Effectiveness of rotary and hand files in gutta-percha and sealer removal using chloroform or chlorhexidine gel

Abstract

The purpose of this study was to assess in vitro the efficacy of nickel-titanium K3 rotary files and hand files for removal of gutta-percha and sealer from obturated root canals using either chloroform or chlorhexidine as solvents. Sixty extracted single-rooted bovine teeth with straight, large canals were prepared, obtured and randomly assigned to 3 groups (n=20). The teeth were stored at 37 degrees C for 1 month and then the gutta-percha and sealer were removed using different techniques, as follows. Group I: size 3 Gates-Glidden drills plus size 30 hand K-files and Hedström files and chloroform; Group II: K3 NiTi rotary files and chloroform; and Group III: K3 NiTi rotary files and 2% chlorhexidine gel. Radiographs were taken and scanned and the images were digitized. The total area of the canal and the area with remaining obturation material were measured in millimeters using a computed image analysis system (ImageLab). Data were analyzed statistically by one-way ANOVA and Tukey test at 5% significance level. The groups differed statistically (p<0.05) with respect to the average percentage of remaining gutta-percha and sealer, presenting the following sequence of effectiveness (from most to least effective): Group I (15.48%), Group II (28.42%) and Group III (35.96%). The findings of this study showed that, despite the technique used for removal of filling material, none of the retreated canals were completely free of gutta-percha and sealer remnants. The use of stainless steel hand files resulted in a lesser amount of filling debris than the use of nickel-titanium rotary instruments.

The efficacy of two rotary NiTi instruments and H-files to remove gutta-percha from root canals

“…Difference may be attributed to the fact that in that study, the K3® instruments that were used to remove the gutta-percha were three sizes larger than the master apical file, compared to using the same final retreatment K3® instrument size as the master apical file size in the present study. In contrast, Bueno et al (27) found that K3® instruments were less effective in removing filling material from root canal walls than manual instruments in straight root canals. The contrast between the outcome of that previous study and the present study may be explained by use of K-files plus H-files to reach the working length.…”

“…The contrast between the outcome of that previous study and the present study may be explained by use of K-files plus H-files to reach the working length. Also, they stated that the design of the flutes of the H-files facilitates gutta-percha removal (27). Therefore, H-files might be remove gutta-percha in large pieces, leaving remaining material of such a small size.…”

Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

“…Many techniques have been employed for the removal of gutta-percha (GP) in root-filled teeth. These include endodontic hand files combined with heat or chemical solvents 7,19 , engine-driven rotary files 9 , ultrasonic instruments, heat-carrying instruments and lasers 18 . Removal of GP using hand files with or without solvents is time-consuming 10,20,22,26 .…”

Apically extruded debris in filling removal of curved canals using 3 NiTi systems and hand files

“…Endodontic retreatment requires total filling removal to enable the subsequent root canal instrumentation and disinfection (4). However, it is known that filling removal can lead to extrusion of debris and cause periapical inflammation, flare-ups or failure of apical healing (5).…”