“interaction effect between multi-mode adhesive...
TRANSCRIPT
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ISADORA RABÊLO GUIMARÃES
“Interaction effect between multi-mode adhesive systems and
dual/chemical curing resin cements on dentin bonding”
“O efeito da interação de sistemas adesivos multi-mode e cimentos resinosos de polimerização química e dual na adesão à dentina”
Piracicaba
2015
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UNIVERSIDADE ESTADUAL DE CAMPINAS
FACULDADE DE ODONTOLOGIA DE PIRACICABA
ISADORA RABÊLO GUIMARÃES
“Interaction effect between multi-mode adhesive systems and
dual/chemical curing resin cements on dentin bonding”
“O efeito da interação de sistemas adesivos multi-mode e cimentos
resinosos de polimerização química e dual na adesão à dentina”
Tese apresentada à Faculdade de Odontologia de Piracicaba
da Universidade Estadual de Campinas como parte dos requisitos exigidos
para a obtenção do título de Doutora em Materiais Dentários.
Thesis presented to the Piracicaba Dental School of the University
of Campinas in partial fulfillment of the requirements for
the degree of Doctor in Dental Materials.
Orientador: Prof. Dr. Mario Fernando de Goes
ESTE EXEMPLAR CORRESPONDE À VERSÃO FINAL DA TESE DEFENDIDA
PELA ALUNA ISADORA RABÊLO GUIMARÃES
E ORIENTADA PELO PROF. DR. MARIO FERNANDO DE GOES
________________________________ Assinatura do Orientador
Piracicaba
2015
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Resumo
O Objetivo deste estudo foi avaliar o efeito da interação de sistemas
adesivos multi-mode e cimentos resinosos de polimerização química e dual sobre
a superfície da dentina.Quarenta terceiros molares humanos não cariados foram
separados em 5 grupos (n=8). Uma superfície plana em dentina foi obtida para
cada dente. Blocos de 3,0x12x12 mm de resina composta indireta (Lava Ultimate)
foram jateados com partículas óxido de alumínio e cimentados na superfície de
dentina,formando os seguintes grupos: I- All Bond Universal fotoativado (AB)/C&B
Bond Cement (CB); II- Scotchbond Universal fotoativado (SBU)/RelyXUltimate
químico (RXU); III- SBU fotoativado/RXU fotoativado, IV- SBU químico/RXU
fotoativado, V- SBU químico /RXU químico. Após a cimentação, os dentes foram
mantidos em umidade relativa a 37⁰C por 24 horas.Os dentes foram seccionados
para obter palitos de aproximadamente 0,8 mm². Os espécimes foram
posicionadosna máquina de ensaio universal EZ-Test para o ensaio de resistência
de união com uma velocidade de 0,5mm/min. Os dados foram estatisticamente
analisados por ANOVA um fator e Teste de Fisher´s PLSD (α=0,05). Os modos de
fratura foram analisados e classificados em microscópio eletrônico de varredura.
Para análise das interfaces dentina/adesivo/cimento, cinco espécimes de cada
grupo foram corados com Rodamina B a 1% por uma hora e analisados em
microscópio confocal de varredura a laser. Nenhuma diferença estatística de
resistência da união (MPa) foi observada entre os grupos: I- 59,9 (9,3); II- 57,6
(15,9); III- 63,9 (12,7) e IV- 53,7 (13,9), e todos foram diferentes estatisticamente
do grupo V, que apresentou o menor valor de resistência da união 16,2 (6,4). O
modo de fratura coesivo foi predominante na interface entre o adesivo e cimento
resinoso em todos os grupos. A análise ultraestrutural sugere a interação entre os
sistemas adesivos multi-mode e o cimento resinoso na dentina, quando o adesivo
ou o cimento resinoso foi fotoativado. A interação adesiva ocorreu entre os
adesivos multi-mode e cimentos resinosos, sempre que o adesivo e/ou o cimento
resinoso foi fotoativado.
Palavras-chave: adesivos, dentina.
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Abstract
This study evaluated the dentin surface interaction effect of multi-mode adhesives
on bonding to chemical-cured and dual-cured resin cements. Forty non-carious
human third molars were divided into five groups (n=8). A flat dentin surface was
created for each tooth. Indirect resin composite block 3,0x12x12 mm (Lava
Ultimate) were sandblasted with aluminum oxide particles and cemented to the
dentin surface following the treatment groups: I- All Bond Universal light-
cured/C&B Bond (self-cured cement), II- Scotchbond Universal (SBU) light-
cured/RelyX Ultimate (RXU) self-cured, III- SBU light-cured/RXU light-cured, IV -
SBU no light-cured/RXU light-cured and V- SBU no light-cured/RXU self-cured.
After 24 h, the teeth were sectioned into beans to produce a cross-sectional area
of 0.8 mm². Specimens of each group were individually mounted on a jig and
placed on a tensile testing universal machine. A tensile force was applied at a
0.5mm/min cross-speed. The bond strength was recorded and failure modes were
classified using scanning electron microscopy. In order to observe dentin/adhesive-
cement interface, selected beans from each group were stained with 0.1%
Rodhamine B for 1 h and analyzed using Confocal Laser Scanning Microscopy.
Statistical analysis was performed using ANOVA and Fisher‟s PLSD test
(α=0.05).Forbond strength (MPa)nostatistical difference of was observed among
the groups: I - 59.9 (9.3); II- 57.6 (15.9); III - 63.9 (12.7) and IV- 53.7 (13.9). Group
V showed statistical lower average value 16.2 (6.4) compared with all others
groups. Cohesive failure modes occurred predominately along of adhesive and
resin cement to all groups. The ultrastructural observation suggested the dentin
surface interaction between multi-mode adhesives and resin cement when the
adhesive or resin cement was light-cured. Theadhesive interaction occurred
between multi-mode adhesive systems and resin cements wheneverthe adhesive
and/or resin cement was light-activated.
Keywords: adhesives, dentin.
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SUMÁRIO
Dedicatória xiii
Agradecimentos xv
Introdução 1
Interaction effect between multi-mode adhesive systems and dual/chemical
curing resin cements on dentin bonding 7
Conclusão 29
Referências 30
Anexo 32
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Dedicatória
Dedico este trabalho,
A Deus,por permitir a realização deste sonho, iluminando sempre o meu
caminho.
Aos meus pais, José Agnaldo Guimarães Bezerra e Nádja MariaRabelo
Guimarães,e aos meus irmãos Irajá Rabelo Guimarães e Iara Rabelo
Guimarães, por todo apoio, incentivo e confiança ao longo destes anos.Vocês
foram fundamentais nesta minha conquista.
Ao meu namorado Daniel, por todos esses anos de amor e carinho. E por
estar ao meu lado em todos os momentos.
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Agradecimentos
Ao meu orientador, Prof. Dr. Mario Fernando de Goes, agradeço os ensinamentos
transmitidos, o incentivo constante ao meu crescimento profissional e as diversas
oportunidades ao longo desses anos que me proporcionaram amadurecimento e
aprendizado.
A todos os amigos e colegas do mestrado e doutorado, obrigada pela amizade e
parceria em todos esses anos. Às amigas Roberta Galetti, Tatyane Araújo,
RavanaSfalcin e Ana Paula Fugolinmuito obrigada pela amizade, pela troca de
experiências e auxílio precioso em muitas ocasiões.
À Faculdade de Odontologia de Piracicaba da Universidade Estadual de
Campinas, no nome do Diretor Prof. Dr. Guilherme Elias Pessanha Henriques e do
Diretor associado Prof. Dr. Franscisco Haiter Neto.
Aos professores do departamento de Materiais Dentários, Prof. Dr. Mário
Alexandre Coelho Sinhoreti, Prof. Dr. Lourenço Correr Sobrinho e Prof. Dr.
Américo Bortolazzo Correr, pelos ensinamentos determinantes na minha formação
profissional.
Aos professores Dr. Marcelo Giannini, professor da Área de Dentística, e Profa.
Dra. Regina Maria PuppinRontani, professora da área de Odontopediatria da
Faculdade de Odontologia de Piracicaba – UNICAMP.
Aos funcionários do Laboratório de Materiais Dentários, o engenheiro Marcos
Blanco Cangiani e Sra. Selma Aparecida Barbosa Segalla, verdadeiros exemplos
de dedicação. Agradeço por todo o auxílio prestado no decorrer do curso. Ao
biólogo Adriano Luis Martins, pela atenção e orientação no uso do MEV.
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Agradeço aos ProfessoresDr. Simonides Consani, Prof Dr. Flávio Henrique Baggio
Aguiar,Prof. Dr. Caio Cezar Randi Ferraz que fizeram parte da banca examinadora
no exame de qualificação, pela importante contribuição na melhoria do trabalho.
À Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) pela
concessão da bolsa de estudo durante o primeiro ano de doutorado.
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“Os que se encantam com a prática sem a ciência
são como os timoneiros que entram no navio sem timão nem bússola,
nunca tendo certeza do seu destino”.
Leonardo da Vinci
xviii
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Introdução
Em busca da estabilidade da adesão e longevidade das restaurações, a
indústria odontológica vem buscando oferecer materiais que proporcionem
técnicas simplificadas com propriedades mecânicas, químicas e biológicas
necessárias para garantir união estável à estrutura dental. O sucesso clínico da
restauração depende da interação entre os materiais e a estrutura dental (Inokoshi,
1993; Sjogren, 1995; Perdigao, 2013).
As estratégias de união para os sistemas adesivos estão estabelecidas em
duas técnicas: técnica úmida e autocondicionante. A técnica úmida (convencional)
utiliza o ácido fosfórico, em concentrações entre 30 a 40%, para promover a
desmineralização do esmalte e/ou dentina e criar condições para a difusão dos
monômeros hidrófilos e hidrófobos(Perdigão, 1996). Diferentemente, os agentes
autocondicionantes eliminam a necessidade de condicionamento com ácido
fosfórico, consistindo na incorporação da smear layer no processo de hibridização,
ou seja, a dissolução e ou modificação da smear layer, em vez da sua completa
remoção pela aplicação e lavagem do ácido fosfórico (Miyazaki, 2002). Os
adesivos autocondicionantes surgiram em duas categorias: agentes de 2 frascos,
os quais possuem condicionador e primer combinados em 1 frasco e o adesivo em
outro frasco; e agentes de frasco único em que o condicionador, primer e adesivo
são combinados juntos. Os adesivos autocondicionantes contêm uma combinação
de monômeros hidrófilos, monômeros diluentes reativos, adesivos resinosos de
alta viscosidade e sistemas fotoiniciadores, contendo etanol ou acetona como
solvente(Eick, 1997). Alguns podem incluir água, partículas de carga e agentes
liberadores de flúor como aditivos(Tay, 1996). A ionização do radical fosfato pela
água promove a acidez (pH = 2,0 a 2,8) do monômero que é capaz de
desmineralizar a dentina e simultaneamente infiltrar-se no tecido dentinário(Van
Meerbeek, 2003). Neste sistema, o procedimento técnico é menos crítico e mais
rápido por não envolver o controle da umidade, como ocorre com as técnicas que
preconizam a aplicação do condicionamento ácido (Frankenberger, 2000). A fim
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de promover a união entre os sistemas adesivos e os substratos dentais,
predominantemente monômeros metacrilatos, com grupamentos carboxílicos ou
fosfóricos, são utilizados para produzir a desmineralização do esmalte e da
dentina. O mecanismo de união dos sistemas adesivos autocondicionantes é
baseado na interação química entre o monômero funcional ácido e o cálcio da
hidroxiapatita (Al-Assaf, 2007). A concentração de monômeros ácidos
desempenha papel crucial no processo de adesão/hibridização: deve ser
suficientemente elevada para garantir desmineralização adequada e união à
dentina e esmalte e o mais baixa possível para minimizar a hidrofilicidade do
material polimerizado. Como relatado por Ferracane et al. (2011), a característica
hidrofílica do material polimerizado devido a um valor de pH baixo pode
comprometer a estabilidade mecânica pela absorção de água excessiva. Por
seremhidrofílicos, os adesivos autocondicionantes de um passo se comportam
como membranas permeáveis, permitindo a transudação de fluidos através da
interface dentina/resina. A presença da água no adesivo polimerizado se
manifesta morfologicamente por meio de glóbulos de resina e poros,responsáveis
pela redução da resistência da união de adesivos dentinários de passo único (Tay,
2002). Entretanto, autores relatam que dependendo do monômero funcional ácido
presente no sistema adesivo, a interface formada entre o adesivo e a dentina tem
sido considerada resistente à biodegradação (Inoue, 2005; Yoshihara, 2011). Os
adesivos dentais incluem em sua composição solventes orgânicos, tal como etanol
ou acetona, para facilitar a infiltração dos monômeros no substratode dentina
úmida. Embora a água e os solventes orgânicos sejam componentes essenciais
nos adesivos de um passo, os solventes devem ser completamente removidos
durante a aplicação do sistema adesivo. Caso não ocorra evaporação adequada,
água e solventes orgânicos residuais podem inibir a polimerização dos
monômeros (Reis, 2003). A evaporação do solvente é realizada por meio da
agitação do adesivo na superfície de dentina, seguida pela aplicação de jatos de
ar(Klein-Junior, 2008). A evaporação do solvente melhora o grau de conversão e
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propriedades mecânicas de sistemas adesivos autocondicionantes de passo único
e dois passos (Sadr, 2007; Ikeda, 2008).
Como qualquer outro composto resinoso, os cimentos resinosos também
requerem polimerização adequada para proporcionar propriedades mecânicas
ótimas, como baixa absorção de água esolubilidade,alémde maior dureza,
resistência à tração e ao desgaste (Braga, 2002; Johnston, 1985). No entanto, ao
contrário das resinas compostas fotoativadas, os cimentos resinosos não podem
depender exclusivamente de fotoativação para atingir grau ótimo de conversão. A
intensidade de luz que atinge a camada de cimento resinoso pode ser atenuada,
ou totalmente eliminada, devido a distância entre o cimento resinoso e a fonte de
luz, ou pelas características absorventes do material restaurador indireto
sobrejacente (Blackman, 1990; Arrais, 2008). Portanto, os fabricantes
desenvolveram o assim chamado cimento resinoso de dupla polimerização, que
contêm componentes foto e quimicamente ativados para assegurar a
polimerização na ausência de luz (Milleding, 1998). A polimerização do cimento
resinoso dual começa logo que os componentes base e catalisador são
misturados. O mecanismo de ativação química se iniciapela reação entre o
peróxido de benzoíla e a amina terciária, enquanto um inibidor fenólico é
adicionado para retardar a polimerização e, portanto, permite tempo de trabalho
suficiente (Cook, 1983). Cada fabricante determina a proporção de componentes
auto e fotopolimerizáveis, o que resulta em diferentes tempose características de
polimerização, tais como grau de conversão e taxa máxima de polimerização (Rp
max). A contribuição da reação de autopolimerização ao modo de dupla
polimerização fornece um indicador de como a polimerização prossegue bem em
locais onde pouca ou nenhuma luz é disponível (Arrais, 2009). O mecanismode
polimerização química é menos eficaz do que o modo dupla polimerização
(Peutzfeldt, 1995; Caughman, 2001; Rueggeberg, 1993). O menor grau de
conversão nos períodos iniciais dos cimentos resinosos autopolimerizáveispode
ser atribuído à baixa taxa de de polimerização, bem como ao atraso no início da
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reação química pelos inibidores, o que é esperado, a fim oferecer tempo de
trabalho adequado (Cook, 1983).
Apesar do uso dos cimentos resinosos fotopolimerizáveis ter superado o
dos cimentos resinosos quimicamente ativados, estes últimos ainda possuem
aplicações importantes, e são utilizados em áreas não facilmente atingidas pela
luz, como cimentação de próteses e pinos intrarradiculares. Entretanto, evidências
que sugerem que a resistência de união de cimentos resinosos à dentina é
influenciada pela compatibilidade entre o sistema adesivo utilizado e o cimento
resinoso. Alguns sistemas adesivos autocondicionantes de um passo
fotopolimerizáveis são incompatíveis com compósitos quimicamente ativados,
comprometendo a adesão (Vargas, 1997; Swift, 1998). Esse fato tem sido
atribuído a alguns tipos de interações adversas que ocorrem entre os monômeros
resinosos não polimerizados do adesivo com o cimento resinoso (Eick, 1997).
Quando adesivos simplificados são utilizados com cimentos resinosos
quimicamente ativados ocorre interação dos monômeros residuais com os
componentes binários peróxido-amina e amina terciária, comumentes presentes
no cimento resinoso por polimerização química, resultando, desta forma,
incompleta polimerização do cimento resinoso (Yamauchi, 1986; Miller,1999;
Sanares, 2001). Estudos relatam que existe correlação positiva entre o pH de
sistemas adesivos autocondicionantes e a resistência da união quando
compósitos quimicamente ativados são utilizados. Quanto maior o pH dos
sistemas adesivos autocondicionantes de frasco único, maior a resistência da
união de restaurações. Análises fractográficas deadesivos com menores valores
de pH revelaram grande quantidade de espaços vazios na interface adesiva, o que
resulta em menor resistência da união e incompatibilidade entre o adesivo e o
cimento resinoso (Sanares , 2001; Tay, 2003).
Visando diminuir tais situações, muitas pesquisas têm sido realizadas na
tentativa de aprimorar a interação entre os sistemas adesivos autocondionantes e
cimentos resinosos na superfície da dentina. Uma nova categoria de sistemas
adesivos autocondicionantes universais ou multi-mode foi introduzida no mercado
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odontológico. Os sistemas adesivos multi-mode são considerados sistemas
autocondicionantes ultra-suaves, devido ao pH relativamente mais alto (pH ≥2,5)
em relação aos sistemas adesivos antecessores, o que poderia contribuir com a
compatibilidade entre os monômeros ácidos residuais e os componentes binários
peróxido-amina e amina terciária do cimento resinoso. Além do maior pH, esses
sistemas universais possuem na composição o monômero funcional 10-MDP
(Metacriloxidecil Di-hidrogênio Fosfato) que permite ligação mais estável com a
hidroxiapatita que recobre as fibrilas de colágeno na área da união (Yoshihara,
2011). Além do alto potencial de união química à hidroxiapatita, o sal de cálcio do
10-MDP é altamente insolúvel (Van Landuyt, 2008). De acordo com o conceito
adesão-descalcificação, quanto menos solúvel o sal de cálcio da molécula, mais
intensa e estável é a adesão molecular ao substrato (Yoshida, 2000) . Além desta
nova categoria de sistemas autocondicionantes multi-mode, encontra-se
disponível no mercado um cimento resinoso de ativação dupla, desenvolvido com
um sistema de oxi-redução formado pelo ter-butil peróxido trimetilhilhexanoato e
persulfato de sódio para suprir as interações adversas entre o sistema adesivo e o
cimento resinoso polimerizado quimicamente que utiliza na reação de
autopolimerização a amina terciária (ativador) e peróxido de benzoíla (iniciador).
Embora o desenvolvimento e aprimoramento das propriedades mecânicas e
técnicas dos sistemas adesivos autocondicionantes e cimentos resinosos
sejamconstantes, as dúvidas a respeito da interação destes materiais com a
superfície da dentina ainda carecem de informações precisas para sugerir o
devido procedimento clínico. Assim, a análise do padrão de fratura por meio de
microscopia eletrônica de varredura representa o complemento ideal para os
ensaios mecânicos de resistência da união nas primeiras 24 horas, para
observação ultraestrutural e possíveis alterações morfológicas ocorridas na área
de união produzida por adesivos universais (pH ≥ 2,5) e cimentos resinosos com
diferentes sistemas de oxi-redução. Assim, o objetivo neste estudo foi avaliar a
interação entre sistemas adesivos multi-mode e cimentos resinosos de ativação
química e duplacom diferentes sistemas de oxi-redução aplicados sobre a
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superfície da dentina. A hipótese nula testadaé que a fotoativação dos sistemas
adesivos universais e/ou cimentos resinosos de polimerização dupla não resulta
em diferença da resistência mecânica e nas características morfológicas da região
da união, quando comparados ao modo de polimerização química.
Esta tese está baseada na resolução CCPG 07/14 UNICAMP que regulamenta o formato
alternativo para teses de Mestrado e Doutorado.
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Interaction effect between multi-mode adhesive systems and dual/chemical
curing resin cements on dentin bonding
O efeito da interação de sistemas adesivos multi-mode e cimentos resinosos
de polimerização química e duplana adesão à dentina
Isadora Rabelo Guimarãesa,MirelaSanaeShinoharab, Mario Fernando de Goesc
aDS Student, Dental Materials Division, Department of Restorative Dentistry,
Piracicaba Dental School, Campinas State University, Piracicaba-SP, Brazil.
b Assistant Professor, Department of Restorative Dentistry, Araçatuba Dental
School, São Paulo State University, Araçatuba-SP, Brazil.
cFull professor, Dental Materials Division, Department of Restorative Dentistry,
Piracicaba Dental School, Campinas State University, Piracicaba-SP, Brazil.
Abstract
Purpose: To evaluate the effect of the interaction between of multi-mode
adhesives and chemical-cured or dual-cured resin cements on dentin bonding.
Materials and Methods: Forty non-carious human third molars were divided into
five groups (n=8). A flat dentin surface was created for each tooth. Indirect resin
composite block 3.0x12x12 mm (Lava Ultimate) were sandblasted with aluminum
oxide particles and cemented to the dentin surface following the treatment groups:
I- All Bond Universal light-cured/C&B Bond (self-cured cement), II- Scotchbond
Universal (SBU) light-cured/RelyX Ultimate (RXU) self-cured, III- SBU light-
cured/RXU light-cured, IV- SBU no light-cured/RXU light-cured and V- SBU no
light-cured/RXU self-cured. After 24 h, the specimens were sectioned into beans to
produce a cross-sectional area of 0.8±0.1 mm². Specimens of each group were
individually mounted on a jig and placed on a tensile testing universal machine. A
tensile force was applied at a 0.5mm/min cross-speed. The failure mode was
recorded using scanning electron microscopy. In order to observe dentin/adhesive-
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cement interface, selected beans of each group were stained with 0.1%
Rodhamine B for 1 h and analyzed using Confocal Laser Scanning Microscopy.
Statistical analysis was performed using ANOVA and Fisher‟s PLSD test (α=0.05).
Results: Forbond strength (MPa)nostatistical difference was observed among the
groups: I-59.9 (9.3); II- 57.6 (15.9); III - 63.9 (12.7) and IV- 53.7 (13.9). Group V
showed statistically lower average value 16.2 (6.4)when compared to others
groups. Cohesive failure modes occurred predominately along the adhesive and
resin cement interface for all groups. The ultrastructural observation suggested
dentin surface interaction between multi-mode adhesives and resin cement when
the adhesive or resin cement was light-activated.
Conclusions: Theadhesive interaction occurred between multi-mode adhesive
systems and resin cements wheneverthe adhesive and/or resin cement was light-
activated.
Keywords: Bond strength; Universal adhesives; Dentin interface morphology
Introduction
The clinical success of indirect restorations has been attributed to the stable
and long lasting bonding of adhesive systems and resin cements to dental tissues
(Inokoshi, 1993; Sjogren, 1995; Perdigao, 2013). Laboratory and clinical research
has assessed the quality of adhesive materials, which are constantly evolving.
Several factors may influence the mechanical, physical and chemical properties,
such as the curing mode and the surface treatment of those materials, which are
fundamental to achieve longevity of the restoration (Aguiar, 2010; André, 2013).
The advancement of the adhesive technique has brought the self-etch
systems to be developed in order to simplify the application and to reduce post-
operative sensitivity (Van Meerbeek, 2011). The self etch adhesive systems
promote partial demineralization of dental substrate whilst, simultaneously,
promotes the penetration of the resin monomer. This process is due to the
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presence of a bifunctional acid monomer in its composition that interacts
chemically with the hydroxyapatite (Yoshida, 2001).
There are different types of adhesive systems on the dental market, which
consist of a similar bonding mechanism, but differ, from the others in several
aspects, such as type of monomer, water content and acidity. A study was found
that some simplified actually adhesive systems are incompatible with some self-
cured resin cements (Suh, 2003). When simplified adhesive systems are used
together with chemically cured resin cements, there could be an interaction of it
residual acidic resin monomers with binary components peroxide-amine and
tertiary amine commonly present in self-cured resin cements.Globular
structuresare formed as product of this reaction, and after light activation, some
voids can be formed along the adhesive/resin cement interface (Yamauchi, 1986;
Miller, 1999; Sanares, 2001). Despite light-cured cements have better mechanical
properties (Braga et al, 2002; Kumbuloglu et al., 2004; Arrais et al, 2008) self-cure
resin cements are advantageous in areas not easily target by light. Thus, dual-
cured cements containing components to initiate the polymerization reaction also in
the absence of light have been used for indirect restoration procedures (Milleding,
1995).
A new category of single-step/self-etch adhesive has been developed and it
is classified as universal or "multi-mode” because of its capability to be used in
various clinical situations. The multi-mode adhesive systems are considered ultra-
mild self-etching systems due to the higher pH (pH≥ 2.5) compared to
previoussimplified adhesive systems. This fact could contribute to ameliorate the
compatibility between adhesives residual acidic monomers andamine
moleculespresent in some dual-cure resin cement. These multi-mode adhesive
systems contain functional monomers such as 10-MDP (Metacriloxidecil Di-
hydrogen phosphate) that allows a stable connection with hydroxyapatite that
surrounds the collagen fibers within the bonding area (Yoshihara, 2011; Yoshida,
2000). It isalso available on the market a new kind of dual-cure resin cement that
substitutes the traditional chemical polymerization system (amine/benzoil peroxide)
10
with an innovative redox complex formed by trimetilhilhexanoate tert-butyl peroxide
and sodium persulfate, in order to avoid the adverse interaction produced between
the adhesive acidic monomers and tertiary amine (activator) present in the
traditional system.
Although the development and improvement of dual resin cements and
adhesive systems are constant, some questions about the interaction of these
materials on dentin surface still remain unanswered. Also the lack ofsubstantial
information on this topic hinders the researchers to drawn a definitive suggestion of
the best clinical procedure when using these materials. Thus, SEM analysis
technique on bonding interface is the ideal complement for bond strength
mechanical tests performed after 24h due to its capability to asses a detailed
ultrastructural observation and the possible detection of morphological changes in
the bonding area formed by universal adhesives (pH ≥ 2.5) and resin cements with
different oxi-reduction systems. The objective of this study was to evaluate the
interaction effect between multi-mode adhesives and chemical-cure and dual-cure
resin cements (containing different redox systems) on the dentin surface. The null
hypothesis is that the light activation of universal adhesive systems and/or dual
resin cementdoes not display differences on the morphology and bond strength,
when compared to those allowed for self-cure only.
11
Material & methods
The present study was approved by the respective Committee of ethics in
research (Protocol #057/2013). Forty caries-free extracted human third molars
were collected, cleaned, and stored in thymol solution under refrigerationfor a
maximum of three monthsprior the experiment.
Preparation of dentin surfaces
The preparation of dentin surfaces for microtensile bond strength (µTBS) is
presented in Figure 1. The root of each tooth was removed and the crown was cut
to obtain a middle-dentin flat surface using a low-speed diamond saw (Extec Corp.;
Enfield, CT, USA) mounted on a precision cutting machine (Isomet 1000, Buehler;
Lake Buff, IL, USA). The dentin surfaces were sanded using 600-grit SiC (silicon
carbide) abrasive paper under water cooling for 60 seconds to produce a
standardized smear layer. After that, samples were randomly assigned into 5
groups (n=8) to be treated with different materials as follows: I - All Bond Universal
(AB) light-cured (LC)/C&B Bond (CB) self-cured (SC), II - Scotchbond Universal
(SBU) light-cured (LC)/RelyX Ultimate (RXU)self-cured (SC), III - SBU LC/RXU LC,
IV - SBU no light-cured (NLC)/RXU LC and Group V – SBU NLC/RXU SC.
Materials, manufacturers, composition, and application protocol are described in
Table 1.
Pre-treatment of indirect composite
The CAD/CAM composite blocks A1 (LAVA Ultimate CAD/CAM blocks for
CEREC, 3M ESPE) were sectioned into 4 blocks of 3.0x12x12 mmusing a water-
cooled diamond saw (Isomet 1000, Buehler, Lake Bluff, IL, USA). The resultant
surface was then sandblasted with aluminium oxide (50 µm; Rønvig Dental Mfg.
A/S, Daugaard, Denmark) for 30s and cleaned with ethanol. Two different
restoration-surface pre-treatments were used: for All Bond group, a silane primer
(„CP‟, RelyX Ceramic Primer, 3M ESPE) was applied; and for the Scotchbond
12
Universal („SBU‟, 3M ESPE) group, the adhesive (SBU) was single applied. The
adhesive applied on the composite block was only air-thinned, but not light-cured.
Studied groups: adhesive application, cementation and curing modes
Both adhesives (AB and SBU), were applied on the dentin surfaces
according to manufacturer‟s instructions (Table 1). For the groups I, II and III the
adhesive was directlylight-activated for 10 s using a LED light-curing unit Elipar
S10 LED Curing Light (3M ESPE; St Paul, MN, USA) operating at 800mW/cm2. For
the group IV, the adhesive was indirectly light-cured through the resin cement and
the composite block for 100 s (20 s each proximal side and at the top surface).
During the experiment, the light output intensity was periodically analyzed using a
radiometer (SybronKerr, Orange, CA, USA). For the group V the adhesive was left
uncured. The internal surface of the restorationwas filled using the respective
composite cement under a constant seating force of 250 g for 10 min. The
cementation procedure (Table 2) when both adhesive and cement were separately
light-cured will be named here in after as „LC/LC‟. In curing protocol named „LC/SC‟,
the adhesive was light-cured as described above, while the composite cement was
left uncured (to be self-polymerized) and submitted equally to the same amount of
load as described before for 10 min. In „NLC/LC‟ curing protocol, the adhesive was
not separately light-cured, but co-polymerized when the composite cement was
light-cured through the composite block for 100 s. For „NLC/SC‟ curing protocol,
the adhesive was not light-cured and the composite cement was left to be self-
cured as described above. After this, all specimens were kept at relative humidity
for 24 h at 37⁰C.
Microtensile Bond Strength Test (µTBS)
After 24 hours storage, the samples were longitudinally sectioned in both „x‟
and „y‟ axes across the adhesive interface using a low-speed diamond saw on a
precision cutting machine to obtain beams of approximately 0.8mm2 of bonding
area. The beans were individualy attached to a testing jig with cyanoacrylate
13
adhesive (Super Bonder Loctite Henkel; São Paulo, SP, Brazil) and subjected to a
tensile force in a universal testing machine (EZ Test, Shimadzu; Kyoto, Japan) at a
crosshead speed of 0,5 mm/min. The cross-sectional areas were calculated in
order to obtain μTBS values in MPa units. The data were statistically analyzed by
one-way ANOVA and Fisher‟s PLSD test (α=0.05) using Statview software. Failure
surface from dentin sides were gold sputter coated and analyzed under SEM (JSM
5600LV, JEOL; Tokyo, Japan). Failure modes were categorized into: Interface (IF)
adhesive-resin cement, IF dentin-adhesive-resin cement, IF adhesive-dentin,
cohesive in resin cement, cohesive in adhesive.
Interfacial Morphology Analysis under Confocal Laser Scanning Microcopy
(CLSM)
The teeth were restored as previously described. After 24 hours storage, the
restored teeth were longitudinally sectioned in both „x‟ and „y‟ axes across the
adhesive interface using a low-speed diamond saw to obtain beams of
approximately 0.8mm2 of bonding area. The beams were embedded in epoxy resin
(Epoxy resin; UK Buehler, Lake Bluff, USA). The dentin-adhesive interfaces were
sequentially polished with #600, 800, 1200, and 2000-grit SiC abrasive papers
(Carborundum Abrasives, Recife, PE, Brazil) under running water. Next, 1.0, 0.3,
and 0.05µm diamond pastes (UK Buehler LTD, Lake Bluff, USA) on polishing felts
were used to complete the polishing procedure. To remove residual diamond paste,
a last polishing felt with no abrasives was used for 20 minutes under water cooling.
Between each diamond paste, the samples were ultrasonically cleaned (Unique
Ind. Co. and Electronic Products Ltda, Sao Paulo, SP, Brazil) for 10 minutes. For
this analysis, it was used the Rhodamine-B dye (Rhodamine-B, Sigma-Aldrich).
Five grams of the dye were weighed on a precision balance and dissolved in a
beaker containing 50ml of buffered saline solution (PBS), using a magnetic beater.
After the preparation,1% Rhodamine-B solution was kept in an amber bottle free of
light. The specimens were immersed in a 1% Rhodamine-B solution for 1h, and
14
then analyzed under a CLSM (LSM 510 Meta confocal microscope, Zeiss,
Göttingen, Germany).
Figure 1 – Specimen preparation for microtensile bond strength.
Human tooth Fragment
N=8 600-grit SiC Adhesive system /
light cure or not
Cementation /
light cure or not
Section – after 24h
Beams 0.8mm²
Bonding test
15
Table 1- Manufacturers, composition, and application mode of the materials used in
the study
Materials/Batch Manufacters Composition Application mode
All Bond Universal (1200009927)
BiscooInc.,Shaumburg,IL,USA
MDP, bis-GMA, HEMA, ethanol, water, initiators
Apply two separate coats of adhesive, scrubbing the preparation with a microbrush for 10–15 s per coat. Do not light polymerize between coats. Evaporate excess solvent by thoroughly air-drying with an air syringe for at least 10 s, there should be no visible movement of the material. The surface should have a uniform glossy appearance 3. Light polymerize for 10 s at 1200 mW/cm2
Scotchbond
Universal Adhesive (148785)
3M ESPE , St.
Paul, MN, USA
10- MDP, HEMA, Vitrebond copolymer, filler, ethanol, water, initiators, silane
1. Apply the adhesive to the entire preparation with a microbrushand rub it in for 20 s. If necessary, rewet the disposable applicator during treatment 2. Apply a gentle stream of air over the liquid for about 5 s until it no longer moves and the solvent to be completely evaporated 3. Light polymerize for 10 s
C&B Bond Cement (120009117)
BiscooInc.,Shaumburg,IL,USA
Base paste: Bis-GMA. EthoxylatedBis-GMA, TriethyleneglycolDimethacrylate, Sodium Fluoride. Catalyst paste: Bis-GMA, Triethyleneglycol,Dimethacrylate,
1. Mix equal amounts of C&B base and catalyst until obtaina uniform paste (10-15 seconds). 2. Fill the internal surface of the restoration with C&B using an instrument. 3. Seat the restoration with a light and passive pressure. 4. Remove excess C&B cement immediately with a brush or instrument.
RelyX Ultimate Cement (469868)
3M ESPE , St. Paul, MN, USA
Base paste: methacrylate monomers, radiopaque, silanated fillers, initiator components, stabilizers, rheological additives. Catalyst paste: methacrylate monomers, radiopaque alkaline (opaque) fillers, initiator components, stabilizers, pigments, rheological additives, fluorescence dye and dark cure activator for scotchbond universal adhesive
RelyX Ultimate is delivered in an automix syringe. 1. Fill the internal surface of the restoration the using the provided tip. 2. Seat the restoration with a light and passive pressure. 3. Remove excess immediately with a brush or instrument.
MDP: 10- methacryloyloxydecyldihydrogen phosphate; Bis-GMA: Bisphenol A diglycidyl ether methacrylate;HEMA: 2-hydroxylethyl metacrylate
16
Table 2 - Overview of the different curing modes employed.
Groups Adhesive System Resin Cement
GI All Bond Universal (Light-cure)
C&B Cement (Light-cure)
GII Single Bond Universal (Light-cure)
RelyX Ultimate (Self-cure)
GIII Single Bond Universal (No light-cured)
RelyX Ultimate (Light-curing)
GIV Single Bond Universal (No light-cured)
RelyX Ultimate (Self-cure)
Results
Microtensile bond strengths (µTBS)
The mean µTBS (MPa) and standard deviations (SD)for all groups are
summarizedin Table 3. Regarding “curing mode”, light-curing of adhesive or resin
cement, or both revealed the significantly highest µTBS for groups I, II, III and IV.
The one-way ANOVA and Fisher‟s PLSD (α=0.05) statistical analysis revealed no
difference between the groups: I - 59.9 (9.3); II- 57.6 (15.9); III - 63.9 (12.7) and IV-
53.7 (13.9). The lowestµTBSwas measured when the no light-cured adhesive was
used with the self-cured resin cement. The one-way ANOVA and Fisher‟s PLSD
(p<0.0001) statistical analysis revealed a significant difference between group V-
16.2 (6.4) and all others groups.
SEM examination of fractured interfaces
Failure modes as determined by SEM are summarized in Figure 2.
Representative adhesive failures from the bonding of universal adhesives and
dual/self-cured resin cements are shown in Fig. 3. Cohesive failure modes
occurred predominately along of adhesive and resin cement for all groups. Fig. 3a
is an adhesive failure that was taken from the dentin side of a fractured beam in
the AB/CB (LC/SC) group. Failure occurred predominantly along the adhesive-
dentin interface. The fractured adhesive-composite interface was characterized by
a large cluster of voids. Fig. 3a‟ correspond higher magnification (x1.000) of the
17
micrograph 3a. The fig. 3b is a representative fractured beam from the SBU/RXU
(LC/LC) group. The fractured resin cement interface was characterized by
cohesive failure with a dense and compact resin matrix, with few porous (Fig.3b‟).
Fig. 3c is an adhesive failure that was taken from the dentin side of a fractured
beam in the SBU/RXU (LC/SC) group. The failure mode occurred predominantly
cohesive along the resin cement, with some microporous seen in the closely
approximating (Fig. 3c‟). In SBU/RXU (NLC/LC) group, the adhesive failure
occurred predominantly along the adhesive-cement interface (Fig. 3d). Fig. 3d‟ is
characterized by the presence of microporous in the resin cement. Adhesive could
be identified along the fractured surface.
In contrast with the previous four groups, the fractured interfaces in
specimens from the SBU/RXU (NLC/SC) were characterized by microporous
inhibition films along the entire surface (Fig. 3e). Adhesive failure occurred
predominantly along the adhesive and resin cement interface. A surface inhibition
film, with several microporosities, was identified in the higher magnification (fig.
3e‟).
CLSM Analysis of Interfacial Morphology
Representative CLSM images of the adhesive/resin cement interfaces from
each group are shown in Figure 4. In the groups AB/CB (LC/SC) and SBU/RXU
(LC/LC) no dye sorption was observed between the adhesive and resin cement
interface (Fig 4a and 4b). For SBU/RXU (LC/SC) group it was possible to detected
dye sorption in self-cured resin cement (Fig 4c). A thin dye sorption was observed
between the dentin and the adhesive layer in SBU/RXU (NLC/LC) group (Fig 4d).
The SBU/RXU (NLC/SC) group showed a mixture between the adhesive and resin
cement represented by the red layer where much of the rhodamine B dye uptake
occurred (Fig 4e).
18
Table 3 - Means and standard deviations (SD) of microtensile bond strength values of
all groups
Groups Curing Mode Bond Strength (MPa)
I- AB/CB LC/SC 59.9 (9.3) A II- SBU/RXU LC/SC 57.6 (15.9) A
III- SBU/RXU LC/LC 63.9 (12.7) A
IV- SBU/RXU NLC/LC 53.7 (13.9) A
V- SBU/RXU NLC/SC 16.2 (6.4) B
Same superscript letters indicate no statistical difference among the groups (p < 0.0001).
Fig 2- Results of the SEM failure analysis for all experimental groups (%). Abbreviation:
IF = Interface.
0
10
20
30
40
50
60IF dentin-resin cement
adhesive+resin cement
IF adhesive-resin cement
IF dentin-adhesive-resin cement
IF adhesive-dentin
IF resin cement
IF adhesive
19
SEM Analysis of Interfacial Morphology
Representative SEM images of the adhesive/resin cement interfaces from
each group are shown in Figure 3.
SBU/RXU AL SBU/RXU AL G H
a’
b’
c’ c
b
a
SBU/RXU (LC/LC)
SBU/RXU (LC/SC) SBU/RXU (LC/SC)
SBU/RXU (LC/LC)
AB/CB (LC/SC) AB/CB (LC/SC)
20
Figure 3 - SEM micrographs of a representative fractured beam. (a) AB/CB LS (x100); (a‟) AB/CB LS (x1.000); (b) SBU/RXU LL (x100); (b‟) SBU/RXU LL (x1.000); (c) SBU/RXU LS (x100) ; (c‟) SBU/RXU LS (x1.000); (d) SBU/RXU NCL (x100); (d‟) SBU/RXU NCL (x1.000); (e) SBU/RXU NCL (x100) and (e‟) SBU/RXU NCL (x1.000). (a‟) A large cluster of voids were observed within the bulk of the resin cement (arrows). (b‟)Resin cement interface showing cohesive surface with a dense resin matrix, compact and with few porous (arrows). (c‟) Some microporous were present on the fractured resin cement surface. (d‟) Microporous were observed within the resin cement (arrows). Adhesive could be identified along the fractured surface (circle). (e‟) Dentin side showing the relationship between the microporous within the surface inhibition film of the adhesive and the underlying resin cement (arrow).
SBU/RXU (NLC/LC) SBU/RXU (NLC/LC) d d’
SBU/RXU (LC/SC)
SBU/RXU (LC/SC)
e e’ SBU/RXU (NLC/SC) SBU/RXU (NLC/SC)
c c’
21
CLSM Analysis of Interfacial Morphology
Representative CLSM images of the adhesive/resin cement interfaces from each
group are shown in Figure 4.
Figure 4 - CLSM micrograph of the multi-mode adhesive systems and resin cement interfaces: resin cement (RC), adhesive system (A), dentin (D). (a) AB/CB (LC/SC): no dye sorptionwas observed between the adhesive/resin cement interfaces. (b) SBU/RXU (LC/LC): no dye absorption was observed between the adhesive/resin cement interfaces. (c) SBU/RXU (LC/SC): it was possible to observe dye sorption (arrow) in self-cured resin cement; meanwhile the adhesive layer was represented by the dark layer (A) where there was not dye sorption. (d) SBU/RXU (NLC/LC): a thin dye sorption(arrow) was observed between the dentin and adhesive layer. (e) SBU/RXU (NLC/SC):a mixture between the no light-cured adhesive and self-cured resin cement was observed and represented by the red layer (arrow) where much of the rhodamine B dye uptake occurred.
b a AB/CB (LC/SC) SBU/RXU (LC/LC)
e
SBU/RXU(NLC/LC) c SBU/RXU(LC/SC) d
SBU/RXU(NLC/SC)
A RC
D
RC A D
RC
A D
RC
A
D
RC A
D
22
Discussion
Dual-cured resin cements consist of a mixture of monomers and catalysts
and are formulated so as not to depend solely on light activation for proper cure.
Then, light activation of such systems prior to delivering an indirect restoration
might not be necessary. However, it was well established that the self-curing
mechanism alone is less effective than the light activated one when a dual-cured
resin cement are used (Blackman, 1990; Hasegawa, 1991). Based on this
evidence, it is recommended light activation of adhesive system prior to applying
resin cement or indirect light-cure of the adhesive through the resin cement and
restoration.
This study evaluated the microtensile bond strength of Universal adhesives
combined with a resin cement based on a newly redox system (trimetilhilhexanoate
tert-butyl peroxide and sodium persulfate) when each is either allowed to self-cured
or is exposed to light through a pre-cured disc of resin composite. The results
demonstrate that the curing mode procedure used when cementing indirect
composite restorations did not affect the microtensile bond strength. No statistical
difference on bond strength values between both universal adhesives with pH
varying 2.7 (SBU) and 3.1(AB) and dual or self-cured resin cement to dentin
surface was observed when either adhesive or resin cement were light activated.
However, the microtensile bond strength values were statistically lower
whenadhesive resin and resin cement was allowed to self-cure only. The null
hypothesis that the light activation of universal adhesive systems or dual resin
cementdisplayno differences on the bond strength when compared to those
allowed for self-cure only was rejected.
Surprisingly, when used the Universal adhesive (Scothbond Universal)
combined with dual-cured resin cement (Rely X Ultimate) and light activated
adhesive or resin cement only during the cementation procedure, the microtensile
bond strength values were not statistically different (Groups - II, III, IV). It was
expected lower bond strength values when the SBU adhesive was left in the
23
uncured state before seating the indirect restoration (G-IV). Two reasons could
explain the initial expectative. First, the Universal adhesive has camphorquinone
only as polymerization initiator process. Then, it is not a dual-cure adhesive.
Besides it presents higher pH (pH ≥ 2.7). Clinically, if low pH acidic resin
monomers are used on the bonded surface before self-cured resin cement, the
adverse interaction between adhesive and dual-cure resin cement could occur
(Tay, 2003; Sanares, 2001). Then, probably, the method of indirect restoration
placement on uncured resin cement promotes with the resin adhesive an
interaction of both materials. Thelight activates all photoinitiators to initiate the
polymerization.In SBU/RXU (NLC/LC) group, the failure mode occurred
predominantly along the adhesive-composite interface (Fig.2d). This group was
characterized by the presence of microporous in the resin cement. Adhesive could
be identified along the fractured surface. When the adhesion interface was
observed by CLSM, these group specimens showed dye sorption between dentin
and adhesive system. This cementation mode is usually preferred in an attempt to
ensure an adequate marginal adaptation and to avoid incomplete seating of the
restoration.
The second cementation procedure used in this study was light-curing the
adhesive system prior to applying resin cement (G-II).This procedure generated
residual acidic resin monomers on the bonding surface due inhibiting adhesive
polymerization of the superficial layer in contact with oxygen from the atmosphere
(Rueggeberg, 1990; Yammauchi, 1986). Then, the resin cement was applied on a
acidic adhesive layer, seating the restoration on the resin cement that is self-cured
only. The contact between residual cured Universal adhesive resins (SBU) and
uncured resin cement did not affect the microtensile bond strength. Probably, the
mean reason for these results is the new redox system used in the resin cement
(RelyX Ultimate), which is based on trimetilhilhexanoate tert-butyl peroxide and
sodium persulfate that allowed self-curing chemical reaction properly.The failure
mode occurred predominantly cohesive along the resin cement. Some microporous
were present on the fractured resin cement surface. In CLSM analysis, it was
24
possible to observe dye sorption in self-cured resin cement; meanwhile the light-
cured adhesive layer was represented by the dark layer where there was not dye
sorption. The effect of the self-cured resin cement (C&B Bond) on the microtensile
bond strengths was not noted when applied on the Universal adhesive (All Bond
Universal) light cured surface (G-I). No statistical difference was found when
compared with microtensile bond strength values from Groups II, III and IV, but
their values was statistically higher then Group V. Microscopic analysis of fractured
specimens indicted voids formation, which can relate to the adverse interaction
between acidic adhesive monomers (All Bond Universal) and tertiary amine
catalytic componentof resin composite (C&B cement). However, the CLSM
micrograph shows no dye sorption between the adhesive layer/resin cement
interfaces for the same experimental group.Probably, this fact occurred due to the
CLSM perform more superficial area of the specimens. It is possible to assume
that the deeper layers of the uncured resin cement were not marked by the
rodhamine B dye. Then, although the bond strength showed higher at 24 hours
evaluation, these adverse interactions can compromise the bonding longevity.
These results are similar to some studies that mean the slow reaction in the self-
cured mode produces lower monomers conversion degree, allowing the presence
of more unreacted monomer groups and water sorption, with probably decrease of
mechanical properties over time (Braga, 2002;Arrais, 2009).
Although the bond strength values did not presentedstatistical difference
among different clinical cementation procedures when the adhesive layer or resin
cement were not light activated, the rodhamine B dye uptake was more intense
due to the polymer network interaction of the interfaces on the interfaces seems
inadequate. The single step adhesive contains water and ethanol to improve
ionization of 10-MDP monomers and to allow dentin interaction. It is very difficult to
remove water and ethanol of the adhesive before its curing. The residual water and
ethanol inhibits polymerization of the adhesive and remains after polymerization in
the bonding area between dentin and adhesive resin and resin cement. Because of
these components, the polymer network formed is less dense and probably was
25
intensely marked by rodhamine B dye. A possible reason why resin films are more
or less permeableto water is due to their degree of conversion (Breschi, 2007).
Under-curedadhesives are more permeable (Cadenaro, 2005; Breschi, 2007) than
optimally curedadhesives. Under-curing can be due to inadequate irradiationor due
to dilution by too much solvent, inadequate solventevaporation and other
variables.All adhesives used in this study contain water. According to the literature,
an increasein water concentration results in decreased degree of conversionand
lower bond strength for BisGMA/HEMA mixtures (Ye, 2007), therefore preventing
optimal polymerization of the adhesive.Sano et al. (1999) investigated the resin-
dentin bonds of a self-etching adhesive using a micro-tensile test.Although analysis
of the results revealed no reduction in bond strength,morphological changes in the
resin composite and adhesive resin wereobserved at the fractured surface over
time, what corroborate this study.
The two cementation method employed in G–II and IV were not different
statistically when compared to microtensile bond strength obtained for both
universal adhesive layer and resin cement light activated separately during the
cementation procedure, as recommended by the manufactured. However, when
universal adhesive layer (Scothbond Universal) and resin cement (Rely X Ultimate)
was left in uncured state on the bonding surface (G-V), the self-curing mechanism
by itself was ineffective in providing reliable mechanical properties for dentin
surface. The bond strength value was statistically lower compared with other
cementation mode (Groups I, II, III and IV). The failure mode in group V occurred
predominately along in the adhesive and resin cement.SEM morphological
analyses indicated poorly polymerized areas in the adhesive and resin cement,
which were detected by the several microporosities within the surface inhibition film
(Fig 2e‟).CLSM images revealed adhesive/resin-cement interface showing a
mixture of no light-cured adhesive and self-cure resin cement represented by the
thick red layer produce byrodhamine B dye uptake by monomers poorly
polymerized (Fig 4e).
26
In the curing mode LC/LC (G-III), both SBU and the RXU were light-cured
separately and consecutively. The SEM morphological analyses revealed cohesive
surface with a dense resin matrix, compact and with few and small voids.When the
adhesion interface was observed by CLSM, the Group III specimens showed the
complete interaction among dentin surface – adhesive – resin cement (Fig 4b).
Although the group III revealed no statistical difference between groups I, II and IV,
the morphological analysis presented better curing characteristics. By separately
light-curing the adhesive at the dentin side, the hybrid and adhesive layer is
thought to be stabilized before the composite cement is subsequently applied,
thereby also immediately sealing dentin and thus preventing water uptake from the
dentin host through osmosis (Van Landuyt, 2007).
Similar our results, previous study showed the bonding effectiveness of
separately light-activated adhesive resin layer at the dentin side and the resin
(Luhrs, 2014). Self-evidently, this can only be done when the adhesive has a
sufficiently low film thickness (after air-thinning), so that the restoration fit is not
impaired. However, inclusion of uncured Universal adhesives system without self-
curing constituent combined with resin cement light activated in this study could
postulate some evidence regarding the interaction effect of newly oxi-reduction
components on mechanical properties of the bonding interface. This alternative
technique may be a reality even in some clinical conditions where light exposition
is partly compromise and could make truth the preferential desire of the dentist to
ensure an adequate marginal adaptation and to avoid incomplete seating of the
restoration. However, further studies are necessary to evaluate the long-term
performance of these news cementation modes and resin cements materials.
Conclusion
Theadhesive interaction occurred between multi-mode adhesive systems
and resin cements wheneverthe adhesive and/or resin cement was light-activated.
27
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24. Van Landuyt KL, Snauwaert J, De Munck J, Coutinho E, Poitevin A, Yoshida Y, Suzuki K, Lambrechts P, Van Meerbeek B. Origin of interfacial droplets with one-step adhesives. J Dent Res. 2007 Aug;86(8):739-44
25. Van Meerbeek B, Yoshihara K, Yoshida Y, Mine A, De Munck J, Van Landuyt KL. State of the art of self-etch adhesives. Dent Mater. 2011 Jan;27(1):17-28.
26. Yammauchi J. Study of dental adhesive containing phosphoric acid methacrylate monomer. Japanese Journal of Dental materials 1986; 5:144-54.
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29. Yoshida Y, Van Meerbeek B, Nakayama Y, Yoshioka M, Snauwaert J, Abe Y, Lambrechts P, Vanherle G, Okazaki M. Adhesion and decalcification of hydroxyapatite by carboxylic acids. J Dent Res 2001;80:1565-1569
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Conclusão
A interação adesiva ocorreu entre os adesivos multi-mode e cimentos
resinosos de polimerização dupla ou química, sempre que o adesivo e/ou o
cimento resinoso foi fotoativado.
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* De acordo com as normas da UNICAMP/FOP, baseadas na padronização do International Committee of Medical Journal Editors. Abreviatura dos periódicos em conformidade com o Medline.
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Anexo