Background, aim: Halitosis, mainly caused by bacteria located on the poster
ior dorsum of the tongue and in periodontal pockets, is due to formation of
volatile sulfur compounds (VSC). The hypothesis to be tested was that the
affinity of a metal for sulfur determines its anti-VSC activity.
Method: Clinical tests were carried out on 12 subjects who rinsed with cyst
eine to induce halitosis (baseline) before rinsing with 7.34 mM ZnCl2, SnF2
and CuCl2. Mouth air VSC analyses were repeated following cysteine rinses
at 1 h, 2 h and 3 h using a gas chromatograph. In vitro experiments tested
toxic metals Hg2+, Pb2+ and Cd2+. 10-mul aliquots of metal salts were added
to 1-ml aliquots of human whole saliva from 30 subjects. Samples were incu
bated overnight at 37 degreesC and saliva headspace was analyzed for VSC in
a gas chromatograph.
Clinical results: Cu2+> Sn2+> Zn2+ (supports hypothesis). Zn2+ had signific
antly less anti-VSC effect compared with Cu2+ and Sn2+ at 1, 2 and 3 h. In
vitro results indicated that Hg2+, Cu2+ and Cd2+ had close to 100% anti-VSC
effect, and that Pb2+ was less effective and Cd2+ more effective than expe
cted in inhibiting VSC.
Conclusions: Apart from Hg2+ and Cu2+, the metals had a significantly great
er effect on H2S than on CH3SH. Cu2+ and Hg2+ have well-known antibacterial
activity and may presumably also operate by this mechanism.