Savage Lisa Braithwaite, 28, grabbed mum-of-one Emma Imeson by the mouth and used brute force to tear her cheek from mouth to chin – leaving her with a "gaping hole" in her face.
Jailing Braithwaite at Leeds Crown Court on Friday, Judge Terence Walsh told her: "The force used to cause these injuries with your bare hands must have been quite incredible."


Carmel Pearson, prosecuting, said Braithwaite had been screaming and shouting at her boyfriend in the street after drinking at Miss Imeson's home in Castleford on July 23.
Miss Imeson saw Braithwaite, of North Street, Castleford, strike him and stepped between the pair to "calm them down".
The court heard Braithwaite – who was "very drunk" – pounced on Miss Imeson's back and knocked her to the floor, where she scratched her neck and delivered blows to her head. Miss Pearson said: "She placed her hand inside Miss Imeson's mouth, who felt the mouth rip. She described the defendant's hand as being like a claw."


Miss Imeson – who said she could feel a "gaping hole" around her lips – was taken by ambulance to Pontefract General Infirmary.
She needed 22 stitches to seal the rip from her mouth to her chin.
Anthony Moore, mitigating, said: "The injuries were incredible given there was no weapon used. I have never encountered anything like that. It's almost beyond belief.
"She finds it hard to believe she acted in this way and it's fair to say she frightened herself with her actions that night."


He told the court Miss Imeson had punched Braithwaite first, but his client had received professional help to manage her anger and had not had a drink since the attack.
He added: "She wants me to express how genuinely sorry she is for that night and the effect this incident has had on Miss Imeson."
Sentencing Braithwaite, the judge described Miss Imeson's injuries as "horrific" and said it was "inevitable" that she would be left permanently disfigured.
Braithwaite had pleaded guilty to wounding with intent to cause grievous bodily harm.