Connor Scott of Main Road, Thoresway, admitted assault and causing actual bodily harm to Drieden Saiger in the early hours of September 5 last year when he appeared before magistrates in Boston.
The court was told that the victim, Mr Saiger, left The Wick in Queen Street at around midnight and stood and watched a fight going on in the street outside, where around 50 people had gathered.
Mr Saiger said he was pushed over, but when he got up, Scott, who he did not know, came over to him and punched him once in the face, knocking some of his teeth out before walking off.
The magistrates heard that Mr Saiger had to have extensive work on his teeth, including having false ones implanted.
Mitigating, Gordon Holt said around 50 people had congregated outside The Wick on the pavements and in the road, where two people were fighting on the ground and it was potentially a serious public disorder.
He said Scott was seen on CCTV to cross the road and punch Mr Saiger, who fell to the ground.
Mr Holt said Scott said he had not been taking his medication for schizophrenia and was drunk and could not remember the incident.
He said Scott had been in prison for assault and possessing a knife, committed since the date of this offence, and was now on post sentence supervision by the Probation Service until next July and added
that prison had had a salutary effect on him.
The magistrates said it was a 'very serious assault' which had resulted in 'life changing injuries', and
imposed a prison sentence of 24 weeks, suspended for two years, and he was ordered to pay the victim £3,600 compensation.