Abstract This study evaluated the effect of adding the hydrophobic monomer 1,12 dodecanediol dimethacrylate (DDDMA) to experimental sealants with and without thermocycling on degree of conversion (DC), water sorption (WS), water solubility (WSB), color stability (ΔE), and micro-shear bond strength (μSBS). Five experimental and one commercially available sealant (Bisco - BIS) were tested. The experimental sealants were formulated by mixing different percentages of DDDMA monomers and urethane dimethacrylate (UDMA). The photoinitiator system was composed by camphorquinone (CQ) and tertiary amine 4-ethyl benzoate dimetilamiono (EDBA). Ethanol was used as a solvent. The experimental groups were named sequentially according to the monomeric content (DDDMA/UDMA): S40/40 (40/40), S50/30 (50/30), S60/20 (60/20), S70/10 (70/10) and S80/0 (80/0). Data were analyzed separately by one-way ANOVA, followed by Tukey’s test (p<0.05). The values of DC ranged from 94.59% (S40/40) to 54.02% (S80/10). BIS showed the highest WS value (p<0.05) and S40/40, S50/30, S60/20 and S80/0 showed the lowest WS values of all tested sealants. WSB values ranged from 7.88 µg/mm3 (BIS) to 13.27 µg/mm3 (S70/10). The highest ΔE value was 11.05±2.88 for BIS and the highest μSBS value was found for S60/20. No significant difference was observed in bond strength between sealants and bovine enamel after thermocycling. Adding DDDMA to the composition of surface sealants can improve its performance, once the monomer increased the degree of conversion and the color stability.

Resumo: Este estudo investigou a influência da armazenagem em água (24 h e 6 meses) e dos materiais para colagem Transbond XT e Fuji Ortho LCO na resistência da união de bráquetes metálicos fixados a cerâmica feldspática. Quatro cilindros de cerâmica foram condicionados com ácido fluorídrico a 10% por 60 s. Todos os cilindros receberam duas camadas de silano. Bráquetes metálicos foram fixados aos cilindros utilizando os materiais Transbond XT ou Fuji Ortho LC. A fotoativação foi realizada com tempo de exposição total de 40 s utilizando Bluephase G2. Metade das amostras de cada material de colagem (n=20) foi armazenada em água destilada a 37 °C por 24 h e outra metade por 6 meses. O ensaio de resistência da união ao cisalhamento foi realizado após os períodos de armazenagem à velocidade de 1 mm/minuto. O Índice de Remanescente Adesivo (IRA) foi utilizado para avaliar a quantidade de adesivo residual na superfície da cerâmica, em lupa estereoscópica com aumento de 8x. Os dados foram submetidos à Análise de Variância de dois fatores e teste de Tukey (p<0,05). Transbond XT apresentou resistência de união significativamente maior do que Fuji Ortho LC. Diferença significante (p<0,05) na resistência da união foi encontrada entre os períodos de armazenagem, qualquer que fosse o material para colagem. O IRA mostrou predominância de escore 0 para todos os grupos, com aumento de escores 1, 2 e 3 para o período de armazenagem de 24 h. Em conclusão, o período de armazenagem e os materiais de colagem influenciaram significativamente a resistência da união de bráquetes à cerâmica.

Abstract: This study investigated the influence of water storage (24 h and 6 months), and Transbond XT and Fuji Ortho LC bonding materials on the bond strength of metallic brackets bonded to feldspathic ceramic. Four cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 60 s. Each cylinder received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT or Fuji Ortho LC. Light-activation was carried out with 40 s total exposure time using Bluephase G2. Half the specimens for each bonding materials (n=20) were stored in distilled water at 37 °C for 24 h and the other half for 6 months. Shear bond strength testing was performed after storage times at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Data were subjected to two-way ANOVA and Tukey's test (p<0.05). Transbond XT showed significantly higher bond strength (p<0.05) than Fuji Ortho LC. Significant differences in bond strength (p<0.05) were found when 24 h and 6 months storage times were compared between materials. ARI showed a predominance of score 0 for all groups, and higher scores at 1, 2 and 3 for 24 h storage time. In conclusion, storage time and bonding materials showed significant influence on the bond strength of brackets to ceramic.