Inhibition of calculus formation by dentifrice formulations containing essential oils and zinc

To examine the effect of three essential oil-containing dentifrice formulations with different zinc salts and concentrations on dental calculus formation in rats.

A total of 150 rats were randomly distributed into five litter and sex-matched groups of 30. They were maintained on a calculogenic diet and topically treated twice daily with undiluted dentifrices. Each experimental dentifrice formulation contained a zinc salt, a fixed combination of essential oils (i.e. eucalyptol, menthol, methyl salicylate, and thymol) and a hydrated silica abrasive. Commercial zinc-free and zinc-containing dentifrices were included as negative and positive controls, respectively. After 17 days calculus was scored post-mortem on molar teeth.

All groups of rats treated with zinc-containing dentifrices had significantly (P < 0.05) lower mean calculus scores than the group treated with a zinc-free control dentifrice. Other variables (e.g. fomulation type, essential oil content, zinc salt and concentration) did not significantly affect calculus scores. Thus, all three essential oil/zinc-containing dentifrices and a commercial, zinc-containing, tartar-control dentifrice inhibited calculus formation in this rat model.