The purpose of this study was to develop an instrument to measure o based on the model and to report on the psychom testing of the instrument. The findings from qualitative initial items. Construct validity was tested using principal research from Sanandaj, Iran, was used to generate the interdental component analysis to extract factors. Results: Factor analysis yielded 7 factors (28 items) related to for factor, 3 factors related to perceived benefits support Cronbach alpha reliability coefficient ranged from .83 preliminary results provide the instrument to measure decisional balance and self-efficacy of interdental cleaning in Iranian adolescents. Kew words: Dental floss, transtheoretical model, reliability, validity, iranian adolescents