Effects of Flavoured Mouth Rinses on Morning Breath Odour: a Sensory, Analytical and Microbial Evaluation

Transient oral malodour such as morning bad breath is very common and is caused by accumulation of bacteria and food residues, mainly at the posterior part of the tongue. The use of antimicrobial flavours may help to reduce malodours with limited side effects. The purpose of this work was to compare the effects of five alcohol-free mouth rinses containing 0.2% w/w antimicrobial flavour oil on 24 human subjects in a randomized, double-blind clinical study. Two mouth rinses containing triclosan and peppermint oil were used as positive controls. Oral malodours and flavour intensities, as well as analytical and microbial analyses of saliva samples, were performed before rinsing and 1 min and 1 h after rinsing the mouth with a 20 ml mouth rinse for 1 min. Immediately after rinsing, oral malodour scores and salivary bacterial counts were markedly reduced (85 ± 9% and 54 ± 12% decreases, respectively). At 1 h after rinsing, maximum efficacy (61 ± 18% reduction in oral malodours, 40 ± 11% decrease in salivary bacterial count) was observed with the mouth rinses containing the highest levels of menthol, limonene, carvone and eugenol, and these ingredients could still be detected in the saliva of most subjects. The finding that selected antimicrobial flavours have beneficial effects against salivary microorganisms and transient oral malodours may be important for the design of oral care products that promote fresh breath up to 1 h after rinsing without compromising taste.