In Vitro Evaluation of Substantivity, Staining Potential, and Biofilm Reduction of Guava Leaf Extract Mouth Rinse in Combination with its Anti-Inflammatory Effect on Human Gingival Epithelial Keratinocytes

Improved Anti-Biofilm Effect against the Oral Cariogenic Streptococcus mutans by Combined Triclosan/CBD Treatment

Streptococcus mutans is a Gram-positive bacterium highly associated with dental caries, and it has a strong biofilm-forming ability, especially in a sugar-rich environment. Many strategies have been undertaken to prevent dental caries by targeting these bacteria. Recently, we observed that a sustained-release varnish containing triclosan and cannabidiol (CBD) was more efficient than each compound alone in preventing biofilm formation by the fungus Candida albicans, which is frequently involved in oral infections together with S. mutans. It was therefore inquiring to study the effect of this drug combination on S. mutans. We observed that the combined treatment of triclosan and CBD had stronger anti-bacterial and anti-biofilm activity than each compound alone, thus enabling the use of lower concentrations of each drug to achieve the desired effect. The combined drug treatment led to an increase in the SYTO 9^low, propidium iodide (PI)^high bacterial population as analyzed by flow cytometry, indicative for bacteria with disrupted membrane. Both triclosan and CBD induced membrane hyperpolarization, although there was no additive effect on this parameter. HR-SEM images of CBD-treated bacteria show the appearance of elongated and swollen bacteria with several irregular septa structures, and upon combined treatment with triclosan, the bacteria took on a swollen ellipse and sometimes oval morphology. Increased biofilm formation was observed at sub-MIC concentrations of each compound alone, while combining the drugs at these sub-MIC concentrations, the biofilm formation was prevented. The inhibition of biofilm formation was confirmed by CV biomass staining, MTT metabolic activity, HR-SEM and live/dead together with exopolysaccharide (EPS) staining visualized by spinning disk confocal microscopy. Importantly, the concentrations required for the anti-bacterial and anti-biofilm activities toward S. mutans were non-toxic to the normal Vero epithelial cells. In conclusion, the data obtained in this study propose a beneficial role of combined triclosan/CBD treatment for potential protection against dental caries.

Composition, Antibacterial Efficacy, and Anticancer Activity of Essential Oil Extracted from Psidium guajava (L.) Leaves

Essential oils (EO) are used as a natural remedy to treat various chronic diseases, although clinical evidence is lacking. In this context, we have endeavored to measure the percentage of chemical composition and biological efficacy of Psidium guajava (guava) leaf essential oil in treating oral infections and oral cancer. The essential oil obtained from hydrodistillation of P. guajava L. leaves was analyzed by gas chromatography−mass spectrometry (GC−MS). The activities of selected oral pathogens Candida albicans (C. albicans) and Streptococcus mutans (S. mutants) were studied in vitro and in silico. MTT assay was used to test for anticancer activity against human oral epidermal carcinoma (KB). GC−MS showed that the main components of PGLEO were limonene (38.01%) and β-caryophyllene (27.98%). Minimum inhibitory concentrations (MICs) of 0.05−0.1% were demonstrated against C. albicans and S. mutans. Antimicrobial activity against C. albicans and S. mutans, as shown by molecular linkage analysis, revealed that the main metabolites, limonene and β-caryophyllene, potentially inhibited the receptors of C. albicans and S. mutans. PGLEO showed significant (p < 0.001) anticancer activity (45.89%) at 200 µg/mL compared to doxorubicin (47.87%) with an IC50 value of 188.98 µg/mL. The outcomes of the present study suggest that PGLEO has promising antimicrobial and anticancer activities and could be a useful source for developing a natural therapeutic agent for oral infections and oral cancer.

A novel in vitro periodontal pocket model to evaluate the effect of root surface instrumentation on biofilm-epithelial cell interactions

Objective

To develop a novel in vitro periodontal pocket model for evaluating the effect of two different root surface instrumentation modalities on biofilm-epithelial cell interactions.

Materials and methods

An artificial periodontal pocket model was created using an impression material. Dentin discs were prepared and incubated for 3.5 days with a biofilm consisting of 12 bacterial strains. Then, the discs were inserted into the pocket model and instrumented for 10 s or 10 strokes either with ultrasonics (US) or hand instruments (HI). Subsequently, a glass slide coated with epithelial cells was placed in close vicinity to the discs. After incubation of the pocket model in a 5% CO2 atmosphere for 6 h, residual bacteria of the biofilm as well as bacteria adhering to or invaded into epithelial cells were determined using colony-forming unit (cfu) counts and real-time PCR. Further, as a parameter of the pro-inflammatory cell response, interleukin (IL)-8 expression was determined by ELISA.

Results

Compared to untreated control, HI reduced the cfu counts by 0.63 log10 (not significant) and US by 1.78 log10 (p = 0.005) with a significant difference between the treatment modalities favoring US (p = 0.048). By trend, lower detection levels of Tannerella forsythia were detected in the US group compared to HI. Concerning the interaction with epithelial cells, half of the control and the HI samples showed epithelial cells with attaching or invading bacteria, while US displayed bacteria only in two out of eight samples. In addition, US resulted in significantly lower IL-8 secretion by epithelial cells compared to the untreated control. Between HI and controls, no statistically significant difference in IL-8 secretion was found.

Conclusion

This newly developed in vitro model revealed in terms of biofilm-epithelial cell interaction after root surface instrumentation that compared to hand curettes, ultrasonic instrumentation appeared to be more effective in removing bacterial biofilm and in decreasing the inflammatory response of epithelium to biofilm.

Clinical relevance

Ultrasonic instrumentation might be more advantageous to reduce cellular inflammatory response than hand instruments.

Mucoadhesive controlled-release formulations containing morin for the control of oral biofilms

This study aimed to evaluate the antimicrobial and anti-biofilm activity of morin on polymicrobial biofilms and its cytotoxicity in controlled-release films and tablets based on gellan gum. Polymicrobial biofilms were formed from saliva for 48 h under an intermittent exposure regime to 1% sucrose and in contact with films or tablets of gellan gum containing 2 mg of morin each. Acidogenicity, bacterial viability, dry weight and insoluble extracellular polysaccharides from biofilms were evaluated. The cytotoxicity of morin was evaluated in oral keratinocytes. Morin released from the systems reduced the viability of all the microbial groups evaluated, as well as the dry weight and insoluble polysaccharide concentration in the matrix and promoted the control of acidogenicity when compared with the control group without the substance. Morin was cytotoxic only at the highest concentration evaluated. In conclusion, morin is an effective agent and shows antimicrobial and anti-biofilm activity against polymicrobial biofilms.

Antimicrobial Activity against Oral Pathogens Confirms the Use of Musa paradisiaca Fruit Stalk in Ethnodentistry

Background

Ethnodentistry is the use of indigenous oral cleansing agents such as plant parts by local folks not only to maintain oral hygiene but also to treat oral infections. Mostly, ethnodentistry is inspired by traditions and belief systems of local communities. Musa paradisiaca is extensively cultivated and used in many cultures for its nutritional and medicinal values. In Ghana, the fruit stalk of Musa paradisiaca is used as an oral cleansing agent to maintain oral hygiene; yet this folk claim remains to be ascertained scientifically.

Objective

The study assessed the antibacterial and antifungal effects of three extract fractions (aqueous, ethanol, and ethyl acetate fractions) of Musa paradisiaca fruit stalk against Lactobacillus acidophilus, Aggregatibacter actinomycetemcomitans, and Candida albicans, common oral pathogens implicated in dental caries and periodontitis.

Materials and Methods

Aqueous, ethanol, and ethyl acetate fractions of Musa paradisiaca fruit stalk were prepared by cold maceration and qualitatively screened for their phytochemical composition. Antimicrobial effects of the three extract fractions were assessed by using serial broth dilutions at increasing concentrations (62.5, 125, 250, 500, and 1000 µg/ml) and compared to standard antimicrobial agents (erythromycin, doxycycline, and fluconazole). Subsequently, the absorbances of the microbial suspensions treated with increasing concentrations of the extract fractions were measured at 450 nm, and the cell densities were determined.

Results

Except for the aqueous extract, which was less effective in decreasing microbial growth, the ethyl acetate and the ethanol extract fractions demonstrated antimicrobial efficacies comparable to those of the standard drugs. All three extract fractions demonstrated concentration-dependent growth inhibitory effects on the tested oral pathogens although not as effective as the standard drugs used.

Conclusion

Musa paradisiaca fruit stalk has demonstrated antimicrobial effects against Lactobacillus acidophilus, Aggregatibacter actinomycetemcomitans, and Candida albicans, common oral pathogens implicated in dental caries and periodontitis, and this finding confirms in part folk use of Musa paradisiaca fruit stalk as a traditional dental care agent. Thus, the fruit stalk of Musa paradisiaca could be explored for use as a cheap and readily available dental care agent for people entrapped in the poverty line.

Combination of enamel matrix derivative and hyaluronic acid inhibits lipopolysaccharide-induced inflammatory response on human epithelial and bone cells

Objectives

The aim of this study was to evaluate the in vitro effect of enamel matrix derivative (EMD) and hyaluronic acid (HA) and their synergistic combination on lipopolysaccharides (LPS)-induced inflammation in human keratinocytes and osteoblasts.

Material and methods

Cells were challenged with LPS (1 μg/ml) and cultured in the following treatment groups with EMD (30 mg/ml) and HA (30 mg/ml): LPS, EMD, HA, EMD + HA, EMD + LPS, HA + LPS, and EMD + HA + LPS. Cell viability, inflammatory cytokine expression, and cell migration were determined using colorimetric assay, quantitative real-time polymerase chain reaction (qPCR), and scratch wound healing assay, respectively.

Results

Cell viability was decreased when exposed to LPS compared to the controls. Overall, LPS treatment expressed upregulation on inflammatory cytokine tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6). EMD and HA reduced up to 3.0-fold the cytokine expression caused by LPS (p < 0.05). EMD and HA statistically induced higher migration in osteoblasts and keratinocytes, respectively. Migration was impaired by LPS, whereas it significantly increased after addition of EMD and HA.

Conclusions

EMD and HA are advantageous biomaterials that individually generate strong directional migratory keratinocyte and osteoblast response. Their combination also enhances cell viability, and anti-inflammatory and migratory abilities to promote healing specially under LPS inflammatory stimulus. Future in vivo and animal research is necessary to further characterize the effect of EMD and HA on periodontal regeneration.

Clinical relevance

The use of EMD in conjunction with HA resulted in a reduction of inflammation and improvement of tissue healing at wound sites. Both biomaterials combined may potentially improve the effectiveness of bone regeneration in periodontal bone defects, pointing to the potential clinical relevance of both materials in regenerative periodontal surgery.

Cannabinoids infused mouthwash products are as effective as chlorhexidine on inhibition of total-culturable bacterial content in dental plaque samples

BACKGROUND

Dental plaque is a global health problem affecting people of various age groups. Cannabinoids are gaining enormous research attention due to its beneficial properties for various applications. A preliminary observation on antimicrobial property of cannabinoids against dental plaque bacteria has been reported recently. As a follow-up research, here we report the in vitro evaluation of cannabinoids infused mouthwash products against total culturable (aerobic) bacterial content from dental plaque samples.

METHODS

We tested two cannabinoid-infused mouthwash products containing cannabidiol (CBD) and cannabigerol (CBG) respectively (each mouthwash containing < 1% cannabinoid by weight) in vitro against total-culturable bacteria from dental plaque samples collected from 72 adults aged between 18 and 83 years. The participants were grouped on the basis of Dutch periodontal screening index (DPSI) score. To compare the efficacy of our products, we included two most commonly available products over the counter (Product A and Product B) to represent commercially available mouthwash products and the gold standard chlorhexidine digluconate 0.2% as a positive control. The product A represents mouthwash containing essential oils and alcohol, and Product B represents alcohol-free mouthwash that contains fluoride. All the mouthwash products were evaluated directly as such without any dilution through disc diffusion and agar well diffusion approaches and the diameter of zone of inhibition was measured. The limitation in methodology was that, the samples were open-label and the person who performed the manual measurements was unblind to test and control products used.

RESULTS

On average, the cannabinoids infused mouthwash products showed the similar bactericidal efficacy as that of chlorhexidine 0.2%. Both chlorhexidine 0.2% and cannabinoids infused mouthwash products were effective against all the samples tested. Product A did not show any significant antimicrobial activity in any of the samples tested, except that a very marginal inhibition with a zone of 7-8 mm was observed only in 9 samples. Product B did not show any detectable inhibition zone at all in any of the samples tested. The ranges of zones of inhibition (and their average) were 8-25 mm (18.1 mm) for CBD-mouthwash, 8-25 mm (17.7 mm) for CBG-mouthwash; 12-25 mm (16.8 mm) for chlorhexidine 0.2%; 0-8 mm (0.1 mm) for Product A; and 0 mm for Product B. Although the difference in performance was slightly higher than chlorhexidine in both the cases, the difference was statistically significant for CBD-mouthwash and near significant for CBG-mouthwash. No significant difference was observed between CBD- and CBG-mouthwash. No significant difference in performance was found between DPSI score groups for any of the product tested. To our knowledge this is the first report on such efficient mouthwash product with natural key ingredients including cannabinoids and without any kind of fluoride or alcohol.

CONCLUSIONS

Our in vitro results demonstrate the potential of cannabinoids in developing efficient and safer mouthwash products and next generation oral care products without fluoride and alcohol.