[Comparison of remaining obturating material on canal walls using rotary and hand instrumentation techniques for endodontic re-treatment]

ABSTRACT

Inadequate removal of the original obturating material during non-surgical endodontic retreatment may lead to failure of root-canal therapy. The purpose of this in vitro study was to quantify and compare the percentage of root canal area occupied by remaining gutta-percha, employing rotary and hand instrumentation techniques with and without use of chloroform. Ninety extracted single-rooted human teeth were prepared by a passive step-back technique in three different working lengths optimum increased [over-instrumented] and reduced [under-instrumented]. Obturation was performed by a combination of cold lateral and warm vertical compaction methods. The teeth were divided into 3 groups according to the methods used for gutta-percha removal Group A, stainless steel K-type hand files plus chloroform; Group B, rotary Ni-Ti files plus chloroform; and Group C, rotary Ni-Ti files without chloroform. The roots were sectioned longitudinally and the percentage of root canal area occupied by root-filling material was calculated by a digital stereomicroscope in three levels coronal, middle and apical. Data were analyzed by ANOVA. The coronal two-thirds contained larger amounts of filling material in all 3 groups, but the difference was not significant. A significantly smaller amount of gutta-percha/sealer was found in the middle and apical thirds in group C [P<0.05]. The relative percentage of canal area occupied by obturating material was not significantly different among the 3 working-lengths. The use of rotary files without solvent resulted in cleaner canals. However, completely clean root canal walls were not achieved with any of the studied instruments