Efficacy of two rotary niti instruments in the removal of gutta-percha during root canal retreatment. An in vitro study.

Abstract

The aim of this study was to evaluate the efficacy of two rotary NiTi instruments, ProTaper and K3, in the removal of gutta-percha during root canal retreatment in comparison with hand instruments using Hedstrom files. Retreatment time and amount of apically extruded debris were also recorded and evaluated. Sixty extracted single-rooted anterior teeth and premolars were instrumented to size # 40 and obturated with laterally condensed gutta-percha using AH-26 sealer cement. The teeth were randomly divided into three groups, 20 teeth each. Removal of gutta-percha was performed with chloroform and one of the following techniques; (I) Hedstrom files, (II) ProTaper, and (III) K3. The roots were split longitudinally and digitized using scanner. The area of the whole canal, the area of each third, and the area of remaining filling materials in the whole canal and in each third were traced using Ulead Photoimpact7 then calculated using SigmaScan software. The remaining filling materials were expressed in percentage. The results indicated that the two rotary NiTi instruments left significantly less remaining materials (P < 0.0001) compared to Hedstrom files while there was no significant difference between the two rotary instruments. In all groups the apical thirds showed the highest ratio of remaining materials compared to middle and coronal thirds. The retreatment time was significantly less (P < 0.0001) when the two rotary NiTi instruments were used compared to hand. There was no statistically significant difference (P = 0.159) found between the three techniques regarding the amount of apically extruded debris. In conclusion, the two rotary NiTi instruments, ProTaper and K3 were found to be effective