Hydroalcoholic Extract of Eugenia uniflora as Denture Disinfectant: Antimicrobial Activity and Effect on the Physical Properties of Polymethylmethacrylate

Abstract To the moment, there is no ideal substance for home-based denture disinfection. This study assessed in vitro the antimicrobial effect of the hydroalcoholic extract of Eugenia uniflora and the effect on the physical properties of denture polymethylmethacrylate (PMMA). Candida albicans, Staphylococcus aureus, and Klebsiella oxytoca were isolated from samples of saliva collected from denture wearers. The extracts were produced in three concentrations, according to the Brazilian Pharmacopeia. One hundred eighty-eight disc-shaped specimens of thermopolymerizable PMMA were prepared and randomly allocated to five treatment groups: sterile saline solution (0.85%; control); chlorhexidine digluconate (0.2%); and hydroalcoholic extract of E. uniflora (0.2%, 0.8%, and 1.16%). The specimens were disinfected for 8 hours/day for 30 days. Adherence of microorganisms to the surface, PMMA surface roughness, and color stability were assessed. Inferential statistics were performed with one- and two-way ANOVA/Tukey test, and Kruskal Wallis, Mann-Whitney U, and paired t-tests, at α=0.05. The extract of E. uniflora at 0.2% and 1.16% reduced the microbial load of K. oxytoca, while chlorhexidine digluconate significantly reduced microbial load of all microrganisms. Microbial adherence at day 10 was reduced by all experimental substances (p<0.001). Surface roughness was not affected by the disinfecting substances (p>0.05). Nevertheless, all experimental groups produced unacceptable color change at the end of the disinfection protocol (p<0.001). The non-adherent potential against microorganisms isolated from the oral cavity confirm the potential of use of the hydroalcoholic extract of E. uniflora as a denture disinfectant. Yet, unacceptable color changes may occur, regardless of extract concentration.

Denture disinfection using Salvia officinalis L: microbial load and selected properties of PMMA

Denture use may aggravate the occurrence of oral infections, considering it enhances microbial adherence. Aim: This study assessed the reduction of microbial loads of Candida albicans, Staphylococcus aureus, and Klebsiella oxytoca by disinfecting the polymethylmethacrylate (PMMA) of complete dentures with hydroalcoholic extract of Salvia officinalis. Additionally, the effect of such extract on the properties of PMMA was examined. Methods: Microorganisms were isolated from saliva samples collected from complete denture wearers. The hydroalcoholic extract of S. officinalis was produced according to the Brazilian Pharmacopoeia 5. The PMMA specimens (n=188) were immersed in microbial inoculum and incubated at 37°C for 16 hours per day. Then, they were subjected to a disinfection protocol for 30 days. The specimens were divided into five treatment groups: sterile saline solution (0.85%; control), 0.2% chlorhexidine digluconate, and hydroalcoholic extract of S. officinalis (0.2%, 0.8%, and 1.16%). Microorganism adherence to the PMMA surface was also assessed, as well as surface roughness (Ra in µm) and color stability of the PMMA (mean ΔE). Changes in microbial load and surface roughness after the disinfection protocol were verified with paired t-test. Substances at day 10, adherence, and color stability were compared by the Kruskall-Wallis and Mann-Whitney tests, and one-way ANOVA was used to compare substances at the beginning and end of the experiment (α=0.05). Results: The 1.16% S. officinalis extract significantly reduced the microbial load of all the microorganisms after 30 days of disinfection (p<0.05). The microbial load of K. oxytoca was also reduced at lower concentrations of the S. officinalis extract (0.2% and 0.8%) (p<0.02). Antimicrobial and anti-adherent effects against microorganisms isolated from the oral cavity were observed. There was no significant change in surface roughness (p>0.05) and color stability was significantly higher in the control group (p<0.0001). Conclusions: The hydroalcoholic extract of S. officinalis may be used as a disinfectant solution for dentures

Antifungal activity of natural compounds against Candida species isolated from HIV-positive patients

Objective: To evaluate the antifungal effect of Cinnamomum zeylanicum (C. zeylanicum) and Melaleuca alternifolia essential oils and honey against strains of Candida sp. from HIV-positive patients in order to subsidize new therapeutic strategies for candidiasis. METHODS: The study evaluated the antifungal effect of natural antimicrobials against 30 strains of Candida sp. isolated from oral cavities in HIV-infected patients. Then, they were compared to the action of fluconazole and amphotericin B. Antifungal susceptibility was evaluated by the broth macrodilution technique and the minimum inhibitory concentration and the minimum fungicidal concentration were determined. RESULTS: Among all antifungals evaluated in this study, amphotericin B was the one showing the best results; however, all compounds studied here showed inhibitory activities against isolates of Candida sp. Honey (0.0313-64 μg/mL) demonstrated fungistatic activity inhibiting 70% of the isolates. C. zeylanicum essential oil (0.0313-64 μg/mL) inhibited 93.3% of the Candida strains and Melaleuca alternifolia essential oil (0.0313-64 μg/mL) was able to inhibit 73.3% of them. CONCLUSIONS: Therefore, all natural compounds evaluated in this study, especially C. zeylanicum essential oil, may become promising agents for oral candidiasis therapy including in HIV-positive patients.