To evaluate the efficacy of three rotary instrumentation systems in removing gutta-percha/sealer and GuttaFlow from root canals and to determine retreatment time.
Sixty palatal roots of extracted first maxillary molars were selected. The samples were prepared with ProTaper Universal and then randomly divided into two groups (n = 30). In groups A and B, the root canals were filled employing lateral compaction of GP/AH Plus and GuttaFlow2, respectively. The samples in each group were randomly divided into three subgroups (n = 10). Groups A1 and B1 were retreated using Reciproc. ProTaper Next was used in groups A2 and B2, whereas groups A3 and B3 were retreated with R-Endo system. Retreatment time was recorded. The roots were split longitudinally and examined under a stereomicroscope and then photographed. The remaining filling material was calculated using Image J software. A two-way analysis of variance (ANOVA) was conducted to examine the effect of three systems in the removal of filling material. Moreover, a Tukey HSD test was used to perform multiple comparisons (α = 0.05).
Removal of GuttaFlow from the canals was easier and faster than that of GP/AH Plus (p < 0.05). Generally, the results revealed that compared to other systems, R-Endo in group A left less filling material inside the canals (p < 0.05). It also required less time to reach working length than the other systems (p < 0.05). One PTN instrument and two Reciproc instruments were fractured during the retreatment procedures.
Based on the findings of this study, none of the systems could completely remove the root filling material from the root canals. However, R-Endo was found to be the most effective instrument in the removal of GP/AH Plus.