Pictures of a bloodied Ella Ekatone, 15, have been posted on Facebook by friends who were at an 18th birthday party in Wellington St on Saturday.
The party got out of control, with reports of people passed out in the streets, and when police arrived they were pelted with dozens of bottles.
About 35 officers tried to disperse 150 party-goers and were responding to a 111 call from the property where the party was being held about a fight that had started in the backyard when Ella was injured.
Ella's mother, Nicola Healey, last night said her daughter had given a statement to police.
Ella had told her police jumped the fence just before midnight and told about 20 teenagers to leave.
"One of them pushed her from behind with such force she tripped. He pushed her again, he swore at her in her face, she said nothing back to him, she just did what she was told.
"[The second push] slammed her face into the concrete and ... the force he's used, her two front teeth have been ripped out of her head, roots and all. I went back to the property and ended up finding the teeth and couldn't believe they were hers."
When Ms Healey saw her daughter that night at Middlemore Hospital Ella was hysterical.
"The hospital have said they don't know if they can replace her teeth until she's 21, so she'll have to have something temporary in the meantime. She's got massive bruises and grazes on her knees from the fall. She saw herself on TV and she cried. It's like she's in shock."
It amounted to police brutality against children and Ms Healey wanted the officer charged with assault. She was disgusted Ella had been told to "f***** move."
Her daughter could not see the officer's face because he was one of about 10 wearing riot gear with helmets covering their heads.
But she'd told police he was on the left side of the line. "The other nine people know who was on the lefthand end of the row."
Counties Manukau Police District Commander Superintendent John Tims said an inquiry was under way.
"Police were called to the address at around 11.15pm, we were advised that there were individuals intoxicated and passed out on grass verges."
Mr Tims said one police unit did a drive-by to assess the party.
"While doing this they observed around 150 people on Wellington St and around 50 bottles were thrown at the police patrol car."
Mr Tims said: "Police officers in the patrol vehicle then called for back-up ... The officers moved in to the address and tried to disperse the partygoers from the house and also the surrounding areas. No one was arrested as a result of the house being cleared of partygoers."
It's understood some arrests occurred nearby when a fight broke out but it was unclear if those involved had been to the party or not.
The complaint was now being investigated by the Independent Police Conduct Authority, he said.
"We are speaking to witnesses and also all the police officers that were present at the Wellington St event to ascertain exactly what happened."
