Effectiveness of four rotary retreatment instruments during root canal retreatment

Abstract

Objectives: The purpose of this in-vitro study was to investigate the residual root canal fillingmaterial after retreatment of root canals using stainless steel hand files, and four nickel- titanium retreatment instruments. Materials and Methods: Seventy five extracted mandibular premolars were instrumented andfilled. The samples were randomly divided into 5 groups (n=15) and retreated using Hedströmfiles, Mtwo R, R-Endo, ProTaper Universal Retreatment, and D-RaCe systems. The roots weredigitally radiographed, then grooved split longitudinally to investigate the area of remainingfilling material. The time of retreatment and the instruments fracture were also recorded. Results: The Hedström files left less filling material than the rotary retreatment instrumentsbut a significant difference was found only in the middle third (p< 0.01). The apical third hadthe most residual gutta-percha and sealer compared to the coronal and middle thirds. Theretreatment time for the D-RaCe and ProTaper Universal Retreatment groups were significantlyshorter than other groups (p< 0.01). Eight Mtwo R files, 2 ProTaper Universal Retreatment filesand 1 R-Endo file were fractured. Conclusions: All groups left residual root canal filling material inside the root canal walls.Nickel-titanium rotary retreatment instruments were faster than Hedström files but had ahigher risk of instruments fracture.