Comparative evaluation of Citrus limetta peel extract and essential oils as natural solvents for gutta-percha dissolution: An in vitro study

INTRODUCTION

Endodontic retreatment is used to solve problems that have resulted from the failure of the original root canal treatment. The first important step in retreating of a root canal includes taking out the existing gutta-percha (GP) to ensure that the old filling materials have been eliminated and the canal system cleaned and sealed again.^[1] Usually, GP is removed from the root canal using mechanical and chemical methods. Due to their rapid dissolution ability, chloroform and xylene are highly employed chemical solvents.^[2] However, people are worried about their toxicity, possible link to cancer, and effects on the environment, which means safer and compatible alternatives must be developed.^[3,4]

Lately, more people have shown interest in the use of natural plant-based substances for undertaking endodontic tasks. It has been studied whether eucalyptus oil and orange oil can help soften and dissolve GP, thanks to their useful biological properties, good scent, and pleasant taste.^[5,6] As these oils are not toxic and eco-friendly, they are suitable for use in a medical setting.

Citrus limetta, commonly called sweet lime, is a citrus fruit that has limonene, flavonoids, and essential oils on its peel. The great solvent qualities of phytochemicals have made them useful in both pharmaceutical and dental solutions for their ability to prevent and treat infections and inflammation.^[7]

Even though C. limetta peel contains similar chemicals to other citrus-based solvents; endodontic retreatment with its extract has not been studied much yet.

Hence, the current study intends to assess and measure the dissolving capabilities of C. limetta peel extract versus eucalyptus oil, orange oil, and the conventional chemical solvent, chloroform. The purpose of this research is to find a substitute drug that dissolves effectively and does not endanger the body.

MATERIAL AND METHODS

The present in vitro study was designed to compare the efficacy of C. limetta peel extract, eucalyptus oil, and orange oil with chloroform in dissolving GP cones. A total of 60 standardized GP cones (International organization for standardization [ISO] size 40) were selected and randomly divided into four groups (n = 15/group) based on the solvent used.

Procedure for dissolution test

Each GP cone was weighed using a precision digital balance (accuracy ± 0.0001 g), and the initial weight was recorded. The cones were then immersed individually in 1 mL of the respective solvent at 10% concentration^[8] in clean, labeled amber glass vials.^[9] All samples were kept in a thermostatically controlled incubator at 37°C for 5 min to simulate intraoral temperature conditions.^[10]

After the immersion period, the cones were removed using forceps, gently blotted with filter paper for 24 h at room temperature to remove excess solvent, and reweighed immediately [Figure 1]. The amount of GP dissolved was calculated by subtracting the post-immersion weight from the initial weight.^[11]

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Figure 1:

Schematic diagram representing dissolution test methodology. (A) Gutta-percha (GP) cones (B) pre-immersion weight of GP measured (C) immersion of GP into GP solvents at 37°C for 5 min (C1) test tube (C2) GP solvent (C3) GP (D) blotting of GP with filter paper to remove excess solvent (E) post-immersion weight of GP measured and weight difference is calculated.

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RESULTS

The mean amount of GP dissolved by each solvent after 5 min of immersion is presented in Table 1. Among all groups, chloroform (Group I) exhibited the highest dissolution capacity with a mean mass loss of 45.36 ± 1.52 mg. This was followed by eucalyptus oil (Group III) with 38.74 ± 2.10 mg, C. limetta peel extract (Group II) with 34.21 ± 1.93 mg, and orange oil (Group IV) with the lowest dissolution at 31.58 ± 2.27 mg. GP was observed to be softer than before as it gets converted to a-phase.

A statistically significant difference was found among the four groups (P < 0.001) using one-way ANOVA. Post hoc analysis (Tukey’s test) revealed that chloroform was significantly more effective than all natural solvents (P < 0.05). Eucalyptus oil showed significantly higher dissolution than orange oil (P = 0.02), while C. limetta extract exhibited significantly greater solubility than orange oil but was slightly less effective than eucalyptus oil (P = 0.04) [Table 2].

These results suggest that while chloroform remains the most effective solvent, C. limetta peel extract demonstrates promising dissolving ability comparable to that of eucalyptus oil and superior to orange oil.

DISCUSSION

To properly disinfect and reshape the root canal, all GP must be removed during retreatment. It has been customary to use chloroform as the preferred chemical for GP dissolution because of how well it works and its fast action.^[1] Still, because it is documented to be toxic to cells, volatile, and possibly cancerous, more studies on safer alternatives are required.^[2,3]

The amount of GP dissolved by C. limetta peel extract was assessed and measured against that of eucalyptus oil, orange oil, and chloroform. The dissolution of chloroform was proven to be greatest, which coincides with previous reports.^[4,5] Eucalyptus oil worked best out of all the natural solvents used, and C. limetta peel extract and orange oil came in after that. Research done in the past also reveals that eucalyptus oil works better than other essential oils because of its rich eucalyptol, which is able to disperse putty-like filling materials in the mouth.

The first test of C. limetta peel extract found that it has good dissolving properties. The peels of many citrus fruits, for example, C. limetta, have a lot of d-limonene, a chemical used for cleaning and in medicine and dental medicines.^[12] Even though d-limonene is slower in softening GP than chloroform, it does it effectively.^[13] It has been suggested that the presence of limonene and flavonoids in large amounts in C. limetta extract makes it respond similarly to eucalyptus oil by weakening the GP.^[14,15]

Even though orange oil is natural and safe for humans, it dissolved less than the other tested solvents.^[16,17] The reason its efficiency may be weaker is because of differences in limonene, and it could also be due to having extra non-polar substances that weaken the solvent’s action.^[18]

According to the results, C. limetta peel extract and eucalyptus oil are useful options for endodontic retreatment. Because they are safe, accepted well within the body, and environmentally sustainable, clinicians can choose these as replacements for routine synthetic solvents. Nonetheless, it is necessary to see that what happens in the laboratory may not relate directly to outcomes in patients. Examples of such influences include solvents reaching into root canals, liaisons between endodontic sealers and various materials, and both debris and moisture in the canals.^[19-21]

Researchers should explore more about the toxicity, the ability to kill bacteria, and the long-term traits of these natural solvents when they contact dentin and periapical tissues. The effectiveness and usefulness of C. limetta extract might also rise with proper concentration and formulation.

CONCLUSION

According to the present study, chloroform does the best job of dissolving GP, but eucalyptus oil and C. limetta peel extract can be a promising and effective natural alternative. Being both biocompatible and naturally sourced, eucalyptus oil and C. limetta extract might be a good alternative when doing endodontic retreatment, calling for more studies.