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

Comparison of remaining obturating material on canal walls using rotary and hand instrumentation techniques for endodontic re-treatment Dr. J. Ghoddusi*- Dr. P. Ghaziani*- Dr. Sh. Nazari** *Associate Professor of Endodontics Dept., Faculty of Dentistry, Mashhad University of Medical Sciences. **Assistant Professor of Endodontics Dept., Faculty of Dentistry, Hamedan University of Medical Sciences. Background and Aim: 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. Materials and Methods: 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. Results: 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.Conclusion: 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. Key words: Rotary instrumentation technique - Re-treatment - Obturating material - Chloroform