H(2)S generation and E(h) reduction in cysteine challenge testing as a means of determining the potential of test products and treatments for inhibiting oral malodor.

Bacterial degradation of the sulfur-containing amino acid, cysteine, involves two biochemical processes that contribute significantly to oral malodor generation. The first is production of hydrogen sulfide, a major component and common indicator of oral malodor formation. The second is generation of the sulfhydryl anion, HS(-), an anion that is central to the lowering of the oxidation-reduction potential (E(h)). A reduced E(h) is fundamental to the growth and metabolism of the oral Gram negative anaerobic bacteria. These microorganisms are responsible for oral putrefaction, a process primary to both oral malodor generation and gingivitis-periodontitis development. One purpose of this paper is to report on the testing of a number of anti-malodor treatments and products for their effects on H(2)S formation and E(h) reduction, two processes that occur rapidly and do so simultaneously after the oral bacteria are challenged with cysteine. A second is to report on aspects of cysteine challenge testing in the development of an anti-malodor product composed of ZnCl(2) and sodium chlorite that simultaneously inhibits both H(2)S formation and E(h) reduction and effectively inhibits oral malodor.