Influence of filler addition, storage medium and evaluation time on biaxial flexure strength and modulus of adhesive systems.

OBJECTIVE: This study evaluated the effects of filler addition, storage medium and time on biaxial flexural strength and flexural modulus of six adhesive systems. MATERIALS AND METHODS: The adhesives were either unfilled resins: Single Bond, Prime&Bond 2.1 and One-Step; or filled resins: Single Bond Plus, Prime&Bond NT and One-Step Plus. Resin discs of each product (0.5 mm thick × 6.0 mm diameter) were prepared using silicon molds (n = 10). The discs were stored dry, in water, mineral oil or ethanol for 1 week or 3 months before biaxial flexural testing. Data were statistically analyzed by 3-way ANOVA and Tukey's post-hoc test (α = 0.05). The specimens were tested in a universal testing machine at 1.27 mm/min until failure occurred. RESULTS: In general, the storage in ethanol led to significantly lower flexural strength and flexural modulus values than the other storage conditions for all adhesives in both storage periods. Filler addition increased flexural strength and flexural modulus for Prime&Bond NT, when it was stored dry or in water for 1 week. For Single Bond Plus, the filler addition resulted in higher flexural modulus, when it was stored for 1 week in oil and in ethanol. No significant differences in flexural modulus were observed between One-Step and One-Step Plus in any storage medium. CONCLUSIONS: Results suggested that filler addition does not necessarily have to increase the flexural strength and flexural modulus. Ethanol and oil storages tended to yield opposite effects.

Evaluation of biaxial flexural strength and modulus of filled and unfilled adhesive systems / Avaliação da resistência flexural biaxial e módulo de flexão de sistemas adesivos

Purpose: The purpose of this study was to evaluate the flexural strength and modulus of two adhesive systems using biaxial flexural strength test. Methods: The bonding agents (Pentron Clinical Technologies) tested were: Bond 1 (B1) and NanoBond (NB). Thirteen disks (6.1 mm diameter and 0.6 mm thick) were prepared with adhesive solutions of each bonding agents using Teflon molds. The adhesive solutions within the molds were light-activated with XL 3000 curing unit (3M ESPE) for 10 s on both sides. The disks were stored for 10 days and were tested in a universal testing machine (1.27 mm/min - Instron 5844). Data were statistically analyzed by one-way ANOVA (á=0.05). Results: The mean values of fracture strength (±SD) for adhesive systems were (in MPa):B1- 89.7±7.6 e NB- 131.1±9.5. Modulus means (±SD) were (in MPa): B1- 1999.9±258.4 e NB- 2314.5±271.0. Conclusion: The filled adhesive system (NB) exhibited higher strength and flexural modulus means than the unfilled adhesive B1.

Objetivo: O objetivo deste estudo foi avaliar a resistência flexural e o módulo de flexão de dois sistemas adesivos, através de ensaio de resistência flexural biaxial. Metodologia: Os adesivos (Pentron Clinical Technologies) estudados foram: Bond 1 (B1) e NanoBond (NB). Treze discos de cada adesivo foram preparados com dimensões aproximadas de 6,1 mm de diâmetro e 0,6 mm de espessura. Os discos de adesivos foram confeccionados utilizando-se moldes de teflon e fotopolimerizados com aparelho XL 3000 (3M ESPE). Após armazenamento por 10 dias, os discos foram testados em máquina universal de ensaio (Instron 5844), com velocidade de 1,27 mm/min. Os dados foram submetidos à análise de variância (1 fator) ao nível de significância de 0,05. Resultados: Os valores médios (±DP) de resistência flexural para os adesivos foram (em MPa): B1- 89,7±7,6 e NB- 131,1±9,5. Os valores médios de módulo flexural (±DP) foram (em MPa): B1- 1999,9±258,4 e NB- 2314,5±271,0.Conclusão: O adesivo contendo partículas de carga (NB) mostrou maiores valores de resistência flexural e módulo de flexão que o adesivo B1.