A customer punched a garage manager in the face because he was unhappy with the service he received when he took his car into the workshop.
Jason Dewar was furious when Michael Anderson refused to do a patch-up job on his Audi tyre because it would make it dangerous to drive.
Newcastle Crown Court heard the 36-year-old threw a forceful, back-handed punch at Mr Anderson, which broke two of his teeth and left a third loose.
Mr Anderson, who was left with cut lips, said he felt “shaken and shocked” by the unexpected blow, which left him in long term pain.
Mechanical engineer Dewar, of Coach Road Estate, Washington, admitted causing grievous bodily harm.
Judge Deborah Sherwin sentenced him to six months imprisonment, suspended for 18 months, with 200 hours unpaid work, £2,500 compensation order and £340 costs.
The judge told him: “I accept you are as appalled as everyone else by what you did.
“You had a sudden flash of temper which resulted in you lashing out.”
The court heard Dewar had taken his car into National Tyres at Concord, Washington, because one of the tyres was losing air.
He was told by Mr Anderson the air was leaking from the rim and as a result it could not be simply patched up or put back on the vehicle.
Instead, Mr Anderson fitted Dewar’s spare tyre to the car and put the damaged one in the boot so that the car would be safe to drive.
Prosecutor Paul Rowland told the court: “While putting the tyre in the boot the defendant struck Mr Anderson with a back handed punch to the face.
“As a consequence of that, the complainant could feel loose teeth in his mouth, which he tried to spit out.”
Glen Gatland, defending, said Dewar had been concerned when his car developed the fault in December last year, while Christmas was looming and he had young children to buy for.
Mr Gatland said: “He didn’t think he needed a new tyre, he wanted the puncture repaired.
“He thought it was the way the firm were trying to make money out of him.
“Then, he was told he would not be allowed to leave because it would be dangerous if he did, if he had an accident they would be at fault.
“He should never have done it, he accepts that.”
Mr Gatland said Dewar works long hours to support his family and is very sorry for what he did that day.