INFLUÊNCIA DA CORRENTE ELÉTRICA NA APLICAÇÃO DE SISTEMAS...
59
MAURICIO BOTTENE GUARDA INFLUÊNCIA DA CORRENTE ELÉTRICA NA APLICAÇÃO DE SISTEMAS ADESIVOS COM E SEM HEMA INFLUENCE OF THE ELECTRIC-CURRENT-ASSISTED APPLICATION OF HEMA-CONTAINING/-FREE ADHESIVE SYSTEMS Piracicaba, SP 2020 UNIVERSIDADE ESTADUAL DE CAMPINAS FACULDADE DE ODONTOLOGIA DE PIRACICABA
Transcript of INFLUÊNCIA DA CORRENTE ELÉTRICA NA APLICAÇÃO DE SISTEMAS...
MAURICIO BOTTENE GUARDA
INFLUÊNCIA DA CORRENTE ELÉTRICA NA
APLICAÇÃO DE SISTEMAS ADESIVOS COM E SEM
HEMA
INFLUENCE OF THE ELECTRIC-CURRENT-ASSISTED
APPLICATION OF HEMA-CONTAINING/-FREE ADHESIVE
SYSTEMS
Piracicaba, SP 2020
UNIVERSIDADE ESTADUAL DE CAMPINAS
FACULDADE DE ODONTOLOGIA DE PIRACICABA
MAURICIO BOTTENE GUARDA
INFLUÊNCIA DA CORRENTE ELÉTRICA NA
APLICAÇÃO DE SISTEMAS ADESIVOS COM E SEM
HEMA
INFLUENCE OF THE ELECTRIC-CURRENT-ASSISTED
APPLICATION OF HEMA-CONTAINING/-FREE ADHESIVE
SYSTEMS
Tese apresentada à Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas como parte dos requisitos exigidos para obtenção do título de Doutor em Materiais Dentários. Thesis presented to Piracicaba Dental School of the University of Campinas, in partial fulfillment of the requirements for degree of Doctor in Dental Materials.
Orientador: Prof. Dr. Simonides Consani
ESTE EXEMPLAR CORRESPONDE À
VERSÃO FINAL DA TESE DEFENDIDA
PELO ALUNO MAURICIO BOTTENE
GUARDA, E ORIENTADA PELO PROF.
DR. SIMONIDES CONSANI.
Piracicaba, SP 2020
Ficha catalográficaUniversidade Estadual de Campinas
Biblioteca da Faculdade de Odontologia de PiracicabaMarilene Girello - CRB 8/6159
Guarda, Mauricio Bottene, 1991- G931i GuaInfluência da corrente elétrica na aplicação de sistemas adesivos com e
sem HEMA / Mauricio Bottene Guarda. – Piracicaba, SP : [s.n.], 2020.
GuaOrientador: Simonides Consani. GuaTese (doutorado) – Universidade Estadual de Campinas, Faculdade de
Odontologia de Piracicaba.
Gua1. Adesivos dentinários. 2. Resistência à tração. 3. Infiltração dentária. 4.
Eletricidade. I. Consani, Simonides, 1939-. II. Universidade Estadual deCampinas. Faculdade de Odontologia de Piracicaba. III. Título.
Informações para Biblioteca Digital
Título em outro idioma: Influence of the electric-current-assisted application of HEMA-containing/-free adhesive systemsPalavras-chave em inglês:Dentin-bonding agentsTensile strengthDental leakageElectricityÁrea de concentração: Materiais DentáriosTitulação: Doutor em Materiais DentáriosBanca examinadora:Simonides Consani [Orientador]João Neudenir Arioli FilhoThatiana de Vicente LeiteLourenço Correr SobrinhoFlavio Henrique Baggio AguiarData de defesa: 18-02-2020Programa de Pós-Graduação: Materiais Dentários
Identificação e informações acadêmicas do(a) aluno(a)- ORCID do autor: https://orcid.org/0000-0002-7333-8753- Currículo Lattes do autor: http://lattes.cnpq.br/7490832400330979
Powered by TCPDF (www.tcpdf.org)
DEDICATÓRIA
Dedico este trabalho a minha família, amigos, professores e todos aqueles que
de alguma forma contribuíram para o meu aprendizado e minha evolução pessoal e
profissional.
AGRADECIMENTOS ESPECIAIS
A Deus, por todas as bênçãos concedidas em minha vida, permitido-me
chegar até este momento.
A minha família, Francisco, Silvia, Guilherme, Gabriela e João Pedro,
por toda base educacional, companheirismo, força de vontade, amparo, valores e
lições de vida que me passaram e sempre passarão.
A minha noiva Natália, por me apoiar em absolutamente tudo, por estar
sempre ao meu lado, não me deixar desanimar em nenhum momento, por acreditar
fielmente em mim e por todo amor, carinho e cuidado dispensado comigo em todos
esses anos.
Ao meu orientador Professor Dr. Simonides Consani, que desde a
graduação continua dando-me oportunidades e não se cansa de transmitir
conhecimento com toda sabedoria para todos ao seu redor, semeando em seu
entorno toda dedicação e paixão pelo que faz na Odontologia.
AGRADECIMENTOS
O presente trabalho foi realizado com apoio da Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) – código de
financiamento 001.
À Faculdade de Odontologia de Piracicaba - UNICAMP, nas pessoas
dos docentes Prof. Dr. Francisco Haiter Neto e Prof. Dr. Flávio Henrique Baggio
Aguiar, respectivamente Diretor e Diretor Associado, pela amizade, ajuda,
ensinamentos e oportunidades ao longo de 10 anos de minha caminhada na
Instituição.
À Profa. Dra. Karina Gonzales Silvério Ruiz, Coordenadora dos
Programas de Pós Graduação da Faculdade de Odontologia de Piracicaba -
UNICAMP, pela oportunidade e pelo respaldo na Pós Graduação.
Ao Prof. Dr. Américo Bortolazzo Correr, Coordenador do Programa de
Pós Graduação em Materiais Dentários da Faculdade de Odontologia de
Piracicaba - UNICAMP, pela amizade e por toda sabedoria transmitida ao longo desta
jornada.
Aos docentes do Programa de Pós Graduação em Materiais, Prof. Dr.
Simonides Consani, Prof. Dr. Mário Fernando de Góes; Prof. Dr. Lourenço Correr
Sobrinho; Prof. Dr. Mário Alexandre Coelho Sinhoreti; Prof. Dr. Américo
Bortolazzo Correr; Profa. Dra. Regina Maria Puppin Rontani; Prof. Dr. Luis
Roberto Marcondes Martins; Prof. Dr. Marcelo Giannini; Prof. Dr. Rafael
Leonardo Xediek Consani; Profa. Dra. Fernanda Miori Pascon; Prof. Dr. Alan
Roger dos Santos Silva e Profa. Dra. Ana Rosa Costa Correr, por todo o conteúdo
didático e humano, pelos ensinamentos inesquecíveis que me passaram ajudando
muito minha formação e ainda vão contemplar os futuros alunos que tiverem a mesma
sorte minha de ingressar no melhor programa em pós-graduação em Materiais
Dentários do Brasil.
Aos amigos Júlia Puppin Rontani, Marcus Vinicius Loureiro Bertolo e
Paolo Tulio di Nizo, pela amizade e companheirismo, partilhando de lembranças
eternas em nossas memórias ao longo de todos esses anos.
Aos amigos Bruna Marin Fronza e Gabriel Flores Abuna, pela valiosa
colaboração em diversas etapas da elaboração desta tese de doutorado.
Ao meu irmão Guilherme Bottene Guarda e aos amigos Ana Paula
Piovezan Fugolin e Rafael Pino Vitti, por me incentivarem a ingressar na pós-
graduação, pelos ensinamentos e valiosa colaboração em todas as etapas.
Aos amigos da turma de doutorado Aline Fedoce Silva, Christian Madrid
Troconsis, Gabriel Nima Bermejo, Isaac Jordão de Souza Araújo, Júlia Puppin
Rontani, Marcus Vinícius Loureiro Bertolo, Mateus Garcia Rocha, Paolo Tulio di
Nizo e Paulo Vitor Campos Ferreira, por compartilharem todas as aulas do
Programa de Doutorado muito além de conhecimento, com momentos bons e ruins
durante essa experiência única para todos nós.
A todos os demais amigos que fiz durante a pós-graduação em Materiais
Dentários, Marina Barreto Pereira Moreno, Pedro Paulo Albuquerque, Renally
Wanderley, Jamille Favarão, Maurício Matté Zanini, pelo apoio, companheirismo e
amizade sempre.
Aos demais amigos ainda presentes do Programa de Pós Graduação em
Materiais Dentários, por compartilharem experiência e sabedoria comigo.
Aos funcionários responsáveis pelo Laboratório de Materiais Dentários,
Engenheiro Marcos Blanco Cangiani e Sra. Selma Aparecida Barbosa Segalla,
por tornarem os dias de laboratório mais tranquilos e pelo apoio.
Aos demais docentes e funcionários da FOP-UNICAMP, quando por
diversas maneiras contribuíram para minha formação.
Aos Professor Dr. Luís Roberto Marcondes Martins, Professora Dra.
Fernanda Miori Pascon e Professor Dr. Américo Bortolazzo Correr, pelas
ponderações e valiosa contribuição por ocasião do Exame de Qualificação.
Aos Professor Dr. Lourenço Correr Sobrinho, Professor Dr. Flávio
Henrique Baggio Aguiar, Professora Dra. Thatiana de Vicente Leite e Professor
Dr. João Neudenir Arioli Filho, pelas ponderações e valiosa contribuição por ocasião
do Consurso de Defesa de Tese.
Aos meus amigos de graduação que caminharam comigo até obtenção
do nosso objetivo: ser cirurgião-dentista pela FOP-UNICAMP.
Aos meus amigos externos ao ambiente acadêmico, os quais sempre
estiveram ao meu lado compartilhando momentos inesquecíveis que levarei por toda
minha vida.
RESUMO
O objetivo neste estudo foi avaliar a influência da corrente elétrica na
resistência da união, capacidade de penetração, nanoinfiltração e grau de conversão,
em sistemas adesivos experimentais com ou sem HEMA, no período de 24 horas e
após termociclagem. Na superfície da dentina de terceiros molares hígidos aplicou-se
os sistemas adesivos experimentais de acordo com os seguintes grupos: Adesivo com
HEMA+0 µA; Adesivo sem HEMA+0 µA; Adesivo com HEMA+50 µA; Adesivo sem
HEMA+50 µA. Os dentes foram restaurados com Flitek Z250 formando um bloco de 5
mm de altura. Os conjuntos dente-restauração foram seccionados em palitos com
secção transversal de 1 mm2 e separados em dois subgrupos para ensaio da
resistência da união à microtração (MPa) no período de 24 horas ou após 10.000
ciclos térmicos de 5 e 55ºC (n=10). Os padrões de fratura dos palitos foram
classificados em falha mista, adesiva, e coesiva em dentina ou resina. A penetração
dos sistemas adesivos na dentina foi analisada em microscopia confocal de varredura
à laser (n=2). Dez palitos de cada grupo (5 para cada tempo) foram imersos em
solução de nitrato de prata amoniacal e analisados em microscopia eletrônica de
varredura. As imagens foram analisadas por software Image J para quantificação do
nitrato de prata na camada híbrida. O grau de conversão (n=5) foi obtido por
espectroscopia no infravermelho próximo por transformada de Fourier. Os dados de
resistência da união e nanoinfiltração foram submetidos à ANOVA três fatores
(armazenamento x sistema adesivo x corrente elétrica) e teste de Tukey com nível de
significância de 5%. Os dados do grau de conversão foram submetidos à ANOVA dois
fatores (sistema adesivo x corrente elétrica) e teste de Tukey com nível de
significância de 5%. Os resultados mostraram menores valores de resistência da
união após termociclagem, qualquer que fosse o sistema adesivo. Adesivos com
HEMA mostraram valores similares quando foi usada a corrente elétrica. Adesivos
sem HEMA mostraram maiores resultados de resistência da união quando a aplicação
foi com corrente elétrica. Na aplicação convencional, os resultados foram similares
entre os adesivos. Na aplicação com corrente elétrica, os adesivos sem HEMA
mostraram maiores valores que os adesivos com HEMA. Análise do padrão de fratura
mostrou predominância da falha mista em 24 horas e após termociclagem. Imagens
de microscopia confocal de varredura a laser mostraram maior penetração do adesivo,
principalmente na aplicação da eletricidade para adesivos com HEMA. A corrente
elétrica também foi responsável pela menor nanoinfiltração em adesivos sem HEMA.
Após termociclagem, os adesivos associados à corrente elétrica mostraram menor
nanoinfiltração. Maior nanoinfiltração (%) foi observado após termociclagem sem
aplicação da corrente elétrica, quando comparado com a aplicação no mesmo
período. O grau de conversão mostrou maiores valores para adesivos associados à
eletricidade, e adesivos sem HEMA mostraram maior conversão que aqueles com
HEMA. Pode-se concluir que a aplicação associada à corrente elétrica proporcionou
maiores valores de resistência da união de adesivos sem HEMA. Maior infiltração do
adesivo, menor nanoinfiltração e maior grau de conversão foram observados qualquer
que fosse o sistema adesivo.
Palavras-chave: Adesivos dentinários; Resistência à Tração; Infiltração Dentária;
Eletricidade.
ABSTRACT
The aim of this study was to evaluate the influence of electric current on
bond strength, penetration capacity, nanoleakage and degree of conversion in HEMA-
containig/-free experimental adhesive systems, after 24 h water storage and after
thermocycling. On the dentin surface of healthy third molars the experimental adhesive
systems were applied according to the following groups: HEMA-containing adhesive +
0 µA; HEMA-free adhesive + 0 µA; HEMA-containing adhesive + 50 µA adhesive;
HEMA-free adhesive + 50 µA. The teeth were restored with Flitek Z250 composite
forming block with 5 mm high. The samples were sectioned into 1 mm2 cross-section
tooth-composite sticks and separated into two subgroups for microtensile bond
strength (µTBS - MPa) testing after 24 h water storage or after 10,000 thermal cycles
of 5 and 55 °C (n=10). Fracture patterns were classified as mixed, adhesive, and
cohesive dentin or resin failure. The adhesive systems penetration in dentin was
analyzed by confocal laser scanning microscopy (n=2). Ten sticks from each group (5
for each time) were immersed in ammonium silver nitrate solution and analyzed by
scanning electron microscopy. The images were analyzed by Image J software for
silver nitrate quantification in the hybrid layer. The degree of conversion (n=5) was
obtained by Fourier transform near infrared spectroscopy. Bond strength and
nanoinfiltration data were submitted to three-way ANOVA (storage x adhesive system
x electrical current) and Tukey’s test with a 5% significance level. The degree of
conversion data were submitted to two-way ANOVA (adhesive system x electric
current) and Tukey’s test with a 5% significance level. The results showed lower bond
strength values after thermocycling, regardless of the adhesive system. HEMA-
containing adhesives showed similar values when electric current was used. HEMA-
free adhesives showed higher bond strength results when applied with electric current.
In the conventional application, the results were similar between the adhesives. In the
application with electric current, HEMA-free adhesives showed higher values than
HEMA-containing adhesives. Fracture pattern analysis showed predominance of
mixed failure at 24 h and after thermocycling. Laser scanning confocal microscopy
images showed greater adhesive penetration, especially when applying electricity to
HEMA-containing adhesives. Electric current was also responsible for the lower
nanoleakage in HEMA-free adhesives. After thermocycling, the adhesives associated
with the electric current showed lower nanoleakage. Higher nanoleakage (%) was
observed after thermocycling without application of electric current, when compared to
application in the same period. The degree of conversion showed higher values for
adhesives associated with electricity, and HEMA-free adhesives showed higher
conversion than HEMA-containing adhesives. In conclusion, the application
associated with electric current provided higher bond strength values for HEMA-free
adhesives. Greater adhesive infiltration, lower nanoleakage and higher degree of
conversion were observed regardless of the adhesive system.
Keywords: Dentin-bonding agents; tensile strength; dental leakage; eletricity.
SUMÁRIO
1. INTRODUÇÃO 15
2. ARTIGO: Influence of the electric-current-assisted application of HEMA-
containing/-free adhesive systems. 19
3. CONCLUSÃO 47
REFERÊNCIAS 48
APÊNDICE 1 – Imagens das metodologias 52
ANEXOS
ANEXO 1 – Relatório de originalidade e prevenção de plágio 58
ANEXO 2 – Submissão de artigo 59
15
1. INTRODUÇÃO
Desde o surgimento dos compósitos resinosos como opção para protocolos
de restaurações dentais, inicialmente por meio do condicionamento ácido do esmalte
(Buonocore, 1955) e depois pela união adesiva à dentina (Pashley et al., 1993), os
pesquisadores têm focado os estudos objetivando desenvolver materiais que
proporcionem melhor união entre os substratos dentários e os materiais restauradores
poliméricos. Assim sendo, os sistemas adesivos são considerados os responsáveis
pela eficiente união adesiva.
Quando foram desenvolvidos, os sistemas adesivos se baseavam no
protocolo do condicionamento total (total-etching) e eram aplicados em esmalte e
dentina em três etapas distintas: 1- condicionamento com ácido fosfórico a 35-40%;
2- aplicação do primer (solução preparadora da dentina, baseada em monômeros
hidrófilos responsáveis pela penetração do adesivo na dentina e recobrimento das
fibrilas colágenas expostas pelo condicionamento ácido) e 3- aplicação do adesivo,
baseado em monômeros hidrófobos responsáveis pela união ao primer, à dentina e
ao compósito restaurador (Van Landuyt et al., 2007). Historicamente, a primeira
grande evolução desses sistemas foi a associação do primer - adesivo numa única
formulação química, capaz de penetrar nos substratos e promover união adesiva ao
compósito, reduzindo o tempo do procedimento clínico (Pashley et al., 2011).
Algum tempo depois foi introduzido no mercado nova abordagem técnica
para os sistemas adesivos, conhecida como auto-condicionante (self-etch). A grande
diferença entre a técnica auto-condicionante e o condicionamento total é que a
primeira emprega monômeros funcionais que conseguem interagir com o substrato e
causar desmineralização tanto do esmalte quanto da dentina, eliminando a etapa do
condicionamento prévio com o ácido fosfórico. Além disso, essa técnica permite
adesão química ao substrato dental, promovendo benefícios como menor tempo
clínico, menor chance de sensibilidade pós-operatória (Unemori et al., 2004; Van
Meerbeek et al., 2011;) e diminuição da ação de metaloproteinases (MMP’s) na
interface adesiva, ocorrência bastante comum quando os sistemas com
condicionamento total são empregados (Mazzoni et al., 2015).
16
Ainda na tentativa de simplificar esse procedimento restaurador e diminuir
o tempo clínico foram introduzidos no mercado os sistemas adesivos universais.
Esses adesivos associam o primer funcional e o adesivo num único frasco, além de
serem empregado em ambos os protocolos de aplicação, ou seja, condicionamento
total ou auto-condicionante, além de possuir silano na composição, permitindo que
esses sistemas adesivos possam ser usados em diferentes substratos como metal e
cerâmica, além do dente (Muñoz et al., 2013; Alex, 2015). Embora ambos os
protocolos promovessem resultados satisfatórios, algumas ocorrências clínicas
negativas mostraram-se relevantes, principalmente em longo prazo. Assim, os
problemas relacionados à composição dos adesivos podem promover união adesiva
menos efetiva mecanicamente, nanoinfiltração, separação de fases monomérica e
menor resistência da união, tornando-a menos estável em longo prazo (Tay et al.,
2004; Van Meerbeek et al., 2005; Sadek et al., 2005; Suppa et al., 2005; Van Landuyt
et al., 2005; Van Landuyt et al., 2007; Van Landuyt et al., 2009).
Compondo a maioria dos sistemas adesivos, o monômero hidrófilo HEMA
(2-hidroxi-etil metacrilato) é extremamente importante na formulação do produto.
Funcionando como umectante da dentina favorece a difusão de outros monômeros no
substrato dentinário e nas fibrilas colágenas, além de dificultar a separação de fases
entre monômeros hidrófilos e hidrófobos (Van Landuyt et al., 2005; Furukawa et al.,
2008; Van Landuyt et al., 2008).
Estruturado quimicamente na composição como monometacrilato, o HEMA
dificulta a remoção da água porque a pressão de vapor diminui durante a volatilização
do solvente, mantendo a camada híbrida umedecida, ocorrência que pode
comprometer a polimerização de monômeros (Furukawa et al., 2008). A menor taxa
de polimerização causa consequências negativas, como a deterioração das
propriedades mecânicas gerando problemas estruturais ao longo do tempo. Assim, os
principais problemas relatados na literatura em adesivos contendo HEMA estão
associados a maior absorção de água pela camada híbrida e degradação da interface
adesiva (Tay et al., 2005; Moszner et al., 2005; De Munck et al.,2006; Torkabadi et al.,
2008).
Além de problemas na interface da união adesiva, o HEMA possui maior
potencial alergênico (Kanerva et al., 1995). Assim, a manipulação e contato com luvas
17
que contenham partículas de monômero não polimerizadas podem causar dermatite
de contato (Andreasson et al., 2003). Na aplicação dos sistemas adesivos, as
partículas de baixo peso molecular podem penetrar nos túbulos dentinários e atingir a
polpa, causando apoptose celular (Paranjpe et al., 2005).
Na tentativa de reduzir os problemas associados ao HEMA, diversos
estudos foram feitos com adesivos sem HEMA na composição, ou seja, conhecidos
na literatura como HEMA-free (Moretto et al., 2013). Entretanto, enquanto alguns
estudos não mostraram diferenças significativas quanto ao desempenho clínico de
ambos os sistemas adesivos (Burrow et al., 2012; Moretto et al., 2013; Hafer et al.,
2015), outros mostraram diferenças significantes no desempenho desses produtos
(Van Dijken et al., 2013; Van Landuyt et al., 2014; Hafer et al., 2015).
Algumas áreas da Odontologia têm utilizado a eletricidade em dispositivos
que verificam a vitalidade pulpar (Nekoofar et al., 2006), detectores de lesões de cárie
em esmalte (White et al.,1978) e localizadores periapicais em procedimento
endodônticos (Keller et al.,1991). Entretanto, nos procedimentos restauradores com
união adesiva um dispositivo conhecido como ElectroBond foi desenvolvido com a
intenção de melhorar a infiltração de monômeros na dentina com aplicação da
corrente elétrica (Pasquantonio et al., 2003), fato que poderia favorecer a união.
Estudos utilizando esse dispositivo mostraram melhor infiltração de monômeros na
dentina desmineralizada (Pasquantonio et al., 2007) e maiores valores de resistência
da união (Breschi et al., 2006; Pasquantonio et al., 2007; Visintini et al., 2008) quando
comparados à técnica convencional de aplicação do adesivo.
Com base nessas considerações, seria interessante avaliar sistemas
adesivos experimentais com ou sem HEMA associados à aplicação da corrente
elétrica. A aplicação tem a intenção de melhorar a infiltração monomérica através de
um aumento da energia de superfície da dentina e melhora do ângulo de contato do
sistema adesivo, levando a maior resistência de união e menor nanoinfiltração.
Entretanto, não existe informação na literatura sobre qual seria o valor da corrente
fornecida pelo ElectroBond e a possibilidade do ajuste ser de acordo com o valor da
energia elétrica de diferentes substratos, considerando que os dentes exibem
composições com pequenas alterações podendo influenciar diretamente os valores
da corrente aplicada.
18
Com o objetivo de esclarecer essas dúvidas foi desenvolvido no Laboratório
de Materiais Dentários da FOP-UNICAMP um dispositivo similar ao ElectroBond
(Pasquantonio et al., 2003), com a diferença de que o dispositivo proposto é capaz de
medir o valor da resistência elétrica estrutural de cada dente e permitir a seleção da
corrente elétrica com intensidade padronizada a ser definida pelo operador.
Diante do exposto, o objetivo neste estudo foi avaliar a influência da
corrente elétrica na resistência da união, capacidade de penetração, nanoinfiltração e
grau de conversão, em sistemas adesivos experimentais com ou sem HEMA, no
período de 24 horas e após termociclagem. As hipóteses do estudo foram que a
aplicação da corrente elétrica seria capaz de: 1 - Aumentar os valores da resistência
da união adesiva, qualquer que fosse o sistema adesivo e ciclagem térmica; 2 -
Promover formação de camada híbrida com maior infiltração monomérica; 3 - Causar
menor nível de nanoinfiltração na interface adesiva; e 4 - Promover maior conversão
monomérica.
Este trabalho foi apresentado no formato alternativo de tese de acordo com
as normas estabelecidas pela deliberação 002/06 da Comissão Central de Pós-
Graduação da Universidade Estadual de Campinas. O artigo referente ao Capítulo
Único foi submetido à publicação em periódico de circulação internacional (Brazilian
Oral Reserach).
19
2. ARTIGO: Influence of the electric-current-assisted application of
HEMA-containing/-free adhesive systems.
Abstract
The aim of this study was to evaluate the influence of electric current on
bond strength, penetration capacity, nanoleakage and degree of conversion in HEMA-
containig/-free experimental adhesive systems, after 24 h water storage or after
thermocycling. On the dentin surface of healthy third molars the experimental adhesive
systems were applied according to the following groups (n=10): HEMA-containing
adhesive + 0 µA; HEMA-free adhesive + 0 µA; HEMA-containing adhesive + 50 µA
adhesive; HEMA-free adhesive + 50 µA and restored with Flitek Z250 composite.The
samples were tested for µTBS (MPa) after 24 h and after 10,000 thermal cycles
between 5 and 55ºC. The penetration capacity of dentin bonding systems was
analyzed by confocal laser scanning microscopy (n=2) (CLSM). Sticks from each group
after storage periods were quantified for nanoleakage in the hybrid layer. The degree
of conversion was obtained by near infrared spectroscopy by Fourier transform. µTBS
and nanoleakage data were submitted to 3-way ANOVA and Tukey’s test (α=0.05).
The degree of conversion data were submitted to 2-way ANOVA and Tukey’s test
(α=0.05). The µTBS results decreased after thermocycling, regardless of the adhesive
systems. HEMA-free adhesives increased bond strength in association with electricity.
In the application with electric current, HEMA-free adhesives showed higher results
than HEMA-containing adhesives. CLSM images showed greater adhesive
penetration, especially with electricity application for HEMA-containing adhesives.
Electric current was responsible for the lower nanoleakage in HEMA-free adhesives.
After thermocycling, adhesives associated with electric current showed lower
nanoleakage. Higher nanoleakage (%) was observed after thermocycling without
electric current application compared to application in the same period. Conversion
degree showed higher values for adhesives associated with electricity, and HEMA-free
adhesives showed higher conversion than HEMA-containing adhesives. It can be
concluded that the application associated with electric current promoted higher bond
strength values for HEMA-free adhesives. Greater adhesive infiltration, lower
nanoleakage and higher degree of conversion were observed regardless of the
20
adhesive system. Thermocycling decreased µTBS values and lower nanoleakage was
observed when the electrical current was applied.
Keywords: Dentin-bonding agents, tensile strength, dental leakage, eletricity.
21
Introduction
The increasing use of adhesive polymers in dentistry was possible due to
the dental acid etching proposed in 1955 (1). Thus, many studies have been based on
developing and improving the adhesive bond between dental substrate and
composites (2). Adhesive systems called total-etching were the first to be introduced
for adhesive bond, just where the bond interaction was exclusively mechanical
between substrate and adhesive system (3).
These adhesives underwent some changes that facilitated the clinical use
and, after some years, the self-etch systems were developed and became an
alternative technique that combines mechanical and chemical interactions (4). Still in
an attempt to simplify the clinical process, the universal systems that can be used in
self-etch or total etch technique were developed and gained popularity due to the ease
clinical procedure (5,6). However, despite satisfactory clinical and laboratory results,
all adhesive systems have shown some long-term bond problems, as less
mechanically effective adhesive bond, nanoleakage, phase separation and lower bond
strength, making this adhesive bond less stable in the long term (7-9).
The majority of commercially available adhesive systems contains in the
compositions the hydrophilic 2-hydroxyethyl methacrylate monomer (HEMA) as an
important component of the chemical formulations. HEMA acts as a dentin wetting
agent, aids in the diffusion of other monomers into the deep dentin and collagen fibrils,
and prevents phase separation between hydrophilic and hydrophobic monomers (10-
12).
In contrast, the HEMA monomethacrylate difficults the water remove during
solvent volatilization by the decreasing vapor pressure, leaves water residues in the
hybrid layer compromising the suitable polymerization and negatively influences the
mechanical properties (11). High HEMA hydrophilicity causes greater water absorption
by the adhesive layer, degrading the bond interface (13-16). HEMA can also cause
problems such as contact dermatitis (17,18) and apoptotic death of dental pulp cells
by migrating the monomer through the dentinal tubules (19), due to the higher
allergenic potential.
22
In an attempt to reduce the problems associated with HEMA, several
studies have been done with the removal of this monomer from the chemical
composition of the adhesive, which were called HEMA-free adhesive systems (20).
However, the literature shows some results with no statistical difference between these
materials (20-22), and other studies where the difference was significant (23-25).
Some dentistry areas have used electricity for devices, as pulp vitalometer
(26), early caries detector (27) and electronic apex locators (28). In adhesive bonding
procedures, the electricity was used with the intention of improving the monomers
infiltration to dentin, favoring the adhesion through a device called ElectroBond,
developed as option to conventional application with microbrush (29). Studies using
this device showed better monomer infiltration to demineralized dentin (30), and higher
bond strength values (30-32) when compared to the conventional technique.
Thus, it would be interesting to evaluate experimental adhesive systems
containing- or not- HEMA monomers in association with the application of electric
current application. The application is intended to improve monomeric infiltration by
increasing the surface energy of the dentin and improving the contact angle of the
adhesive system, leading to greater bond strength and lower nano-infiltration. For this,
it was used a device developed in the Dental Materials Laboratory at FOP-UNICAMP,
whose main difference in relation to ElectroBond is the possibility to control the emitted
current, which level can be defined by the operator whatever the electric resistance
level shown by the teeth.
Based on these considerations, the aim of this study was to evaluate the
influence of electric current on experimental HEMA and HEMA-free adhesive systems
regarding the immediate bond strength and after aging, as well as the degree of
conversion and the hybrid layer quality through tests, images and nanoleakage.The
study hypotheses were the electrical current application would able of: 1- to increase
the adhesive bond strength values, whatever the adhesive system and the aging time;
2- to promote hybrid layer formation with greater monomeric infiltration; 3- to cause
lower level of nanoleakage at the adhesive interface; and 4- to promote greater
monomer conversion.
23
Materials and methods
Experimental adhesive formulation
Two experimental single-step self-etch adhesive systems HEMA containing or HEMA-
free were fabricated. The HEMA contianing solution consisted of 20% bisphenol A
glycidyl dimethacrylate (BisGMA; E Sigma-Aldrich, San Luis, MO, USA), 20%
hydroxyethyl methacrylate (HEMA; SigmaAldrich), 20% Glycerol-dimethacrylate
phosphate (GDMA-P; Sigma-Aldrich), 10% distilled water, 25.5% ethanol, and at a
ratio of 60% monomers and 35.5% solvents. 0.5% butylhydroxytoluene (BHT; Sigma-
Aldrich), 1% diphenyliodonium hexafluorophosphate (DPIHP, Sigma-Aldrich) and 1%
camphorquinone/2% amine (CQ/EDAB, Sigma-Aldrich) in the monomer mixture
previously homogenized at a ratio of 95,5% monomers/solvents and 4,5% photo-
initiator agents. The HEMA-free solution consisted of similar composition, changing
the 20% HEMA for Glycerol-dimethacrylate monomer (GDMA; Sigma-Aldrich) in the
same concentration. The others components and concentrations were the same for
the HEMA containing system.The adhesive blend presented proper viscosity for dental
application, absence of phase-separation and clear-uniform appearance. The
adhesive systems were prepared in a dark room under controlled temperature and
humidity, and then kept under refrigeration (4 °C). Prior to use, the adhesives were
stirred for 15 min. All material concentrations utilized in the formulations were
calculated in weight.
24
Teeth surface preparation
This study was approved by the local Research Ethics (protocol
21820719.0.0000.5418). For the µTBS test, healthy human molars extracted from
patients aged from 18 to 45 years old were used. The teeth were cleaned and stored
immersed in water at 4º C and used for a period not exceeding 6 months.
After storage, the teeth were sectioned on a cutting machine (Isomet 1000
Buehler, Lake Bluff, IL, USA) with low speed diamond disc cooled with distilled water.
The cut was made approximately 1.5 mm below the cementum-enamel junction and 4
mm above the cementum-enamel junction in order to obtain similar slices in medium
dentin. The resulting dentine slices were stored in distilled water and refrigerated at 4º
C. After storing and prior to adhesive procedures, flat dentin surfaces were manually
polished with # 600 sandpaper and water for 30 s to obtain a standard smear layer.
Description of the experimental groups
The materials and the protocols are listed in Table 1. The following
experimental groups were considered: HEMA 0 - HEMA adhesive without electrical
current application stored for 24 h; HEMA-free 0 - HEMA-free adhesive without
electrical current application stored for 24 h; HEMA 50 - HEMA adhesive with 50 µA
electrical current application stored for 24 h ; HEMA-free 50 - HEMA-free adhesive
with 50 µA electrical current application stored for 24 h; HEMA 0TC - HEMA adhesive
without electrical current application and 10,000 thermal cycles; HEMA-free 0TC -
HEMA-free adhesive without electrical current application and 10,000 thermal cycles;
HEMA 50TC - HEMA adhesive with 50µA electrical current application and 10,000
thermal cycles; HEMA-free 50TC - HEMA-free adhesive with 50µA electrical current
application and 10,000 thermal cycles.
25
Table 1. Materials and protocols.
Material
Manufacturer
Composition (%wt)
Instructions
Self-etching
Experimental
Adhesive with
HEMA (EHEMA)
20% HEMA, 20% Bis-
GMA, 20% GDMA-P,
10% water, 25,5%
ethanol, 1% CQ, 2%
EDAB, 1% DPHIF,
0.5% BHT.
Active adhesive
application for 30 s,
light air blast and
photoactivation for 20
s (1200mW/cm2).
Self-etching
Experimental
Adhesive HEMA-
Free (EHEMA-
Free)
20% GDMA, 20%
BisGMA, 20% GDMA-
P, 10% water, 25,5%
ethanol, 1% CQ, 2%
EDAB, 1% DPHIF,
0.5% BHT.
Active adhesive
application for 30 s,
light air blast and
photoactivation for 20
s (1200mW/cm2).
Filtek Z250 XT
3M-ESPE, St.
Paul, MN,
USA
Bis-GMA, Bis-EMA,
UDMA, TEGDMA, silica
nanoparticles (20 nm),
zirconia / silica nano
agglomerates (5-20
nm), 78.5 wt% (total
charge).
Restauration with 2
mm increments, each
one photo-activated
by 20 s.
The samples of teeth were restored according to the protocols showed in
Table 1 (n=10). For the conventional application mode (HEMA 0, HEMA-free 0, HEMA
0TC and HEMA-free 0TC), the adhesive systems was performed as recommended by
the manufacturers using microbrushes, which were replaced for each sample. The
adhesive system application in the experimental groups (HEMA 50, HEMA-free 50,
HEMA 50TC and HEMA-free 50TC) was performed similarly, except that at one end of
26
the electrical current generator there was a metallic tweezers replacing the microbrush.
At the other end of the electrical circuit there was a metal cable attached to a damp
sponge to simulate periodontal moisture conditions. In these conditions, the electrical
current was applied to the adhesive-dentin assembly. This device was developed in
the Dental Materials Laboratory of FOP-UNICAMP. The equipment has a device (chip)
that determines the value of the electrical resistance of the samples and automatically
adjusts the emitted current in 50 µA for all samples.
The 5 mm-height restoration with Filtek Z250 (3M ESPE, St. Paul, MN, USA)
was performed using the incremental technique and each increment was
photoactivated with 1200mW/cm2 irradiance LED (Bluephase G2, Ivoclar Vivadent,
Liechtenstein) for 20s
The samples were cut to obtain tooth-composite sticks of approximately 1-
mm² cross-sectional area. The sticks were aleatory divided in two equal parts and
distributed for the tests: 1- storage in deionized water at 37ºC for 24 h, and 2- 10,000
thermal cycles with 5 and 55 oC baths for 30 s in OMX 300 TSX thermal cycling
machine (Odeme Dental Research, Luzerna, SC, Brazil). After storage and thermal
cycling, the sticks were subjected to the µTBS test.
Microtensile bond strength (µTBS) test
The microtensile test was performed on an EZ Test EZ-S tensile testing
machine (Shimadzu, Kyoto, Japan). The sticks were fixed at the ends in the machine
devices and tested under tensile strength at a speed of 1 mm/min with a 500 N load
cell, until rupture. After fracture, the sticks were removed and the cross-sectional area
measured with a digital caliper (0.01 mm accuracy). The stress required to cause was
determined by the ratio between the load at the time of fracture (N) and the cross-
sectional area of the fracture (mm2) in MPa. Failure pattern was evaluated by an optical
microscope at 50x magnification, and classified as adhesive, cohesive
(dentin/composite) or mixed failure (evolving dentin, adhesive and composite).
27
Penetration Analysis by Confocal Laser Scanning Microscopy
Eight teeth were divided into 4 groups. For each mL of adhesive system
(n=2), 0.07 µg of rhodamine B was incorporated (Sigma Chemicals, St. Louis, MO,
USA). The restorative procedures followed the same protocols applied in the samples
for microtensile test. After the restoration, the tooth was stored in 0.1 wt% aqueous
fluorescein solution (FL: Sigma Chemicals) at room temperature for 24 h under
simulated pulp pressure condition (33). After this period, they were submitted to
ultrasonic cleaning in water for 2 min. Following, they were sectioned into 1 mm thick
slices (Isomet 1000 Buehler, Lake Bluff, IL, USA) with low speed diamond disc and
distilled water cooling. After, each slice was polished with #1200 granulated silicon
carbide sandpaper for 30 s and ultrasounded for 1 min to remove debris. Infiltration
analysis and hybrid layer formation was done with confocal laser scanning microscopy
(CLSM: TPS-SP5 CLSM; Leica, Heidelberg, Germany) (34).
Nanoleakage Analysis
Two tooth-composite sticks from each experimental unit of each group (at
24 h or after 10,000 thermal cycles) were embedded in epoxy resin (Epoxicure Buheler,
Lake Bluff, Illinois, 60044, USA). Ammonium silver nitrate was prepared by dissolving
25 g of silver nitrate crystals to 25 mL of deionized water. The 28% ammonium
hydroxide was dripped in the silver nitrate solution to titrate the initially transparent to
dark solution, and to become transparent again transforming ammonium ions into
silver diamine ions. The solution was diluted in deionized water to obtain 50 mL of
solution, formulating 50% ammonia silver nitrate concentration at pH 9.5. The sticks
were immersed in the tracing solution for 24 h. Following, they were washed with
deionized water and immediately immersed in developer solution (Kodak GBX
developer, Rochester, NY, USA) for 8 h in a fluorescent light environment to reduce
diamine silver ions in metallic silver grains in the adhesive-dentin interface spaces (35).
After dehydration, the tooth-composite sticks were polished with 600, 800
and 1200 silicon carbide sandpaper and felt, followed by diamond pastes (MetaDi
Supreme Diamond Suspensions; Buheler, Lake Bluff, IL, USA) with decreasing
granulations of 6, 3, and 1 μm, and ultrasound interleaved cleanings with water for 3
28
min. They were covered with a thin carbon layer in metallizer (Desk ll, Denton Vacuun
Inc., NJ, USA) at 40 mA for 120 s and observed under a low vacuum scanning electron
microscope (JSM 5900 LV, Jeol, Peabody, MA, USA) with a voltage of 15Kv, WD 15
mm and spotsize 50 nm operating with backscattered electrons.
Magnification images of 500x at the central regions and ends of the sticks
were evaluated with Image J software (Image J 1.42q, Wayne Rasband, National
Institutes of Health, USA) to calculate the infiltrated hybrid layer area, considered as
100%. In the hybrid layer base, the calculation of the infiltrated area (%) for each
adhesive system was made considering the hybrid layer and the adhesive layer ends.
With the particle analysis system it was possible to count the area (μm2). Thus, the
infiltration value (%) of each tooth-composite stick was obtained by the arithmetic mean
of three images. The total silver infiltration value (%) in the tooth was obtained by the
arithmetic mean of the sticks.
Degree of conversion analysis
Degree of conversion was obtained by Fourier transform near-infrared
spectroscopy (Vertex 70, Bruker Optics) in samples (n=5) with 5 mm in diameter and
1 mm in thick, laminated between two glass slides for the Groups HEMA 0 and HEMA-
free 50. For the Groups HEMA 50 and HEMA-free 50, the adhesive systems were
inserted into a metal matrix connected to the electric current generating device and
shaken for 30 s. A pipette was used to place the adhesive systems between two glass
slides for spectroscopy analyses. A initial spectrum was obtained for the
unpolymerized adhesives, and the sample was light-activated for 20 s at an incident
irradiance of 1200 mW/cm2 at 380 and 515 nm wavelength (Bluephase G2, Ivoclar
Vivadent). The area of the methacrylate vinyl absorbance band centered at 6165 cm-
1 was used to track the double bond C=C conversion. Measurements were taken in
4000 to 1000 cm-1 range at a wave number resolution of 4 cm-1 with 16 scans per
spectrum at 10 kHz acquisition rate (Opus 7.8 Spectrocopy Software Bruker). Degree
of conversion was calculated following the equation:
DC= [1- (peak area) polymerized / (peak area) unpolymerized] ×100
29
Statistical analysis
Data were submitted to the normality test and descriptive tests pertinent to
each methodology. Three-way ANOVA was performed for the µTBS and nanoleakage
test. For degree of conversion, 2-way ANOVA was used. In these cases, the means
comparison was performed by the Tukey’s test with a significance level of 5%.
Qualitative analyzes were made in CLSM images.
30
Results
There was no interaction between time x adhesive x electric current factors
(p=0.627). Tables 3 and 4 show the mean values (Mpa) and standard deviation for the
adhesive bond strength.
Table 2 shows that all groups presented a statistically significant reduction
of the adhesive bond strength after thermocycling regardless of the adhesive system
and electric current application.
Table 2: Means (MPa) and standard deviations for the µTBS after 24 h and
thermocycling for all adhesive systems.
24 h Thermocycling
28.46 (5.33) A 25.74 (6.85) B
Different capital letters show statistical difference (α = .05).
Table 3 shows that there was no statistical difference for the adhesive
containing HEMA when the electric current was used. The electric current application
significantly increased the adhesive bond strength for HEMA-free groups. In the
comparison between the adhesive systems, the convencional application (0 µA) did
not showed values with statistical difference. For the adhesives submitted to electric
current application, the HEMA-free showed higher statistical diference when compared
to the HEMA.
Table 3: Means (MPa) and standard deviations of the µTBS for HEMA-containing and
HEMA-free adhesive systems submitted to electric current.
0 µA 50 µA
HEMA 25.5 (5.90) Aa 25.92 (5.44) Ab
HEMA-free 25.22 (5.83) Ba 31.75 (5.79) Aa
Different capital letters in row and different lower case letters in column show statistical
difference (α = .05).
31
Figure 1 shows a representative images of the fracture mode classification.
Figure 1: Representative images of the fracture mode.
Figure 1A. Cohesive dentin fracture, with failure between dentinal tubules. Figure 1B.
Cohesive composite fracture. Figure 1C. Mixed fracture, showing dentin (#) and
composite (*) failures. Figure 1D. Adhesive fracture, with failure in the adhesive layer.
Figure 2 shows the failure modes (%) at 24 h-storage and after thermal
cycling. Mixed failure was predominant for all groups in both aging times. Adhesive
failures also occurred in all groups after aging. The fractures cohesive in composite
and cohesive in dentin were minority failures.
32
Figure 2: Failure mode (%) observed in the groups.
Figure 3 shows the hybrid layer permeability assessed by Confocal Laser
Scanning Microscope (CLSM) images. Figure 3A and C: Fluorescein sodium solution
infiltration through the hybrid layer was observed for both convencional application
groups. Figure 3B: The solution infiltration did not increase with electrical current
application for the HEMA in convencional application. The HEMA-containing adhesives
infiltration applied with electric current was better revealed by the sodium fluorescence
solution (in yellow). Figure 3A and B: The hybrid layer was also infiltrated by water.
Figure 3C: The HEMA-free groups without electrical current showed water infiltration
(in green color). Figure 3:D There was not water infiltration with electric current
application.
33
Figure 3: Representative CLSM images showing the adhesive interface.
Groups: A- HEMA + 0 µA; B: HEMA + 50 µA; C: HEMA-free + 0 µA, and D: HEMA-free + 50
µA. Adhesive layer (red) and die infiltration (green).
Tables 5 and 6 show the mean values and standard deviations of silver
particles nanoleakage in the adhesive layer (%). There was no interaction between the
factors (p=0.80959).
Table 4 shows that the HEMA-free adhesive systems showed lower
nanoleakage (%) regardless the time and electric current.
Table 4: Means and standard deviations of silver nitrate nanoleakage values (%) in the
hybrid layer.
HEMA HEMA-free
2.52 (0.71) A 2.25 (0.77) B
Different capital letters show statistical difference (α = .05).
34
Table 5 shows that 24-h storage and electric current application association
did not influence on the nanoleakage (%) of the adhesive systems. After thermocycling,
the groups with electric current showed significantly lower values for nanoleakage than
the groups without electric current. In the groups without electric current application,
the thermocycled promoted higher values than those for 24 h. There was no significant
difference in nanoleakage (%) between the samples thermocycled or stored for 24 h
when submitted to electric current.
Table 5: Means and standard deviations of silver nitrate nanoleakage values (%) on
the hybrid layer of adhesive systems applied with or without electric current after 24-h
storage or thermocycled.
0 µA 50 µA
24 h 2.7 (0.70) Ab 2.17 (0.65) Aa
Thermocycling 2.87 (0.81) Aa 2.13 (0.63) Ba
Different capital letters in row and different lower case letters in column show statistical
difference (α = .05).
35
Figure 4 shows representative images of the 24-h storage nanoleakage.
There was low nanoleakage (arrows) in the hybrid layer for all groups.
Figure 4: Representative images of silver nitrate nanoleakage in 24 h-storage.
Groups: A- HEMA + 0 µA; B- HEMA + 50 µA; C- HEMA-free + 0 µA, and D: HEMA-
free + 50 µA at 24-h storage.
Figure 5 shows representative images of 10,000 thermal cycles
nanoleakage. There are increase in nanoleakage in groups without electric current
(Figure 5: A-C, arrows), whereas in groups with electric current occurred lower silver
particles incidence in the hybrid layer (Figure 5: B-D, arrows).
36
Figure 5: Representative images of silver nitrate nanoleakage after 10,000 thermal
cycles.
Groups: A- HEMA + 0 µA; B- HEMA + 50 µA; C- HEMA-free + 0 µA, and D: HEMA-
free + 50 µA at 10,000 thermal cycles.
Table 6 shows the mean and standard deviation values for degree of
conversion for the adhesive systems with or without electric current application. There
was no interaction between the factors (p=0.90752). It was observed that the adhesive
containing HEMA showed greater capacity for monomer to polymer conversion,
regardless the electric current application. The electric current significantly increased
the degree of conversion, regardless the adhesive.
Table 6: Means and standard deviations of the degree of conversion (%).
0 µA 50 µA Mean
HEMA 62.79 (1,58) 71.5 (2.63) 67.14 (5.02) a
HEMA-free 56.01 (1,90) 64.4 (3,35) 60.24 (5.14) b
Mean 59.4 (3.93) B 67.48 (4.66) A
Different capital letters in row and different lower case letters in column show statistical
difference (α = .05).
37
Discussion
The results of this study showed that the adhesive bond strength values
decreased after 10,000 thermal cycles, regardless the adhesive system or the
application method (Table 1). These results are in agreement with some previous
studies, in which the bond strength decreased after thermal cycling (36,37). The choice
of this protocol was due to some studies provening the aging ability for the adhesive
bonding, since thermal cycling promotes detrimental effects on the interface and the
thermal changes accelerate the adhesive interface hydrolysis process, increasing
water uptake and monomer degradation (38). The high stress promoted by the
constant process of dimensional changes (contraction and expansion) in the adhesive
interfaces promotes cracks and fissures on the adhesive material due to the higher
thermal expansion coefficient when compared to dentin (39).
Analyzing the bond strength data when associated to electric current, the
HEMA-free adhesive systems showed better µTBS values. HEMA-containing adhesive
systems presented similar values for both application methods. When comparing the
different adhesive systems, there was no difference for the conventional application.
However, the HEMA-free adhesives showed better bond strength values with the
electric current application (Table 2).
These results are in agreement with those in previous studies when electric
current improved the adhesive systems bond strength (32,36,37). The difference
between the adhesive types seems to be related to the greater penetration capacity of
monomers. However, HEMA (molecular weight: 113.14 g/mol) has great hydrophilicity
and its infiltration also occurs associated to water molecules, contributing to greater
hydrolytic degradation (13-16). This fact can promote lower bond strength values and
to contribute for decreasing these values after also thermocycling. In the HEMA-free
adhesive systems, the present findings seem to show that higher molecular weight
monomers, as GDMA (molecular weight 228.24 g/mol), also can penetrate into the
adhesive layer (Figure 3D).
It can be assumed that these adhesive systems associated with electric
current act similarly to HEMA-containing adhesives, decreasing the deleterious effects
associated to this material, such as high hydrophilicity and consequent greater
38
hydrolytic degradation. Thus, the first hypothesis of the study was rejected, since the
adhesive bond strength values decreased after thermal cycling.
Figure 2 shows that there was predominance of mixed failures for all groups
in both sample aging times. After thermocycling, there was increase of adhesive
failures for all groups. This fact could explain the reduction of the bond strength values
after thermocycling. However, this decrease was more pronounced for the groups with
adhesive systems applied without electric current. In addition, groups with higher µTBS
showed great number of mixed failures.
As only HEMA-containing adhesives showed the highest adhesive
penetration (Figure 3: B), the second hypothesis that electrical current would increase
adhesive penetration was rejected. The increase adhesive strenght value was
probably due to changes in the dentin organic structure (40). This fact occurs when
electric current interacts with the polar characteristic of collagen and proteoglycans,
which may favor the water infiltration and hydrophilic monomers due to little changes
in the collagen fibrils orientation. Moreover, changes in intra and interfibrillar hydrogen
bonds also increase substrate wettability, favoring greater penetration of adhesive
systems (30,32,41).
In addition, the cathode (negative pole) of the electricity generating device
negatively charges the dentin surface, attracting the monomer molecules polarized by
the electricity action (positive pole), improving the adhesive penetration (31). In
addition to these allegations, the electric current application also increase the water
substitution rate due to molecules polarized, favoring the water and solvente exit, and
improving the enter of resinous monomers (42).
Similar fact could happen to HEMA-free adhesive systems, but the absence
of this highly hydrophilic monomer decreases the adhesive penetration, while water
shows more difficulty to penetrate in the adhesive interface (Figure 3:D), probably
generating a more stable hybrid layer. In addition, the assumption of previous studies
that the additional acid etching associated to HEMA-free single-step self-etching
adhesive systems may improve monomeric infiltration into dentin (43) and the bond
strength (44) appears to be a viable clinically protocol to follow. These findings were
confirmed by evaluating silver nitrate nanoleakage in the specimens. HEMA-containing
39
adhesive systems showed higher nanoleakage values (%) (Table 2; Figure 5:A) when
compared to HEMA-free (Table 2; Figure 5:C), which is in agreement with the results
shown in previous study (45).
When the adhesive systems were compared between storage times, the
electric current was not effective in decreasing nanoleakage at 24-h storage (Table 3;
Figure 4), while lower values were observed after thermocycling procedure (Table 3;
Figures 5:B-D), as also was shown in previous study (32). The adhesive systems
without electric current application showed higher infiltration level after thermocycling
(Table 3; Figures 5: A-C), while those with electric current application did not show this
difference, even after aging procedure (Table 3; Figure 5: B-D) (36). This fact
corroborates with the findings of CLSM, which showed lower water penetration at the
adhesive interface for HEMA-free materials (Figure 3: D) and higher monomeric
penetration for materials containing HEMA (Figure 3: B), factors that may contribute to
better adhesive bond when compared to conventional method. Thus, the third
hypothesis that electric current would promote lower nanoleakage was accepted.
Similarly, the fourth hypothesis that electric current would increase
monomer conversion was also accepted, since higher degree of conversion values are
associated with lower rate of residual monomers not converted to polymer and,
therefore, less susceptible to degradation level over storage time (46).
In addition, HEMA-containing adhesives showed a higher degree of
conversion than HEMA-free adhesives (Table 4). These values are opposite to showed
in previous study, where there was no difference between these adhesives systems,
but the HEMA concentration in the materials studied was lower (46). The difference
may be related to more amount of high molecular weight monomers in the HEMA-free
adhesive, which reduces the mobility of unreacted double bonds (47), coupled with a
low crosslinking density (48).
Another factor that may explain the increase in the degree of conversion is
the higher solvent evaporation rate when electric current is applied (49), probably this
occurs since the electric energy generates heat. This fact can be clarified by Joule's
Law: Q = I2. R. t (Where Q= heat; I= electroc current; R= electric resistance; and T=
time). This law relates the relations between heat and other forms of energy (such as
40
electrical and chemical), and by extension, the relationships between all energy forms
(Thermodynamics). Based on this law, when the electric current flows during the
adhesive application, it is necessary that energizes the molecules of the monomer to
promote energy (heat).
Considering that the electric current promoted positive effects on the
adhesives application, as for HEMA-free µTBS; greater adhesive infiltration; lower
nanoinfiltration, and higher degree of conversion. However, the thermocyclage
promoted lower µTBS for both adhesives, and lower nanoinfiltration (%) when
associated to electric current. These results appear to be related to HEMA
composition. Further studies are necessary to clarify the behavior of other adhesive
systems, mainly when the clinical long term is considered for the adhesive restoration
sucess.
41
Conclusion
The effects of electric current were: 1. Better bond strength of HEMA-free
adhesive systems when compared to HEMA-containing. 2. Better dentin adhesive
infiltration and decreased nanoleakage level. 3. Increased degree of conversion of both
adhesive systems. 4. Thermocycling decreased µTBS values and lower nanoleakage
was observed when the electrical current was applied.
42
References
1. Buonocore MG. A simple method of increasing the adhesion of acrylic filling
materials to enamel surfaces. J Dent Res. 1955; 34(6):849-53.
2. Pashley DH, Ciucchi B, Sano H, Horner JA. Permeability of dentin to adhesive
agents. Quintessence Int. 1993; 24(9):618-31.
3. Van Landuyt KL, Snauwaert J, De Munck J, Peumans M, Yoshida Y, Poitevin A, et
al. Systematic review of the chemical composition of contemporary dental
adhesives. Biomaterials. 2007; 28(26):3757-85.
4. Pashley DH, Tay FR, Breschi L, Tjäderhane L, Carvalho RM, Carrilho M et al. State
of the art etch-and-rinse adhesives. Dent Mater. 2011; 27(1):1-16.
5. Muñoz MA, Luque I, Hass V, Reis A, Loguercio AD, Bombarda NHC. Immediate
bonding properties of universal adhesives to dentine. J Dent. 2013; 41(5):404-11.
6. Alex L. Universal adhesives: the next evolution in adhesive dentistry? Compend
Contin Educ Dent. 2015; 36(1):15-26.
7. Van Meerbeek B, Van Landuyt K, De Munck J, Hashimoto M, Peumans M,
Lambrechts P. Technique-sensitivity of contemporary adhesives. Dent Mater J.
2005; 24:1-13.
8. Sadek FT, Goracci C, Cardoso PE, Tay FR, Ferrari M. Microtensile bond strength
of current dentin adhesives measured immediately and 24 hours after application.
J Adhes Dent. 2005; 7:297-302.
9. Suppa P, Breschi L, Ruggeri A, Mazzotti G, Prati C, Chersoni S, et al. Nanoleakage
within the hybrid layer: a correlative FEISEM/TEM investigation. J Biomed Mater
Res B: Appl Biomater. 2005; 73:7-14.
10. Van Landuyt KL, De Munck J, Snauwaert J, Coutinho E, Poitevin A, Yoshida Y, et
al. Monomer-solvent phase separation in one-step self-etch adhesives. J Dent Res.
2005; 84(2)183-8.
11. Furukawa M, Shigetani Y, Finger WJ, Hoffmann M, Kanehira M, Endo T, et al. All-
in-one self-etch model adhesives: HEMA-free and without phase separation. J
Dent. 2008; 36(6)402-8.
12. Van Landuyt KL, Snauwaert J, Peumans M, De Munck J, Lambrechts P, Van
Meerbeek B. The role of HEMA in onestep self-etch adhesives. Dent Mater. 2008;
24: 1412-9.
43
13. Tay FR, Pashley DH, Suh BI, Hiraishi N, Yiu CK. Water treeing in simplified dentin
adhesives – déjà vu? Oper Dent. 2005; 30:561-79.
14. Moszner N, Salz U, Zimmermman J. Chemical aspects of self-etching enamel-
dentin adhesives: a systematic review. Dent Mater. 2005; 21:895-910.
15. De Munck J, Van Landuyt K, Peumans M, Pointevin A, Lambrechts P, Braem M, et
al. A critical review of the durability of adhesion to tooth tissue: methods and results.
J Dent Res. 2006; 85:1016-21.
16. Torkabadi S, Nakajima M, Ikeda M, Foxton RM, Tagami J. Bonding durability of
HEMA-free and HEMA-containing onestep adhesives to dentine surrounded by
bonded enamel. J Dent 2008; 36: 80-6.
17. Kanerva L, Jolanki R, Leino T, Estlander T. Occupational allergic contact dermatitis
from 2-hydroxyethylmethacrylate and ethylene glycol dimethacrylate in a modified
acrylic structural adhesive. Contact Dermat. 1995; 33:84-9.
18. Andreasson H, Boman A, Johnsson S, Karlsson S, Barregard L. On permeability of
methyl methacrylate, 2-hydroxyethyl methacrylate and triethyleneglycol
dimethacrylate through protective gloves in dentistry. Eur J Oral Sci.
2003; 111:529-35.
19. Paranjpe A, Bordador LC, Wang MY, Hume WR, Jewett A. Resin monomer 2-
hydroxyethyl methacrylate (HEMA) is a potent inducer of apoptotic cell death in
human and mouse cells. J Dent Res. 2005; 84:172-7.
20. Moretto SG, Russo EMA, Carvalho RCR, De Munck J, Van Landuyt K, Peumans
M, et al. 3-year clinical effectiveness of one-step adhesives in non-carious cervical
lesions. J Dent. 2013; 41:675-82.
21. Hafer M, Jentsch H, Haak R, Schneider H. A three-year clinical evaluation of a one-
step self-etch and a two-step etch-and-rinse adhesive in non-carious cervical
lesions. J Dent. 2015; 43:350-61.
22. Burrow MF, Tyas MJ. Comparison of two all-in-one adhesives bonded to non-
carious cervical lesions – results at 3 years. Clin. Oral Invest. 2012; 16:1089-94.
23. Van Dijken JWV. A randomized controlled 5-year prospective study of two HEMA-
free adhesives, a 1-step self-etching and a 3-step etch-and-rinse, in non-carious
cervical lesions. Dent Mater. 2013; 29:e271-e80.
44
24. Van Landuyt KL, De Munck J, Ermis RB, Peumans M, Van Meerbeek B. Five-year
clinical performance of a HEMA-free one-step self-etch adhesive in noncarious
cervical lesions. Clin Oral Invest. 2014; 18:1045-52.
25. Hafer M, Jentsch H, Haak R, Schneider H. A three-year clinical evaluation of a one-
step self-etch and a two-step etch-and-rinse adhesive in non-carious cervical
lesions. J Dent. 2015; 43:350-61.
26. Nekoofar MH, Ghandi MM, Hayes SJ, Dummer PMH. The fundamental operating
principles of electronic root canal length measurement devices. Int endod J. 2006;
39: 595–609. 21.
27. White GE, Tsamtsouris A, Williams DL. Early detection of occlusal caries by
measuring the electrical resistance of the tooth. J dent res. 1978; 57: 195–200. 20.
28. Keller ME, Brown CE Jr, Newton CW. A clinical evaluation of the endocater–an
electronic apex locator. J endod. 1991; 17: 271–274.
29. Pasquantonio G, Breschi L, Petrone A. A method and device for preparing the hard
structures of teeth for the application of dental restorative materials. US Patent
2003; 6: 641,396.
30. Pasquantonio G, Tay FR, Mazzoni A, Suppa P, Ruggeri A Jr, Falconi M, et al.
Electric device improves bonds of simplified etch-and-rinse adhesives. Dent
Mater 2007; 23:513-8.
31. Breschi L, Mazzoni A, Pashley DH, Pasquantonio G, Ruggeri A, Suppa P, et al.
Electric-current-assisted application of self-etch adhesives to dentin. J Dent
Res. 2006; 85:1092-6.
32. Visintini E, Mazzoni A, Vita F, Pasquantonio G, Cadenaro M, Di Lenarda R, et al.
Effects of thermocycling and use of ElectroBond on microtensile strength and
nanoleakage using commercial one-step self-etch adhesives. Eur J Oral Sci. 2008;
116:564-70.
33. Tay FR, Pashley DH. Water treeing--a potential mechanism for degradation of
dentin adhesives. Am J Dent. 2003 Feb;16(1):6-12.
34. Feitosa VP, Leme AA, Sauro S, Correr-Sobrinho L, Watson TF, Sinhoreti MA et al.
Hydrolytic degradation of the resin-dentine interface induced by the simulated
pulpal pressure, direct and indirect water ageing. J Dent. 2012; 40(12):1134–43.
45
35. Sauro S, Osorio R, Watson TF, Toledano M. Assessment of the quality of resin-
dentin bonded interfaces: An AFM nano-indentation, μtBS and confocal
ultramorphology study. Dent Mater. 2012; 28(6):622-31.
36. González-Serrano C, Baena E, Fuentes MV, et al. Shear bond strength of a flash-
free orthodontic adhesive system after thermal aging procedure. J Clin Exp Dent.
2019; 11(2):e154-e61.
37. Labriaga W, Song SY, Park JH, Ryu JJ, Lee JY, Shin SW. Effect of non-thermal
plasma on the shear bond strength of resin cements to Polyetherketoneketone
(PEKK). J Adv Prosthodont. 2018; 10(6):408-14.
38. Hashimoto M, Ohno H, Kaga M, Endo K, Sano H, Oguchi H. In vivo degradation of
resin-dentin bonds in humans over 1 to 3 years. J Dent Res. 2000; 79 (6): 1385-
91.
39. Gale MS, Darvell BW. Thermal cycling procedures for laboratory testing of dental
restorations. J Dent. 1999; 27 (2): 89-99.
40. Pethig R. Dielectric properties of body tissues. Clin Physics and Physiological
Measurement. 1987; 8A: 5-12.
41. Toledano M, Mazzoni A, Monticelli F, Breschi L, Osorio E, Osorio R.
ElectroBond application may improve wetting characteristics of etched dentine. J
Dent. 2011; 39(2):180-6.
42. Pashley DH, Agee KA, Carvalho RM, Lee KW, Tay FR. Effects of water and water-
free polar solvents on the tensile properties of demineralized dentin. Dent
Mater. 2003; 19(5):347-52.
43. Wagner A, Wendler M, Petschelt A, Belli R, Lohbauer U. Bonding performance of
universal adhesives in different etching modes. J Dent. 2014; 42(7):800-7.
44. Kim Y, Kim S, Jeong T, Son SA, Kim J. Effects of Additional Acid Etching on the
Dentin Bond Strengths of One-Step Self-Etch Adhesives Applied to Primary Teeth.
J Esthet Restor Dent. 2017; 29: 110-117.
45. Takahashi M, Nakajima M, Hosaka K, Ikeda M, Foxton RM, Tagami J. Long-term
evaluation of water sorption and ultimate tensile strength of HEMA-containing/-free
one-step self-etch adhesives. J Dent. 2011; 39(7):506-12.
https://www.ncbi.nlm.nih.gov/pubmed/?term=Toledano%20M%5BAuthor%5D&cauthor=true&cauthor_uid=21126555
46
46. Collares FM, Leitune VCB, Portella FF, Ogliari FA, Werner-Samuel SM. Long-term
bond strength, degree of conversion and resistance to degradation of a HEMA-free
model adhesive. Braz J Oral Sci. 2014; 13(4):261-5.
47. Collares FM, Ogliari FA, Zanchi CH, Petzhold CL, Piva E, Samuel SM. Influence of
2-Hydroxyethyl Methacrylate Concentration on Polymer Network of Adhesive
Resin. J Adhes Dent. 2011; 13: 125-9.
48. Rueggeberg F, Tamareselvy K. Resin cure determination by polymerization
shrinkage. Dent Mater. 1995; 11: 265-8.
49. Chen H, Fu D, Yang H, Liu Y, Huang Y, Huang C. Optimization of direct currents
to enhance dentine bonding of simplified one-step adhesive. Eur J Oral Sci 2014;
122: 286–292.
47
3. CONCLUSÃO
Aplicação associada à corrente elétrica promoveu melhores valores de
resistência da união de sistemas adesivos HEMA-free em relação aos contendo
HEMA. Sistemas adesivos associados à corrente elétrica promoveram maior
infiltração adesiva em dentina e diminuição do nível de nanoinfiltração pela água. O
método da corrente elétrica para aplicação do sistema adesivo aumentou o grau de
conversão de ambos os sistemas adesivos.
A termociclagem promoveu diminuição dos valores de resistência da união,
qualquer que fosse o sistema adesivo. Menores valores de nanoinfiltração (%) foram
mostrados com adesivos associados à corrente elétrica.
48
REFERÊNCIAS*
Alex L Universal adhesives: the next evolution in adhesive dentistry? Compend
Contin Educ Dent. 2015;36(1):15-26.Andreasson H, Boman A, Johnsson S, Karlsson
S, Barregard L. On permeability of methyl methacrylate, 2-hydroxyethyl methacrylate
and triethyleneglycol dimethacrylate through protective gloves in dentistry. Eur J Oral
Sci. 2003; 111:529-35.
Breschi L, Mazzoni A, Pashley DH, Pasquantonio G, Ruggeri A, Suppa P, et al.
Electric-current-assisted application of self-etch adhesives to dentin. J Dent Res. 2006;
85:1092-6.
Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials
to enamel surfaces. J Dent Res. 1955; 34(6):849-53.
Burrow MF, Tyas MJ. Comparison of two all-in-one adhesives bonded to non-carious
cervical lesions – results at 3 years. Clin Oral Invest. 2012; 16:1089-94.
De Munck J, Van Landuyt K, Peumans M, Pointevin A, Lambrechts P, Braem M, et al.
A critical review of the durability of adhesion to tooth tissue: methods and results. J
Dent Res. 2006; 85:1016-21.
Furukawa M, Shigetani Y, Finger WJ, Hoffmann M, Kanehira M, Endo T, et al. All-in-
one self-etch model adhesives: HEMA-free and without phase separation. Journal of
Dentistry. 2008; 36(6)402-8.
Hafer M, Jentsch H, Haak R, Schneider H. A three-year clinical evaluation of a one-
step self-etch and a two-step etch-and-rinse adhesive in non-carious cervical lesions.
J Dent. 2015; 43:350-61.
Hafer M, Jentsch H, Haak R, Schneider H. A three-year clinical evaluation of a one-
step self-etch and a two-step etch-and-rinse adhesive in non-carious cervical lesions.
J Dent. 2015; 43:350-61.
Kanerva L, Jolanki R, Leino T, Estlander T. Occupational allergic contact dermatitis
from 2-hydroxyethylmethacrylate and ethylene glycol dimethacrylate in a modified
acrylic structural adhesive. Contact Dermat. 1995; 33:84-9.
* 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.
49
Keller ME, Brown CE Jr, Newton CW. A clinical evaluation of the endocater–an
electronic apex locator. J endod. 1991; 17: 271–274.
Mazzoni A, Tjäderhane L, Checchi V, Di Lenarda R, Salo T, Tay FR, et al. Role os
dentin MMPs in caries progression and bond stability. J Dent Res. 2015; 94(2):241-51.
Moretto SG, Russo EMA, Carvalho RCR, De Munck J, Van Landuyt K, Peumans M, et
al. 3-year clinical effectiveness of one-step adhesives in non-carious cervical lesions.
J Dent. 2013; 41:675-82.
Moszner N, Salz U, Zimmermman J. Chemical aspects of self-etching enamel-dentin
adhesives: a systematic review. Dent. Mater. 2005; 21: 895-910.
Muñoz MA, Luque I, Hass V, Reis A, Loguercio AD, Bombarda NHC. Immediate
bonding properties of universal adhesives to dentine. J Dent. 2013; 41(5):404-11.
Nekoofar MH, Ghandi MM, Hayes SJ, Dummer PMH. The fundamental operating
principles of electronic root canal length measurement devices. Int endod J. 2006; 39:
595–609. 21.
Paranjpe A, Bordador LC, Wang MY, Hume WR, Jewett A. Resin monomer 2-
hydroxyethyl methacrylate (HEMA) is a potent inducer of apoptotic cell death in human
and mouse cells. J Dent Res. 2005; 84:172-7.
Pashley DH, Ciucchi B, Sano H, Horner JA. Permeability of dentin to adhesive agents.
Quintessence Int. 1993;24(9):618-31.
Pashley DH, Tay FR, Breschi L, Tjäderhane L, Carvalho RM, Carrilho M et al. State of
the art etch-and-rinse adhesives. Dent Mater. 2011; 27(1):1-16.
Pasquantonio G, Breschi L, Petrone A, inventors; A methodand device for preparing
the hard structures of teeth for the application of dental restorative materials. US
Patent, 6: 641,396; 2003.
Pasquantonio G, Tay FR, Mazzoni A, Suppa P, Ruggeri A Jr, Falconi M, Di Lenarda
R, et al. Electric device improves bonds of simplified etch-and-rinse adhesives.Dent
Mater. 2007; 23:513-8.
Sadek FT, Goracci C, Cardoso PE, Tay FR, Ferrari M. Microtensile bond strength of
current dentin adhesives measured immediately and 24 hours after application. J
Adhes Dent. 2005; 7:297-302.
50
Suppa P, Breschi L, Ruggeri A, Mazzotti G, Prati C, Chersoni S, et al. Nanoleakage
within the hybrid layer: a correlative FEISEM/TEM investigation. J Biomed Mater Res
B: Appl Biomater. 2005; 73:7-14.
Tay FR, Pashley DH, Suh B, Carvalho R, Miller M. Single-step, self-etch adhesives
behave as permeable membranes after polymerization. Part I. Bond strength and
morphologic evidence. Am J Dent. 2004; 17:271-8.
Tay FR, Pashley DH, Suh BI, Hiraishi N, Yiu CK. Water treeing in simplified dentin
adhesives –déjà vu? Oper Dent. 2005; 30:561-79.
Torkabadi S, Nakajima M, Ikeda M, Foxton RM, Tagami J. Bonding durability of HEMA-
free and HEMA-containing onestep adhesives to dentine surrounded by bonded
enamel. J Dent. 2008; 36: 80-6.
Unemori M, Matsuya Y, Akashi A, Goto Y, Akamine A. Self-etching adhesives and
postoperative sensitivity. Am J Dent. 2004; 17(3):191-5.
Van Dijken JWV. A randomized controlled 5-year prospective study of two HEMA-free
adhesives, a 1-step self-etching and a 3-step etch-and-rinse, in non-carious cervical
lesions. Dent Mater. 2013; 29:e271-e80.
Van Landuyt K, De Munck J, Snauwaert J, Coutinho E, Poitevin A, Yoshida Y, et al.
Monomer-solvent phase separation in one-step self-etch adhesives. J Dent Res. 2005;
84:183-8.
Van Landuyt KL, Mine A, De Munck J, Jaecques S, Peumans M, Lambrechts P. Are
one-step adhesives easier to use and better performing? Multifactorial assessment of
contemporary one-step self-etching adhesives. J Adhes Dent. 2009; 11:175-90.
Van Landuyt KL, Snauwaert J, De Munck J, Coutinho E, Poitevin A, Yoshida Y, et al.
Origin of interfacial droplets with one-step adhesives. J Dent Res. 2007; 86:739-744.
Van Landuyt KL, Snauwaert J, De Munck J, Peumans M, Yoshida Y, Poitevin A, et al.
Systematic review of the chemical composition of contemporary dental adhesives.
Biomaterials. 2007; 28(26):3757-85.
Van Landuyt KL, Snauwaert J, Peumans M, De Munck J, Lambrechts P, Van
Meerbeek B. The role of HEMA in onestep self-etch adhesives. Dent Mater. 2008; 24:
1412-9.
51
Van Landuyt KL, De Munck J, Ermis RB, Peumans M, Van Meerbeek B. Five-year
clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical
lesions. Clin Oral Invest. 2014;18:1045-52.
Van Meerbeek B, Van Landuyt K, De Munck J, Hashimoto M, Peumans M, Lambrechts
P. Technique-sensitivity of contemporary adhesives. Dent Mater J. 2005; 24:1-13.
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; 27(1):17-28.
Visintini E, Mazzoni A,Vita F, Pasquantonio G, Cadenaro M, Di Lenarda R, et al.
Effects of thermocycling and use of ElectroBond on microtensile strength and
nanoleakage using commercial one-step self-etch adhesives. Eur J Oral Sci. 2008;
116:564-70.
White GE, Tsamtsouris A, Williams DL. Early detection of occlusal caries by measuring
the electrical resistance of the tooth. J dent res. 1978; 57: 195–200. 20.
52
APÊNDICE 1 – Imagens das metodologias
Figura 1: Identificação, composição e protocolo de aplicação dos sistemas adesivos.
A) Adesivo Experimental com HEMA; B) Adesivo Experimental sem HEMA.
Figura 2: Preparo das amostras.
A) Dente fixado na placa de acrílico; B) Corte em cotadeira metalográfica (Isomet)
aproximadamente 1,5 mm abaixo da junção cemento-esmalte e aproximadamente 4
mm acima da junção cemento-esmalte; C) Superfície da dentina exposta; D)
Superfície abrasionada com lixa de carbeto de silício #600 por 30 segundos.
53
Figura 3: Descrição de funcionamento do aparelho emissor de corrente elétrica
Esquema do aparelho controlador e emissor de corrente elétrica.
Etapas:
1. A – multímetro: Inserir uma bateria alcalina no multímetro (A) e outra de 9V no
controlador de corrente (B).
2. Ligar o multímetro (A) no controlador de corrente (B), conectando os eletrodos
negativos (1 e 3) e positivos (2 e 4). Eletrodo positivo do controlador de corrente
(4) conectado à pinça metálica.
3. Controlador de corrente (B): Selecionar a amperagem que será utilizada na
aplicação do adesivo por meio do potenciômetro (5), conferindo no visor do
multímetro (6).
4. Procedimento clínico: Colocar o eletrodo negativo (vermelho) na boca do
paciente;
Procedimento em laboratório: colocar o eletrodo negativo (vermelho) numa
superfície esponjosa umedecida, onde será fixado o dente para simular a
umidade do periodonto e transmitir a corrente elétrica (ex: esponja);
5. Aplicar o sistema adesivo sobre o dente (dentina ou esmalte) espalhando-o
com o auxílio da pinça metálica, seguindo as recomendações do fabricante (4).
54
Durante o procedimento, o dispositivo identifica a resistência do dente (em ohm
- significando a oposição do dente à passagem da corrente elétrica) pela emissão da
amperagem da corrente elétrica, previamente estabelecida pela fonte de energia
(bateria), estabelecendo a tensão do dente. O operador define a tensão da corrente
elétrica que será fornecida pelo controlador da corrente e mostrada no visor do
multímetro. Ajustada a corrente, o chip do controlador da corrente define o valor da
resistência elétrica do dente com os eletrodos conectados. O aparelho
automaticamente estabelece a intensidade elétrica de acordo com a resistência
encontrada no dente, padronizando a corrente elétrica e mantendo a amperagem
selecionada pelo operador.
O aparelho está em processo de patente no setor INOVA da UNICAMP e sujeito
à confidencialidade.
Figura 4: Aplicação do sistema adesivo utilizando o aparelho emissor de corrente
elétrica.
55
O dente é fixado numa esponja umedecida. O sistema adesivo é aplicado
com a pinça metálica (polo positivo) enquanto a haste metálica está inserida na
esponja na direção da amostra (polo negativo), permitindo o fechamento do circuito.
O multímetro mostra o valor da corrente de 50 µA durante a aplicação do sistema
adesivo.
Figura 5: Teste de resistência da união à microtração (24 horas).
A) Dente restaurado com compósito resinoso; B) Dente fatiado utilizando a cortadeira
metalográfica Isomet; C) Obtenção dos palitos (1 mm x 1 mm aproximadamente); D)
Palitos armazenados em água destilada por 24 horas; E) Palito sendo submetido ao
teste de resistência de união à microtração na máquina de ensaio universal (Ez test).
56
Figura 6: Teste de resistência da união à microtração (10.000 ciclos térmicos).
A) Dente restaurado com compósito resinoso; B) Dente fatiado utilizando a cortadeira
metalográfica Isomet; C) Obtenção dos palitos (1 mm x 1 mm aproximadamente); D)
Palitos submetidos a 10.000 mil ciclos térmicos; E) Palito sendo submetido ao teste
de resistência de união à microtração na máquina de ensaio universal (EZ Test).
Figura 7: Preparo das amostras para teste de análise de penetração através de
microscopia confocal de varredura a laser.
A) Adição de 0,07µg de Rodamina B em cada mL de cada sistema adesivo; B) Dente
restaurado com compósito resinoso; C) Fixação das amostras com cera utilidade em
dispositivo de simulação de pressão pulpar; D) Imersão em solução de fluoresceína
0,1% em peso a 24ºC, por 24 horas em condição de simulação pulpar; E) Amostras
57
fatiadas em cortadeira metalográfica (1 mm aproximadamente); F) Microscópio
Confocal de Varredura a Laser; G) Amostra representativa da análise de penetração.
Figura 8: Preparo das amostras para teste de nanoinfiltração.
A) Palitos; B) Cobertura dos palitos com esmalte para unha deixando 1 mm da
interface exposto; C) Armazenagem dos palitos em solução de nitrato de prata por 24
horas; D) Armazenagem dos palitos em solução reveladora por 8 horas; E) Inclusão
dos palitos em resina epóxi para polimento das amostras.
Figura 9: Grau de conversão
A) Aparelho emissor de corrente elétrica; B) Sistema adesivo aplicado na matriz
metálica e manipulado por 10 segundos, utilizando o polo positivo (pinça) para
agitação; C) 50 µL de adesivo removidos com pipeta; D) Aplicação de sistema adesivo
no molde de silicone por condensação, colocado entre duas lamínulas de vidro presas
por grampos; E) Equipamento para mensuração do grau de conversão dos sistemas
adesivos.
58
ANEXOS
ANEXO 1 - Relatório de verificação de originalidade e prevenção de
plágio
59
ANEXO 2 - Submissão do artigo
