The effect of post space preparation on the apical seal of root canal obturated teeth.

The dental literature is contradictory about the quality of the apical seal as it relates to the length of remaining gutta-percha following post-space preparation. The purpose of this study was to compare apical leakage with varying remaining lengths of gutta-percha in an in vitro system. Fifty disarticulated single canal human mandibular premolar teeth were used in five experimental groups. All root canals were prepared 1 mm short of the apical foramen through a size 50 k-file and sequentially flared through a size 70 k-file. Four groups were obturated using gutta-percha with lateral condensation and Roth's 801 Elite Grade root canal sealer. Post-space preparation was accomplished by removing gutta-percha with heated pluggers so that the lengths of the remaining filling varied by increments of one millimeter between 3 and 7 mm. Specimens were covered with enamel paint leaving only the apical foramen exposed. All roots were then submerged in 1 percent methylene blue dye for two weeks, sectioned longitudinally, and measured for depth of dye penetration. No significant difference was found between the 4 and 5 mm groups or between the 6 and 7 mm groups. Significant difference (p less than .05) in leakage did exist between the 3, 4-5, and 6-7 mm groups, showing the least in the latter groups. The best apical seal was obtained when the maximum of 6 mm of gutta-percha remained.