Direct Analysis: used for the analysis of water and oral care products. It is conducted using a combination fluoride ion-specific electrode and a pH/ion meter. Samples are mixed 1:1 with TISAB II to adjust ionic strength. Readings are obtained directly from the ion-selective electrode.Â
Diffusion Analysis: used for the analysis of environmental and biological samples (i.e. saliva, food, soil, serum). It is conducted using a modification of the hexamethyldisiloxane micro-diffusion method of Taves (1968).Â
Microdirect Analysis: directly measures the activity of Â fluoride ions in samples of minimal fluid volume (usually less than 0.005 ÂµL).Â This method is used primarily for determining fluoride content of dental biofilm fluids / solids and plasma from human and animal models (mice, zebra fish). Samples are placed under mineral oil directly on the electrode surface and numerous samples can be measured in rapid succession.
Enamel Fluoride Uptake: this method can evaluate the effect of treatment time and dilution on the ability of oral care products to promote fluoride uptake. The test procedure is a modification of Test Method #40 in the FDA Monograph, which includes the formation of a caries-like (subsurface) lesion that is formed using a solution of 0.1M lactic acid and 0.2% Carbopol 907, 50% saturated with HAP at a pH of 5.0. Enamel microbiopsies are conducted using modification of the microdrill enamel biopsy technique as described by Sakkab et al. to analyze the fluoride content of partially demineralized enamel.
Equipment: Microdrill Apparatus (3 units)
Model: Custom-made, Stellar Systems, Inc
Capabilities: This apparatus allows precise drilling of dental experimental units. The resulting enamel powder is collected and analyzed for fluoride concentration. It is connected to a video monitor through digital camera and allows the dimensions of the drill hole to be accurately measured.
Equipment: pH/ISE Meters (3 units)
Models: Thermo Electron, Orion Dual Star (2)
Thermo Electron, Orion 920A+ (1)
Capabilities: This ion-analyzer is connected to a fluoride ion-specific electrode and allows the determination of fluoride concentration in samples collected from dental specimens, beverages, water, etc.
Equipment: Inverted Electrode for Microanalysis
Capabilities: This custom-made apparatus allows determination of fluoride concentration in small samples (nanoliter level). Most recently, it has been used for analysis of plaque fluid, total plaque, mouse plasma and human plasma.