Aim of the study: the purpose of this study is to compare the two rotary systems in terms of efficiency and quality of curved root canals instrumentation. Material and methods: to perform this study. 20 molars with fully formed apexes and root canals with curves between 25 and 35 degrees were used. Subsequently. https://www.roneverhart.com/Bob-The-Boxcutter-R1P-Aluminum-Grey/