Recent Development of Active Ingredients in Mouthwashes and Toothpastes for Periodontal Diseases.

Periodontal diseases like gingivitis and periodontitis are primarily caused by dental plaque. Several antiplaque and anti-microbial agents have been successfully incorporated into toothpastes and mouthwashes to control plaque biofilms and to prevent and treat gingivitis and periodontitis. The aim of this article was to review recent developments in the antiplaque, anti-gingivitis, and anti-periodontitis properties of some common compounds in toothpastes and mouthwashes by evaluating basic and clinical studies, especially the ones published in the past five years. The common active ingredients in toothpastes and mouthwashes included in this review are chlorhexidine, cetylpyridinium chloride, sodium fluoride, stannous fluoride, stannous chloride, zinc oxide, zinc chloride, and two herbs-licorice and curcumin. We believe this comprehensive review will provide useful up-to-date information for dental care professionals and the general public regarding the major oral care products on the market that are in daily use.

Enhanced Biofilm Eradication and Reduced Cytotoxicity of a Novel Polygalacturonic and Caprylic Acid Wound Ointment Compared with Common Antiseptic Ointments.

Antiseptic wound ointments are widely used to treat dermal wounds that are microbially contaminated. Polygalacturonic acid (PG)+caprylic acid (CAP) is a novel combination that has been shown to eradicate biofilms. We developed a novel PG+CAP ointment and compared the biofilm eradication capability and cytotoxicity of PG+CAP with that of commercially available antiseptic wound ointments. We used a well-established biofilm model to quantitatively assess the eradication of organisms following exposure to the wound ointments for 2 hours. PG+CAP ointment completely eradicated Candida albicans, multidrug-resistant Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus biofilms, whereas MediHoney, polyhexamethylene biguanide (PHMB), and benzalkonium chloride (BZK) ointments failed to eradicate all biofilms within 2 hours. We assessed cytotoxicity by exposing L-929 fibroblasts to extracts of each ointment; Trypan blue exclusion was used to assess cell viability, and Alamar blue conversion was used to assess metabolic function. After exposure to PG+CAP and MediHoney, fibroblast viability was 96.23% and 95.23%, respectively (Trypan blue), and was comparable to untreated cells (98.77%). PHMB and BZK showed reduced viability (83.25% and 77.83%, respectively, p < 0.05). Metabolic activity results followed a similar pattern. Cytotoxicity of PG+CAP ointment towards erythrocytes was comparable to saline. PG+CAP ointment seems to be safe and can rapidly eradicate microbial biofilm; thus, PG+CAP ointment merits further in vivo testing as a potential antimicrobial wound ointment.

Evaluation of tea tree oil physicochemical features and its antimicrobial activity against Cutibacterium acnes (Propionibacterium acnes) ATCC 6919 / [Evaluación de las características fisicoquímicas y de la actividad antimicrobiana del aceite del árbol de té contra Cutibacterium acnes (Propionibacterium acnes) ATCC 6919].

Introduction: Tea tree oil is an essential oil recognized for its antimicrobial properties. Objective: To evaluate the composition, features, and antimicrobial effect at 2% v/v, and its minimal inhibitory concentration (MIC) against Cutibacterium acnes (Propionibacterium acnes). Materials and methods: Three different batches of tea tree oil were evaluated. We characterized its chemotype by gas chromatography and its 2% v/v antimicrobial activity against C. acnes by agar diffusion assay (guide M11-A8 CLSI). Results: The three batches of oil had the chemotypes required by the ISO 4730 standard, which indicates that it is a high-quality product. Additionally, they had 30% to 40% of terpinen-4-ol, a compound that favors its antimicrobial activity. Antimicrobial activity against C. acnes for all batches had a concentration-dependent effect with microbial growth inhibitory activity in all assays at 2% v/v. The MIC obtained against C. acnes for all batches was 0.25% v/v. The antimicrobial activity of tea tree oil against this microorganism has been previously reported with a MIC between 0.05% and 1.25% v/v, a range that covers the one obtained in this study. Conclusion: These results show the high quality of the oil and its capacity as an antibacterial agent against C. acnes. New studies should be conducted to confirm its activity and that of its components in isolates of the microorganism from patients with acne vulgaris.

Introducción. El aceite del árbol de té es un aceite esencial reconocido por sus propiedades antimicrobianas. Objetivos. Evaluar la composición, características y efecto antimicrobiano del aceite al 2 % del árbol de té y su concentración inhibitoria mínima (CIM) contra Cutibacterium acnes (Propionibacterium acnes). Materiales y métodos. Se evaluó el quimiotipo en tres lotes diferentes de este aceite mediante cromatografía de gases, así como su actividad antimicrobiana en concentración al 2 % v/v y la CIM contra C. acnes mediante ensayo de difusión en agar (guía M11-A8 CLSI). Resultados. Los lotes evaluados presentaron los quimiotipos ajustados a la norma ISO 4730, lo que indicó la alta calidad del producto. Los lotes contenían de 30 a 40 % de terpinen-4-ol, compuesto que favorece la actividad antimicrobiana, la cual presentó en todos los lotes un efecto dependiente de la concentración contra C. acnes, con una inhibición del crecimiento microbiano en concentración al 2 % v/v en todas las pruebas. La concentración inhibitoria mínima fue de 0,25 % v/v. La actividad antimicrobiana del aceite del árbol de té contra este microorganismo ya ha sido reportada con una concentración inhibitoria mínima entre 0,05 y 1,25 % v/v, rango que cobija la obtenida en este estudio. Conclusiones. Los resultados evidenciaron la gran calidad de este producto y su capacidad como agente antibacteriano contra C. acnes. Se deben hacer estudios con otros aislamientos del microorganismo provenientes de pacientes con acné vulgar para confirmar su actividad general y la de cada uno de sus componentes.

Evaluation of the antimicrobial activity and compressive strength of a dental cement modified using plant extract mixture.

Literature lacks sufficient data regarding addition of natural antibacterial agents to glass ionomer cement (GICs). Hence, the aim of the study was to increase the antimicrobial properties of GICs through its modification with mixture of plant extracts to be evaluated along with an 0.5% chlorohexidine-modified GIC (CHX-GIC) with regard to biological and compressive strength properties. Conventional GIC (freeze-dried version) and CHX were used. Alcoholic extract of Salvadora persica, Olea europaea, and Ficus carcia leaves were prepared using a Soxhlet extractor for 12 h. The plant extract mixture (PE) was added in three different proportions to the water used for preparation of the dental cement (Group 1:1 PE, 2:1 PE, and 1:2 PE). Specimens were then prepared and tested against the unmodified GIC (control) and the 0.5% CHX-GIC. Chemical analysis of the extract mixture was performed using Gas chromatography-mass spectrometry. Antimicrobial activity was evaluated using agar diffusion assay against Micrococcus luteus and Streptoccocus mutans. Compressive strength was evaluated according to ISO 9917-1:2007 using a Zwick testing machine at a crosshead speed of 0.5 mm/min. Antimicrobial activity against Streptoccocus mutans was significantly increased for all the extract-modified materials compared to the unmodified cement, and the highest concentration was comparable to the CHX-GIC mixture. The activity against Micrococcus luteus was also significantly increased, but only for the material with the highest extract concentration, and here the CHX-GIC group showed statistically the highest antimicrobial activity. Compressive strength results revealed that there was no statistically significant difference between the different mixtures and the control except for the highest tested concentration that showed the highest mean values. The plant extracts (PEs) enhanced the antimicrobial activity against S. mutans and also against M. luteus in the higher concentration while compressive strength was improved by addition of the PE at higher concentrations.

Evaluation of the Effectiveness of Crotoxin as an Antiseptic against Candida spp. Biofilms.

The growing number of oral infections caused by the Candida species are becoming harder to treat as the commonly used antibiotics become less effective. This drawback has led to the search for alternative strategies of treatment, which include the use of antifungal molecules derived from natural products. Herein, crotoxin (CTX), the main toxin of Crotalus durissus terrificus venom, was challenged against Candida tropicalis (CBS94) and Candida dubliniensis (CBS7987) strains by in vitro antimicrobial susceptibility tests. Minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and inhibition of biofilm formation were evaluated after CTX treatment. In addition, CTX-induced cytotoxicity in HaCaT cells was assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) colorimetric assay. Native CTX showed a higher antimicrobial activity (MIC = 47 µg/mL) when compared to CTX-containing mouthwash (MIC = 750 µg/mL) and nystatin (MIC = 375 µg/mL). Candida spp biofilm formation was more sensitive to both CTX and CTX-containing mouthwash (IC100 = 12 µg/mL) when compared to nystatin (IC100 > 47 µg/mL). Moreover, significant membrane permeabilization at concentrations of 1.5 and 47 µg/mL was observed. Native CTX was less cytotoxic to HaCaT cells than CTX-containing mouthwash or nystatin between 24 and 48 h. These preliminary findings highlight the potential use of CTX in the treatment of oral candidiasis caused by resistant strains.

Development of Chitosan-Based Hydrogel Containing Antibiofilm Agents for the Treatment of Staphylococcus aureus-Infected Burn Wound in Mice.

Methicillin-resistant Staphylococcus aureus (MRSA) is considered a common colonizer of burn wound and accounts for high morbidity and mortality all across the globe. Systemic antibiotic therapy which is generally prescribed for these patients has a number of limitations. These include high drug dose, toxicity, and chances of development of drug resistance. However, local delivery of drug not only addresses these limitations but also provides better efficacy at the site of infection. In the present study, hydrogel preparations were developed for the topical delivery of moxifloxacin for the treatment of S. aureus-infected burn wound. Moxifloxacin was characterized by UV, FTIR, DSC, hot-stage microscopy, NMR, and HPLC and loaded into conventional and Boswellia-containing novel gels. Gels were characterized by visual examination, pH, UV spectroscopy, and release assays. In vivo studies showed that both gels were effective in eradicating the bacteria completely from the wound site when treatment was started during the early stage of infection. On the contrary, delayed treatment of planktonic and biofilm cells with novel gel showed better efficacy as compared with conventional gel in S. aureus-infected burn wound. Histopathological analysis also showed better skin healing efficacy of novel gel than conventional gel. Our results show that moxifloxacin can be efficiently used topically in the management of burn wound infections along with other antibacterial agents. Since biofilm-mediated infections are on the rise especially in chronic bacterial disease, therefore, a preparation containing antibiofilm agent-like Boswellia as one of the excipients would be more meaningful.

Melaleuca alternifolia (tea tree) oil and its monoterpene constituents in treating protozoan and helminthic infections.

Australian tea tree (Melaleuca alternifolia) oil (TTO) and its monoterpene constituents such as terpinen-4-ol (T4O), 1,8-cineole, limonene, p-cymene, and α-terpinene have been shown to be effective in controlling a wide range of parasitic infections. The anti-parasitic effects of these compounds are mainly due to their anti-histamine and anti-acetylcholinesterase activities as well as their ability to modulate host inflammatory responses. This review attempts to summarize recent advances in the uses of TTO and its 15 major monoterpene constituents in treating parasitic infections in both humans and animals. Activities against parasitic protozoans (Plasmodium falciparum, Leishmania spp., Trypanosoma spp., Acanthamoeba castellanii, Trichomonas vaginalis, Eimeria, and Ichthyophthirius multifiliis), nematodes (Haemonchus contortus and Anisakis simplex), cestode (Echinococcus ortleppi), and monogeneans (Gasterosteus spp. and Dactylogyrus minutus) have been reported, showing good potentials in treating parasitic infections. Further studies are necessary for developing anti-parasite therapies using TTO or its monoterpenes constituents.

Local Treatment of Local Staphylococcal Infection with Complex Preparations Based on Metal Nanoparticles in the Experiment.

Antibacterial activity of powdered preparations based on copper and silver nanoparticles was compared with activity of the reference preparation Baneocin on the model of local staphylococcal infection in white rats. The developed preparations exhibited pronounced antibacterial activity against methicillin-resistant S. epidermidis strains in vivo significantly (p<0.001) exceeding that of Baneocin, reduced microbial contamination of the wound on day 5 of study by 2 lg and more in comparison with bacterial load before treatment, and provided effective decontamination of the wound within 7-10 days.

In-situ forming implants loaded with chlorhexidine and ibuprofen for periodontal treatment: Proof of concept study in vivo.

Control of infection and inflammation is crucial for the success of periodontal treatment. In this study, in-situ forming implants (ISFI) loaded with chlorhexidine dihydrochloride (CHX) and ibuprofen (IBU) were developed and tested to optimize periodontal treatment outcomes. Release profiles were promising. Exposure to 1.5% and 5.3% CHX-IBU loaded ISFI's release media decreased significantly the P. gingivalis growth up to 20-fold and 35-fold, respectively, after 48 h (p < 0.05). The metabolic activity assay of gingival epithelial cells (EC) demonstrated 1.5% CHX-IBU-loaded ISFI to be non-toxic, therefore, it was selected for further experimentation. Furthermore, significant down-regulation of TNF-α release (34% at 6 h and 43% at 24 h, p < 0.05) in P. gingivalis lipopolysaccharide (Pg-LPS) stimulated EC exposed to 1.5% CHX-IBU ISFI release medium was demonstrated by ELISA. In vivo, 1.5% CHX-IBU ISFI was injected into the periodontal pocket in an experimental periodontitis mouse model and the reduction in inflammation and improvement in periodontal wound healing was evaluated through inflammatory cell scoring and histomorphometry at 7- and 15-days post-treatment. The results indicate that CHX-IBU loaded ISFI could be efficient as adjuvant to periodontal therapy for the control of infection and inflammation. Moreover, other (e.g., pro-regenerative) drugs could be incorporated into ISFI to further improve periodontal treatment outcomes.

Spray coating of foley urinary catheter by chlorhexidine-loadedpoly(ε-caprolactone) nanospheres: effect of lyoprotectants, characteristics, and antibacterial activity evaluation.

In this study, chlorhexidine-loaded poly(ε-caprolactone) nanospheres (CHX-NS) were prepared and successfully coated on the urinary catheters. Properties of CHX-NS were evaluated including drug loading content and the nanosphere size. Effects of different lyoprotectants for long-term storage of CHX-NS were also investigated. In vitro release study and antibacterial activity were also conducted using 20 cycles coated-urinary catheters. Results showed that the high-pressure emulsification-solvent evaporation technique provided the drug loading content at 1.14 ± 0.16% and the size of nanospheres was 152 ± 37 nm. The suitable lyoprotectant for long-term storage of CHX-NS was sucrose which provided noticeably no aggregation at the degree of reconstitution at 89.95%. The amount of CHX loading on coated catheters was at 4.55 ± 0.31 mg. Drug release from the coated catheters in artificial urine could be prolonged up to 2 weeks and bacteria proliferation was inhibited up to 14 days. These results suggest that the antimicrobial activity of CHX-NS reduces the adherence of the uropathogens to the catheter surface. Chlorhexidine-loaded polymeric nanospheres were fabricated which can be successfully coated on urinary catheters. These systems have potential use for prolonged antimicrobial applications.

Inhibition of Bromelain Activity During Enzymatic Debridement of Burn Wounds Pretreated With Frequently Used Products.

An enzyme mixture containing bromelain (NexoBrid®) was found to be suitable for enzymatic debridement of burn wounds, as determined by the criteria of patient comfort and pain, selectivity, and efficiency. Nevertheless, daily experience showed that pretreatment of burn wounds with several other clinical agents may inhibit debridement efficiency. Therefore, the current study was performed to identify those agents and evaluate their debridement inhibition capabilities. The impact of several common agents as well pH, on NexoBrid® debridement efficiency was evaluated in vitro. A collagen-based dermal substitute (MatriDerm®) was exposed to NexoBrid® in the presence of different agents of varying concentrations. Digestion was documented. The criteria used for judging digestion were independently classified by 3 investigators at least 3 times in succession. When a low concentration (1.0 mg/ml) of NexoBrid® was used, a ≥ 50% concentration of Prontosan® had an impact on enzymatic activity. Comparable results were obtained when even lower concentrations of Octenisept® (≥ 10%) were used. A 100-µmol/L concentration of copper inhibited the enzymatic activity of both a low (1.0 mg/ml) and high (10 mg/ml) concentration of NexoBrid®. Silver-sulfadiazine at concentrations of 10% and 90% inhibited the activity of 1 mg/ml NexoBrid®. No complete inhibition of NexoBrid® activity occurred at any concentration of iron. We recommend using polyhexanide-containing agents (Prontosan®) to rinse and presoak burn wounds. Pretreatment of burn wounds with agents containing silver and copper should be avoided. Experimentally, we found a partial inhibition of NexoBrid® activity at the distinct pH values of 3 and 11.

Delivery of adapalene using a novel topical gel based on tea tree oil nano-emulsion: Permeation, antibacterial and safety assessments.

The aim of present study was to design and optimize 0.1% adapalene loaded nano-emulsion to improve the drug efficacy and increase its user compliance. Effect of type and concentration of surfactants was studied on size of 0.1% adapalene loaded nano-emulsion. Optimized formulation was then evaluated for particle size, polydispersity index, morphology, viscosity, and pH. Subsequently, 1% carbopol® 934 was incorporated to the optimized formulation for preparation of its gel form. The efficacy and safety of 0.1% adapalene loaded nano-emulsion gel was assessed compared to marketed gel containing 0.1% adapalene. In-vitro studies showed that adapalene permeation through the skin was negligible in both adapalene loaded nano-emulsion gel and adapalene marketed gel. Furthermore, drug distribution studies in skin indicated higher retention of adapalene in the dermis in adapalene loaded nano-emulsion gel compared with adapalene marketed gel. Antibacterial activity against Propionibacterium acnes showed that adapalene loaded nano-emulsion is effective in reducing minimum inhibitory concentration of the formulation in comparison with tea tree oil nano-emulsion, and pure tea tree oil. In vivo skin irritation studies showed absence of irritancy for adapalene loaded nano-emulsion gel. Also, blood and liver absorption of the drug, histological analysis of liver and liver enzyme activity of rats after 90 days' treatment were investigated. No drug was detected in blood/liver which in addition to an absence of any adverse effect on liver and enzymes showed the potential of adapalene loaded nano-emulsion gel as a novel carrier for topical delivery of adapalene.

Assessment of Ions released from Three Types of Orthodontic Brackets immersed in Different Mouthwashes: An in vitro Study.

AIM: Herbs are used widely in medicine. The purpose of the present study was to assess the ion release from gold-plated orthodontic bracket compared with other stainless steel brackets, and based on the findings of the study, the orthodontists can choose the most biocompatible brackets and mouthwashes useful in the clinical practice. MATERIALS AND METHODS: A total of 150 orthodontic brackets from Orthotechnology™ Company, USA (50 stainless steel one-piece brackets, 50 stainless steel two-piece brackets, and 50 gold brackets) were immersed in four mouthwashes in addition to distilled water. Ten of each type of brackets in every media were immersed under 37°C for 45 days. Ions released in these mouthwashes were measured, and comparisons among different bracket types and among various mouthwashes were done by one-way analysis of variance (ANOVA) and then with Games-Howell tests. RESULTS: Increased amounts of ions released in herbal mouth-washes were recorded in gold and two-piece brackets in comparison with one-piece stainless steel brackets. CONCLUSION: Herbal mouthwashes must be used with caution as they showed an increased amount of ions released in comparison with chlorhexidine. One-piece stainless steel bracket system is the most compatible bracket type, as they released the least amount of ions. CLINICAL SIGNIFICANCE: One-piece stainless steel brackets are better than two-piece brackets in terms of ions released.

Synthesis and potential applications of silver-porous aluminium oxide nanocomposites as prospective antiseptics and bactericides.

Alumina micro-spheres with mesoporous structure called porous aluminium oxide (POA) were prepared through a hydrothermal method using Al2(SO4)3·18H2O followed by a thermal decomposition process. Silver nanocomposites of POA (Ag/POAs) with high biochemical activity were synthesized by sorption of silver nanoparticles in the matrix of POA. Synthesis of Ag/POAs using photochemical reduction enables the producing silver nanoparticles preventing their aggregation. Ag/POAs demonstrated a stronger bactericidal activity than POA. The colony-forming ability of Escherichia coli was completely lost in 1 day on Ag/POAs at silver nanoparticles concentration of 0.241 ppm. Staphylococcus epidermidis displayed higher tolerance to Ag/POAs at all silver nanoparticles concentrations, the growth of Staphylococcus epidermidis was stopped at concentration of 0.374 ppm. The bactericidal activity of Ag/POAs against bacteria in drinking water was found to be highly effective, the growth of bacteria was completely lost in 1 day at silver nanoparticles concentration of 0.108 ppm.

Efficacy and safety of a therapeutic apparatus using hydrogen peroxide photolysis to treat dental and periodontal infectious diseases.

The present study aimed to evaluate the acute locally injurious property of our most current hydroxyl radical generation system by hydrogen peroxide (H2O2) photolysis. This system, which releases 3% H2O2 with a 405-nm laser, was developed in our laboratory for the treatment of dental and periodontal infectious diseases. First, the hydroxyl radical yield generated by H2O2 photolysis was examined by applying an electron spin resonance-spin trapping technique. Second, the bactericidal effect of the device was examined under a simulant condition in which Streptococcus mutans, a pathogenic bacterial species that causes caries, was irrigated with running 3% H2O2 concomitantly with laser irradiation. Finally, the acute topical effect of the model apparatus on rat palatal mucosa was evaluated by histological examination. We found that the hydroxyl radical yield was dependent upon laser output power. The bacterial count was substantially reduced within as little as 3 min. No abnormal findings were observed in the palatal mucosa, even when rats received three treatments of 3% H2O2 with laser irradiation at an output power of 40 mW. These results suggest that our apparatus has the ability to kill bacteria via hydroxyl radical generation and is safe to use at the lesion site of dental and periodontal infectious diseases.

Inhibitory Effect of Three Diketopiperazines from Marine-Derived Bacteria on HMGB1-Induced Septic Responses in Vitro and in Vivo.

The nucleosomal protein high-mobility group box-1 (HMGB1), which has recently been established as a late mediator of lethal systemic inflammation, has a relatively wide therapeutic window for pharmacological interventions. Compounds produced by marine-derived microbes have been widely investigated for their potential use as bioactive natural products. Cyclic dipeptides, which are also known as diketopiperazines, are molecules that are frequently found in marine-derived microorganisms. While their pharmacological potential has been well established, their biological activities against septic responses have not yet been reported. Here, three diketopiperazines (1-3) isolated from two strains of marine-derived bacteria were investigated for their potential activities against HMGB1-mediated septic responses. The data showed that 1-3 effectively inhibited the lipopolysaccharide (LPS)-induced release of HMGB1 and suppressed the HMGB1-mediated septic responses, including hyperpermeability, leukocyte adhesion and migration, and cell adhesion molecule expression. In addition, 1-3 inhibited the HMGB1-mediated production of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text] and interleukin (IL)-6 and the activation of nuclear factor-[Formula: see text]B (NF-[Formula: see text]B) and extracellular signal-regulated kinase (ERK) 1 and ERK2. Collectively, these results indicated that 1-3 might act as potential therapeutic agents for various severe vascular inflammatory diseases through the inhibition of the HMGB1 signaling pathway.

Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin.

OBJECTIVE: Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin. MATERIAL AND METHODS: Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm2 of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (µTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey's test (α=0.05). RESULTS: After 24 hours, there was no significant difference in the µTBS of the groups. After 6 months, the GT group had significantly higher µTBS values. CONCLUSION: It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.

The dynamics and mechanism of the antimicrobial activity of tea tree oil against bacteria and fungi.

Tea tree oil (TTO) is a yellow liquid extracted from Melaleuca alternifolia. Although the antimicrobial activity of TTO has been known for a long time, its specific antimicrobial effects and mechanism underlying these remain poorly characterized. The present study investigated the chemical composition of TTO and the dynamics and mechanism of its antimicrobial activities in two bacterial and two fungal strains. Gas chromatography-mass spectrometry analysis identified alkenes and alcohols as the main constituents of TTO. Terpinen-4-ol was the most abundant individual component, accounting for approximately 23 % of the TTO. Poisoned food technique assessment showed that the minimum inhibitory concentrations of TTO for bacterial strains (Escherichia coli and Staphylococcus aureus) and fungal strains (Candida albicans and Aspergillus niger) were 1.08 and 2.17 mg/mL, respectively. Antimicrobial dynamic curves showed that with increasing concentrations of TTO, the rate of cell killing and the duration of growth lag phase increased correspondingly. These data indicated that TTO produced concentration and time-dependent antimicrobial effects. The minimum bactericidal and fungicidal concentrations of TTO were 2.17, 4.34, and 4.34 against E. coli, S. aureus, and C. albicans, respectively. However, A. niger conidia were not completely eradicated, even after 3 days in the presence of 17.34 mg/mL TTO. Transmission electron microscopy images indicated that TTO penetrated the cell wall and cytoplasmic membrane of all the tested bacterial and fungal strains. TTO may also penetrate fungal organelle membrane. These findings indicated that TTO maybe exerts its antimicrobial effects by compromising the cell membrane, resulting in loss of the cytoplasm and organelle damage, which ultimate leads to cell death.

Effect of green tea extract on bonding durability of an etch-and-rinse adhesive system to caries-affected dentin

ABSTRACT Objective Green tea extract has been advocated as a matrix metalloproteinase (MMP) inhibitor; however, its effect on bond durability to caries-affected dentin has never been reported. Thus, the aim of this in vitro study was to evaluate the effect of two MMP inhibitors (2% chlorhexidine and 2% green tea extract), applied after acid etching, on bond durability of an etch-and-rinse adhesive system to caries-affected dentin. Material and Methods Occlusal enamel was removed from third molars to expose the dentin surface, and the molars were submitted to a caries induction protocol for 15 days. After removal of infected dentin, specimens were conditioned with 37% phosphoric acid (15 seconds) and randomly divided into three groups, according to the type of dentin pretreatment (n=10): NT: no treatment; GT: 2% green tea extract; CLX: 2% chlorhexidine. The etch-and-rinse adhesive system (Adper™ Single Bond 2, 3M ESPE, St. Paul, MN, USA) was applied according to the manufacturer's instructions, and composite resin restorations were built on the dentin. After 24 hours, at 37°C, the resin-tooth blocks were sectioned perpendicularly to the adhesive interface in the form of sticks (0.8 mm2 of adhesive area) and randomly subdivided into two groups according to when they were to be submitted to microtensile bond strength (μTBS) testing: immediately or 6 months after storage in distilled water. Data were reported in MPa and submitted to two-way ANOVA for completely randomized blocks, followed by Tukey’s test (α=0.05). Results After 24 hours, there was no significant difference in the μTBS of the groups. After 6 months, the GT group had significantly higher μTBS values. Conclusion It was concluded that the application of 2% green tea extract was able to increase bond durability of the etch-and-rinse system to dentin. Neither the application of chlorhexidine nor non-treatment (NT - control) had any effect on bond strength after water storage.

Tea tree oil nanoemulsions for inhalation therapies of bacterial and fungal pneumonia.

Tea tree oil (TTO) is a natural essential oil with strong antimicrobial efficacy and little drug resistance. However, the biomedical applications of TTO are limited due to its hydrophobicity and formulation problems. Here, we prepared an inhalable TTO nanoemulsion (nanoTTO) for local therapies of bacterial and fungal pneumonia. The optimal formulation of nanoTTOs consisted of TTO/Cremophor EL/water with a mean size of 12.5nm. The nanoTTOs showed strong in vitro antimicrobial activities on Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus and Candida albicans. After inhalation to the lung, the nanoTTOs had higher anti-fungal effect than fluconazole on the fungal pneumonia rat models with reduced lung injury, highly microbial clearance, blocking of leukocyte recruitment, and decrease of pro-inflammatory mediators. In the case of rat bacterial pneumonia, the nanoTTOs showed slightly lower therapeutic efficacy than penicillin though at a much lower dose. Taken together, our results show that the inhalable nanoTTOs are promising nanomedicines for local therapies of fungal and bacterial pneumonia with no obvious adverse events.