Efeito de vernizes à base de copolímeros do polimetacrilato na proteção contra o desgaste dental erosivo
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Data
2021-07-06
Autores
Santos, Tamires Maria de Andrade
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Universidade Estadual Paulista (Unesp)
Resumo
O aumento da prevalência de desgaste dental erosivo nos últimos anos, que apresenta uma etiologia multifatorial, se deve principalmente à mudança no estilo de vida das populações em geral. Assim, o diagnóstico precoce e a adoção de medidas preventivas são essenciais para o controle deste problema. Os copolímeros do polimetacrilato apresentaram um promissor potencial anti-erosivo associado a soluções fluoretadas em estudos prévios de nosso grupo de pesquisa. Abordagens adicionais envolvem o uso de agentes aplicados em consultório, que podem estar associados a concentrações mais elevadas de agentes fluoretados. Assim, o objetivo deste trabalho foi investigar a efetividade de uma nova formulação experimental com agentes formadores de película bioadesiva à base de copolímeros do polimetacrilato, bem como a associação destes ao fluoreto de sódio (F) em proteger o esmalte dental frente a desafios erosivos e abrasivos. Amostras de esmalte bovino polidas foram preparadas e os perfis superficiais iniciais determinados por meio de um perfilômetro de contato. Foi realizada então a desmineralização do esmalte (ácido cítrico 0,3%, pH 2,6- 5 min) para simulação da erosão inicial e nova leitura de perfil. Os espécimes foram estratificados para receberem os tratamentos de acordo com os seguintes grupos (n= 15): Controle negativo (água ultrapura); verniz comercial (Duraphat – NaF – 22600 ppm F-); formulação experimental à base de copolímero catiônico aminometacrilato (AMC) (Eudragit E100 – 15%); formulação experimental à base de copolímero aniônico metilmetacrilato (MMC) (Eudragit L100- 15%). As formulações experimentais foram ainda testadas associadas ao fluoreto de sódio (NaF – 22600 ppm F-). Os produtos foram aplicados sobre a superfície dos espécimes e foi realizada novamente a leitura do perfil para mensuração da espessura da camada de tratamento aplicada sobre o esmalte. Estes foram então armazenados em saliva artificial por 6 h. Foi então realizada a ciclagem erosiva-abrasiva, com imersão em ácido cítrico a 0,3% (5 min) intercalado com saliva artificial (1h). A abrasão foi realizada após o primeiro e último desafio erosivo diários. Foram realizadas leituras de perfil após o 1º, 3º, 5º, 7º e 9º dias de ciclagem para determinação da perda do esmalte (em µm), comparando-se os perfis obtidos após a erosão inicial e após a ciclagem. Adicionalmente, foi mensurada em espécimes adicionais tratados, a quantidade de flúor fracamente adsorvido à superfície do esmalte (solúvel em KOH), utilizando eletrodo específico (dados em µg/cm²). Foram utilizados os testes ANOVA e Tukey (5%) para os dados medidos ao final da ciclagem. Os dados de perda superficial (média±desvio-padrão) obtidos com os copolímeros AMC (-11,23 ± 3,50)b e MMC (-11,26 ± 2,38)b mostraram potencial protetor significantemente maior do que o controle negativo (-18,31±2,62)a. Os menores valores de perda de esmalte foram observados para os grupos Duraphat (-4,56±1,78)c, AMC+F (-6,26±1,79)c e MMC+F (-7,03±2,49)c, sem diferença significante entre eles (p<0,05). Para o teste adicional de concentração de flúor solúvel em KOH, foram aplicados os testes não paramétricos de Kruskal Wallis e de comparações múltiplas de Dunn (5%). O controle negativo apresentou valores (mediana / distância interquartil) significantemente menores de flúor adsorvido ao esmalte (0,90 / 0,43-1,04)a comparado aos demais. Observou-se maior valor de mediana para o grupo MMC+F (27,42 / 18,30-29,73)b do que para o AMC+F (6,50 / 5,48-8,71)c e o valor obtido para o Duraphat foi intermediário (9,15 / 7,97-14,95)bc. Concluiu-se que os copolímeros do polimetacrilato foram capazes de diminuir a perda do esmalte, apresentando potencial protetor similar ao do Duraphat quando associados ao fluoreto de sódio. O copolímero aniônico (MMC) proporcionou formação de maior quantidade de flúor adsorvido ao esmalte do que o copolímero catiônico (AMC), sendo ambos similares ao verniz comercial Duraphat.
The increase in the prevalence of erosive tooth wear in the last years, which has a multifactorial etiology, is mainly due to the changes in the lifestyle of populations in general. Thus, early diagnosis and the adoption of preventive measures are essential for controlling this problem. Polymethacrylate copolymers showed promising anti-erosion potential associates with fluoride solutions in previous studies conducted by our research group. Additional approaches involve the use of office-applied agents containing higher concentrations of fluorides. Thus, the aim of this study was to investigate the efficacy of a new formulation with bioadhesive film forming agents based on polymethacrylate copolymers, as well as its association with sodium fluoride (F) in protecting dental enamel against erosive and abrasive challenges. Polished bovine enamel samples were used and surface profiles was determined with a contact profilometer. Then, demineralization of enamel (0,3% citric acid pH 2,6-5 min) was performed to simulate the initial erosion and a new profile reading was made. The specimens were randomized to receive treatments according to the following groups (n=15): Negative control (ultrapure water); commercial varnish (Duraphat- NaF-22600 ppm F-); experimental formulation based on cationic polymethacrylate copolymer (Eudragit E100 – 15%); experimental formulation based on anionic polymethacrylate copolymer (Eudragit L100 – 15%). The experimental formulations were also tested in association with sodium fluoride (NaF – 22600 ppm F-). The surface profile of the specimens was read again to observe the thickness of the treatment layer applied to the enamel. These were then stored in artificial saliva for 6 h. Erosive-abrasive cycling was then carried out, with immersion in 0,3% citric acid (5 min) interspersed with artificial saliva (1h). Abrasion was carried out after the first and last daily erosive challenge. Profile readings were performed after the 1st, 3rd, 5th, 7th and 9th cycling days to determine the enamel loss (in µm), comparing the profiles obtained after initial erosion and after cycling. Additionally, the amount of fluoride weakly adsorbed to the enamel surface (soluble in KOH) was measured in additional treated specimens, using a specific electrode (data in µg/cm2). ANOVA and Tukey tests (5%) were used for the data measured at the end of the cycle. The surface loss data (mean ± standard deviation) obtained with the AMC (-11.23 ± 3.50)b and MMC (-11.26 ± 2.38)b copolymers showed significantly greater protective potential than the negative control (-18.31 ± 2.62)a. The lowest values of enamel loss were observed for the groups Duraphat (-4.56 ± 1.78), AMC +F (-6.26 ± 1.79)c and MMC +F (-7.03 ± 2.49)c, with no significant difference between them (p<0.05). For the additional KOH- soluble fluoride concentration test, Kruskal Wallis non-parametric tests and Dunn´s multiple comparisons tests (5%) were applied. The negative control showed significantly lower values (median/ interquartile distance) of fluoride adsorbed to the enamel (0.90 / 0.43-1.04)a compared to the others. A higher median values was observed for the MMC+F (27.42/18.30-29.73)b group than for the AMC+F (6.50 / 5.48-8.71)c and the value obtained for Duraphat was intermediate (9.15 / 7.97-14.95)bc. It was concluded that the polymethacrylate copolymers were able to reduce enamel loss, presenting a protective potential similar to that of Duraphat when associated with sodium fluoride. The anionic copolymer (MMC) provided formation of a greater amount of fluoride adsorbed to the enamel than the cationic copolymer (AMC), both being similar to the commercial varnish Duraphat.
The increase in the prevalence of erosive tooth wear in the last years, which has a multifactorial etiology, is mainly due to the changes in the lifestyle of populations in general. Thus, early diagnosis and the adoption of preventive measures are essential for controlling this problem. Polymethacrylate copolymers showed promising anti-erosion potential associates with fluoride solutions in previous studies conducted by our research group. Additional approaches involve the use of office-applied agents containing higher concentrations of fluorides. Thus, the aim of this study was to investigate the efficacy of a new formulation with bioadhesive film forming agents based on polymethacrylate copolymers, as well as its association with sodium fluoride (F) in protecting dental enamel against erosive and abrasive challenges. Polished bovine enamel samples were used and surface profiles was determined with a contact profilometer. Then, demineralization of enamel (0,3% citric acid pH 2,6-5 min) was performed to simulate the initial erosion and a new profile reading was made. The specimens were randomized to receive treatments according to the following groups (n=15): Negative control (ultrapure water); commercial varnish (Duraphat- NaF-22600 ppm F-); experimental formulation based on cationic polymethacrylate copolymer (Eudragit E100 – 15%); experimental formulation based on anionic polymethacrylate copolymer (Eudragit L100 – 15%). The experimental formulations were also tested in association with sodium fluoride (NaF – 22600 ppm F-). The surface profile of the specimens was read again to observe the thickness of the treatment layer applied to the enamel. These were then stored in artificial saliva for 6 h. Erosive-abrasive cycling was then carried out, with immersion in 0,3% citric acid (5 min) interspersed with artificial saliva (1h). Abrasion was carried out after the first and last daily erosive challenge. Profile readings were performed after the 1st, 3rd, 5th, 7th and 9th cycling days to determine the enamel loss (in µm), comparing the profiles obtained after initial erosion and after cycling. Additionally, the amount of fluoride weakly adsorbed to the enamel surface (soluble in KOH) was measured in additional treated specimens, using a specific electrode (data in µg/cm2). ANOVA and Tukey tests (5%) were used for the data measured at the end of the cycle. The surface loss data (mean ± standard deviation) obtained with the AMC (-11.23 ± 3.50)b and MMC (-11.26 ± 2.38)b copolymers showed significantly greater protective potential than the negative control (-18.31 ± 2.62)a. The lowest values of enamel loss were observed for the groups Duraphat (-4.56 ± 1.78), AMC +F (-6.26 ± 1.79)c and MMC +F (-7.03 ± 2.49)c, with no significant difference between them (p<0.05). For the additional KOH- soluble fluoride concentration test, Kruskal Wallis non-parametric tests and Dunn´s multiple comparisons tests (5%) were applied. The negative control showed significantly lower values (median/ interquartile distance) of fluoride adsorbed to the enamel (0.90 / 0.43-1.04)a compared to the others. A higher median values was observed for the MMC+F (27.42/18.30-29.73)b group than for the AMC+F (6.50 / 5.48-8.71)c and the value obtained for Duraphat was intermediate (9.15 / 7.97-14.95)bc. It was concluded that the polymethacrylate copolymers were able to reduce enamel loss, presenting a protective potential similar to that of Duraphat when associated with sodium fluoride. The anionic copolymer (MMC) provided formation of a greater amount of fluoride adsorbed to the enamel than the cationic copolymer (AMC), both being similar to the commercial varnish Duraphat.
Descrição
Palavras-chave
Erosão dental, Perfilometria, Esmalte, Polímeros, Fluoreto de sódio, Tooth erosion, Profilometry, Enamel, Polymers, Sodium fluoride