The effect of enriching denture adhesives with chlorhexidine diacetate on the proliferation of Candida albicans: an in vitro analysis.

Denture adhesives are widely used in dentistry. The growth of Candida albicans on the denture base is common on both jaws, particularly in elderly patients. A strong correlation has been found between the growth of Candida albicans and dentures, potentially leading to denture stomatitis. Recent studies show that the addition of chlorhexidine diacetate (CHDA) to denture adhesives can have a protective effect against denture stomatitis. The aim of this research is to examine the antifungal properties of three denture adhesives when CHDA is added. We hypothesize that the addition of CHDA to denture adhesives will result in antifungal activity against Candida albicans. Three denture adhesive materials (Corega, Protefix and Kukident) were prepared with and without the addition of CHDA in order to measure whether CHDA increased the resistance of the adhesives to the growth of Candida albicans. Dynamic and static intercellular changes were assessed through direct contact test (DCT) and confocal microscopy. The tested materials were evaluated immediately after setting and at 14 days post-setting. When combined with CHDA, all three denture adhesive materials decreased Candida albicans growth compared to the control (p less than 0.0001). This inhibition of growth was more prominent in the first 24 h. The confocal microscopy results supported the DCT findings. The addition of CHDA to denture adhesive pastes inhibits growth of Candida albicans, and may potentially reduce the incidence of denture stomatitis. Further studies are warranted.

The effects of in vitro fluoride mouth rinse on the antibacterial properties of orthodontic cements.

OBJECTIVES: To investigate the ability of orthodontic cements to regain their antibacterial effect after aging for 1 month, followed by 2 weeks of fluoride 'recharging' through daily fluoride rinse. MATERIALS AND METHODS: Four orthodontic cements were tested: composite resin-based materials (Transbond XT and Transbond Plus), a conventional glass ionomer cement (CX Plus) and dual-cured resin-reinforced glass ionomer cement (Fuji ORTHO LC) by direct contact test. After polymerization and a 30-day aging process, the samples were rinsed daily with 0.05% NaF solution for 14 days. Twenty-four hours after the last fluoride rinse, Streptococcus mutans cells (approximately 1 x 10(6) ) were placed on the surface of each sample for 1 h at 37°C to establish direct contact. Bacterial growth was monitored for 24 h by temperature-controlled spectrophotometry. Similar experiments were conducted after aging for 48 h and 72 h after the last fluoride rinse. One-way anova, two-way anova, and Tukey's multiple comparison test were applied to the data. RESULTS: Twenty-four hours after the last fluoride rinse, the resin-modified glass ionomer and the glass ionomer showed potent antibacterial properties, whereas the composite-based material Transbond XT encouraged bacterial growth. After 72 h, only Fuji Ortho LC maintained its bacteriostatic properties while all the other tested materials showed no antibacterial activity. CONCLUSIONS: Fourteen days daily fluoride rinse temporarily revives the antibacterial properties of the resin-modified glass ionomer cement and glass-ionomer-based cement.

In vitro CPC retention and VSC adsorption by IPM oil droplets: possible mechanisms of action of a two phase mouthwash.

Two phase oil-water mouthwash has been previously shown to efficiently bind oral microorganisms, relying on their cell surface hydrophobicity. The aim of the present in vitro study was to test the cetylpyridinium chloride (CPC) retention and volatile sulfide compounds (VSCs) adsorption abilities of the oil droplets created by mixing of a two phase oil-water solution. VSC adsorption was assayed using a salivary incubation assay and garlic powder solutions, and demonstrated using microscopic sulfide assay. CPC retention was assayed by kinetic and endpoint measurement of Streptococcus salivarius outgrowth using microplate (ELISA) reader. Results showed that the isopropyl myristate (IPM) oil droplets in the two phase solutions were able to adsorb 68-80% of VSCs. CPC at a concentration of 0.05% was most affectively retained by the oil droplets showing a significantly increase in residual antibacterial activity against Streptococcus salivarius. These results taken together, suggests that VSC adsorption and CPC retention by IPM oil droplets may be two additional mechanisms in the activity of the two phase mouthwash formulation.

Surface antibacterial properties of compomers.

AIM: This was to evaluate the antibacterial properties of four different compomers, using direct contact test (DCT) and agar diffusion test (ADT). Compomers (Polyacid Modified Composite Resin) form a group of dental restorative materials which were developed in order to improve conventional glass-ionomer and are widely used by pediatric dentists in primary dentition. Microorganisms captured under restorations or penetrating through the micro-gap at the tooth-restoration interface are the cause of secondary caries and pulpal pathology. METHODS: For the DCT, 8 samples of Freedom (SDI), F2000 (3M-ESPE), Dyract (Dentsply) and Hytac Hplitip (3M-ESPE) were placed on the sidewalls of wells in 96 microtiter plate. After polymerization, freshly grown streptococcus mutans cells (1x10(6)) were placed on the surface of each sample for one hour at 37 degrees C, fresh media was then added to each well and bacterial growth was followed for 16 hours by temperature controlled spectrophotometer. Similarly prepared samples were aged in phosphate buffered saline for 1, or 7 days and the DCT was repeated. The ADT was performed by placing samples in uniform wells punched in agar plates. RESULTS: In the DCT, freshly polymerized samples of F2000 showed the most potent antibacterial properties, while those of Hytac Hplitip showed moderate antibacterial phenomena. Dyract and Freedom did not show any antibacterial activity relative to the control material. None of the four aged materials showed antibacterial activity in the DCT after 1 or 7 days. In the ADT the halo in the bacterial lawn was measured after 48 hours and only F2000 demonstrated an inhibition zone of 2.15+/-0.3 mm. Statistics. Two way ANOVA indicated a significant difference in the growth rate of bacteria placed both on the different compomers (P<0.001) and in different tested time points (P<0.001). CONCLUSION: None of the compomers tested provided significant long term antibacterial activity.