Angie Stone -- Daughter's Teeth Were Rotting Before the Fight Broke Out

Angie Stone's daughter definitely has a messed up grill after the fight that got Angie arrested, but the real reason her teeth fell out might be failure to root canal ... instead of a blow from her mother.

As TMZ first reported, Angie admitted to cops she hit Diamond with a metal jewelry stand in self defense. Diamond says the stand knocked out 2 teeth.

Sources close to Angie tell TMZ ... the teeth fell out because they'd been rotting out of Diamond's mouth long before the fight. In fact, Diamond cops to her teeth being rotten but tells us -- "It don't matter if my teeth were rotten or not ... I could have gotten a root canal, but she finished the job."

Diamond also disputes her mother's claim she was acting in self defense -- telling us the fight started with both women yelling ... but says Angie grabbed the stand to threaten her. She claims it only got physical when she threatened to call cops -- and Angie struck her in the face with the stand.

Diamond admits wrestling her mother to ground at that point, and says her brother had to break up the scrap. As we reported ... only Angie got arrested and booked for aggravated assault.