Objectives: this study was carried to evaluate the invivo bond degradation resistance of light and dual cure NanoBond adhesive system by assessing the nanoleakage of class II resin composite restoration with and without etching, and interfacial analysis using ESEM and to investigate whether the curing mode and pre-etching could affect microtensile bond strength at 24 hours and after 3 monthes.Methods: Standardized class II cavities were prepared in 80 premolars of 20 patients. Dual and light cured NanoBond self etch adhesive was applied with and without pre-treatment. Then, teeth were extracted as part of orthodontic treatment according to testing periods. Sticks of 1mm2cross section were prepared for testing both microtensile bond strength and nanoleakage evaluation. The results were presented as mean and SD values; repeated measures anova followed by Mann-Whitney test were used to analyze the results.Results: the results showed that there was significant different in both microtenile bond strength and nanoleakage evaluation between light and dual cure NanoBond adhesive systems. While, there was no significant difference when using pre-etch treatment when using light cure but there was a significant difference when using dual cure. In time evaluation, there wasn’t a significant difference.Conclusion: The NanoBond adhesive system either light or dual cure showed high microtensile bond strength and lowest bond degradation when used according to manufactures instruction.