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).

Fungicidal and inhibitory efficacy of cinnamon and lemongrass essential oils on Candida albicans biofilm established on acrylic resin: An in vitro study.

STATEMENT OF PROBLEM: It is unclear whether cinnamon and lemongrass essential oils can effectively reduce the Candida-biofilm frequently formed on dental devices made from heat-polymerized polymethyl methacrylate (PMMA) resin that contributes to the development of mild oropharyngeal as well as life-threatening candidiasis in patients wearing the devices. PURPOSE: The purpose of this in vitro study was to determine the efficacy of cinnamon and lemongrass essential oils in eradicating Candida albicans biofilm on heat-polymerized PMMA specimens and to determine whether they retard the formation of fungal biofilm. MATERIAL AND METHODS: The antifungal effect of cinnamon and lemongrass essential oils was determined by using agar disk diffusion and broth microdilution methods to obtain minimum inhibitory concentrations. The mature C albicans biofilm (48 hours) was pre-established on PMMA specimens before being individually treated with various concentrations (½, 1, 2, 4, 8, 16 times minimum inhibitory concentration) of each tested oil for different exposure times (1, 2, 4, 8, and 24 hours). In another experiment, fungal biofilm was established on the PMMA specimens that were primed individually with various concentrations of the tested oils for different times. The 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT)-reduction assay was used to quantitate biofilm viability in both experiments. Statistical analysis was performed by using the 1-sample Kolmogorov-Smirnov test and 2-way ANOVA followed by the Tukey multiple comparison test (α=.05). RESULTS: Minimum inhibitory concentration values of cinnamon and lemongrass essential oils against planktonic C albicans were 0.1 µL/mL (0.01% v/v) and 0.4 µL/mL (0.04% v/v). At 8 times the minimum inhibitory concentration, cinnamon oil (0.8 µL/mL or 0.08% v/v) and lemongrass oil (3.2 µL/mL or 0.32% v/v) eradicated the pre-established fungal biofilm by 99.0% in an exposure time of 1 hour. In contrast, high concentrations of 8 and 16 times the minimum inhibitory concentration of cinnamon oil (0.8 µL/mL or 0.08% v/v) and lemongrass oil (6.4 µL/mL or 0.64% v/v) coated on PMMA specimens for 24 hours were only able to inhibit the formation of fungal biofilm by approximately 70.0%. CONCLUSIONS: Cinnamon and lemongrass essential oils can eliminate pre-established C albicans biofilm and restrain the formation of fungal biofilm on heat-polymerized PMMA specimens. Both effects of the tested essential oils depended on dose and exposure or priming time.

Lemongrass-Incorporated Tissue Conditioner with Adjustable Inhibitory Effect Against Candida albicans: An In Vitro Study.

PURPOSE: To develop and assess lemongrass-incorporated tissue conditioners (LG-TCs) with a potent and long-lasting inhibitory effect against Candida albicans cultures to control the accumulation of fungi. MATERIALS AND METHODS: LG essential oil with concentrations of 7.17%, 3.56%, 1.77%, and 0.89% (w/w) or nystatin were mixed with the liquid part of the TC before being added to the powder part to form 486 TC samples of 6-mm diameter x 2-mm thickness (n = 81 samples for each group of LG-/nystatin-incorporated or unmodified TCs). After being immersed in 37°C water for 1, 2, 3, 5, 7, 9, 12, or 14 days, these TC samples were removed, blotted with sterile filter paper, and then exposed to fungal suspension (1 × 105 CFU/mL). The TC samples were evaluated for their capacity to inhibit fungal growth by 99.9%. RESULTS: The anti-Candida effect of the unmodified TCs was reduced significantly after the samples were immersed in water. Interestingly, a long-lasting anti-Candida effect was observed in the TCs incorporated with LG essential oil. After being immersed in water for at least 14 days, the TCs with 1.77% LG oil were still able to inhibit fungal growth substantially. In contrast, a shorter-lasting (5 days) anti-Candida effect was found in the TCs with 0.89% (w/w) LG oil. Additionally, the TCs incorporated with LG oil at concentrations of 3.56% (w/w) or more inhibited the growth of the fungus by 99.99%, and its anti-Candida effect lasted for 14 days. CONCLUSION: LG-TCs showed an impressive and long-lasting inhibitory effect against C. albicans.

Antimicrobial Properties of Ocimum Species: An In Vitro Study.

Objective: This study aimed to determine the antimicrobial activity of ethanol-extracts obtained from Ocimum gratissimum L. (clove or African basil, Lamiaceae) and O. santum L. (holy basil) against some microorganisms present in oral cavity related to either medical or dental disease. Materials and Methods: Antimicrobial properties of both ethanol-extracts of Ocimum species against Streptococcus mutans KPSK2, S. pyogenes ATCC 19615, Staphylococcus aureus ATCC 16794, and Candida albicans ATCC 10231 were primarily determined by agar disk diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal or fungicidal concentration (MBC or MFC) of these herbal extracts were further determined by broth micro-dilution method. Results: Ethanol-extracts of O. sanctum L. and O. gratissimum L. inhibited the growth of all tested microorganisms in various degrees ranging from the strongest antimicrobial activity of O. sanctum against S. pyogenes [MIC at 0.19% (w/v); MBC at 0.78% (w/v)] to the least inhibitory activity of O. gratissimum against C. albicans [MIC at 12.5% (w/v); undetectable MFC]. The ethanol-extract of O. sanctum showed stronger antimicrobial property against the tested bacteria and fungus than O. gratissimum. The ethanol-extracts of both Ocimum species showed stronger antibacterial than antifungal activity. However, the ethanol-extract of O. gratissimum even at a high concentration of 50% (w/v) was unable to eliminate the tested fungus. Conclusion: Ethanol-extracts of Ocimum species contain effective antibacterial and antifungal properties that may be beneficial for further development of antimicrobial agents in medical and dental fields.

In Vitro Anti-Cariogenic Plaque Effects of Essential Oils Extracted from Culinary Herbs.

INTRODUCTION: Cariogenic bacteria including mutans streptococci and lactobacilli are partly but significantly involved in dental caries development. An effective prevention strategy against dental caries is to decrease the accumulation of this microbiota either in planktonic or in biofilm form. AIM: To examine the antimicrobial and anti-plaque effects of some culinary herbs (spices), so the herbs are plausibly used as alternative and effective herbal plaque control supplements to promote good oral health. MATERIALS AND METHODS: Essential oils extracted from sweet basil (Ocimum basilicum), cinnamon bark (Cinnamomum zeylanicum), sweet fennel (Foeniculum vulgare), kaffir lime (Citrus hystrix), black pepper (Piper nigrum), peppermint (Mentha piperita), and spearmint (Mentha spicata) were primarily examined for their antimicrobial activities against the cariogenic bacteria (Streptococcus mutans KPSK2 and Lactobacillus casei) using the agar disk diffusion and broth microdilution methods, respectively. These essential oils were then analysed for anti-plaque effects (retardation of S. mutans biofilm formation and reduction of the in vitro established biofilm). This experimental study was performed at the Department of Oral Microbiology, Faculty of Dentistry, Mahidol University during June 2015 till August 2016. RESULTS: All selected essential oils showed different degrees of antimicrobial activity against the planktonic form of both cariogenic bacteria. Cinnamon bark essential oil expressed the strongest inhibitory effect against S. mutans {MIC of 0.08% (v/v)} and L. casei {MIC of 0.16% (v/v)}, whereas the weakest effect was found in kaffir lime essential oil {MIC values of 2.5% and 5.0% (v/v) for S. mutans and L. casei, respectively}. Up to 80% of S. mutans biofilm was retarded to form on the substratum primed with these spice essential oils, especially cinnamon oil. The preventive effect of these oils was in dose- and exposure time-dependent manners. For reductive effect against the 24-hour pre-established S. mutans biofilm, at least 50% of the biofilm mass was reduced when the biofilm was treated with each essential oil at the MIC for an hour. The reductive effect against the in vitro established S. mutans biofilm of these culinary herb essential oils only depended on the exposure time. CONCLUSION: Cinnamon and sweet basil essential oils with impressive in vitro anti-cariogenic bacteria and anti-plaque effects may be proposed as alternative and effective supplements to promote oral health status.

Effects of sonicated Prevotella intermedia, Fusobacterium nucleatum and Lactobacillus casei extracts on interleukin-8 production by human dental pulp cells.

The objective of this study was to determine the effects of Prevotella intermedia, Fusobacterium nucleatum and Lactobacillus casei on the production of IL-8 by human dental pulp cells. Human dental pulp cells from teeth of young patients (aged 18-25 years) were cultured and tested with sonicated P. intermedia ATCC 25611, F. nucleatum ATCC 25586 and L. casei ATCC 4646 extracts. IL-8 secreted into the culture supernatants were measured at 6, 12 and 24 hours using a quantitative sandwich enzyme immunoassay technique. Cell viability was evaluated using trypan blue exclusion technique. IL-8 production by human dental pulp cells increased significantly at 12 and 24 hours after exposure to P. intermedia and F. nucleatum, whereas L. casei extract exhibited low IL-8 production. The sonicated bacterial extracts did not significantly affect viability or total number of dental pulp cells.

Induction of type I collagen and osteocalcin in human dental pulp cells by retinoic acid.

Retinoic acid has been known to play a key role in the regulation of bone cell differentiation and function. The effects of retinoic acid on human dental pulp cells, which contain several characteristics similar to those of bone cells, has yet to be elucidated extensively. The effects of retinoic acid on human dental pulp cells in terms of type I collagen and osteocalcin induction were investigated in vitro. Dental pulp cells obtained from the teeth of young patients (age between 18-22 years) were cultured and subsequently treated with various concentrations of retinoic acid (0, 10(-7), 10(-6), 10(-5) M) in serum-free DMEM. At different time intervals (8, 12 and 24 hours), the levels of type I collagen and osteocalcin secreted were determined using Type I Procollagen C-Peptide and Gla-type Osteocalcin EIA kits, respectively. Induction effects were evaluated using analysis of variance and the Duncan's multiple rank test. Retinoic acid at concentrations of 10(-5), 10(-6), 10(-7) M was able to induce type I collagen and osteocalcin production in human dental pulp cells within 12 hours of exposure. Dose-dependent induction was observed only after 24 hours. A two-fold increase in osteocalcin level was detected after exposed to 10(-5) M retinoic acid within 24 hours. Our data suggest that retinoic acid at concentrations of 10(-5), 10(-6), 10(-7) M has the ability to induce type I collagen and osteocalcin secretions in human dental pulp cells in vitro.

Lemongrass-Incorporated Tissue Conditioner Against Candida albicans Culture.

BACKGROUND: Tissue conditioner is applied popularly with dental prosthesis during wound healing process but it becomes a reservoir of oral microbiota, especially Candida species after long-term usage. Several antifungal drugs have been mixed with this material to control fungal level. In this study, lemongrass essential oil was added into COE-COMFORT tissue conditioner before being determined for anti-Candida efficacy. MATERIALS AND METHODS: Lemongrass (Cymbopogon citratus) essential oil was primarily determined for antifungal activity against C. albicans American type culture collection (ATCC) 10231 and MIC (minimum inhibitory concentration) value by agar disk diffusion and broth microdilution methods, respectively. COE-COMFORT tissue conditioner was prepared as recommended by the manufacturer after a fixed volume of the oil at its MIC or higher concentrations were mixed thoroughly in its liquid part. Antifungal efficacy of the tissue conditioner with/without herb was finally analyzed. RESULTS: Lemongrass essential oil displayed potent antifungal activity against C. albicans ATCC 10231and its MIC value was 0.06% (v/v). Dissimilarly, the tissue conditioner containing the oil at MIC level did not cease the growth of the tested fungus. Both reference and clinical isolates of C. albicans were completely inhibited after exposed to the tissue conditioner containing at least 0.25% (v/v) of the oil (approximately 4-time MIC). The tissue conditioner without herb or with nystatin was employed as negative or positive control, respectively. CONCLUSION: COE-COMFORT tissue conditioner supplemented with lemongrass essential oil obviously demonstrated another desirable property as in vitro anti-Candida efficacy to minimize the risk of getting Candidal infection.

Crevicular Porphyromonas gingivalis-specific immunoglobulin A levels in healthy and periodontitis-affected Thai cohorts.

UNLABELLED: Abstract Aim: Immunoglobulin A is a key humoral immune component involved in defense mechanisms against infections. Periodontitis, the chronic inflammatory disease causing periodontal destruction, adversely affects adults worldwide, including Thailand. As the development of periodontitis is partly mediated by immune components, levels of total and Porphyromonas gingivalis-specific immunoglobulin A in gingival crevicular fluid of Thai cohorts were studied. METHODS: Gingival crevicular fluid was collected from 24 patients with severe generalized chronic periodontitis and 22 healthy controls. The amount and concentration of total and Porphyromonas gingivalis-specific immunoglobulin A in each gingival crevicular fluid sample were determined by enzyme-linked immunosorbent assay. RESULTS: The control group contained the highest concentrations of both types of gingival crevicular fluid-immunoglobulin A, but the lowest levels of these antibodies were found in the deep sites of the periodontitis group. Moreover, the concentrations of gingival crevicular fluid-immunoglobulin A and the degree of periodontitis severity appeared to have an inverse relationship. There was no significant difference in the amounts of gingival crevicular fluid-immunoglobulin A in the control and periodontitis groups. CONCLUSIONS: This study supports the hypothesis that high concentrations of specific gingival crevicular fluid-immunoglobulin A antibodies directed against Porphyromonas gingivalis, a potent periodontic microorganism, could retard periodontitis development.