Comparison of the retreatment files in the removal of gutta percha and the evaluation of the defects in the canal walls

Objectives: To evaluate and compare the defects produced on root canal walls during the use of H-files, Pro Taper retreatment files and M-two retreatment files in removal of gutta-percha and also to evaluate the time required for complete removal of gutta-percha. Method: Root canals of 60 single-rooted mandibular premolars were cleaned, shaped, and obturated with gutta-percha and AH plus sealer. The teeth were then randomly divided into four main groups. The group where retreatment was not carried out served as the control group. Gutta-percha was removed in the other three groups using either H-files, ProTaper retreatment files or M-two retreatment files. The roots were sectioned horizontally at 3, 6, and 9mm from the apex with a diamond disc. The root slices were viewed under a stereomicroscope for presence of cracks. Total time required for complete removal of gutta-percha was recorded for each sample. Results: Cracks were observed in all the groups. Total number of cracks present in ProTaper retreatment group, M-two retreatment group, H-files and control group was 44.4%, 35.6%, 13.3% and 4.4% respectively. H-files took significantly more time for removal of gutta-percha when compared with rotary files. Conclusion: Use of rotary Ni-Ti retreatment files leads to increased chances for dentinal defects and cracks. ProTaper retreatment files, though faster than M-two retreatment files or H-files, produced the most number of defects and cracks in the canal walls.