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.

O objetivo deste estudo foi avaliar a resistência à tração diametral (DTS) de três compósitos fotoativados com dois aparelhos de fotoativação (LCU). Os compósitos utilizados neste estudo foram: resina de micropartículas A110 (3M Espe); P60 (3M Espe), indicada para restaurações posteriores, e micro-híbrida Charisma (Heraeus-Kulzer). As fontes de luz foram: halógena (HAL) - Degulux (Degussa) e luz emitida por diodos (LED) - Ultrablue (DMC). As amostras foram confeccionadas através de dois incrementos inseridos em uma matriz de Teflon bipartida medindo 3 mm de profundidade e 6 mm de diâmetro interno e foram fotoativadas pelas LCUs (n = 10). As amostras foram armazenadas dentro de recipientes escuros contendo água destilada a 37°C por 7 dias. O ensaio de DTS foi realizado com a Máquina de Ensaio Universal Instron com velocidade de 0,5 mm/min. Os dados obtidos foram submetidos à Análise de Variância e ao teste de Tukey. Os resultados foram (MPa): A110/HAL: 276,50 ± 62,94ª; A110/LED: 306,01 ± 65,16ª; P60/HAL: 568,29 ± 60,77b e P60/LED: 543,01 ± 83,65b; Charisma/HAL: 430,94 ± 67,28c; Charisma/LED: 435,52 ± 105,12c. Desta forma, os resultados indicaram que não houve diferença significativa de DTS em relação aos aparelhos para uma mesma resina. Entretanto, entre os materiais ocorreram diferenças significativas nos valores de DTS.

The aim of this study was to evaluate the diametrical tensile strength (DTS) of three light-curing photo-activated composites with two different light curing units (LCU). Three types of dental restorative composites were used in this study: micro filled A110 (3M Espe); P60 (3M Espe) for posterior restorations, and micro-hybrid Charisma (Heraeus-Kulzer). The two LCUs were: halogen light (HAL) (Degulux, Degussa) and blue light emitting diode (LED) (Ultrablue, DMC). Resin composite specimens were inserted incrementally into a Teflon split mold meas-uring 3 mm in depth and 6 mm in internal diameter, and cured using either LCU (n = 10). Specimens were placed into a dark bottle containing distilled water at 37°C for 7 days. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). Data were submitted to two-way ANOVA and Tukey's test. Results were (MPa): A110/HAL: 276.50 ± 62.94ª; A110/LED: 306.01 ± 65.16ª; P60/HAL: 568.29 ± 60.77b and P60/LED: 543.01 ± 83.65b; Charisma/HAL: 430.94 ± 67.28c; Charisma/LED: 435.52 ± 105.12c. Results suggested that no significant difference in DTS was obtained with LCUs for the same composite. However, resin composite restorative materials presented different DTS.