The patient was anaesthetised and the access cavity was prepared. Four canals were found and the rubber dam was placed. The working length was obtained with the help of an apex locator. MB and ML canals were 23 mm and distal canals 22 mm. The canals were instrumented with small K-files and FlexoFiles to size #20. The canals were continuously irrigated with 1% sodium hypochlorite and 17 % EDTA. The canals were then prepared with the ProTaper rotary system at 300 rpm using the following sequence: S1, S2, F1, and F2. Finally, the apical canals were enlarged to size #45 mesially and #50 distally by manual preparation with NiTiFlex instruments using the balanced force technique.

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