry mass (m3). Water sorption and solubility were calculated in µg/mm3 from the percentage differences in mass gain or loss during the sorption and desorption cycles by the formulas; sorption = m2-m3(µg) / V(mm3); solubility = m1-m3(µg) / V(mm3).
27 Statistical analysis
For the bond strength test, the experimental unit considered was the ceramic/composite blocks, not the sticks. Normality and homoscedasticity of data were evaluated using Shapiro Wilk test. Bond strength values were submitted to repeated measures 3-way ANOVA and Tukey’s test (α=0.05). The other tests results were submitted to 2-way ANOVA and Tukey’s test (α=0.05).
Results
Atenuation of light promoted by ceramic
Table 1 shows the irradiance of the light source (1265.6 mW/cm2) that was reduced to 62 mW/cm2 whenthe exposure was performed through the ceramic block. This reduction lead to a reduction of 95.1% of the energy delivered to ERCs (75.9 J/ cm2 to 3.7 J/ cm2 after 60s).
Table 1. Irradiance values in different light-curing modes.
Irradiance (mW/cm2) Radiant exposure after 60s (J/ cm2) Loss of energy/irradiance (%) Without ceramic 1265.6 75.9 - Beneath ceramic 62 3.7 95.1
Microtensile bond strength and failure pattern
Values for ceramic bond strength are described on table 2. According to values, addition of DPI salt to ERCs did not improve the bond strength values (p>0,05).
28 Groups with and without adhesive addition were not statistically different (p>0,05). Similarly, there was no statistical difference between immediate bond strength and after one year of water storage (p>0,05).
Table 2. Microtensile bond strength means and standard deviations (MPa) for all groups according to time, use of adhesive and DPI concentration.
Time Adhesive DPI salt (mol%)
0 0.25 0.5 1 2
immediate with 32.30 (6.11) 36.00 (5.14) 36.24 (8.36) 37.22 (8.74) 34.19 (6.19)
without 37.50 (7.92) 39.04 (4.09) 33.88 (7.82) 39.32 (8.31) 34.33 (6.03)
after 1 year with 31.62 (3.86) 32.09 (4.95) 36.46 (6.66) 34.55 (5.26) 31.38 (1.99)
without 37.64 (3.31) 32.36 (3.52) 32.39 (4.65) 38.06 (6.14) 35.36 (4.58)
All groups were statistically similar. ANOVA repeated measures (α=0.05).
Failure pattern evaluation was performed for both times of microtensile bond strength test (immediate and after 1 year of storage). In both times, predominantly, it can be observed mixed failure (Figure 1 and 2) and almost none adhesive failure. Still, it can be noticed similar performance of ERCs comparing both times.
Figure 1. Distribution (%) of failure pattern observed for ERCs after immediate microtensile bond strength.
29
Figure 2. Distribution (%) of failure pattern observed for ERCs after 1 year of water storage.
Ultimate tensile strength
Values for UTS are described on table 3. There was no statistical difference between groups with and without adhesive (p>0,05). The 0 mol% DPI ERC showed the lowest values (p<0,05) and the others cements were not statistically different between them (p>0,05).
Table 3. Ultimate tensile strength (UTS) of ERCs according to adhesive use and DPI concentrations.
Lower case letters compare rows (ERCs). There was no significant interaction between the factors regarding adhesive application.
30
Polymerization kinetics and Degree of conversion
Degree of conversion was significantly lower for ERCs without DPI (p<0.0001; Table 4). The mixing of adhesive with the ERC without DPI promoted an increase in DC values, statistically higher compared to ERC (0%DPI) without adhesive addition (p<0.0001). For other ERCs, the adhesive did not influence DC values (p>0.05). Observing the rate of polymerization (Figure 3), it could be noted that the ERC without DPI presented inferior results, with best values observed when the adhesive was mixed with cement. The cements containing DPI presented similar rate of polymerization regardless the addition of adhesive.
Figure 3. Real time polymerization kinetics and rate of polymerization beneath a lithium disilicate ceramic (3mm thickness, MO1 shade) of the experimental groups.
31 Table 4. Degree of conversion of ERCs according to adhesive use and DPI concentrations.
Capital letters compare columns (addition of adhesive). Lower case letters compare rows (ERCs).
Water Sorption and Solubility
Table 5 shows the means and standard deviations of the water sorption and solubility data obtained in this study. The 0 mol% DPI ERC showed higher values of water sorption. The addition of adhesive improved only the solubility values for the 0 mol% DPI ERC. The others ERCs presented similar values between them.
Table 5. Water sorption and solubility of ERCs according to adhesive use and DPI concentrations.
Solubility Sorption
ERCs without adhesive with adhesive without adhesive with adhesive
0 mol% 77.06 (4.76) Aa 56.12 (4.69) Ba 40.36 (3.44) Aa 50.36 (6.82) Aa
0.25 mol% 20.92 (2.71) Ac 20.36 (1.68) Ab 31.36 (2.71) Aa 36.68 (1.27) Ab
0.5 mol% 25.52 (3.56) Abc 24.10 (2.85) Ab 36.65 (4.53) Aa 43.05 (6.18) Aab
1 mol% 27.50 (2.65) Abc 21.17 (3.01) Ab 40.83 (9.13) Aa 35.94 (3.03) Ab
2 mol% 30.03 (3.17) Ab 24.03 (1.57) Ab 33.05 (4.24) Aa 40.97 (4.14) Aab
Capital letters compare columns (addition of adhesive). Lower case letters compare rows (ERCs). Discussion
The present study used a lithium disilicate ceramic with a thickness of 3 mm and medium opacity shade, which can be considered a counterindication for a light curing cement due to light attenuation effects. The intention was precisely to challenge the
32 ternary photoinitiator system in adverse conditions of low light. Moreover, the idea of an exclusively light curing material that performs well in all different clinical situations from pin to metal free crowns cementation would be interesting and would eliminate the issue of working and setting time control of dual cure cements.
The first hypothesis of the study was rejected since there was no difference in bond strength among immediate and after one year of water storage. One might say that the ceramic bond strength should be jeopardized by water storage. Indeed, the hydrolytic degradation is a point to be considered regarding resin composites, specially when a long time of storage is applied. But, the substrate (resin composite block) that ceramic was bonded to is another important factor that should be considered. One of the big issues in dentin bonding that compromises the durability of adhesion is the enzymatic/hydrolytic degradation38,39. The lack of tooth tissue as a substrate for bonding excludes the enzymatic issue, leaving only the hydrolytic degradation which was not capable of reducing the bond strength. Maybe more time of water storage should be necessary to jeopardize the ceramic bonding.
Due to light attenuation through the ceramic blocks, the radiant exposure used was considerably reduced (table 1). A previous study reported a 58% decrease in light irradiance through IPS Empress Esthetic ceramic discs (shade A3, 2 mm thick)32. However, in the present study, the ceramic thickness (3mm) and shade (MO1-Medium Opacity) resulted in 95% loss in irradiance resulting in a radiant exposure of 3.7 J/cm2 that reached the resin cementafter 60 s light exposure. Considering that 6-24 J/cm2 is an adequate range to promote a suitable polymerization in clinical conditions33-35, maybe the radiant exposure obtained could not properly excite CQ, jeopardizing not only the amount
33 of photons reaching the composite but also the supply of electrons needed to interact with DPI and create the additional free radicals. However, if we consider the size of a cement film between 50-100 µm42, it might be considered that the low radiant exposure (3.7 J/cm2) was sufficient to polymerize the composite and allow suitable bond strength, even in the control group (0 mol% DPI).
It is known that adequate polymerization and degree of conversion are required to obtain good mechanical properties43. However, there are no reports in the literature showing a linear correlation between degree of conversion and ceramic bond strength, or minimum values of degree of conversion required to obtain suitable bond strength. This is due to the fact that ceramic bonding depends not only on degree of conversion but also on other factors such as surface treatment, cementation protocol and chemical composition of ceramics44,45. Moreover, some studies have shown that, depending on the material and condition, surface treatment of ceramic plays a more important role than the chemical composition of resin cement46,47. According to the results of the present study, it is possible to obtain a stable ceramic/resin composite bonding against hydrolytic degradation challenge, even with a low conversion degree (46% of the control group).
Further, the distribution of failure modes suggests similar bond quality even without the use of adhesive, which was not able to improve the bond strength values. The results of bond strength test corroborate with the values of failure pattern analysis, where all groups showed similar performance regarding the amount and type of failure in both times (immediate and after one year of storage). The same can be considered for groups without adhesive (G1-G5) and with adhesive (G6-G10), where there was no difference in
34 performance either, leading to believe that use of the adhesive was not able to promote better wettabilty of ceramic surface, nor better bond strength values. Probably the monomeric composition (BisGMA / TEGDMA ratio 1: 1) added to the amount of inorganic filler (60% by mass) gave the CREs a viscosity capable of promoting good surface wetting. Addition of an adhesive was able to improve DC only for the control group (0mol% DPI), while for the other cements (containing DPI salt) it had no effect. This result leads to rejection of our second hypothesis. Possibly the adhesive reduced the viscosity of the system (adhesive + resin cement), resulting in higher mobility of the reacting chains, increasing DC of the cement. This effect was not observed in the ERCs containing DPI, possibly due to the higher reactivity already established of this system.
The third hypothesis was also rejected once DPI salt improved physicochemical properties of ERCs, but it did not improve ceramic bond strength. Physicochemical properties of ERCs with same composition of materials tested in the present study were demonstrated in previous studies26,28. The addition of DPI salt was able to reduce the sorption and solubility of the cements, as well as increase the flexural strength and modulus of experimental materials tested26. The same effect of DPI salt on the physicochemical properties could be observed in this study. The DC for all ERCs containing DPI were similar and significantly higher compared with the control (without DPI). Increased reactivity and improved polymerization of methacrylate-based dental materials as consequence of DPI addition associated to camphorquinone has been reported in previous studies26, 27. The salt intercepts the ketone radical anion, preventing back electron transfer from occurring and then irreversibly decomposes to an aryl radical and an aryl iodide, providing more free radicals and improving the curing of the
35 CQ/amine system27, 31. If the DC of ERCs improve, the others properties will also get better as a consequence, once physical/mechanical properties depends directly on DC of composites18-20,36,37. This could be observed in this study for water sorption and solubility and ultimate tensile strength.
It was obtained no difference on bond strength values of light cured ERCs to overlying ceramic, despite low irradiance, low radiant exposure, ceramic opacity and thickness, and water storage. It is important to highlight that the present results were obtained “in vitro” and using experimental materials, which might not be fully extrapolated to the clinical situation. Further aspects such as more time of water storage, different concentration and composition of initiator systems as well as use of dentin as a substrate for bonding warrant future investigation in order to improve the properties of resin cement materials.
Conclusion
According to obtained results, it can be concluded that:
• One year of water storage was not sufficient to decrease ceramic bond strength of light curing ERCs.
• Adhesive addition did not influence bond strength to ceramic, neither physicochemical properties for ERCs with DPI salt, but it was able to increase DC only for no DPI ERC.
• DPI salt is capable of increasing rate of polymerization and DC of light curing ERCs even when cured beneath thick lithium disilicate ceramic, although it did not affect ceramic bond strength.
36
Acknowledgments
The authors are grateful for grants (2014/02898-7) provided by FAPESP. It was used by the corresponding author in partial fulfillment of the requirements to obtain the degree of Doctor in Clinical Dentistry (PhD) and as part of his PhD thesis.
References
1. Borges GA, Sophr AM, de Goes MF, Sobrinho LC, Chan DC. Effect of etching and airborne particle abrasion on the microstructure of different dental ceramics. J Prosthet Dent. 2003 May; 89(5):479-88.
2. Kukiattrakoon B, Thammasitboon K. The effect of different etching times of acidulated phosphate fluoride gel on the shear bond strength of high-leucite ceramics bonded to composite resin. J Prosthet Dent. 2007 Jul; 98(1):17-23. 3. Zogheib LV, Bona AD, Kimpara ET, McCabe JF. Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic. Braz Dent J. 2011 22(1):45-50.
4. Oh WS, Shen C, Alegre B, Anusavice KJ. Wetting characteristic of ceramic to water and adhesive resin. J Prosthet Dent. 2002 Dec; 88(6):616-21. 5. Naves LZ, Soares CJ, Moraes RR, Goncalves LS, Sinhoreti MA, Correr-Sobrinho L. Surface/interface morphology and bond strength to glass ceramic etched for different periods. Oper Dent. 2010 Jul-Aug; 35(4):420-7.
6. Addison O, Marquis PM, Fleming GJ. Adhesive luting of all-ceramic restorations--the impact of cementation variables and short-term water storage on the strength of a feldspathic dental ceramic. J Adhes Dent. 2008 Aug; 10(4):285-93.
7. Burke FJ, Fleming GJ, Nathanson D, Marquis PM. Are adhesive technologies needed to support ceramics? An assessment of the current evidence. J Adhes Dent. 2002 Spring; 4(1):7-22.
8. Fleming GJ, Hooi P, Addison O. The influence of resin flexural modulus on the magnitude of ceramic strengthening. Dent Mater. 2012 Jul; 28(7):769-76. 9. Guazzato M, Albakry M, Ringer SP, Swain MV. Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part I. Pressable and alumina glass-infiltrated ceramics. Dent Mater. 2004 Jun; 20(5):441-8.
10. Isgro G, Addison O, Fleming GJ. The deformation and strength of a dental ceramic following resin-cement coating. J Dent. 2011 Feb; 39(2):122-7.
11. Baena E, Fuentes MV, Garrido MA, Rodriguez J, Ceballos L. Influence of post-cure time on the microhardness of self-adhesive resin cements inside the root canal. Oper Dent. 2012 Sep-Oct; 37(5):548-56.
12. Pedreira AP, Pegoraro LF, de Goes MF, Pegoraro TA, Carvalho RM. Microhardness of resin cements in the intraradicular environment: effects of water storage and softening treament. Dent Mater. 2009 Jul; 25(7):868-76.
37 13. Good ML, Orr JF, Mitchell CA. In vitro study of mean loads and modes of failure of all-ceramic crowns cemented with light-cured or dual-cured luting cement, after 1 and 30 d of storage. Eur J Oral Sci. 2008 Feb; 116(1):83-8. 14. Hekimoglu C, Anil N, Etikan I. Effect of accelerated aging on the color stability of cemented laminate veneers. Int J Prosthodont. 2000 Jan-Feb; 13(1):29-33.
15. Arrais CA, Giannini M, Rueggeberg FA. Effect of sodium sulfinate salts on the polymerization characteristics of dual-cured resin cement systems exposed to attenuated light-activation. J Dent. 2009 Mar; 37(3):219-27.
16. Moraes RR, Brandt WC, Naves LZ, Correr-Sobrinho L, Piva E. Light- and time-dependent polymerization of dual-cured resin luting agent beneath ceramic. Acta Odontol Scand. 2008 Oct; 66(5):257-61.
17. Pick B, Gonzaga CC, Junior WS, Kawano Y, Braga RR, Cardoso PE. Influence of curing light attenuation caused by aesthetic indirect restorative materials on resin cement polymerization. Eur J Dent. 2010 Jul; 4(3):314-23. 18. Ferracane JL. Hygroscopic and hydrolytic effects in dental polymer networks. Dent Mater. 2006 Mar; 22(3):211-22.
19. Ruttermann S, Dluzhevskaya I, Grosssteinbeck C, Raab WH, Janda R. Impact of replacing Bis-GMA and TEGDMA by other commercially available monomers on the properties of resin-based composites. Dent Mater. 2010 Apr; 26(4):353-9.
20. Watts DC. Reaction kinetics and mechanics in photo-polymerised networks. Dent Mater. 2005 Jan; 21(1):27-35.
21. Prieto LT, Souza EJ, Jr., Araujo CT, Lima AF, Dias CT, Paulillo LA. Knoop hardness and effectiveness of dual-cured luting systems and flowable resin to bond leucite-reinforced ceramic to enamel. J Prosthodont. 2013 Jan; 22(1):54-8.
22. Ghavam M, Amani-Tehran M, Saffarpour M. Effect of accelerated aging on the color and opacity of resin cements. Oper Dent. 2010 Nov-Dec; 35(6):605-9.
23. Kilinc E, Antonson SA, Hardigan PC, Kesercioglu A. Resin cement color stability and its influence on the final shade of all-ceramics. J Dent. 2011 Jul; 39 Suppl 1:e30-6.
24. Lu H, Powers JM. Color stability of resin cements after accelerated aging. Am J Dent. 2004 Oct; 17(5):354-8.
25. Runnacles P, Correr GM, Baratto Filho F, Gonzaga CC, Furuse AY. Degree of conversion of a resin cement light-cured through ceramic veneers of different thicknesses and types. Braz Dent J. 2014 Jan-Feb; 25(1):38-42.
26. Gonçalves LS, Moraes RR, Ogliari FA, Boaro L, Braga RR, Consani S. Improved polymerization efficiency of methacrylate-based cements containing an iodonium salt. Dent Mater. 2013 Dec; 29(12):1251-5.
27. Ogliari FA, Ely C, Petzhold CL, Demarco FF, Piva E. Onium salt improves the polymerization kinetics in an experimental dental adhesive resin. J Dent. 2007 Jul; 35(7):583-7.
28. Andrade KM, Palialol AR, Lancellotti AC, Aguiar FH, Watts DC, Gonçalves LS, et al. Effect of diphenyliodonium hexafluorphosphate on resin
38 cements containing different concentrations of ethyl 4-(dimethylamino)benzoate and 2-(dimethylamino)ethyl methacrylate as co-initiators. Dent Mater. 2016 Jun; 32(6):749-55.
29. Dressano D, Palialol AR, Xavier TA, Braga RR, Oxman JD, Watts DC, et al. Effect of diphenyliodonium hexafluorophosphate on the physical and chemical properties of ethanolic solvated resins containing camphorquinone and 1-phenyl-1,2-propanedione sensitizers as initiators. Dent Mater. 2016 Jun; 32(6):756-64. 30. Song L, Ye Q, Ge X, Misra A, Spencer P. Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property. Dent Mater. 2016 Jan; 32(1):102-13.
31. Guo X, Wang Y, Spencer P, Ye Q, Yao X. Effects of water content and initiator composition on photopolymerization of a model BisGMA/HEMA resin. Dent Mater. 2008 Jun; 24(6):824-31.
32. Moraes RR, Correr-Sobrinho L, Sinhoreti MA, Puppin-Rontani RM, Ogliari FA, Piva E. Light-activation of resin cement through ceramic: relationship between irradiance intensity and bond strength to dentin. J Biomed Mater Res B Appl Biomater. 2008 Apr; 85(1):160-5.
33. Cunha LG, Alonso RC, Correr GM, Brandt WC, Correr-Sobrinho L, Sinhoreti MA. Effect of different photoactivation methods on the bond strength of composite resin restorations by push-out test. Quintessence Int. 2008 Mar; 39(3):243-9.
34. Lohbauer U, Rahiotis C, Kramer N, Petschelt A, Eliades G. The effect of different light-curing units on fatigue behavior and degree of conversion of a resin composite. Dent Mater. 2005 Jul; 21(7):608-15.
35. Seth S, Lee CJ, Ayer CD. Effect of instruction on dental students’ ability to light-cure a simulated restoration. J Can Dent Assoc. 2012 78:c123. 36. Lovell LG, Lu H, Elliott JE, et al: The effect of cure rate on the mechanical properties of dental resins. Dent Mater. 2001; 17(6): 504-11.
37. Elliott JE, Lovell LG, Bowman CN: Primary cyclization in the polymerization of bis-GMA and TEGDMA: a modeling approach to understanding the cure of dental resins. Dent Mater. 2001;17(3): 221-29.
38. Liu R, Fang M, Xiao Y, Li F, Yu L, Zhao S, Shen L, Chen J. The effect of transient proanthocyanidins preconditioning on the cross-linking and mechanical properties of demineralized dentin. J Mater Sci Mater Med 2011 Nov;22(11): 2403-1.
39. Hashimoto M, Ohno H, Sano H, Kaga M, Oguchi H. In vitro degradation of resin-dentin bonds analyzed by microtensile bond test, scanning and transmission electron microscopy. Biomaterials. 2003 Sep;24(21):3795-803. 40. Gresnigt M, Ozcan M. Esthetic rehabilitation of anterior teeth with
porcelain laminates and sectional veneers. J Can Dent Assoc. 2011;77: b143. 41. Rigolin FJ, Miranda ME, Flório FM, Basting RT. Evaluation of bond strength between leucite-based and lithium disilicate-based ceramics to dentin after cementation with conventional and self-adhesive resin agents. Acta Odontol Latinoam. 2014;27(1):16-24.
42. Cekik-Nagas I, Canay S, Sahin E. Bonding of resin core materials to lithium disilicate ceramics: The effect of resin cement film thickness. Int J Prosthodontics.
39 2010; 23(5): 469-471.
43. Calheiros FC, Kawano Y, Stansbury JW, Braga RR. Influence of radiant exposure on contraction stress, degree of conversion and mechanical properties of resin composites; Dent Mater, 22 (2006), pp. 799–803.
44. Guarda GB, Correr AB, Gonçalves LS, Costa AR, Borges GA, Sinhoreti MAC, Correr-Sobrinho L. Effects of surface treatments, thermocycling, and cyclic loading on the bond strength of a resin cement bonded to a lithium disilicate glass ceramic. Oper Dent. 2013; 38(2): 208-17.
45. Sundfeld Neto D, Naves LZ, Costa AR, Correr AB, Consani S, Borges GA, et al. The Effect of Hydrofluoric Acid Concentration on the Bond Strength and Morphology of the Surface and Interface of Glass Ceramics to a Resin Cement. Oper Dent. 2015; 40(5): 470-479.
46. Aboushelib MN, Sleem D. Microtensile bond strength of lithium disilicate ceramics to resin adhesives. J Adhes Dent. 2014; 16(6): 547-52.
47. Lise DP, Perdigão J, Van Ende A, Zidan O, Lopes GC. Microshear bond strength of resin cements to lithium disilicate substrates as a function of surface preparation. Oper Dent. 2015; 40(5): 524-32.
3 CONCLUSÃO
De acordo com os resultados obtidos, pode-se concluir que:
• O tempo de armazenamento de um ano em água destilada não foi capaz de reduzir os valores de resistência de união à cerâmica dos CREs fotoativados.
• O adesivo não exerceu influência na resistência de união à cerâmica, tampouco nas propriedades físico-químicas dos CREs contendo sal de DFI, mas foi capaz de aumentar o grau de conversão apenas para o CRE sem o sal de DFI.
• O sal de DFI foi capaz de aumentar a taxa de polimerização e o grau de conversão dos CREs fotoativados, mesmo utilizando uma cerâmica vítrea de grande espessura como barreira para luz. Porém, nenhuma concentração do sal exerceu efeito na resistência de união à cerâmica, tanto imediata quanto após armazenamento em água.
* De acordo com as normas da UNICAMP/FOP, baseadas na padronização do International Committee of Medical Journal Editors – Vancouver Group. Abreviatura dos periódicos em conformidade com o PubMed.
40 REFERÊNCIAS
Aboushelib MN, Sleem D. Microtensile bond strength of lithium disilicate ceramics to resin adhesives. J Adhes Dent. 2014; 16(6): 547-52.
Aguiar TR, Andre CB, Arrais CAG, Bedran-Russo AK, Giannini M. Micromorphology of resin-dentin interfaces using self-adhesive and conventional resin cements: A confocal laser and scanning electron microscope analysis. Int J Adhesion & Adhesives. 2012; 38: 69-74.
Anusavice KJ (1996) Philips Science of Dental Materials, ed. 10. Philadelphia: Saunders.
Borges GA, Spohr AM, De Goes MF, Correr-Sobrinho L, Chan DNC. Effect of etching particle abrasion in the microstructure of different dental ceramics. J Prost Dent. 2003; 89(5): 479-88.
Burke FJ, Flemming GI, Nathanson D, Marquis PM. Are adhesive technologies needed to support ceramics? An assessment of the current evidence. J Aesthet Dent. 2002; 4: 7-22.
Cekik-Nagas I, Canay S, Sahin E. Bonding of resin core materials to lithium disilicate ceramics: The effect of resin cement film thickness. Int J Prosthodontics. 2010; 23(5): 469-471.
Conrad HJ, Seong WJ, Pesun IJ. Current ceramic materials and systems with clinical recommendations: a systematic review. J Prost Dent. 2007; 98(5): 389-404.
Crivello JV, Lam JH. Diaryliodonium salts - new class of photo-initiators for cationic polymerization. Macromolecules 1977; 10: 1307-1315.
Crivello, J. V.; Dietliker, K. In Photoinitiators for Free Radical Cationic and Anionic Photopolymerisation; Bradley, G., Ed.; Wiley: New York, 1998; Vol. 3, p 374.
41 MAC. Effect of different photoactivation methods on the bond strength of composite resin restorations by push-out test. Quintessence Int. 2008; 39(3): 243-249.
el-Mowafy OM, Rubo MH, el-Badrawy WA. Hardening of new resin cements cured through a ceramic inlay. Oper Dent. 1999; 24: 38-44.
Ferracane JL. Hygroscopic and hydrolytic effects in dental polymer networks. Dent Mater. 2006; 22: 211-222.
Gómez ML, Avila V, Montejano HA, Previtali CM. A mechanistic and laser flash photolysis investigation of acrylamide polymerization photoinitiated by the three component system safranine-T/triethanolamine/diphenyliodonium chloride. Polymer. 2003; 44: 2875-2881.
Gonçalves LS, Moraes RR, Ogliari FA, Boaro L, Braga RR, Consani S. Improved polymerization efficiency of methacrylate-based cements containing an iodonium salt. Dent Mater. 2013 Dec; 29(12):1251-1255.
Groten M, Probster L. The influence of different cementation modes on the fracture resistance of feldspathic ceramic crowns. Int J Prosthodont 1997; 10:169-177.
Guarda GB, Correr AB, Gonçalves LS, Costa AR, Borges GA, Sinhoreti MAC, Correr-Sobrinho L. Effects of surface treatments, thermocycling, and cyclic loading on the bond strength of a resin cement bonded to a lithium disilicate glass ceramic. Oper Dent. 2013; 38(2): 208-217.
Hashimoto M, Ohno H, Sano H, Kaga M, Oguchi H. In vitro degradation of resin-dentin bonds analyzed by microtensile bond test, scanning and transmission electron microscopy. Biomaterials. 2003 Sep;24(21):3795-803.
Höland W, Schweiger M, Frank M, Rheinberger V. A comparison of the microstructure and properties of the IPS Empress 2 and the IPS Empress glass-ceramics. J Biomed Mater Res. 2000; 53(4): 297-303.
42 Kern M. Resin bonding to oxide ceramics for dental restorations. J Adhes Sci Technol. 2009; 23(7-8):1097-111.
Kukiattrakoon B, Thammasitboon K. The effect of different etching times of acidulated phosphate fluoride gel on the shear bond strength of high-leucite ceramics bonded to composite resin. J Prosthet Dent. 2007; 98(1): 17-23.
Lee JH, Um CM, Lee IB. Rheological properties of resin composites according to variations in monomer and filler composition. Dent Mater. 2006; 22: 515-526.
Lise DP, Perdigão J, Van Ende A, Zidan O, Lopes GC. Microshear bond strength of resin cements to lithium disilicate substrates as a function of surface preparation. Oper Dent. 2015; 40(5): 524-32.
Liu R, Fang M, Xiao Y, Li F, Yu L, Zhao S, Shen L, Chen J. The effect of transient proanthocyanidins preconditioning on the cross-linking and mechanical properties of demineralized dentin. J Mater Sci Mater Med 2011 Nov;22(11): 2403-1.
Lohbauer U, Rahiotis C, Kramer N, Petschelt A, Eliades G. The effect of different light-curing units on fatigue behavior and degree of conversion of a resin composite. Dent Mater. 2005; 21: 608-615.
Lu H, Powers JM. Color stability of resin cements after accelerated aging. American J of Dent. 2004; 17: 354–358.
Moraes RR, Brandt WC, Naves LZ, Correr-Sobrinho L, Piva E. Light- and time-dependent polymerization of dual-cured resin luting agent beneath ceramic. Acta Odontol Scand. 2008; 66: 257-261.
Moraes RR, Correr-Sobrinho L, Sinhoreti MA, Puppin-Rontani RM, Ogliari FA, Piva E. Light-activation of resin cement through ceramic: relationship between irradiance intensity and bond strength to dentin. J Biomed Mater Res B Appl Biomater 2008; 85:160-165.
Correr-
43 Sobrinho L. Surface/Interface morphology and bond strength to glass ceramic etched for different periods. Oper Dent. 2010; 35(4): 420-427.
Ogliari FA, Ely C, Petzhold CL, Demarco FF, Piva E. Onium salt improves the polymerization kinetics in an experimental dental adhesive resin. J Dent. 2007; 35: 583-587.
Oh WS, Shen C, Alegre B, Anusavice KJ. Wetting characteristic of ceramic to water and adhesive resin. J Prosthet Dent. 2002; 88(6): 616-21.
Ozturk N, Usumez A, Usumez S, Ozturk B. Degree of conversion and surface hardness of resin cement cured with different curing units. Quintessence Int. 2005; 36: 771-777.
Prieto LT, Souza-Junior EJ, Araújo CTP, Lima AF, Dias CTS, Paulillo LAMS. Knoop hardness and effectiveness of dual –cured luting systems and flowable resin to bond leucite-reinforced ceramic to enamel. J Prosthodont. 2013; 22: 54–58.
Rigolin FJ, Miranda ME, Flório FM, Basting RT. Evaluation of bond strength between leucite-based and lithium disilicate-based ceramics to dentin after cementation with conventional and self-adhesive resin agents. Acta Odontol Latinoam. 2014;27(1):16-24.
Rosenstiel SF, Land MF, Crispin BJ. Dental luting agents: A review of the current literature. J Prosthet Dent. 1998; 80: 280-301.
Ruttermann S, Dluzhevskaya I, Grosssteinbeck C, Raab WH, Janda R. Impact of replacing Bis-GMA and TEGDMA by other commercially available monomers on the properties of resin-based composites. Dent Mater. 2010; 26: 353-359.
Sakaguchi RL, Berge HX. Reduced light energy density decreases post-gel contraction while maintaining degree of conversion in composites. J Dent. 1998; 26: 695-700.
Santos-Daroz CB, Oliveira MT, Góes MF, Nikaido T, Tagami J, Giannini M. Bond strength of a resin cement to dentin using the resin coating technique. Braz Oral
