After pulp chamber trepanation, rubber dam and disinfection, the main canal and the invagination were instrumented with reamers and Hedstroem files. The canals were constantly irrigated with 0.5 % sodium hypochlorite. At the end of the preparation the canals were irrigated with 17 % neutral EDTA, dried with paper points and filled with calcium hydroxide. The tooth was sealed with zinc oxide eugenol filling.