• grapefruit oil;
  • gutta-percha solvent;
  • lemon oil;
  • lime oil;
  • tangerine oil



In the present study, we evaluate the efficiency of four kinds of oil as solvents for softening gutta-percha in root canal retreatment procedures. The performance of grapefruit, tangerine, lime, and lemon oils specifically were evaluated and compared to chloroform.


Eighty-four cylinder-shaped glass tubes (5 × 30 mm) were filled with gutta-percha. A total of 0.1 mL solvent was added to the upper part of the glass tubes. After 5 min, the spreader attached to the universal testing machine was moved downward through gutta-percha with header speed of 5 mm/min into a depth of 5 mm. An initial depth of spreader penetration without force produced was recorded in millimeters. The load used to penetrate the spreader into the 5-mm depth was recorded in Newton.


The results of the surface-dissolving depth and maximum force used to penetrate the spreader to 5 mm revealed that chloroform was significantly the best solvent in softening gutta-percha (< 0.05), followed by grapefruit oil and tangerine oil, while the least effective solvents were lime oil and lemon oil.


Under the conditions of the present study, grapefruit oil and tangerine oil performed best as gutta-perch solvents among four natural oils.