JÉSSICA DIAS THEOBALDO
EFEITO DA FUMAÇA DE CIGARRO NAS
PROPRIEDADES FÍSICAS DE RESINAS
COMPOSTAS CONVENCIONAIS E BULK-FILL
EFFECT OF CIGARETTE SMOKE ON PHYSICAL
PROPERTIES OF CONVENTIONAL AND BULK-FILL
COMPOSITE RESINS
Piracicaba 2019
EFEITO DA FUMAÇA DE CIGARRO NAS
PROPRIEDADES FÍSICAS DE RESINAS
COMPOSTAS CONVENCIONAIS E BULK-FILL
EFFECT OF CIGARETTE SMOKE ON PHYSICAL
PROPERTIES OF CONVENTIONAL AND BULK-FILL
COMPOSITE RESINS
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 Clínica Odontológica, na Área de Dentística.
Thesis presented to the Piracicaba Dental School of the University of Campinas in partial fulfillment of the requirements for the degree of Doctor in Dental Clinic, in Operative Dentistry area.
Orientador: Prof. Dr. Flavio Henrique Baggio Aguiar
Este exemplar corresponde à versão final da tese defendida pela aluna Jéssica Dias Theobaldo e orientada pelo Prof. Dr. Flavio Henrique Baggio Aguiar.
Piracicaba 2019
Theobaldo, que inúmeras vezes abriram mão dos seus sonhos para realizarem os meus, tornando-os, assim, seus sonhos também. Meu amor por vocês é infinito. Vocês são BRILHANTES!
“Bons pais corrigem erros, pais brilhantes ensinam a pensar.” Augusto Cury
bons e difíceis, me acompanhando, protegendo e dando forças para seguir sempre em frente.
Ao meu orientador, Prof. Dr. Flavio Henrique Baggio Aguiar, pelas inúmeras oportunidades concedidas e por todo conhecimento transmitido durante esses anos. Você é um professor no qual me inspiro, minha admiração por você é enorme. Uma pessoa inteligentíssima, íntegra e sempre disposto a ajudar. Sou privilegiada em tê-lo como orientador. Não há palavras suficientes que possam descrever o quanto sou grata por tudo que me proporcionou, conte comigo sempre!
elas certas ou erradas. Se hoje estou aqui é porque vocês estiveram o tempo todo comigo. Essa conquista é de vocês também!
Ao meu irmão Guilherme, por todos os momentos compartilhados, não só em Piracicaba, mas em toda minha vida. Sempre cuidarei de você meu “babyssauro”! Te amo!
Aos meus avós, por que sem eles eu não teria meus pais!
A minha vó Ermira e ao meu Vô Antônio (in memorian), que hoje não estão mais presentes fisicamente entre nós, mas tenho certeza que estão sempre ao meu lado. Vô, nunca vou me esquecer do primeiro pedaço de bolo, para a primeira “Doutora” da família, antes mesmo de ser Doutora!
A minha vozinha Elza, agora uma estrelinha! Minha bonequinha, uma pessoa incrível, sinto você presente todos os dias! Muito do que sou hoje aprendi com a senhora. Para você... meu amor eterno.
Aos meus tios, tias e primos queridos! Sempre presentes em minha vida. A “Turma da minha mãe”, que fazem meus finais de semana mais felizes e engraçados! Amo vocês.
A minha segunda família, e não menos importante, Sr Luis e Irani. Sou muito grata por todo apoio e incentivo para concluir essa importante etapa em minha vida. Conviver com vocês é um privilégio. Cada gesto de carinho e acolhimento foi essencial!
Ao meu futuro marido, Rafael, agradeço imensamente por não ter desistido de nós em nenhum momento. Seu amor e carinho me fortalece e me dá ânimo para nunca desistir dos nossos sonhos e da nossa família. Todo sacrifício é por vocês e apenas um sorriso seu faz que todo cansaço desapareça. Te amo cada dia mais!
Em especial, agradeço ao meu “irmão de alma” Professor Dr. Waldemir, Pesquisador Vieira-Júnior, Waldemir, Wal ou simplesmente Brow! Palavras não podem descrever a quão grata sou por tudo que me ensinou e me ajudou nesses anos de pós-graduação, e acima de tudo amizade. Você é um ser humano incrível, sem sua ajuda e dedicação não teria conseguido finalizar esse ciclo. Que nossa parceria seja eterna! Conte comigo sempre.
As minhas amigas – irmãs Nathalia e Adriele, por toda compreensão nos períodos de ausência, e por sempre estarem presentes nos momentos importantes na minha vida.
As minhas “bests” Mariana e Clízia, amizades que a FOP me apresentou na graduação e as quais faço questão de levar para o resto da vida! Cada reencontro é como se o tempo não tivesse passado. Amo vocês, amo estar com vocês e dividir nossas conquistas!
A todos os meus amigos de pós-graduação, sem exceção, agradeço a oportunidade de tê-los conhecido e compartilhado momentos especiais. Todas as trocas de conhecimento e experiências foram essenciais para o meu desenvolvimento pessoal e profissional. Vocês foram extremamente importantes para minha formação. A Thayla, Michele e Mari, irmãs que a FOP me deu, pessoas incríveis, com as quais tive o prazer de conviver no meu dia – dia, além da FOP. A “Casa do Cavalo” tem histórias e histórias que valem a pena serem lembradas com muita alegria! Rafa e Thalita, obrigada pela convivência. A pós - graduação ficou mais leve com as sessões de terapias no jantar!
A Cris e Diogo! Obrigada por tudo, por todo acolhimento e conhecimento transmitido. Vocês são referências para mim.
A Profa. Dra. Núbia Pini, agradeço a amizade e parceria. Obrigada por todas as trocas de conhecimento, foram essenciais para o meu desenvolvimento profissional. Você é uma pessoa incrível e inspiradora.
A Profa. Dr. Lucia Trazzi Prieto, ou Lucinha. Obrigada por toda amizade, apoio, dicas e a excelente convivência durante todos esses anos. Meus dias com você na FOP são mais felizes, sua energia e alegria contagiam!
As queridas “Joaninhas” Renata, Joyce, Maria e em especial a Marcela, a qual tive a oportunidade de orientar na iniciação científica. Obrigada pela oportunidade de aprendizado e acima de tudo amizade. Vocês são especiais.
Aos alunos de graduação da FOP, por me permitirem com eles aprender e ensinar. Essa troca recíproca foi essencial para meu crescimento pessoal e profissional. Especialmente aos alunos de graduação a qual tive a honra de trabalhar nesse período, através da iniciação científica, Lorena Costa, Raíssa Garcia, Vitória Massoneto, Carolina Gachet e Gabriela Borgo.
A Profa. Dra. Carla Müller Ramos Tonello por toda ajuda e parceria. Agradeço também toda paciência e carinho, aprendi muito sobre docência com você. A minha grande amiga Ana Lívia, e seu querido irmão Artur, vocês são incríveis e minha família em São Paulo. Tudo, absolutamente tudo, ficou mais fácil sabendo que tenho vocês por perto.
A Carol Ventura e Diogo Silva por toda a parceria. Presentes que a FOP me deu! Sou admiradora de vocês.
Ao Centro Universitário das Faculdades Metropolitanas Unidas (FMU), em especial a coordenadora do curso de Odontologia da FMU Profa. Dra. Fernanda Aurora Stabile Gonnelli e coordenadora adjunta Profa. Ms. Samantha Cavalcanti pelo apoio nessa etapa. A todos os meus colegas de docência na FMU, os quais tenho o prazer de conviver semanalmente. A troca de conhecimento e experiência é simplesmente maravilhosa! Obrigada pela excelente convivência.
pesquisa através de um estágio no CPQBA, para concluir meu curso de Técnico em Bioquímica. Uma pessoa admirável e de alegria contagiante.
A Profa. Dra. Renata de Oliveira Mattos Graner, que me orientou durante a graduação em um projeto de iniciação científica, me inserindo assim, no mundo da ciência, na área de Odontologia.
Aos professores Dr. Américo B. Correr, Dra. Cindy G. Dodo e Dra. Cristiane F. Yanikian, por terem aceitado o convite em fazer parte da banca no exame de qualificação. Suas considerações foram extremamente importantes para a conclusão deste trabalho.
Aos professores da Área de Dentística, Prof. Dr. Luis Roberto Marcondes Martins, Prof. Dr. Marcelo Giannini, Prof. Dr. Luis Alexandre Maffei Sartini Paulillo e Profa. Dra. Débora Alves Nunes Leite Lima pela convivência diária e pelo conhecimento transmitido desde a graduação até os dias de hoje.
Em especial as Professoras Dra. Vanessa Cavalli e Dra. Giselle Maria Marchi pela confiança e oportunidade de participar do Curso de Atualização e Especialização. É sempre um imenso aprendizado. Vocês são grandes exemplos e referências profissionais para mim.
Ao professor Dr. Lourenço Correr Sobrinho pelo suporte para o uso dos equipamentos do laboratório da Área de Materiais Dentários.
Magnífico Reitor Prof. Dr. Marcelo Knobel.
À Faculdade de Odontologia de Piracicaba – FOP, nas pessoas do diretor Prof. Dr. Francisco Haiter Neto e do diretor associado Prof. Dr. Flavio Henrique Baggio Aguiar.
À Coordenadora Geral do programa de Pós-Graduação FOP-UNICAMP, Profa. Dra. Karina Gonzales Silvério Ruiz.
Ao Coordenador do curso de Pós-Graduação em Clínica Odontológica FOP-UNICAMP, Prof. Dr. Valentim Adelino Ricardo Barão.
Ao Adriano Martins, sempre disposto a nos ajudar em análises de microscopia eletrônica por varredura.
Ao técnico de Laboratório Marcos Blanco por todo suporte dado para o uso dos equipamentos.
A todos os funcionários da FOP/UNICAMP. O trabalho de vocês foi essencial para proporcionar essa conquista!
ÀCoordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) – Código Financiamento 001, pela concessão da bolsa para desenvolvimento desta pesquisa.
A todos que de alguma forma participaram comigo nessa caminhada, meu muito obrigada!
(Capítulo 1) e resinas do tipo bulk-fill (Capítulo 2) à fumaça de cigarro (FC) nas propriedades de cor (Capítulo 1 e 2), rugosidade e brilho (Capítulo 2). Materiais e Métodos: No Capítulo 1, foram confeccionados discos de resina com 5 mm de diâmetro e por 2 mm de espessura [Filtek Z250XT (3M ESPE) e Filtek Z350XT (3M ESPE)], os quais foram expostos à cigarros com diferentes concentrações de seus principais componentes do cigarro [alcatrão, nicotina, monóxido de carbono (CO)], sendo: Marlboro Red (MR)>Marlboro Blue Ice (MBI)>Marlboro Filter Plus (MFP)>Marlboro Silver Light (MSL) e controle (sem exposição) (n=10). As amostras foram armazenadas em saliva artificial, a 37 oC. Os espécimes foram expostos à 20 cigarros por dia, durante 5 dias. A análise da cor (ΔE, L*, a*, b*) foi realizada nos tempos: baseline e após exposição à FC. Os dados foram submetidos à ANOVA dois fatores e Teste de Tukey. A análise de regressão linear (RL) analisou a relação da concentração do alcatrão, nicotina e CO nas variáveis de cor (α = 0,05). No Capítulo 2, utilizou-se discos de resina (10 x 2 mm; n=10), sendo avaliadas: Filtek Z250XT (3M ESPE, Controle); Filtek One Bulk-Fill (3M ESPE, FOBF); Tetric N-Ceram Bulk-Fill (Ivoclar Vivadent, TNCBF) e Aura Bulk-Fill (SDI - ABF). A análise de cor (ΔE, ΔL*,Δa*, Δb*), rugosidade (Ra) e brilho foram realizadas nos tempos: baseline e após exposição à FC (10 maços de cigarro - Marlboro Red). Os dados foram submetidos a análise de medidas repetidas e Tukey teste (Ra e B); ANOVA um fator (∆L*, ∆a*, ∆b* e ∆E) e Teste de Tukey (α = 0,05). Resultados: No Capítulo 1, as variáveis de cor ΔL*, Δa* e ΔE, para ambas resinas, diferiram estatisticamente do controle (p < 0,05), independentemente do tipo de cigarro, apresentando maiores valores. A análise de RL mostrou relação significativa entre os parâmetros de cor (L*, a* e ΔE) e os principais componentes do cigarro (p < 0,05), sendo maior nas resinas nanoparticuladas. No Capítulo 2, para ΔL* e ΔE, todas as resinas bulk-fill apresentaram maior variação diferindo estatisticamente do controle. Entre as resinas, ABF apresentou maior variação (p < 0,05). Para Ra, após FC, ABF apresentou menores valores (p < 0,05) quando comparada aos valores iniciais. Para brilho todos os grupos apresentaram aumento após FC, sendo estatisticamente diferentes do controle. Conclusão: Cigarros com maiores concentrações de alcatrão, nicotina e CO promovem o aumento na pigmentação das resinas compostas. A pigmentação de
manchamento pela fumaça do cigarro quando comparadas à resina microhíbrida. Palavras-chave: Resina Composta, Fumar Cigarro, Propriedades físicas.
Objective: To evaluate the effect of exposure to conventional composite resins (Chapter 1) and bulk-fill resins (Chapter 2) to cigarette smoke on physical properties such as color (Chapter 1 e 2), roughness (Ra) and gloss (GU) (Chapter 2). Materials and Method: In Chapter 1, resin discs with 5 mm of diameter and 2 mm of thickness were obtained (Filtek Z250XT (3M ESPE); Filtek Z350XT (3M ESPE)) and exposed to cigarettes with different concentrations of main cigarette components [tar, nicotine, carbon monoxide (CO)]: Marlboro Red (MR)>Marlboro Blue Ice (MBI)>Marlboro Filter Plus (MFP)>Marlboro Silver Light (MSL) and control (without exposure) (n=10). All samples were stored in artificial saliva at 37 oC. The samples were exposed to 20 cigarettes/day for 5 days. Color analysis (ΔE, L*, a*, b*) was performed at two times: at the baseline and after CS exposure. The data were submitted to a two-way ANOVA and Tukey’s test. Linear regression (LR) was used to analyze the influence of tar, nicotine and CO on the color variable (α = 0.05). In Chapter 2, resin discs (10 x 2 mm) were prepared for each restorative material used (n=10): Filtek Z250XT (3M ESPE, control), Filtek One Bulk-Fill (3M ESPE, FOBF), Tetric N-Ceram Bulk-Fill (Ivoclar Vivadent, TNCBF) and Aura Bulk-Fill (SDI - ABF). The color (ΔE, ΔL*, Δa*, Δb*), Ra and GU analyses were performed at two times: at the baseline and after CS exposure (10 pack of cigarettes – Marlboro Red, (Philip Morris Brazil Ind. e Com)). The data were analyzed with repeated measures ANOVA (PROC MIXED) and Tukey test (Ra and GU); a one-way ANOVA (∆L*, ∆a*, ∆b* and ∆E); and Tukey’s test (α = 0.05). Results: In Chapter 1, for all analyses, control groups did not differ. For ΔL*, Δa* and ΔE, both resins showed statistical difference from the control (p < 0.05), regardless of tobacco type, presented the highest values. LR analysis showed a significant relationship between all color parameters (L*, a* and ΔE) and the tar, nicotine and CO concentration, were higher in nanofilled resins comparing to microhybrid resins. In Chapter 2, for ∆L* and ∆E, all bulk-fill resins differed statistically from the control, which presented the lower value. Among resins, ABF showed greater variation (p < 0.05). For Ra, after CS, only ABF presented lower values (p < 0.05) than the baseline. For GU, all groups presented an increase in values after exposure to CS, and they were statistically different from the control. Conclusion: Cigarettes with higher concentrations of tar, nicotine and CO promote an increase in pigmentation of the
compared to the microhybrid resin.
2 ARTIGOS 21
2.1 Artigo: Relationship of tar, nicotine and carbon monoxide of cigarette smoke with the color variables of micro hybrid and nanofilled composite resins 21
2.2 Artigo: Effect of cigarette smoke on color, roughness and gloss of high-viscosity bulk-fill regular resin composite. 41
3 DISCUSSÃO 60
4. CONCLUSÃO 63
REFERÊNCIAS* 64
APÊNDICE 1 – METODOLOGIA ILUSTRADA 71
ANEXOS 85
ANEXO 1 - Relatório Turnitin 85
1 INTRODUÇÃO
O tabagismo é considerado pela Organização Mundial de Saúde (OMS) como uma das maiores epidemias do mundo, uma vez que, o consumo de tabaco está relacionado com mais de 7 milhões de mortes de pessoas a cada ano, segundo dados da OMS publicados em 2017 (OMS, 2017). Políticas de prevenção e monitoramento do uso do tabaco têm sido aplicada em todo o mundo, por meio de programas governamentais, em que resultados positivos têm sido alcançados (OMS, 2017). Em 2018, a OMS publicou um relatório global sobre as tendências na prevalência do tabagismo 2000-2025 no qual a análise dos dados mostrou uma tendência de redução da prevalência do consumo do tabaco quase em todas as regiões do mundo, com exceção de algumas regiões africanas e do mediterrâneo oriental, que apresentam dados lineares. Entretanto, o número de fumantes no mundo ainda é considerado alto, em torno de 20% da população, estimando 1 11 bilhões de pessoas (dados do ano de 2015), sendo ainda considerado um problema de saúde pública (OMS, 2018).
O consumo de tabaco está relacionado a diversas alterações sistêmicas, como por exemplo: câncer de cabeça e pescoço, câncer de pulmão, problemas cardiovasculares, problemas respiratórios, alterações no desenvolvimento fetal, entre inúmeros outros problemas (U.S. Department of Health and Human Services, 2014; Peterson e Hecht, 2017; Roco et al., 2018). Na cavidade bucal, o tabaco está relacionado a diversas doenças e alterações, como por exemplo, câncer bucal, doença periodontal, expansão de lesões de cáries, contaminação da estrutura dental / resinas compostas por metais pesados e a diminuição da resistência de união de alguns sistemas adesivos (Almeida e Silva et al., 2010; Fujinami et al., 2011; Takeuchi et al., 2011; Theobaldo et al., 2016, 2018; Song et al., 2016). Além disso, há relatos na literatura de que a exposição de materiais restauradores à fumaça de cigarro altera as propriedades físicas e químicas dos mesmos, como por exemplo, sorção e solubilidade, cor, brilho e rugosidade de superfície de resinas compostas, sistemas adesivos e selantes resinosos (Mathias et al., 2010a, 2010b, 2014; Alandia-Roman et al., 2013; Vitória et al., 2013; Zhao et al., 2017). Entretanto há poucos estudos na literatura que avaliam o efeito da fumaça do cigarro em resinas de baixa-contração de polimerização do tipo bulk-fill (Zhao et al., 2017). Estas propriedades são importantes
para um bom desempenho dos materiais restauradores e, consequentemente, sucesso clínico das restaurações.
A fumaça do cigarro inalada, proveniente da combustão do tabaco, principal constituinte do cigarro, é composta por uma fase gasosa e uma fase particulada (Ingebrethsen 1986; Vellappally et al., 2007; Thielen et al., 2008). A fase gasosa consiste basicamente nos constituintes do ar (nitrogênio e oxigênio), dióxido de carbono, óxido nítrico e monóxido de carbono, sendo esses três últimos gases exclusivos dessa fase (Thielen et al., 2008). A fase particulada representa 30-40% do tabaco queimado e é constituída por mais de 4700 produtos químicos, apresentando partículas com diâmetros que variam entre 0,1 a 1 mm, sendo que o tamanho médio das partículas varia de 0,35 a 0,4 µm. A concentração dessas partículas na fumaça do cigarro está entre 109 - 1010 cm-3 que, em peso, representa 4,5% da fumaça total, entretanto, removendo a água, esse valor é reduzido para 3,8%, sendo que mais de 99% da nicotina encontra-se na fase particulada (Thielen et al., 2008). O contato dessa fumaça com a superfície de materiais restauradores à base de resina, como por exemplo, as resinas compostas, provoca alterações em suas propriedades (Mathias et al., 2010a, 2010b, 2014; Alandia-Roman et al., 2013; Vitória et al., 2013; Zhao et al., 2017). Entretanto, a interação entre os constituintes da fumaça, como por exemplo, alcatrão, nicotina e monóxido de carbono, com os materiais resinosos ainda não é bem estabelecido. Sendo assim, mais estudos são necessários para o compreendimento desses efeitos.
As resinas compostas são constituídas por uma matriz resinosa, partículas de carga inorgânicas, um agente de união (silano) e um sistema de fotoiniciadores, podendo ser classificadas de acordo com o tamanho de suas partículas e/ou pelos tipos de monômeros que as constituem (Chen, 2010; Ferracane, 2011; Stansbury, 2012). Em relação às partículas de carga, as resinas compostas podem ser classificadas como macroparticuladas (10 - 50 µm); microparticuladas (40 – 50 nm), híbridas (10 - 50 µm + 40 nm), microhíbridas (0.6 - 1µm + 40 nm) e nanoparticuladas (5 – 100 nm) (Ferracane, 2011), sendo as duas últimas indicadas para restaurações anteriores e posteriores (Gouveia et al., 2017). Paralelo ao desenvolvimento das partículas de carga ocorre o desenvolvimento de novos monômeros com a finalidade de reduzir a contração de polimerização e, consequentemente, tensões de contração (Klapdohr e Moszner, 2005; Chen, 2010; Ferracane, 2011). Para reduzir as tensões
provenientes da contração de polimerização que ocorre em resinas convencionais, uma das técnicas preconizadas é a técnica incremental oblíqua com incrementos de, no máximo, 2 mm de espessura (Lutz, et al., 1986; Pollack, 1987). Entretanto, esta técnica exige maior tempo clínico e maior habilidade manual do cirurgião-dentista, uma vez que, a formação de gaps e/ou bolhas durante a reconstrução das paredes proximais pode ocorrer com facilidade (Bicalho, et al., 2014a, 2010b; Lutz, et al., 1986; Pollack, 1987). A fim de minimizar as falhas técnicas e a tensão de contração de polimerização novos monômeros de baixa - contração tem sido desenvolvidos (Ferracane, 2011; Leprince et al., 2013).
Com o desenvolvimento dos monômeros surge uma nova classe de resina composta, denominada, resinas de baixa-contração ou resinas tipo bulk-fill (Leprince et al., 2013). A composição dessas resinas permite a modulação da reação de polimerização, por meio de monômeros modificados capazes de aliviar as tensões, do uso de fotoiniciadores mais reativos e da incorporação de diferentes tipos de partículas de carga, como por exemplo, as partículas pré-polimerizadas e incorporação de hastes de fibra de vidro (Lima et al., 20018; Fronza et al., 2015, 2017; Zorzin ey al., 2015). Segundo os fabricantes, resinas bulk-fill podem ser inseridas na cavidade em incrementos únicos de 4 - 5 mm de espessura. Além disso, apresentam como proposta e vantagens a simplificação da técnica, menor incorporação de bolhas, contaminação entre as camadas e redução do tempo clínico (Par et al., 2015). Além disso, os compósitos à base de monômeros de baixa-contração possuem desempenho clínico similar às resinas compostas convencionais (à base de dimetacrilatos) (Veloso et al., 2019; Kruly et al., 2018).Para um bom desempenho clínico é necessário avaliar diversos parâmetros ao longo do tempo, como por exemplo, adaptação marginal, resistência ao desgaste, resistência à fratura e estabilidade de cor (Demirci et al., 2018).
Um material pode sofrer alterações de cor devido a pigmentações de origem extrínsecas e intrínsecas. A pigmentação de origem extrínseca está associada à pigmentação externa (acúmulo de biofilme cromógeno, pigmentou ou manchas) que através da adsorção, devido a alterações superficiais e subsuperficiais provenientes da degradação, podendo ser internalizados. A pigmentação de origem intrínseca é proveniente de reações físico-químicas nas porções profundas do material restaurador (Dietschi et al., 1994). Dentre os agentes pigmentantes externos
encontram-se os corantes presentes em alimentos, bebidas e substâncias presentes no cigarro, como por exemplo, alcatrão e nicotina (da Silva et al., 2017; Usha et al., 2018). A literatura relata alterações de cor significativas na resina composta convencional, quando em contato com a fumaça de cigarro (Mathias et.al, 2011; Alandia-Roman et al., 2013; da Silva et al., 2017; Zhao et al., 2017). Entretanto, em relação às resinas bulk-fill, há poucos estudos na literatura que avaliam essas alterações (Zhao et al., 2017). É possível que modificações monoméricas e partículas de carga possam causar alterações de propriedades físicas importantes para o desempenho clínico dessa nova classe de materiais, como por exemplo, a estabilidade de cor.
Sendo assim, o objetivo desta tese foi verificar os efeitos da exposição de resinas compostas convencionais e bulk-fill à fumaça de cigarro nas propriedades físicas de cor, rugosidade e brilho de superfície. Para isso, o mesmo foi dividido em dois capítulos. O Capítulo 1 objetiva analisar os efeitos da fumaça de cigarro, de diferentes composições, na propriedade de cor de resinas compostas convencionais microhíbridas e nanoparticuladas e estabelecer a relação entre o aumento das concentrações de alcatrão, nicotina e monóxido de carbono com a alteração de cor dessas resinas. O Capítulo 2 tem como objetivo avaliar o comportamento das resinas compostas bulk-fill, frente à exposição à fumaça de cigarro, na alteração de cor, rugosidade e brilho.
2 ARTIGOS
2.1 Artigo: Relationship of tar, nicotine and carbon monoxide from cigarette smoke with the color of microhybrid and nanofilled composite resins
Authors: Theobaldo JD, Vieira-Júnior WF, Costa L, Lima DANL, Marchi, GB, Aguiar FHB ABSTRACT
Objective: To establish the relationship between cigarette smoke (CS) types with various tar, nicotine and carbon monoxide (CO) increasing concentrations and color variables of microhybrid and nanofilled conventional composite resins. Methods and Materials: Disc-shaped specimens (5 mm x 2 mm) of each resin composite Filtek Z250XT [3M ESPE, microhybrid (MH)] and Filtek Z350XT [3M ESPE, nanofilled (NF)] were exposed to CS according to the concentration of main cigarette components [tar, nicotine, carbon monoxide (CO)]: Marlboro Red (MR)>Marlboro Blue Ice (MBI)>Marlboro Filter Plus (MFP)>Marlboro Silver Light (MSL) and control (without CS exposure) (n=10). All samples were stored in artificial saliva at 37 oC. The samples were exposed to 20 cigarettes per day for 5 days. Color analysis (L*, a*, b* and ΔE) were performed at baseline and after exposure to CS. Data were submitted to a two-way ANOVA and Tukey’s test. Linear regression evaluated the relationship of tar, nicotine and CO on the color variables (α = 0.05). Results: For ΔL* and Δa* and ΔE, MH and NF resins showed statistical difference from the control (p < 0.05) regardless of CS type and presented the highest values. Linear regression analysis showed a significant relationship among color parameters (L*, a* and ΔE) and the increasing concentration of tar, nicotine and CO (p < 0.05). Conclusion: An increase in concentration of tar, nicotine and CO promoted color alteration independently of the composite resin. However, the relationship is more evident for nanofilled than for microhybrid resins. Clinical Significance: The pigmentation of conventional composite resins by the cigarette is concentration-dependent at cigarette smoke and is most evident in nanofilled resins.
INTRODUCTION
Composite resins are good materials for direct restorations due to their high applicability and versatility. These materials have the advantages of minimally invasive cavity preparations or even the absence of any cavity preparation, resulting in preservation of tooth structure and longevity due to great clinical performance. They have beneficial physical and mechanical properties, including esthetic properties [1-3]. However, this material is dependent of the conditions of the buccal environment, as condition related to color degradation and staining [4]. Some studies showed color instability on composite resins after bleaching, exposure to beverages and a diet with pigments or exposure to cigarette smoke [5-11]. Color change is one of the main factors associated with treatment failure indicating replacing of restoration [12]. Thus, to understand the relationship between cigarette smoke and composite resin is important.
Cigarette smoke is constituted by a particulate and a gas phase, being a complex mixture of more than 4700 chemical constituents [13,14]. During curing, many chemical and physical changes take place in the tobacco leaf. For example, starch is converted into sugar, the green color vanishes and the tobacco changes in color from light yellow to orange and brown. Moreover, more than 99% of nicotine is present in the particulate phase [15]. These substances play an important role in the staining of composite resins; however, the mechanism, interaction and relationship by which the color changes are not established.
The main component of a cigarette is tobacco, but cigarettes contain much more than just tobacco. The mechanism and interaction with the various changes it causes in the human body are highly complex and difficult to understand [15]. “Tar” is analytically defined as the raw water and nicotine-free smoke condensate and is believed to be the major carcinogen along with nicotine, the addictive agent in tobacco smoke. Therefore, measurements of tar and nicotine were chosen as characteristic analytical parameters for each marketed brand. Carbon monoxide (CO) has recently been added as a major smoke constituent of concern. The yields of tar and nicotine in mainstream smoke of a given cigarette brand, as printed on the pack, are measured by smoking the cigarette in a smoking machine under conditions standardized and informed by the manufacturers, that respect an ISO. This ISO regulates smoke yields
and serves as a regulatory limit, prohibiting brands that generate yields above 10 mg of tar, 1mg of nicotine or 10 mg of CO per cigarette [15].
The objective of this study is to verify the effect and establish the relationship between various cigarette smoke types and color properties of microhybrid and nanofilled composite resins as well as to establish the relationship between these variables with a line regression. Therefore, the null hypotheses of this study are: (1) The exposure to cigarette smoke would not alter color properties of conventional composite resins; (2) No difference exists between the effects of concentration of main compounds of cigarette on color alterations in composite resin; (3) No difference exists between microhybrid and nanofilled composite resins when they are exposed to cigarette smoke; (4) No relationship exists between concentrations of main components to cigarette smoke and the color variables of conventional composite resins.
METHODS AND MATERIALS
Experimental design Sample preparation:
A total of one hundred disc-shaped specimens 5.0 mm in diameter and 2.0 mm in thickness (fifty units of each resin composite, Filtek Z250XT (3M ESPE, microhybrid, and Filtek Z350XT, 3M ESPE, nanofilled (Table 1) were fabricated and divided into 5 groups (n = 10) according to the type of cigarette, as described in Table 2.
Table 1: Description of components of composite resins*.
*Information Provided by the Manufacturers. Abbreviations: Bis-EMA, bisphenol-A hexaethoxylated dimethacrylate; TEGDMA, triethylene glycol dimethacrylate; UDMA, urethane dimethacrylate; Bis- GMA, bisphenol a diglycidyl ether dimethacrylate; 1,12- Dodecane dimethycrylate – DDDMA;YbF3- ytterbium trifluoride.
Table 2: Division of study groups and concentrations of tar, nicotine and carbon monoxide of different cigarettes.
*manufature: Philip Morris Brasil Ind. e Com. Ltda., Santa Cruz do Sul, RS, Brazil.
To obtain the samples, the composite resin was inserted into the Teflon matrix in one single increment with a metal spatula (Goldstein XTS flex, Hu-friedy, Chicago, USA). After insertion of the resin, the increment was covered with a polyester strip and glass slide to remove bubbles that may eventually form. The photoactivation of the composite was performed using a third-generation LED source (VALO- Ultradent Products Inc., South Jordan, UT, USA) on standard mode with an irradiance of 1000 mW/cm2 for 20 s. Afterward, the samples were stored in a relative humidity environment at 37 oC for 24 hours. Posteriorly, the samples top surfaces were submitted to the polishing process with a polishing machine (model APL-4; Arotec,
Composite
Resin Classification Matrix and other compounds Filler type
Filtek Z250 XT Microhybrid
Bis -EMA (1-10 % wt.); UDMA (1-10% wt.); Bis-GMA (1-6% wt.); TEGDMA (<3% wt.);
Ceramic treated silane; silica treated silane (70-85% wt.); aluminum oxide (<=1% wt.)
Filtek Z350 XT Nanocomposite
Bis- EMA (1-10% wt.); UDMA (1-10% wt.); Bis-GMA (1-10% wt.); TEGDMA
(<1% wt.); Polyethylene glycol dimethacrylate (<5% wt.);
Silane treated ceramic (60-80% wt.); Silane treated silica
(1-10% wt.); Silane treated zirconia (1-5% wt.); Composite Resin Cigarette Additional information Composition*
Tar Nicotine Carbon Monoxide Microhybrid (Filtek Z250XT, 3M ESPE) ______________________ Nanofilled (Filtek Z350XT, 3M ESPE)
Without exposure (Control) - - - -
Marlboro Silver Light (MSL) - 4 mg 0.4 mg 5 mg
Marlboro Filter Plus (MFP) Additional Filter
With tobacco
6 mg 0.5 mg 6 mg
Marlboro Blue Ice (MBI) Flavoring 8 mg 0.6 mg 7 mg
Cotia, SP, Brazil). The resin surface was polished with 600-, 1200- and 4000-grit silicon carbide (SiC) abrasive papers under constant irrigation (CARBIMET Paper Discs; Buehler, IL, EUA). The latter grit was standardized in 1 min. Felts (TOP, RAM E SUPRA- Arotec, Cotia, SP, Brazil) with diamond pastes (3, ½, and ¼ μm) were used to finish the polishing process. Samples were ultrasonically cleaned (Marconi, Piracicaba, São Paulo, SP, Brazil) for 15 minutes between each step of polishing and at the end of the procedures. The samples were stored in relative humidity for the entire experiment (7 days).
Color Analysis
The color analyze were performed at two times, at the baseline and after exposure to cigarette smoke, using a reflectance spectrophotometer (CM 700d, Minolta, Osaka, Japan). The samples were evaluated inside a light cabin (GTI mini matcher MM1e; GTI Graphic Technology, Newburgh, NY, USA) to standardize the ambient light during the measurement process. The color results obtained were quantified in the coordinates of the CIE L*a*b* color system with the On Color software (Konica Minolta). The L* coordinate represents the black-white axis (luminosity), a* represents the green-red axis and b* represents the blue-yellow axis. Initially, the equipment was previously calibrated according to the manufacturer’s recommendation.In addition, the differences in the L*, a* and b* values between times were expressed using Δ values of the variables (ΔL*, Δa*, Δb*), and the color difference (ΔE) was calculated using the following equation: ΔE = [(ΔL*)2 +(Δa*)2 + (Δb*)2]1/2. For linear regression was considerate the L*, a* and b* values and ΔE. The initial L* values was used for randomization of samples among the groups.
Exposure to cigarette smoke
For the groups with CS exposure, was used a smoke machine developed by the Department of Restorative Dentistry, Piracicaba Dental School – UNICAMP - 2011 (registered under # 01810012043 INPI - National Institute of Industrial Property), to expose the sample to cigarette smoke after initial color analysis. The machine operates with the aspiration and conduction of the smoke through compartments with the purpose of circulating smoke throughout the environment, thereby enabling the deposition of chemical compounds and pigments in the samples. The cycle was scheduled on a time interval, simulating the smoking behavior usually performed by a
smoker, with the smoke remaining in contact with the samples for 3 s. The machine allows for the ambient air to be inhaled every 10 s, thus simulating smoke inhalation and subsequent elimination.Prior to exposure of the samples to cigarette smoke, all samples were isolated with wax (Kota, Cotia, SP, Brazil), except the top surface.In this study, the samples were exposed to 20 cigarettes per day for 5 days according to type of tobacco present in the cigarette. (Philip Morris Brazil Ind. e Com., Santa Cruz do Sul, RS, Brazil) (Table 2) [16]. The samples were stored in artificial saliva throughout the experiment at 37 °C [1.5 mM Ca, 0.9 mM Pi, 150 mM KCL, 0.05 µg F/mL, 0.1M Tris buffer (pH = 7.0)] [17]. Prior to the final color analysis, the samples’ surfaces were cleaned with cotton for to remove the leavings formed by cigarette smoke.
Statistical Analysis
The color data were submitted to a two-way ANOVA analysis of variance and Tukey’s test (Software STATGRAPHICS Centurion XVI, Version 16.2.04 (32-bit), License Corporate Enterprise). Linear regression was used to establish the influence of compound concentrations in cigarettes (tar, nicotine, CO) on color variables. The significance level was established at 5% (α = 0.05).
RESULTS
The color change (ΔE) and color variables (ΔL *, Δa * and Δb *) of microhybrid and nanofilled composite resins after exposure to smoke from different cigarettes are presented in Table 4. For all color coordinate variables (ΔL*, Δa * and Δb *) and color change (ΔE), the groups exposed to cigarette smoke was statistically different from the groups without exposure (control) to cigarette smoke (p < 0.05).
For ∆L* values, when exposed to cigarette smoke, both resins showed a decrease in luminosity values, differing statistically from the control group (p < 0.05). Between resins, nanofilled showed the lowest values and the highest variation of ΔL* values, for groups exposure to different type of CS, differing statistically from microhybrid (p < 0.05). Among cigarettes, for the microhybrid composite resin, MBI showed lower values that were statistically different from MR, MSL and MFP, which showed no differences between them (p > 0.05). For nanofilled composite resin, MBI
was statistically different from MFP presenting a higher decrease of luminosity. MSL and MR showed intermediate values and did not differ statistically from MBI or MFP.
For Δa*, all groups exposed to various types of CS, independent of the resin, were statistically different from the control groups (p < 0.05). Among the resins, the nanofilled composite showed the highest a* axis variations (more red) and differed statistically from the microhybrid composite resin (p < 0.05). For the microhybrid resin, MR showed the lower values, differing statistically from MSL, MBI and MFP (p < 0.05), which did not differ from each other (p > 0.05). For the nanofilled resin, the MR and MSL groups showed the highest variation, being different statistically from that of MFP and MBI, which were statistically different from each other (p < 0.05).
For Δb* values of microhybrid resin, all groups exposed to CS were statistically different from the control group (p < 0.05), presenting a higher variation of coordinate b* values.Comparing the cigarettes, no statistical difference was found for this resin (p > 0.05). For the nanofilled resin, MSL presented the highest variation in the b* axis in direction of the blue axis (negative), differing statistically from the control, MFP and MBI (p < 0. 05). MR and MBI presented intermediate values and were not different from each other (p > 0.05). Comparing the resins, nanofilled presented the highest variation of coordinate b* values for MSL and MR, differing statistically from microhybrid composites (p < 0. 05).
The color variation analysis (ΔE) showed an effect for the factors of resin (p = 0.0001), cigarette (p = 0.0001) and interaction between factors (p = 0.0001). The resins without exposure to cigarette smoke (control) were similar. Comparing the resins with each other, for all types of cigarettes, color variation of nanofilled was significantly higher than that of the microhybrid resin. Regarding composite, all groups exposed to cigarette smoke differed statistically from the control group, presenting a highest color change (p < 0.05). For the microhybrid resin, among the cigarettes, MBI showed the highest color alteration values and was statistically different from the MR and MFP groups. MSL showed intermediate values and did not differ from other cigarette types. For nanofilled resin, among the cigarettes, MFP showed greater color alteration and was statistically higher than MR, MSL and MBI, which did not differ from each other.
Table 4: Means (standard deviation) of color variables (∆L*, ∆a*, ∆b* and ∆E) according to different cigarette smoke and composite resin.
Variable CS exposure Composite resin
Microhybrid Nanofilled ∆L* Without (control) 0.33 (0.15) Aa 0.00 (0.25) Aa MSL -1.11 (0.26) Ab -3.02 (0.58) Bbc MFP -1.37 (0.36) Ab -2.44 (0.56) Bb MBI -2.51 (0.63) Ac -3.56 (1.10) Bc MR -1.23 (0.53) Ab -3.17 (0.79) Bbc ∆a* Without (control) 0.08 (0.15) Ac 0.44 (0.06) Ad MSL 1.57 (0.26) Ba 2.87 (0.37) Aa MFP 1.23 (0.26) Ba 1.71 (0.26) Ac MBI 1.38 (0.39) Ba 2.36 (0.16) Ab MR 1.09 (0.35) Bb 2.85 (0.46) Aa ∆b* Without (control) -0.45 (0.28) Aa -0.80 (0.25) Aa MSL -1.62 (0.26) Ab -2.32 (0.54) Bc MFP -1.50 (0.30) Ab -1.10 (0.41) Aa MBI -1.82 (0.51) Ab -1.41 (0.76) Aab MR -1.17 (0.54) Ab - 1.90 (0.54) Bbc ∆E Without (control) 0.62 (0.24) Ac 0.94 (0.21) Ac MSL 2.53 (0.31) Bab 4.8 (0.64) Aa MFP 2.40 (0.38) Bb 3.21 (0.56) Ab MBI 3.25 (0.42) Ba 4.6 (0.91) Aa MR 2.06 (0.72) Bb 4.72 (0.83) Aa
Means followed by different letters (uppercase letters in the rows and lowercase letters in the columns) indicate statistical differences (p < 0.05). MSL: Marlboro Silver Light; MFP: Marlboro Filter Plus; MBI: Marlboro Blue Ice; MR: Marlboro Red.
Figures 1 and 2 correspond to linear regression graphics of the microhybrid and nanofilled resins, respectively, where the independent variable was the concentration of cigarette compounds and the dependent variable is the color. Analyzing the figures it is possible to observe a significant relationship between color parameters, especially L *, a * and ΔE, and the main components of cigarette (tar, nicotine and CO), indicating that an increase in concentration of cigarettes main components impacts the increase in color alteration independently of the composite resin. However, this relationship is greater for nanofilled resins.
In Figure 1, the relationship is statistically significant for L* values vs. tar (R2 = 0.2758, p = 0.0002), L* values vs. nicotine (R2 = 0.2656, p = 0.0002) and L* values vs. CO (R2 = 0.2359, p = 0.0004), demonstrating that an increase of the concentration at cigarettes components leads to a decrease in luminosity of the composite resins. The relationship ofa* values and the concentration of tar, nicotine and CO are statistically
significant (p = 0.001), that is, an increase of the concentration at cigarettes components promote an increase for a*values (a* values vs. tar (R2 = 0.3580); a* values vs. nicotine (R2 = 0.4287); and a*values x vs. CO (R2 = 0.4152). This relationship also exists for b* values except for tar (R2 = 0.045, p = 0.0718). However, this relationship for b* values is lower: b*values vs. nicotine (R2 = 0.0663, p = 0.03772), b*values vs. CO (R2 = 0.0565, p = 0.0495)]. For color variation (ΔE), the relationship is statistically significant (p = 0.001), whereas the higher the concentration of tar, nicotine and CO increase the color change: ΔE values vs. tar (R2 = 0.3482), ΔE values vs. nicotine (R2 = 0.3588) and ΔE values vs. CO (R2 = 0.3239).
Figure 1: Linear regression graphics of microhybrid composite resin (Filtek Z250XT). Dependent variable: color variations (L*, a*, b* and ΔE); Independent variable: cigarette composition (tar, nicotine and carbon monoxide). X axis: represent the compound concentration in cigarettes; Y axis: represent the color variable. p < 0.05 indicate statistically significant. Legend: R2 = determination coefficient. A) L*
In Figure 2, the relationship for nanofilled composite resin was stronger and more evident than for microhybrid resin. The L* values vs. tar (R2 = 0.4003), L* values vs. nicotine (R2 = 4428) and L* values vs. CO (R2 = 0.4299) showed that the increased concentration of these components decreased the luminosity of composite resins (p = 0.0001). For a* values, the relationship is more evident than other color variables. An increase in concentration of tar (a* values vs. tar, R2 = 0.4930), nicotine (a* values vs. nicotine, R2 = 0.5815) and CO (a* values vs. CO, R2 = 0.5920) increase the a* values, indicating the incorporation of red pigments.This relationship also exists for b* values for CO (R2 = 0.067, p = 0.0365), and was not statistically significant for tar (R2 = 0.0277, p = 0.1242) or nicotine (R2 = 0.0475, p=0.0583). For color variation (ΔE), the relationship is statistically significant (p < 0.001), fallowing: ΔE values vs. tar (R2 = 0.5175), ΔE values vs. nicotine (R2 = 0.5917) and ΔE values vs. CO (R2 = 0.5905).
Figure 2: Linear regression graphics of nanofilled composite resin (Filtek Supreme - Z350XT). Dependent variable: color variations (L*, a*, b* and ΔE); Independent variable: cigarette composition
(tar, nicotine and carbon monoxide). X axis: represent the compound concentration in cigarettes; Y axis: represent the color variable.p < 0.05 indicate statistically significant. R2 = determination coefficient. A)
DISCUSSION
The results of this study showed that cigarette smoke produced a significant increase in color alteration for both resins evaluated, with ∆E > 2 for microhybrid and ∆E > 3 for nanofilled. However, when we compared the resins for all types of cigarettes, the nanofilled resin’s color variation was significantly higher than that of the microhybrid resin. Therefore, null hypotheses 1 and 3 were rejected. This finding is corroborated by the results from linear regression analysis, in which the relationship between the increase of tar, nicotine and carbon monoxide in cigarette smoke and the color variables is more evident in nanofilled resins.
The results for all color coordinate variables (ΔL*, Δa* and Δb*) and color change (ΔE) after exposure to cigarette smoke found in this study are in accordance with the literature. Studies conducted by Mathias [18], Alandia-Roman [8] and Zhao [11] evaluated the exposure of various conventional composite resins to cigarette smoke. The resins presented alterations in all color coordinates and showed a decrease in luminosity and an increase in a* and b* coordinate values. In all studies, including this one, all color changes (ΔE) of nanofilled resins were clinically unacceptable (ΔE > 3). According to Janda [20] ΔE = 0-2 is considered clinically imperceptible; at ΔE > 2-3, the change is perceptible and at ΔE > 3-8, change is perceptible and esthetically unacceptable.
The chemistry, structural composition and degree of conversion of resinous monomers play a major role in physical-chemical properties, such as hydrophilicity and wear resistance, and affect surface integrity and color stability [19]. Due to organic matrix content of material, the monomers could be related to staining and sorption potential [20,21]. The incorporation of pigments into the composite resin following cigarette smoke exposure can still be attributed to the types and sizes of particles that are present in composite resins. The nanofilled composite used in this study has in its composition zirconia and silica particles and pre-polymerized fillers that form aggregates or “nanoclusters” due to their small size [20,22]. The gaps formed between the inorganic particles and resinous matrix [23] may favor staining because the particulate phase of cigarette smoke comprises particles with diameters ranging from 0.1 to 1mm, the average particle size measuring 0.35 to 0.4μm [15].
Alzraikat et al., [24] evaluated the properties and clinical performance of nanofilled resins compared to microhybrid resin composites and concluded that nanocomposites presented higher sorption and solubility values than hybrid composites, which might influence their clinical performance. This information corroborates with present study, which demonstrated an increase in staining because nanofilled resin color variation was significantly higher than that of microhybrid resin. This difference could be associated with how the samples were stored. The samples were stored in artificial saliva solution throughout experiment, and it is possible that saliva immersion-enhanced exposure to cigarette smoke contributed to higher staining in nanofilled composite resins due to higher sorption [25]. According to Fonseca [21], a direct correlation exists between ∆E x water sorption and solubility, indicating that the increases in sorption and solubility increase the color variation. In addition, the presence of water and solvents, such as alcohol, methanol, and oils [15], in cigarette smoke can contribute to surface degradation of the organic matrix, favoring the adsorption of pigments and consequently contributing to the staining.
The MBI cigarette demonstrated a color alteration. This result could be attributed the presence of flavors in this cigarette. According to Thielen et al. (2008), the top flavors are highly volatile; therefore, these aroma substances and ethereal oils are added in an alcohol base, which evaporates after the flavor is applied. In the end, the amount of flavor represented 0.1% of the weight of the cigarette tobacco. It is possible that the top flavors interact with resin monomers that did not react after light-curing. For nanofilled, the MFP presented the lowest staining capacity, which could be attributed to the presence of an additional filter. The presence of specific paper, filter materials, inks and adhesives impart specific desirable properties and controls to the cigarette’s performance while it is smoked [15].
The relationship between tar, nicotine and CO concentration and the color alteration of composite resins promoted by cigarette smoke is unknown; therefore, in this study, linear regression was usedto establish this relationship. Statistical analysis and correlations by linear regression are used in dentistry to study color, measuring the degree of relationship between variables or determine whether one depends on the other [21,25].There is always a fixed independent variable, as concentration of the cigarette’s components, and a dependent variable, as the color coordinates. The value of R2 represents how much this relation is explained by the model. However, in the
current study design is not possible to determine each exact values of compound concentration in cigarette, being the values used in accordance to manufacturers. Measurements of tar, nicotine, and CO concentrations were chosen as analytical parameters for each market brand because they have a relationship with many problems that cigarettes cause [15], including alterations in dental structure, such as heavy metal contamination [26,27], and decrease of systems adhesive bond strength [28,29]. Tar is analytically defined as the raw water and nicotine-free smoke condensate and is believed to be the major carcinogen along with nicotine, the addictive agent in tobacco smoke. the compounds concentrations in mainstream smoke of a given cigarette brand, printed on the pack, are measured by smoking the cigarette in a smoking machine under standardized conditions given by the manufactures and with respect to the ISO, which serves as a regulatory limit [15]. Brands that generate yields above 10 mg of tar, 1mg of nicotine or 10 mg of CO per cigarette are prohibited [15].
During curing of a tobacco leaf, many chemical and physical changes occur; for example, compounds are converted into sugar, the green color vanishes and the tobacco changes in color from light yellow to orange and red chrome. The presence of orange, red and brown pigments in the tobacco leaf favor the alteration of a* values and promote an increase in the a* coordinate values (green-red axis). The relationship between tar, nicotine and CO vs. a* values demonstrated by linear regression analysis exists for both resins, being more evident for nanofilled composites (p = 0.001). Another important finding was non-significant color interaction with b* values. Initially, it could hypothesize that cigarette smoke would make the sample more yellow; however, this study revealed a color shift to red chrome. Moreover, more than 99% of nicotine, yellowish pigment, is present in the particulate phase [15], indicating a relationship between this compound and staining, which is demonstrated by linear regression analysis. Nevertheless, this relationship was less evident in both resins when compared to a*-axis variation. Therefore, null hypothesis 2 was rejected because nicotine can stain the resin even at low concentrations.
Linear regression analysis demonstrated that the increase in tar, nicotine and CO concentrations present in cigarette smoke decreases the luminosity of composites independent of resin type. This is an important information because de luminosity alteration is easily perceptible from people, due the presence of a high quantity of cells
cones in human eyes [30]. Luminosity parameters, which are influenced by the presence of pigments, are very important to esthetic clinical results of restorations [31], and all composite resins exposed to smoke from all cigarettes presented negative values and showed decreased luminosity. According to linear regression analysis for the L* coordinate, this effect occurs in both resins and shows a strong relationship with the nanofilled composite. Therefore, null hypothesis 4 was rejected because a relationship exists between tar, nicotine and CO and alteration of color variables of the conventional composite resins.
In direct restorative procedures, longevity of aesthetic characteristics is desired; however, based on the results, the exposure to cigarette smoke, regardless of the type of cigarette, can affect the color of composite resins mainly in nanocomposites with perceptible and unacceptable clinically.
CONCLUSION
1. Cigarette smoke has a negative influence on color of conventional composite resins. Microhybrid and nanofilled resins undergo color changes regardless of the type of cigarette. However, nanofilled resin is more susceptible to staining by components of cigarette smoke
2. Tar, nicotine and carbon monoxide concentrations are related to color change in conventional resins. An increase at concentrations of these components in cigarette smoke leads to an increase in color alteration independent of the composite resin. Therefore, the pigmentation by the cigarette is concentration-dependent at cigarette smoke.
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21. A.S.Q.S. Fonseca, A.D. Labruna Moreira, P.P.A.C de Albuquerque, L.R. de Menezes, C.S. Pfeifer, L.F.J. Schneider, Effect of monomer type on the C C degree of conversion, water sorption and solubility, and color stability of model dental composites, Dent. Mater. 33 (2017) 394–401.
22. A. Kang, S.A. Son, B. Hur, Y.H. Kwon, J.H. Ro, J.K. Park, The color stability of silorane- and methacrylate-based resin composites, Dent. Mater. J. 31 (2012) 879-884.
23. Y.J. Wei, N. Silikas, Z.T Zhang, D.C. Watts, Diffusion and concurrent solubility of self-adhering and new resin-matrix composites during water sorption/desorption cycles, Dent. Mater. 27 (2011) 197-205.
24. H. Alzraikat, M.F. Burrow, G.A. Maghaireh, N.A. Taha, Nanofilled Resin Composite Properties and Clinical Performance: A Review, Oper. Dent. 43 (2018) 173-190.
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2.2 Artigo: Effects of cigarette smoke on color, roughness and gloss of high-viscosity bulk-fill resin composite.
Authors: Theobaldo JD, Vieira-Júnior WF, Mendes KLC, Lima DANL, Marchi GB, Aguiar FHB
Running title: Effect of cigarette smoke on physical properties of bulk-fill composites
Clinical Significance: Bulk-fill composites are more susceptible to staining by cigarette smoke
than conventional composite resins, presenting a clinically unacceptable color change. ABSTRACT
Objective: To evaluate the effect of cigarette smoke (CS) on color, roughness and gloss of high-viscosity bulk-fill composites. Methods and Materials: Resin discs (10 x 2 mm) were made for resin composites (n=10): Filtek Z250XT (3M ESPE, control), Filtek One Bulk Fill (3M ESPE, FOBF), Tetric N-Ceram Bulk-Fill (Ivoclar Vivadent, TBF) and Aura Bulk-Fill (SDI - ABF). The color (ΔL*, Δa*, Δb*,ΔE), roughness (Ra) and gloss analyses were performed at the baseline and after CS exposure (10 pack of cigarettes – Marlboro Red(Philip Morris Brazil Ind. e Com). The data were analyzed with repeated measures ANOVA and Tukey test for Ra and gloss; and one-way ANOVA and Tukey’s test for ∆L*, ∆a*, ∆b* and ∆E (α = 0.05). Results: For ∆L*, all groups presented reducing the luminosity and all bulk-fill composite resins differed statistically from the control (p < 0.05). ABF presented greater variation of ∆L*, differing statistically from all composite resins (p < 0.05). For ∆E, all bulk-fill composite resins showed greater staining, differing statistically from the control, that presented the lower values. For Ra, after CS, only ABF presented a decrease differing statistically from baseline (p < 0.05). After CS smoke, all groups presented gloss increase being statistically different from the baseline (p < 0.05), and when compared among composite resins no difference was founded. Conclusion: Bulk-fill composites were more susceptible to staining by cigarette smoke than conventional microhybrid resin. All bulk-fill composite resins showed a clinically unacceptable color change.
Keywords: Cigarette smoking, Physical properties, Bulk-Fill, Resin-composites, Color stability.
INTRODUCTION
Cigarettes are an industrial form of tobacco consumption. When burned, they produce smoke. During the smoking process, two kinds of smoke are produced: sidestream smoke, which is released into the environment, and mainstream smoke, which is inhaled by smoker, and in general, the same substances are present in both types of cigarette smoke.1 The mainstream smoke, the focus of this study, comprises a particulate and a gas phase.2,3The gas phase consists basically of the constituents of air (nitrogen and oxygen) as well as carbon dioxide, nitric oxide and carbon monoxide (CO). These last three gases are exclusive to this phase.1 The particulate phase represents 30-40% of the burned tobacco and consists of more than 4700 chemicals, with particles of diameters ranging from 0.1 to 1 mm. The average particle ranges from 0.35 to 0.4 μm. The concentration of these particles in cigarette smoke ranges from 109-1010 cm-3, which by weight represents 4.5% of the total smoke. It is extremely important to cite that more than 99% of nicotine is in the particulate phase.1
When cigarette smoke comes into contact with dental structures and conventional composite resins, it causes significant tooth color change, leading to color mismatch between dental hard tissues and composite resin restorations.4 Moreover, the cigarette smoke in contact with teeth and composite resins may cause contamination by heavy metals; 5,6 a decrease in adhesive systems’ bond strength7,8 and chemical-physical property alterations, such as surface roughness, microhardness, water sorption, solubility and staining, which are considered important properties for clinical success of resin composite restorations.9-15
The improvement of composite resins over time led to development of new composites, such as composite resin bulk-fill, which has a low polymerization shrinkage and is apparent in posterior restorations.16 The composition of these composite resins allows for modulation of the polymerization reaction by means of special monomers that relieve stresses, the use of more reactive photoinitiators and the incorporation of various types of filler particles, for example the pre-polymerized particles and the use of fiber glass rods.17,18 This type of composite, according to the manufacturer, can be inserted into the cavity with thickness increments of 4-5mm in a single step. The first generation of bulk-fill materials was developed in flowable form, which required an additional layer of conventional resin on an occlusal surface.19
Posteriorly, was developed a high-viscosity bulk-fill resin that can be insert into a single increment into a cavity (until 4 - 5 mm) because it has specific modulators and photoinitiators.17, 20
A meta-analysis published by Kruly et al., (2018), based on clinical studies, showed that the modified monomer-based composites (silorane, ormocer or bulk-fill) have clinical performances similar to those of conventional composite resins (based on dimethacrylates). For good clinical performance, it is necessary to evaluate several parameters over time, such as marginal adaptation, wear resistance, fracture resistance and color stability.22 In relation to color stability, roughness and gloss surface, for bulk-fill composite resins, few studies in the literature evaluated these properties when they are exposed to cigarette smoke15.
Based on that, the aim of this study is to evaluate the effect of cigarette smoke on physical properties of high-viscosity bulk-fill composites, such as color, gloss and surface roughness. The null hypothesis is that exposure of bulk-fill composites to cigarette smoke does not affect this resin type (1) color, (2) roughness and (3) gloss.
METHODS AND MATERIALS Sample preparation
Disc-shaped specimens were prepared for each type of resin composite (n=10): Filtek Z250 XT (3M ESPE, Saint Paul, MN, USA), Filtek One Bulk Fill (3M ESPE, Saint
Paul, MN, USA), Tetric N-Ceram Bulk-Fill (Ivoclar Vivadent, Schaan, Liechtenstein) and
Aura Bulk-Fill (SDI,Bayswater, Perth, Australia) (Table 1). To obtain the samples, the composite resin was inserted into the silicon matrix (10.0 mm in diameter and 2.0 mm in thickness) in a single increment with a metal spatula (Goldstein XTS flex, Hu-friedy, Chicago, USA). After insertion of the resin, the increment was covered with a polyester strip and a glass slide to remove bubbles that may eventually form. The photoactivation of the composite was performed using a third-generation LED source (VALO-Ultradent Products Inc., South Jordan, UT, USA) on High Power mode with an irradiance of 1400 mW/cm2 for 20 s. Afterward, the samples were stored in a relative humidity environment at 37 oC for 24 hours. Then the samples top surfaces were submitted to the polishing process with a polishing machine (model APL-4; Arotec, Cotia, SP,
