A comparative study of the softening abilities of three gutta-percha solvents used during endodontic retreatment

Background: The chemomechanical removal of gutta-percha involves the use of solvents, which serve as an adjunct to mechanical instrumentation during Root Canal Treatment (RCT). The most commonly used solvents for softening gutta-percha are Chloroform and Eucalyptol. Due to some unfavourable properties, their usage in the dental setting is debatable. D-limonene is an essential oil which has fewer undesirable properties when utilised as a gutta-percha solvent. Objective: This study sought to determine whether D-Limonene had comparable gutta-percha softening properties with Eucalyptol and Chloroform. Methods: This study was a prospective comparative study. Extracted single-rooted teeth were root-treated using the rotary ProTaper system and stored in normal saline for three months. The teeth were randomly assigned to the three solvent groups, and root-filling removal was performed using K-files and solvents. The median initial penetration depth of the K-file into the softened gutta-percha, the median amounts of additional drops of solvent used, and the median of the total time used to remove all the gutta-percha obturating material from the root canal were statistically evaluated for each of the solvents. The Kruskal-Wallis test was used to compare the medians with the statistical significance set at p < 0.05. Results: D-Limonene utilised the least number of additional drops of solvent (p < 0.001) during the gutta-percha removal process, while chloroform utilised the greatest number of additional drops of solvent. There was no statistical difference between the three solvents in the initial penetration depth of the K-file into the gutta-percha and the total time it took to completely remove all gutta-percha from the root canals. Conclusion: Smaller volumes of D-Limonene produced comparable results as Eucalyptol and Chloroform in the softening and removal of gutta-percha during re-endodontic treatment.