This In-Vitro study was conducted to compare the wasted dentin during separated instrument (SI) removal using two different methods (ultrasonic versus tube technique), and to determine the mechanical strength of the dental root after this procedure. Teeth used in this study (n=40) were all single-rooted. Each tooth was first fixed in a putty silicon base, then an instrument (Protaper 25#) was intentionally separated in middle and apical third of root canal. In group I (n1=20), ultrasonic tips were used to retrieve separated instruments (SIs), while Zumax kit were used in group II (n2=20). A CBCT image were taken for all teeth before and after the removal attempt in each group, and amount of losted dentin during the procedure was compared. All the teeth were prepared for mechanical testing in Testometric machine to measure the required force for root fracture. Statistical analysis was done using PASW Statistic® 18. Results showed that tube technique removed more dentine than ultrasonic tips when SI was in the apical third of root canal, while no statistical difference was found between the two methods when SI was in the middle third. Also fracture resistance declined significantly with tube technique comparing with ultrasonic tips.