Efetividade de dissolução da guta-percha e segurança do uso de óleos essenciais dos gêneros Citrus e Cymbopogon

Abstract

In cases of endodontic failure, the preferential therapy should be non-surgical endodontic retreatment. For this procedure, it is necessary to remove the filling material from the root canals, and the use of chemical solvents is indicated to assist in the procedure. However, these substances generally have high toxicity and do not fulfill the requirements of an ideal solvent. Thus, essential oils have been sought to find substances with good gutta-percha dissolution activity, satisfactory antimicrobial activity against pathogens associated with cases of endodontic failure, greater biocompatibility, less tissue toxicity, and that generate less environmental impact. Therefore, this study aimed to assess the efficacy and safety of essential oils belonging to the Citrus and Cymbopogon genus as an alternative to conventional endodontic solvents. It investigated the solvent capacity and the biological activity in this work the inheritance in gutta-percha was evaluated, the biological heirs and the safety of six essential oils were measured; three Citrus (1-Citrus paradisi, 2-Citrus limon and 3-Citrus sinensis) and three Cymbopogon (4-Cymbopogon martinii, 5-Cymbopogon nardus and 6-Cymbopogon shoenanthus) and three controls (eucalyptol, endossolv® E, and chloroform). Gas chromatography/mass spectrometry gave the chemical profile of the essential oils, disintegration tests assessed the oils effectivity on gutta-percha removal, and scanning electron microscopy evaluated the durability by penetration and the guttapercha's surface. Moreover, the biological assessments included: a) antimicrobial analysis through the turbidimetric analysis against Enterococcus faecalis (ATCC 51299) and Candida albicans (ATCC 10231); b) antioxidant activity using the method of sequestration of reactive oxygen species; c) cell toxicity on L929 fibroblasts through 3-(4,5-dimethyl2thiazolyI)-2,5-diphenyl-2Htetrazolium (MTT) assay. For the genus Citrus, D-limonene was the major compound for all oils. As for the genus Cymbopogon, the major components were geraniol, citronellol and citral for oils 4, 5 and 6, respectively. Oils 1 and 3 showed excellent effectiveness in removing gutta-percha, being more effective than control 1 (eucalyptol) and statistically similar to control 2 (endosolv® E) in the penetration hardness test. In the disintegration test, the most effective was oil 3, being superior to C1 and equal to C2. In surface analysis (SEM), it was possible to observe the changes caused by oil 3. All oils showed bacteriostatic activity against Enterococcus faecalis ATCC 51299, with oil 3 showing the highest inhibition rate. Only oils 1, 3 and 6 showed fungicidal action against Candida albicans ATCC 10231, and no control was able to inhibit the growth of this strain. All oils showed greater antioxidant activity than the controls, with the highest activity shown by oil 6, followed by oil 3. Oils 1-3 and 5-6 did not demonstrate cytotoxicity for murine fibroblasts at a concentration of 7.81 µg/mL. By the joint analysis of the results, it is concluded that oil 3 (Citrus sinensis) seems to be a natural, viable and safe alternative when compared to conventional endodontic solvents, since it presents chemical compounds with effective capacity of dissolving gutta percha, in addition, it exhibited desirable complementary activities such as antimicrobial, antioxidant, and low cytotoxicity.