Mechanical properties of dental tissue conditioner containing lemongrass essential oil

Statement of problem

Overcoming compromised oral hygiene and susceptibility to opportunistic oropharyngeal candidal infections in patients with a maxillectomy are critical challenges. Tissue conditioners incorporated with lemongrass essential oil has been shown to have promising antifungal properties, but the effects of this incorporation on the mechanical properties of tissue conditioners remain unexplored.

Purpose

The purpose of this in vitro study was to assess the effects of lemongrass essential oil incorporation at various concentrations on the tensile bond strength (TBS) and Shore A hardness (SAH) of tissue conditioners. The presence of lemongrass essential oil in the tissue conditioner was evaluated by using Raman spectroscopy.

Material and methods

Unmodified tissue conditioner served as the control, whereas tissue conditioner incorporated with lemongrass essential oil (final concentrations of 1.77%, 3.56%, and 7.17% [w/w]) and tissue conditioner incorporated with Nystatin served as the experimental groups. The SAH of Coe-Comfort specimens was measured at 2 hours, 24 hours, 7 days, and 30 days for each testing group (n=3/group). The TBS of tissue conditioner to denture base acrylic resin was determined by using a universal testing machine at a crosshead speed of 10 mm/minute (n=10/group). Furthermore, Raman spectra for the control and experimental tissue conditioner groups were obtained at 24 hours and 14 days. The data were analyzed with 2-way repeated measures ANOVA followed by the post hoc Bonferroni multiple comparison test for SAH testing and the 1-way ANOVA followed by the post hoc Tukey HSD multiple comparison test for TBS testing (α=.05).

Results

The unmodified tissue conditioner, 1.77% (w/w) lemongrass essential oil incorporated tissue conditioner, and Nystatin incorporated tissue conditioner showed no significant difference in SAH at ≤7 days (P>.05). However, at 30 days, the 1.77% (w/w) lemongrass essential oil and Nystatin groups showed no significant difference in SAH (P=.136), but both groups had significantly lower SAH compared with the control group (P=.016 and P<.001, respectively). The incorporation of 1.77% (w/w) lemongrass essential oil in tissue conditioners had no significant effect on TBS compared with the control group (P=.184), although both possessed significantly higher TBS than all remaining groups. In contrast, tissue conditioner incorporated with lemongrass essential oil concentrations ≥3.56% (w/w) and Nystatin showed a statistically significant decrease in TBS (P<.001). Raman spectrum analysis confirmed the presence of citral bands in the lemongrass essential oil incorporated specimens at 2 hours and 14 days, verifying its long-lasting presence.

Conclusions

Incorporation of lemongrass essential oil in tissue conditioners at 1.77% (w/w) concentration produced both long-lasting antifungal properties and acceptable mechanical properties (SAH and TBS).