Not sure about just kissing, but here is about couples living together: https://journals.asm.org/doi/10.1128/msystems.00043-17 https://journals.asm.org/doi/10.1

Not sure about just kissing, but here is about couples living together: https://journals.asm.org/doi/10.1128/msystems.00043-17 https://journals.asm.org/doi/10.1128/msystems.00043-17 I have a friend who started having a lot of teeth issues after moving in together. She swears nothing else has changed (i.e. food or stuff)