An in vitro experiment on the effect of an attempt to create an apical matrix during root canal preparation on coronal leakage and material extrusion

Objective, A common approach to creating an apical matrix (apical stop) in the apical dentin is to enlarge the root canal to 3 sizes greater than that of the first rile that binds at the working length. The aim of this study was to test the hypothesis that this procedure will reduce the amount of material extruded and the leakage along the apical root fillings. Study design. The canals of half of 120 maxillary and mandibular canines were prepared to the apical foramen through use of the serial shaping technique; the apical matrix creation procedure was not used. Each of the other 60 canals was prepared to 1 mm short of the apical foramen, and the canal was enlarged to at least 3 sizes greater than that of the first binding file to create an apical matrix. All the canals prepared with and all the canals prepared without the apical matrix creation procedure were obturated with laterally or vertically compacted cold or warm gutta-percha. In the leakage test, after post space preparation, the amount of fluid transport along the apical root fillings was measured. In the material extrusion test, the number of teeth with gutta-percha extrusion was recorded and the weight of the apically extruded materials was measured. Results, In both the leakage and the extrusion tests, no significant difference was found between canals prepared with and canals prepared without the apical matrix creation procedure. Conclusion, The hypothesis that a procedure to enlarge root canals to 3 sizes greater than that of the first binding file will reduce the amount of filling materials extruded and the leakage was not proved, as our results show.