Effect of the morphology of S-shaped root canals with reciprocating single file system on root canal irrigation

To evaluate eff ect of the morphology of simulated S-shaped root canals with Reciproc or Mtwo instruments on root canal irrigation. A total of 40 simulated S-shaped resin blocks were randomly divided into 2 groups (n=20), which was prepared by Reciproc or Mtwo. Blue ink was injected with constant speed and volume into the canals using 30G lateral opening syringe. Th e distance from needle tip to apex and vapor lock length were measured. A type of 25# 0.04 gutt a-percha point was used to stir and remove the vapor lock. Th e time for removal of the vapor lock was recorded. Another syringe was used to inject saline into the canals and to measure the length of stagnant water. The distance from needle tip to apex in the Reciproc group was significantly longer than that in the Mtwo group [(4.276 ± 0.221) mm vs (3.459 ± 0.205) mm, P