Rees, formerly of Aberystwyth Street, Splott, Cardiff, also assaulted PC Carly Brown on the night of January 12.
Miss Shepherd said: “This was a sustained incident which lasted around 25 minutes and in which the defendant’s teeth were used as a weapon.”
He pleaded guilty to causing actual bodily harm, two counts of assaulting an emergency worker and resisting a constable.
The defendant also admitted the criminal damage of a police body worn camera and to a Gwent Police van by spitting in it.
Rees has previous convictions for common assault, resisting a constable and drink driving.
Giles Hayes, representing him, said: “Drugs and alcohol played their part in his behaviour. He wasn’t thinking properly.