A handy'Okay to kiss' kit can warn partners of foul breath, thus averting a smelly kiss.
Tel Aviv researchers, who have come up with this ultimate solution, have revealed that a blue result suggests that a person needs a toothbrush.
However, add the researchers, one would be "okay to kiss" if it is clear.
The researchers thus far believed that only one population of bacteria (the Gram-negative ones) break down the proteins in the mouth and produce foul odor.
However, lead researchers Prof. Mel Rosenberg and Dr. Nir Sterer have found that the other population of bacteria (the Gram-positive ones) are bad breath's bacterial partner.
They say that such bacteria seem to help the Gram-negative ones by producing enzymes that chop sugary bits off the proteins that make them more easily degraded.
According to them, the presence of this enzymatic activity in saliva serves as the basis for the new "OkayToKiss" test.
The patent-pending okay-to-kiss device, containing a color indicator and saliva collector, is the result of ongoing research in Prof. Rosenberg's laboratory.
"All a user has to do is dab a little bit of saliva onto a small window of the OkayToKiss kit. OkayToKiss will turn blue if a person has enzymes in the mouth produced by the Gram-positive bacteria. The presence of these enzymes means that the mouth is busily producing bacteria that foster nasty breath," says Prof. Rosenberg.
He says that besides its social uses, the test can be used as an indicator of a person's oral hygiene, encouraging better health habits, such as flossing, brushing the teeth, or scheduling that long-delayed visit to the dentist.
He reckons that the kit may be ready in about a year for commercial distribution, probably in the size of a pack of chewing gum, to fit in a pocket or purse.
It is disposable and could be distributed alongside breath-controlling products, says the researcher.
A research article describing the kit has been published in the Journal of Breath Research.