Coronal leakage along apical root fillings after immediate and delayed post space preparation

The seal provided by a full-length root canal filling may be compromised by post space preparation. Eighty human mandibular premolars each with a sing le canal were obturated with laterally condensed gutta-percha cones and a s ealer. Immediate post space preparation was carried out on half the number of teeth and delayed post space preparation on the remaining 40 teeth. Leak age along the apical root fillings was determined using a fluid transport d evice under a head space pressure of 30 kPa (0.3 atm). More leakage was fou nd after delayed preparation than after immediate preparation (P=0.0059).