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Variação da rugosidade de superfície e tempo de aplicação na preparação cavitária em dentina e o seu efeito nas características interfaciais e adesão de resinas compostas auto-adesivas
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Abstract(s)
Objetivos: Avaliar a resistência adesiva ao microcisalhamento de duas resinas compostas auto-adesivas comerciais, variando o seu tempo de aplicação (0, 1 e 5 min) e a rugosidade de superfície na dentina. Comparar de forma qualitativa, com recurso à microscopia eletrónica de varrimento (MEV), a topografia da superfície.
Materiais e Métodos: Setenta molares humanos hígidos foram aleatoriamente distribuídos por 12 grupos de estudo, de acordo com 3 tempos de aplicação, 2 granulometrias de broca e 2 resinas compostas auto-adesivas comerciais (Vertise Flow e Constic). Foram ainda adicionados grupos de controlo com resina composta e sistema adesivo, para fins comparativos. Cada dente foi seccionado em discos de dentina média
coronária, de 2 mm de espessura (Accutom-50 a 0.350 mm/s, Struers, Dinamarca), preparados com uma broca troncocónica diamantada (risca preta ou amarela), de forma a simular a smear layer e rugosidade. Utilizou-se um molde CAD/CAM cilíndrico de forma a padronizar 3 cilindros de resina composta em cada disco, seguindo um tempo de aplicação de 0, 1 ou 5 minutos antes da fotopolimerização (20 s, a 0 distância; 950 mW/cm2, LED alta intensidade). Após 24 h em água destilada (37ºC), os cilindros foram sujeitos ao teste de microcisalhamento (1 mm/min, Shimadzu AGS-X, Japão). Uma amostra aleatória de cada grupo foi analisada no MEV. Estatística inferencial contemplou ANOVA three-way, com teste Tukey post-hoc, a um nível de significância de 5%.
Resultados: O teste ANOVA three-way confirmou que a resina composta auto-adesiva (p<0,05) e o tempo de aplicação (p<0,0001) influenciaram a resistência adesiva. Contudo, a rugosidade de superfície não foi significativa (p=0,97). O tempo de aplicação, foi de facto altamente significativo, sendo os 5 min, onde se obtiveram melhores resultados para ambas as resinas compostas testadas.
Conclusões: As resinas compostas auto-adesivas beneficiaram de um tempo de aplicação mais longo de 5 minutos, enquanto que as diferenças na rugosidade de superfície testada não influenciou a resistência adesiva. Estes resultados confirmam que o fraco desempenho das resinas auto-adesivas poderá estar relacionada com a limitada interação dos monómeros com o substrato.
Objectives: To evaluate the micro-shear bond strength of two commercial self-adhesive composite resins, varying their application time (0, 1 and 5 min) and surface roughness on dentin. To qualitatively compare the surface topography using scanning electron microscopy (SEM). Materials and Methods: Seventy healthy human molars were randomly assigned to 12 study groups, according to 3 application times, 2 drill sizes and 2 commercial selfadhesive composite resins (Vertise Flow and Constic). Control groups with composite resin and adhesive system were also added for comparative purposes. Each tooth was sectioned into 2 mm-thick coronal middle dentin disks (Accutom-50 at 0.350 mm/s, Struers, Denmark), prepared with a diamond truncated bur (black or yellow stripe), in order to simulate the smear layer and roughness. A cylindrical CAD/CAM mold was used in order to standardize 3 cylinders of composite resin on each disc, following an application time of 0, 1 or 5 minutes before light curing (20 s, at 0 distance; 950 mW/cm2, high intensity LED). After 24 hours in distilled water (37ºC), the cylinders were subjected to the microshear test (1 mm/min, Shimadzu AGS-X, Japan). A random sample from each group was analyzed in the SEM. Inferential statistics included a three-way ANOVA with a Tukey post-hoc test at a 5% significance level. Results: The three-way ANOVA test confirmed that self-adhesive composite resin (p<0.05) and application time (p<0.0001) influenced adhesive strength. However, surface roughness was not significant (p=0.97). Application time was in fact highly significant, with 5 min being the best result for both composite resins tested. Conclusions: Self-adhesive composite resins benefited from a longer application time of 5 minutes, while differences in the surface roughness tested did not influence adhesive strength. These results confirm that the poor performance of self-adhesive resins may be related to the limited interaction of the monomers with the substrate.
Objectives: To evaluate the micro-shear bond strength of two commercial self-adhesive composite resins, varying their application time (0, 1 and 5 min) and surface roughness on dentin. To qualitatively compare the surface topography using scanning electron microscopy (SEM). Materials and Methods: Seventy healthy human molars were randomly assigned to 12 study groups, according to 3 application times, 2 drill sizes and 2 commercial selfadhesive composite resins (Vertise Flow and Constic). Control groups with composite resin and adhesive system were also added for comparative purposes. Each tooth was sectioned into 2 mm-thick coronal middle dentin disks (Accutom-50 at 0.350 mm/s, Struers, Denmark), prepared with a diamond truncated bur (black or yellow stripe), in order to simulate the smear layer and roughness. A cylindrical CAD/CAM mold was used in order to standardize 3 cylinders of composite resin on each disc, following an application time of 0, 1 or 5 minutes before light curing (20 s, at 0 distance; 950 mW/cm2, high intensity LED). After 24 hours in distilled water (37ºC), the cylinders were subjected to the microshear test (1 mm/min, Shimadzu AGS-X, Japan). A random sample from each group was analyzed in the SEM. Inferential statistics included a three-way ANOVA with a Tukey post-hoc test at a 5% significance level. Results: The three-way ANOVA test confirmed that self-adhesive composite resin (p<0.05) and application time (p<0.0001) influenced adhesive strength. However, surface roughness was not significant (p=0.97). Application time was in fact highly significant, with 5 min being the best result for both composite resins tested. Conclusions: Self-adhesive composite resins benefited from a longer application time of 5 minutes, while differences in the surface roughness tested did not influence adhesive strength. These results confirm that the poor performance of self-adhesive resins may be related to the limited interaction of the monomers with the substrate.
Description
Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas Moniz
Keywords
Microcisalhamento Resinas compostas auto-adesivas Resistência adesiva Rugosidade