Why is a salt water rinse necessary after tooth extraction?

Not necessary: This is commonly tecmended but there is no scientific proof that it is beneficial. Regular brushing and rinsing your mouth with plain water after each emal is fine.

Cleanliness: Its important to keep a surgical site clean to insure good healing. Its not a good idea to brush around a new surgical site because that may cause bleeding. Rinsing the site is a good way to clean it. Warm salt water works well, is soothing, and costs virtually nothing.