The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments(Profile, ProTaper and K³) and a hand instrument(Hedstrom file) used to remove these materials.

The results of this study were as follows:

In the total time for gutta-percha removal, Profile group was the fastest and followed by K³, Protaper, Hedstrom file group.

These results showed that instrumentation using nickel-titanium rotary instrument groups was faster than that using hand instrument group. The effect of gutta-percha removal using Profile group was better than that using Protaper and K³ group in the nickel-titanium rotary instrument groups.

The purpose of this study was to investigate the quantity of debris which was extruded apically after canal instrumentation using different types of enlarging instrument in endodontic resin models.

Five groups of 9 endodontic resin models were instrumented using each different technique: hand instrumentation without early coronal flaring, hand instrumentation after early coronal flaring, and three nickel-titanium engine-driven instrumentations (Hero 642, Protaper, K³). Debris extruded from apical foramen during instrumentation was collected on preweighed CBC bottle, desiccated and weighted using electronic balance. The results were analyzed using Kruskal-wallis test and Mann-Whitney U rank sum test at a significance level of 0.05.

The results were as follows:

All of instrumentation techniques produced apically extruded debris.

The early coronal flaring is very important to reduce the amount of debris extruded apically.