This study was conducted to evaluate the appropriate methods and techniques for retrieval of two different lengths of a separated reused ProTaper Rotary Nickel titanium F2 files from root canal of mandibular premolars. This was followed by evaluation for success of retrieval and number of fragments retrieved within each method, the amount of removed dentin linearly and volumetrically after successful retrieval and the operating time.Eighty mandibular premolars were selected and classified in to two groups, each group comprised 40 samples according to the length of the separated fragments, group A (long fragments) and group B (short fragments). Each group was again classified in to two subgroups, each comprised 20 samples according to the method of retrieval, subgroup I utilized ultrasonic technique and needle-and-wire method whereas, subgroup II utilized ultrasonic technique and chloroform- dipped gutta-percha. The retrieval process was carried out by creating a circumferential staging platform, on the 40 short fragments, using modified Gates Glidden Drills. Then the ultrasonic tip was applied to trephine around the coronal end of all separated 80 fragments till they became loose enough to be retrieved with wire and gutta-percha. All the specimens were placed in rubber molds for pre and post digital radiographs. Dentin thickness was evaluated bucco-lingually and mesio-distally using Digora software. CBCT was used for scanning the samples to measure pre- and post- retrieval canal volume and amount of removed dentin was calculated. All data were collected, tabulated and statistically analyzed.Results of the study showed that both retrieval maneuvers successfully retrieved the separated long and short fragments. A significant reduction in dentin thickness was observed after retrieval of long and short fragments on using both maneuvers. With the long fragments, a significant reduction in the amount of removed dentin was observed with the needle-and-wire maneuver than the chloroform-dipped gutta-percha maneuver. With the short fragments, no significant difference was observed. A significant increase in the canal volume was observed after the retrieval of both long and short fragments with both maneuvers. The chloroform-dipped gutta-percha maneuver showed significant increase in the canal volume than the needle-and-wire maneuver with both fragments on comparing between the percentage of changes in the root canal volume. With long and short fragments, there was a significant increase in the retrieval time on using the chloroform-dipped gutta-percha maneuver and the ultrasonic technique than the needle-and-wire maneuver and the ultrasonic technique. A significant increase in the retrieval time was observed with the short fragments than the long fragments.