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Doctoral Thesis
DOI
https://doi.org/10.11606/T.58.2020.tde-08082018-112131
Document
Author
Full name
Sergio Augusto de Freitas Vincenti
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2018
Supervisor
Committee
Souza, Fernanda de Carvalho Panzeri Pires de (President)
Borsato, Maria Cristina
Sinhoreti, Mário Alexandre Coelho
Yamauti, Monica
Title in Portuguese
Caracterização e resistência adesiva de cimentos de ionômero de vidro modificados por resina incorporados com vitrocerâmica bioativa
Keywords in Portuguese
Bioatividade
Ciclagem termomecânica
Cimentos de ionômero de vidro modificados por resina
Liberação de flúor
Propriedades mecânicas
Resistência de união
Vitrocerâmica
Abstract in Portuguese
O objetivo deste estudo foi incorporar 2% e 6,5% de vitrocerâmica bioativa (Biosilicato®, Vitrovita) a cimentos comerciais de ionômero de vidro modificados por resina (CIVMR) utilizados para forramento (Vitrebond®, 3M ESPE Dental Products) e restauração (Vitremer®, 3M ESPE Dental Products), caracterizá-los em diferentes propriedades, avaliar a influência do envelhecimento artificial sobre a resistência de união dos materiais experimentais à dentina, bem como seu potencial remineralizador. A caracterização mecânica foi realizada pela análise de resistência à compressão e à flexão (EMIC 23-20, INSTRON/EMIC) e microdureza Knoop (HMV-2, Shimadzu). Além disso, foram analisadas liberação de fluoretos por potenciometria direta (Hanna Instruments Inc., Woonsocket) e atividade antimicrobiana em meio de cultura ágar (Ágar Müller Hinton). Para cada um dos testes realizados, as médias obtidas foram analisadas estatisticamente segundo 1-way ANOVA (Tukey, p<0,05). A resistência de união (RU) foi avaliada em 240 molares humanos hígidos. Os dentes foram preparados em cavidades de 7 x 6 x 2 mm e, antes de serem restaurados com os materiais testados, metade das amostras foi submetida a ciclagem de pH para obtenção de dentina cariada artificialmente. As amostras foram separadas de acordo com o tipo de envelhecimento submetido (n=10): ciclagem termomecânica (CTM) (ER 37000, ERIOS Equipamentos Ltda) e armazenamento em água destilada (AAD), por 6 meses. Todos os corpos de prova foram seccionados em amostras de 1 mm2 (IsoMet® 1000 Precision Saw, Buehler) e submetidos a ensaio de microtração (OM100, Odeme Equipamentos Médicos e Odontológicos Ltda). As médias obtidas foram analisadas segundo 3-way ANOVA, teste de Tukey, intervalo de confiança de 95%. O padrão de fratura das amostras foi analisado em estereomicroscópio (Stereomaster® Microscope, Fisher Scientific) e a razão molar Ca/P foi obtida em análise por EDX (JSM-5600LV, JEOL). Verificou-se que a incorporação de Biosilicato® interferiu negativamente nas propriedades mecânicas do material. A liberação de fluoretos aumentou significativamente (p<0,05) quando incorporado 6,5% de Biosilicato® ao Vitrebond® e ambas as concentrações experimentais ao Vitremer®. Não houve diferença na atividade antimicrobiana dos materiais testados em relação aos respectivos grupos Controle. A presença de Biosilicato® não aumentou significativamente a RU dos materiais testados em nenhum dos substratos, e a CTM foi fator significativo para a diminuição dessa propriedade. A CTM aumentou a razão Ca/P em dentina hígida, em ambas as concentrações de Biosilicato®, tanto em Vitrebond® quanto em Vitremer®. Em dentina artificialmente cariada, a CTM aumentou a Ca/P do Vitremer® com 6,5% de Biosilicato® incorporado, mas diminuiu essa propriedade com 2% de Biosilicato®. Concluiu-se que a incorporação de Biosilicato® aos CIVMR, nas concentrações propostas, não resulta em propriedades melhoradas do material, independentemente do tipo de substrato testado.
Title in English
Characterization and bond strength of a bioactive glass-ceramic incorporated on resinmodified glass ionomer cements
Keywords in English
Bioactivity
Bond strength
Fluoride release
Glass-ceramic
Mechanical properties
Resin-modified glass ionomer cements
Thermal-mechanical cycling
Abstract in English
The aim of this study was to incorporate 2% and 6.5% in weight of bioactive glass-ceramic (Biosilicate®, Vitrovita) into commercial resin-modified glass ionomer cements (RMGIC) used for lining (Vitrebond®, 3M ESPE Dental Products) and restoration (Vitremer®, 3M ESPE Dental Products), to characterize them in different properties, to evaluate the influence of artificial aging on the bond strength of the experimental materials to dentin, as well as its remineralization potential. The mechanical characterization was performed by the compressive and flexural strength (EMIC 23-20, INSTRON/EMIC) and Knoop microhardness test (HMV-2, Shimadzu). Besides, the fluoride ion release was measured using direct potentiometry (Hanna Instruments Inc., Woonsocket) and the antimicrobial activity was investigated in Müller Hinton agar plates. For each of the tests performed, the mean values were analyzed by 1-way ANOVA followed by Tukey's post-hoc test (p<.05). The bond strength (BS) was evaluated in 240 sound human molars. The teeth were prepared in 7 x 6 x 2 mm cavities, and half of the samples were subjected to pH cycling to obtain artificially caries-affected dentin before being restored with the experimental materials. The samples were separated by aging methods (n=10): thermal-mechanical cycling (TMC) (ER 37000, ERIOS) and storage in distilled water for 6 months. All the specimens were sectioned in 1 mm2 samples (IsoMet® 1000 Precision Saw, Buehler) and subjected to microtensile bond strength test (OM100, Odeme). The mean values were analyzed by 3-way ANOVA followed by Tukey's post-hoc test (p<.05). The fracture pattern of the samples was observed with a stereomicroscope (Stereomaster® Microscope, Fisher Scientific) and the Ca/P molar ratio was obtained by EDX analysis (JSM-5600LV, JEOL). The incorporation of Biosilicate® was found to adversely affect the mechanical properties of the material. The fluoride release increased significantly (p<.05) when 6.5% of Biosilicate® was incorporated into Vitrebond®, and both experimental concentrations were incorporated into Vitremer®. There was no difference in the antimicrobial activity of the tested materials compared to the respective Control groups. Biosilicate® did not significantly increase the BS of the tested materials on any of the substrates, and the TMC was a significant factor to decrease of this property. The TMC increased the Ca/P ratio in sound dentin at both Biosilicate® concentrations, both in Vitrebond® and Vitremer®. In artificially caries-affected dentin, the TMC increased the Ca/P molar ratio of Vitremer® incorporated by 6.5% Biosilicate®, but it decreased this property when 2% Biosilicate® was incorporated. It was concluded that the incorporation of Biosilicate® into the RMGIC at the proposed concentrations does not result in improved properties of the material, regardless of the type of substrate tested.
 
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Publishing Date
2020-05-15
 
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