METHODS: Each dentifrice was prepared for 1H NMR analysis via the addition of 2.00 ml of doubly-distilled H2O to 200 mg samples by thorough rotamixing, centrifugation and removal of the clear supernatants. Unstimulated human saliva samples were collected from healthy human volunteers (n=8) and supernatants derived therefrom were each divided into three equivalent 0.60 ml portions. The first and second of these were treated with 0.01-0.08 ml volumes of supernatants obtained from dentifrices [1] and [2] respectively, whilst the third group served as untreated controls. Samples were subjected to 1H NMR analysis (operating frequency 600.13 MHz).
RESULTS: Results acquired demonstrated that each 1H NMR-responsive component present in either dentifrice (glycerol, stearate, sodium lauryl sulphate and acesulfame) was readily observable in the 1H spectra acquired with little or no interference from resonances arising from salivary components. Plots of ratios of the electronically-integrated intensities of each dentifrice component's 1H NMR signals to that of an added internal standard were all linear (r > 0.997), data indicating the applicability of this technique to determinations of the salivary levels of each of the above dentifrice ingredients.
CONCLUSION: High resolution 1H NMR analysis provides much valuable information regarding the identification and quantification of dentifrice components in human saliva, and may also serve as a useful means for evaluating the mechanisms of action of such products.
[1]: Oravive Tooth Revitalising Paste and [2] Denshield Shield Builder, NovaMin Technology, Inc., Alachua, FL 32615 USA.