In vitro comparative analysis of 2 mechanical techniques for removing gutta-percha during retreatment.

OBJECTIVE To compare the capacity of a reciprocating system (Endo-Gripper) and a rotary system (Profile .04) for mechanical removal of root-filling material from curved root canals in vitro. MATERIALS AND METHODS Eighty canals (40 mesiobuccal and 40 mesiolingual) from mandibular first molars were instrumented and had their roots filled. After 6 months, 3-dimensional images of the roots were obtained by computed tomography (CT), and the volume of root-filling mass was measured. Root fillings were removed by either the reciprocating system with K-type files or the rotary system with NiTi files. The volume of filling debris remaining after the removal procedures was assessed by CT. The data were analyzed statistically by analysis of variance. RESULTS Neither system completely removed the root-filling material. No significant differences were observed between the reciprocating and rotary systems in terms of the volume of filling material left within the canals after mechanical instrumentation. The volume of filling debris remaining was significantly lower for mesiolingual canals than for mesiobuccal canals. CONCLUSIONS Currently available mechanical systems are unable to completely remove filling material during retreatment. Use of the "threshold" function of the CT software allowed precise outlining of the remnants of filling material and calculation of its volume.