In vitro the effect of apical stop on the filling material extrusion during root canal treatment

Objective:To investigate the effect of apical stop which had been created by enlarging the root canal to three sizes greater than that of the first file binding at the working length on the material extrusion.Method: Eighty maxillary and mandibular caines with single straight canals were choosen. Forth were instrumented to 1mm short of the apical foramen through step-back technique with apical stop created. The other forty teeth were prepared to the apical foramen through the serial shaping technique with no apical stop. All the canals with and all the canals without apical stop were randomly divided into two groups with twenty canals each and were obturated with cold lateral and vertical warm condensation technique, respectively. The number of teeth with gutta-percha extrusion and the weights of extruded material including gutta-percha and sealer were all recorded. Then, the results were analyzed statistically.Result: During the extrusion tests, no significant difference was found between canals prepared with and canals prepared without the apical matrix creation procedure in two lateral condensation or vertical condensation groups.Conclusion: The procedure to enlarge root canals to 3 sizes greater than that of the first binding file will not always reduce the amount of filling materials extruded.