Rattiporn Kaypetch

Adhesion of Candida to Vanillin-Coated PMMA Resin

Denture stomatitis is a common clinical disorder seen among denture wearers. Candida albicans is considered to be the major cause which can adhere to and colonize the surface of denture base material made of polymethyl methacrylate (PMMA) resin. This study aims to investigate the effect of vanillin-coated PMMA resin on the adhesion of C. albicans. Heat-polymerized PMMA resin (Vertex RS, Dentimex, Netherlands) samples were prepared and coated with vanillin at various concentrations of 7, 11, and 15 mM. Sterile distilled water and 0.2% chlorhexidine gluconate solution were used to coat the surfaces in negative and positive controls, respectively. The adhesion assay was performed with 3 strains of C. albicans based on the method described by Samaranayake and MacFarlane. The numbers of adherent yeast cells on PMMA resin surfaces were counted under microscope by random selection of 20 fields at 400x magnification. It was found that all vanillin-coated PMMA resin samples had significant decrease of candida adhesion (50-90% reduction) compared to the negative control. The effect was observed to be in a dose dependent manner (p<0.05). Chlorhexidine exhibited strong reduction effect (96-98% reduction). In conclusion, coating PMMA resin with 7-15 mM vanillin can inhibit candida adhesion to the surface. With further testing and development, vanillin may be used as coating agent for denture to prevent candida adhesion and reduce risk of denture stomatitis.

Type IV Dental Stone Incorporated with Antimicrobial Agents and its Physical Properties

Contamination of dental casts can occur via direct contact with impression materials that are contaminated by patients fluids. Thus, the development of dental stone with antimicrobial activity to reduce cross-contamination between patients and laboratory personnel is needed. This study aims to evaluate the influence of incorporation of disinfectants into type IV dental stone on its antimicrobial activities and physical properties such as setting time and dry compressive strength. Type IV dental stone incorporated with 4 types of disinfectants; Diamond Rock D (3-iodo-2-propynylbutylcarbamate), Diamond Rock B (zeolite), Diamond Rock Z (thiabendazole) and Diamond Rock T (2-benzimidazole carbamic acid), were tested in this study compared with the control, Diamond Rock O (type IV dental stone without disinfectant). Microorganisms tested were Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 1023. One hundred μL of each microbial suspension (108 CFU/mL) was dropped on hydrocolloid impression (Jeltrate; Caulk/Dentsply, Milford, DE) and left dry. All types of stone mixes were prepared and poured into the impressions and allowed to set for 60 min. Then the stone samples were removed and the microbial contact surfaces were imprinted on Brain Heart Infusion agar plates. After incubation, colonies appeared on agar were gram-stained and counted. The setting time and dry compressive strength were tested in accordance with International Standard (ISO) 6873: 1998 (E). Dental stone incorporated with 4 types of disinfectants showed antimicrobial activity against all tested microorganisms with the percentage of microbial reduction ranging from 83% to 100%. Among all types of dental stone, no significant difference in setting time was observed. In dry compressive strength testing, the disinfectant-containing dental stone had significant higher strength than that without the disinfectant. The newly developed type IV dental stone incorporated with disinfectants had antimicrobial effects against all tested microorganisms. The physical properties of the modified dental stones were within the ISO standards. However, further investigation on other properties such as dimensional stability, detail reproduction and clinical usage are still needed.

Antifungal, Anti-Inflammatory and Cytotoxic Effects of Zingiber cassumunar Gel

This study aimed to investigate the antifungal, anti-inflammatory and cytotoxic effects of Zingiber cassumunar gel. The gel was prepared from essential oil of Zingiber cassumunar rhizome by the Thailand Institute of Scientific and Technological Research. Antifungal activity of the gel was firstly determined by the well diffusion method against Candida albicans ATCC 10238 and candida strain isolated from the patient’s lesion. Then, the Agar overlay technique was used to test the cytotoxicity of Z. cassumunar gel on mouse fibroblasts (ATCC clone 929) according to ISO 7405. For anti-inflammatory effect of the gel, TPA (carrageenan lambda type IV, 12-O-tetradecanoylphorbol-13- acetate)-induced mouse ear edema method was used. The results of well diffusion showed that Z. cassumunar gel was quite a potent antifungal agent against both strains of tested C. albicans with inhibition zones of 12-13 mm. In the cytotoxicity test, the gel exhibited no toxicity to cell culture. In addition, topical administration of Z. cassumunar gel could decrease mouse ear edema induced by TPA. At 30 and 60 min-time points, Z. cassumunar gel showed higher anti-inflammatory activity than triamcinolone which was used as reference anti-inflammatory drug. In conclusion, gel prepared from Z. cassumunar oil showed antifungal activity against both strains of C. albicans. In addition, its anti-inflammatory effect was demonstrated within 30 min by the TPA-induced mouse ear edema model. The gel was non-toxic to cell culture after 24-h incubation. Further studies are needed to clarify the safety and benefit of this gel for clinical use in the treatment of candidal infection and inflammation.

Effect of Kaempferia parviflora on Streptococcus mutans Biofilm Formation and its Cytotoxicity

Streptococcus mutans is the most prevalent bacterial species isolated from the human oral cavity. Its ability to form biofilms is an important factor in the pathogenesis of dental caries. Thus, the search for new antimicrobial agents, especially from plants, has been intensified. Kaempferia parviflora has been the subject of research for many pharmacological and antimicrobial activities. In this study, we evaluated the effect of ethanolic extract of K. parviflora root (0.46, 0.94, 1.87, 3.75, 7.5, 15, and 30 mg/ml) on S. mutans KPSK2 biofilm formation using crystal violet assay. Cytotoxicity was determined according to 10993-5/2009 on human gingival fibroblast by MTT assay. The results showed that K. parviflora extract could inhibit biofilm formation to approximately 62-82% at the concentrations of 0.46-30 mg/ml. In the case of cytotoxicity, no cytotoxic potential was demonstrated at concentration of £ 7.5 mg/ml of K. parviflora. In conclusion, K. parviflora extract is a potentially useful anti-biofilm agent against caries-associated bacteria and could be used as adjunct to other caries preventive measures.

In Vitro Inhibitory Effect of Vanillin on Candida Biofilm

Vanillin is a major constituent of vanilla seeds which is used as a flavoring agent in both food and non-food industries. Previous reports have showed that vanillin had antimicrobial properties against food spoilage bacteria, yeasts, and molds. However, investigations about its effect on oral pathogenic yeasts are scarcely found. Objective: This study aims to determine the effect of vanillin on candida biofilm formation in vitro. Method: Vanillin (Sigma-Aldrich, UK) was prepared in 99.7% ethyl alcohol and diluted to concentrations of 0.5-20 mM. Biofilms of Candida albicans (ATCC 10231 and 2 clinical strains) were grown on the bottom of 96-well plate with Yeast Nitrogen Base (YNB) medium supplemented with 100 mM glucose in a shaking incubator at 37oC for 24 h. After washing, each concentration of vanillin was added with YNB supplemented with 200 mM glucose. The plate was incubated in shaking incubator for another 24 h at 37oC. Evaluation of biofilm was assessed through the XTT reduction assay. A solution of 0.2% chlorhexidine gluconate solution and 99.7% ethyl alcohol were used as positive and negative controls respectively. Result: It was found that 75-80% candida biofilm reduction was demonstrated at concentrations of 10.5-20 mM vanillin whereas chlorhexidine exhibited 94% biofilm reduction. Conclusion: Our results indicate that vanillin is a promising agent that can be used to cure candida infection in the oral cavity. Further studies are required to evaluate its effect on other yeast strains and cytotoxicity before consideration for usage in patients.

Initial Tensile and Residual Forces of Pigmented Elastomeric Ligatures from Various Brands

This study aimed to investigate the initial tensile and residual forces of pigmented elastomeric ligatures (clear, pink, and metallic) from three commercial brands – Brand 1 (USA), Brand 2 (USA), and Brand 3(China). Twelve elastomeric ligatures of each brand and color were evaluated for initial tensile and residual forces after stretching for 28 days at 37°C by a Universal Testing Machine. The results showed that the highest initial tensile force was 14.78 N, 20.71 N, and 15.1 N for the metallic color of Brand-1, pink color of Brand -2, and metallic color of Brand -3, respectively. There were significant (p<0.05) differences in the initial tensile force of each brand, except clear and metallic color of Brand-1 & 3 and pink color of Brand-2 & 3. Similarly, among the pigmented ligatures from each brand, significant (p<0.05) differences were observed in the initial tensile force, except metallic color of Brand-1 & 3. Brand-3 had the highest residual force after 28 days, whereas the loss of force was 80-90% in Brand-1 & 2 and 20-30% in Brand-3. There were also significant (p<0.05) differences in the residual forces in each color and brand, except metallic color of Brand-1. In conclusion, there were significant differences in the initial tensile and residual forces among the three pigmented elastomeric ligatures of the three commercial brands.

In Vitro Antimicrobial Properties of Propolis against Caries-Associated Microorganisms

Natural products have attracted much attention in recent years as a useful substance used in medicine and dental products. Propolis is a lipophilic resinous mixture collected from various plant sources by honeybees. It has been known for many biological activities including antimicrobial properties. Objective: To evaluate the in vitro antimicrobial activity of propolis against caries-associated microorganisms, Streptococcus mutans, Lactobacillus casei and Candida albicans. Materials and methods: The antimicrobial activity was initially screened using agar disc diffusion and then the minimum lethal concentrations (MLCs) were determined using broth dilution technique. Chlorhexidine (0.2%) and dimethyl sulfoxide (5%) were used as positive and negative controls, respectively. Results: Propolis exhibits the zones of inhibition ranged from 15 to 18 mm for S. mutans, and from 10 to 12 mm for L. casei, but presented no activity against C. albicans. The MLC against S. mutans was 2.86 mg/mL and those against L. casei were 11.44 mg/mL and 12.87 mg/mL. Conclusion: Propolis shows a potent antimicrobial effect against S. mutans and L. casei. This could provide a scientific basis to its application of usage in oral care products for the prevention of dental caries. However, further studies are necessary to evaluate other biological activities and molecular mechanisms of action as well as its cytotoxic effect.