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

OBJECTIVE: To evaluate eff ect of the morphology of simulated S-shaped root canals with Reciproc or Mtwo instruments on root canal irrigation. METHODS: 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. RESULTS: 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<0.05]. The vapor lock length in the Reciproc group was significantly longer than that in the Mtwo group [(4.472 +/- 0.230) mm vs (3.668 +/- 0.217) mm, P<0.05]. The time to remove vapor lock was significantly shorter in the Reciproc group than that in the Mtwo group [(10.13 +/- 1.79) s vs (15.29 +/- 2.15) s, P<0.05]. The length of stagnant water was also shorter in the Reciproc group than that in the Mtwo group [(1.351 +/- 0.142) mm vs (2.245 +/- 0.206) mm, P<0.05]. CONCLUSION: The morphology of S-shaped root canal affects the root canal irrigation. The effect of root canal irrigated by Reciproc is better than that by Mtwo.