Kim Kardashian Posts Photo of Saint's Bloody Front Tooth

Kim Kardashian is showing off her kiddo Saint -- but in a toothy sort of way ... 'cause his little chompers are front and center for everyone to see!

The reality star posted an Instagram photo Sunday that showed her alongside 9-year-old Saint, who was flashing a bloody smile with one of his front teeth about to fall out, and another one missing.

Pretty gnarly, but Kim made light of it all with a cute caption ... “The tooth fairy has been good to us 🦷🧚💸💎."

In another IG pic ... Saint gave us a big smile showing his new teeth coming in. Kim also posted a bunch of throwback snaps of Saint with 2 different grills. In one, he flashes gold Louis Vuitton teeth and, in the other, he flaunts titanium teeth, mirroring his rapper dad Kanye West.

But, Kim wasn't finished ... she also uploaded pics of her other children -- North, 12, Chicago, 7, and Psalm, 6 -- mostly with their gem-studded teeth.