Iranian Dental Association Journal of Iranian Dental Association 3060-8201 19 1 2007 06 01 Comparison of remaining obturating material on canal walls using rotary and hand instrumentation techniques for endodontic re-treatment 13 20 EN Jamileh Ghoddusi Pari Ghaziani Shahrzad Nazari Journal Article 2007 08 08 2013 02 25 Comparison of remaining obturating material on canal walls using rotary and hand instrumentation techniques for endodontic re-treatment <u>Dr. J. Ghoddusi</u>*- 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