High-resolution (1)H NMR investigations of the capacity of dentifrices containing a "smart" bioactive glass to influence the metabolic profile of and deliver calcium ions to human saliva.

Abstract

Dentifrices containing H(2)O-reactive bioactive glasses alleviate hypersensitivity in teeth via the blockage of open dentinal tubules. Here, the ability of two such products to release Ca(2+) ions into human saliva was investigated, together with their influence on the status of this biofluid's (1)H NMR-detectable biomolecules. Human salivary supernatants were equilibrated with increasing volumes of those derived from each dentifrice (5.00 min at 37 degrees C). These biofluids were also equilibrated at 37 degrees C with a preselected quantity of the intact products (samples were collected at increasing timepoints). Salivary Ca(2+) concentrations were monitored by a (1)H NMR technique involving ethylenediamine tetra-acetate addition and/or atomic absorption spectrometry. Added Ca(2+)- and dentifrice supernatant volume (DSV)-induced modifications to the salivary (1)H NMR profile were explored by spectral titration. Data acquired demonstrated added DSV-dependent increases in salivary Ca(2+) concentrations and (Ca(2+)-independent) modifications to the intensities of selected salivary (1)H NMR signals, particularly those of the malodorous amines methyl-, dimethyl-, and trimethylamines, which were diminished by up to 80% of their prior values. Time-dependent elevations in salivary Ca(2+) level were observed on equilibration with the intact dentifrices. Added Ca(2+) ions exerted a concentration-dependent influence on a range of resonances (including those of citrate, succinate, pyruvate, and lactate). These data provide valuable information regarding the mechanisms of action of the products tested.