system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a saltwater rinse help wounds in the mouth heal faster?

Shouldn't the salt irritate the wound, causing it to heal slower or get re-injured from swelling?
gpt
Salt water works in three ways. First, it dehydrates the bacteria due to osmosis -  that is, the water in the bacteria gets "sucked" across the cell membrane into your salt solution due to the concentration differences of the solutions to the point where the bacteria is no longer functional, effectively killing it. 
Second, it serves to physically remove any of the bacteria from the wound, and is able to penetrate deep (giggity) into the wound to get any bacteria that may be lurking below the surface. 
Third, it also dehydrates your cells in the wound, effectively killing off the surface cells that have been damaged by the bacteria, and washes them away so that the cells underneath can be regenerated and heal more effectively.
Any irritation that is caused simply causes inflammation to redirect the healing processes of your body towards the wound, which also contributes to the healing process.