As per a study, men live up to five years longer if they kiss their wife before going to work.
Kissing is good for our teeth as the anticipation of a kiss increases the flow of saliva to our mouth, giving the teeth a plaque-dispersing bath. Source
The Kama Sutra describes over 30 types of kisses, one of which also includes “fighting of the tongue”. Source
When two people kiss, they exchange between 10 million and 1 billion bacteria.
It is possible for a woman to reach an orgasm through kissing. Source