Influence of instrument taper on the resistance to fracture of endodontically treated roots.

Objective: The aim was to compare the force required to fracture uninstrumented and instrumented canines and to investigate the root-reinforcing capability of AH Plus sealer.

Study Design: In groups 1-3 (n = 24) canals were instrumented with either GT files, FlexMaster, or stainless steel hand instruments. Twelve teeth from each group were obturated with lateral compaction using gutta-percha and AH Plus.