Effects of different platform preparation and retrieval techniques on broken file removal and fracture strength

The aim was to evaluate the effects of different strategies on broken instrument removal and root fracture strength. After canal preparation of anterior single-rooted teeth, the samples were divided into one control group (n = 10) and six experimental groups (n = 15). A #25/.06 rotary file was broken at a length of 4 mm in the middle-third canal region in the experimental groups, and no instrument fractures were created in the control group. Access to the instrument was achieved with Gates-Glidden (GG) burs or ultrasonic tips. Dentin around the instrument was removed to create partial or full platforms. Finally, the instruments were removed with ultrasonic tips or a BTR Pen. The effectiveness of broken instrument removal, the duration of removal, and any complications that occurred were recorded. All the root canals were obturated. Fracture strength analysis was performed using a universal testing machine. Statistical analysis was performed using the Kruskal-Wallis and Dunn tests (p < 0.05). All broken instruments were successfully removed. The access time to the broken instrument in the groups using GG burs was shorter than that in the groups using ultrasonic tips (p < 0.05), while there was no significant difference between the groups in terms of total removal time (p > 0.05). The fracture strength of the control group was similar to that of the group in which ultrasonic tips were used to access the broken instrument and to create a full platform, and the BTR Pen was used for the removal of the broken instrument (p > 0.05), but showed higher fracture strength than that of the other experimental groups (p < 0.05). Different strategies used in the removal of broken instruments affected access time and root fracture strength.