Efeito de diferentes tratamentos de superfície na resistência de união, ângulo de contato, morfologia e análise da distribuição de tensão de laminados ultrafinos de cerâmica reforçada por dissilicato de lítio
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Data
2017-11-30
Autores
Escobar, Lorena Cristina Bogado
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Laminados cerâmicos são utilizados em tratamentos conservadores para restabelecer estética e função com mínimo desgaste da estrutura dental. O objetivo deste estudo foi avaliar, in vitro, o efeito de dois tratamentos de superfície em espécimes cerâmicos ultrafinos de dissilicato de lítio na resistência de união com o cimento resinoso. Laminas ultrafinas de cerâmica (14 X 12 X 0,3 mm) foram distribuídas aleatoriamente em dois grupos (n=20) de acordo com o tratamento de superfície: ácido hidrofluorídrico 5% durante 20 s e silano (HF) e Monobond Etch & Prime (Ivoclar, Vivadent) por 60 s (MEP). Dois cilindros de cimento resinoso foram confeccionados utilizando matrizes cilíndricas. Após 24 h de armazenamento, os espécimes foram submetidos ao ensaio mecânico de microcisalhamento (1 mm/min) e o modo de falha foi estabelecido. Dados de resistência de união foram analisados pelo teste t de Student (α=0.05). O ângulo de contato foi determinado. Análise morfológica das superfícies cerâmicas por meio de microscopia de força atômica e eletrônica de varredura foi realizada. Através de análise por elementos finitos foi estudada a distribuição de tensão em incisivos centrais superiores restaurados com laminados cerâmicos ultrafinos de dissilicato de lítio (0,3 mm). O modelo tridimensional foi elaborado no software Rhinoceros e exportado para software de análise Ansys. Foram modelados e analisados 04 grupos sob duas condições: desgaste ou não de esmalte e tipo de preparo. Foi aplicada uma carga de 100 N e a tensão gerada analisada pelo critério de Tensão Máxima Principal. Não houve diferença estatística nos valores de resistência de união entre o grupo HF e MEP (p=0,117). O ângulo de contato foi influenciado pelo tratamento de superfície (p=0,001); espécimes sem tratamento de superfície tiveram o maior ângulo de contato (65, 37˚) entanto que o grupo HF exibiu o menor ângulo de contato (33,80˚). A análise morfológica mostrou que o condicionamento da superfície com HF foi mais obvio mostrando poros, irregularidades e maior rugosidade em comparação com o condicionamento com MEP. A análise por elementos finitos mostrou que o grupo com laminado cerâmico cimentado sobre o esmalte sem preparo apresentou as menores concentrações de tensão tanto no esmalte como no laminado. Laminados cimentados sobre esmalte preparado mostraram concentração de tensão na interface dente/laminado. O Monobond Etch & Prime se mostrou estatisticamente equivalente ao ácido fluorídrico e silano em termos de resistência de união. Laminados cerâmicos ultrafinos cimentados sobre esmalte hígido geram menos tensão na superfície do dente e laminado. Laminados cerâmicos cimentados sobre esmalte preparado não provocam concentração de tensão adicional no esmalte.
Laminate veneers are becoming a technique used in the conservative treatments by the ability to restore aesthetics and function. This study aimed to evaluate, in vitro, the effect of two surface treatments on ultrathin lithium disilicate specimens in bond strength between treated ceramics and resin cement. Ceramic ultrathin laminates (12 X 14 X 0.3 mm) were obtained and randomly distributed into two groups (n=20) according to the surface treatment: 5% hydrofluoric acid for 20 s and silane (HF) and Monobond Etch & Prime (Ivoclar, Vivadent) for 60 s (MEP). Two resin cement cylinders were made using cylindrical matrices. After 24 h storage, microshear bond strength tests were performed in a universal testing machine (1 mm/min) and failure mode was analyzed. Bond strength data were submitted to Student's t-test (α=0.05). The contact angle was measured. Micromorphogical analyses of representatives specimens were also performed (atomic force and scanning electron microscopy). Finite element analysis studied the distribution of stress in maxillary central incisors restored with ultrathin laminate veneers of lithium disilicate (0.3 mm). 3D model was elaborated in CAD Rhinoceros® software and exported to analysis software Ansys®. Four groups were modeled and analyzed under two experimental conditions: wear or non-enamel and type of preparation. A load of 100 N was applied at the palatal face. The stress was analyzed by Maximum Principal Stress criteria. Microshear bond strength values showed that HF group was not statistically different from MEP group (p=0.117). Microshear bond strength values showed that HF group was not statistically different from MEP group (p=0.117). Contact angle was influenced by surface treatments (p=0.001); specimens without surface treatment had the highest contact angle (65.37˚) whereas HF group exhibited the lowest contact angle (33.80˚). Surface morphological evaluation showed that hydrofluoric acid etching promoted a more obvious surface pattern regarding pores and irregularities with higher surface roughness in comparison to self-etching glass ceramic primer. Finite element analysis showed that laminates without enamel prepared generated the lowest stress in the enamel and in the laminate. Laminates with enamel prepared showed the stress concentration in the finishing lines of preparation in the tooth/laminate interface. Monobond Etch & Prime obtained statistically equivalent results in terms of bond strength to hydrofluoric acid and silane. Ultrathin laminate veneer cemented over sound enamel generate less stress on the surface of the tooth and laminate. Laminates veneers on prepared enamel do not cause additional tension in the tooth structure.
Laminate veneers are becoming a technique used in the conservative treatments by the ability to restore aesthetics and function. This study aimed to evaluate, in vitro, the effect of two surface treatments on ultrathin lithium disilicate specimens in bond strength between treated ceramics and resin cement. Ceramic ultrathin laminates (12 X 14 X 0.3 mm) were obtained and randomly distributed into two groups (n=20) according to the surface treatment: 5% hydrofluoric acid for 20 s and silane (HF) and Monobond Etch & Prime (Ivoclar, Vivadent) for 60 s (MEP). Two resin cement cylinders were made using cylindrical matrices. After 24 h storage, microshear bond strength tests were performed in a universal testing machine (1 mm/min) and failure mode was analyzed. Bond strength data were submitted to Student's t-test (α=0.05). The contact angle was measured. Micromorphogical analyses of representatives specimens were also performed (atomic force and scanning electron microscopy). Finite element analysis studied the distribution of stress in maxillary central incisors restored with ultrathin laminate veneers of lithium disilicate (0.3 mm). 3D model was elaborated in CAD Rhinoceros® software and exported to analysis software Ansys®. Four groups were modeled and analyzed under two experimental conditions: wear or non-enamel and type of preparation. A load of 100 N was applied at the palatal face. The stress was analyzed by Maximum Principal Stress criteria. Microshear bond strength values showed that HF group was not statistically different from MEP group (p=0.117). Microshear bond strength values showed that HF group was not statistically different from MEP group (p=0.117). Contact angle was influenced by surface treatments (p=0.001); specimens without surface treatment had the highest contact angle (65.37˚) whereas HF group exhibited the lowest contact angle (33.80˚). Surface morphological evaluation showed that hydrofluoric acid etching promoted a more obvious surface pattern regarding pores and irregularities with higher surface roughness in comparison to self-etching glass ceramic primer. Finite element analysis showed that laminates without enamel prepared generated the lowest stress in the enamel and in the laminate. Laminates with enamel prepared showed the stress concentration in the finishing lines of preparation in the tooth/laminate interface. Monobond Etch & Prime obtained statistically equivalent results in terms of bond strength to hydrofluoric acid and silane. Ultrathin laminate veneer cemented over sound enamel generate less stress on the surface of the tooth and laminate. Laminates veneers on prepared enamel do not cause additional tension in the tooth structure.
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Palavras-chave
Laminados, Lentes de contato, Cerâmica, Dissilicato de lítio, Resistência de união, Microcisalhamento, Análise por elementos finitos, Laminates veneers, Contact lens, Ceramic, Lithium disilicate, Bond strength, Microshear bond strength, Finite element analysis