• Peraya Surapipongpuntr D.D.S., Ph.D.
• Niratcha Chaisomboon B.Sc.
• Thosapol Piyapattamin D.D.S., Ph.D.

Objective To evaluate the efficacy in assisting gutta-percha removal of an essential oil from Citrus
maxima (pomelo oil) and its cytotoxicity on human gingival fibroblasts when compared to orange oil
and xylene.

Materials and methods Forty human single-rooted teeth were instrumented and filled with gutta-percha
at their apical one third. The gutta-percha filled in root canal was softened with each solvent, pomelo
oil, orange oil, xylene or distilled water (n=10 for each group). Gutta-percha was firstly removed with
#25 K-file to reach a working length and then completely removed with Hedström files. The complete
removal was verified by a microscope and a digital radiography. Times required to reach the working
length and to completely remove filled gutta-percha were recorded. For the toxicity test, the clinically
used concentration of three solvents was tested on human gingival fibroblasts using the MTT assay.
Cell viability was determined after exposure to each solvent for 1 s, 10 s and 30 s.

Results The results showed no statistically significant difference in time to reach the working length
or time required to completely remove gutta-percha among three solvents (p > 0.05). All three solvents
were toxic to gingival fibroblasts but xylene was the most cytotoxic solvent in all exposure times.
Pomelo oil was less cytotoxic than orange oil and xylene when the exposure time increased.

Conclusion This study demonstrated the usefulness of the pomelo oil in assisting the removal of
gutta-percha and that it was less toxic to gingival fibroblasts than orange oil and xylene.

(CU Dent J. 2014;37:289-98)