Samuel Clarke’s stunned partner described being “shocked” and confused by the impulsive attack - which came about with no warning as she watched TV with the defendant.
Derby Crown Court heard how Clarke, 28, had been drinking since 10am when threw the bottle at his partner - at around midnight on January 23.
Annabel Lenton, prosecuting, told Derby Crown Court Clarke and his partner were watching TV game shows on a sofa at the time.
She said: “The defendant got up out of nowhere and threw a Prosecco bottle at her directly in the mouth with such force that it broke a tooth in half.
“She described being confused, not knowing why the defendant had done this.
“The defendant then threatened that he would tell the police that she smashed his face and hand to discourage her from reporting it.”
Clarke and his victim had been friends before getting into a relationship in July last year and he was described as suffering mental health issues and alcoholism.
However the victim had no faith that a domestic violence protection order would work - as they had not worked in the past, added Ms Lenton.
The girl’s mother said in a statement that she “had not been the same since meeting the defendant”.
The court heard Clarke had eight convictions for 10 offences - including three domestic incidents with past partners.
During one he punched a woman to the chest and took her handbag, stealing £50.
In 2016 Clarke was handed a six-month restraining order when he stripped his girlfriend of her upper clothing and left her standing outside in just a bra.
The nasty incident came about following a row at a Swanwick pub during which the long-suffering girlfriend told him the relationship was over.
Clarke, of Ashton Close, Swanwick, who was sentenced this week for the Prosecco bottle attack, admitted assault with actual bodily harm.
His barrister had previously applied for an adjournment giving the defendant more time to prepare his mitigation.
Before adjourning the sentence Recorder Michael Auty QC told him to be prepared for “a sentence of imprisonment of some length”.