Two girls aged 17 and 18, were taken to Royal Stoke University Hospital with respiratory and abdominal issues.
Christopher Wardle, 25, formerly of Barrack Road, Newcastle-upon-Tyne, and Spencer Benham, 23, of Wilberforce Road, Leicester, pleaded guilty to possessing a prohibited weapon.
They were sentenced at Stafford Crown Court on 15 July.
More on this story and others from Staffordshire
Twelve people, who were inside the restaurant at the time, were also examined by paramedics after reporting "varying degrees of respiratory and stomach irritation", West Midlands Ambulance Service said.

Reich's Grammy-winning 1988 work was performed at Edge Hill station, with passenger trains rolling in and out of Liverpool on both sides of the stage.
About 1,200 people watched on the station's Victorian carriage ramp.
The US composer introduced the show, which is one of a number of events to celebrate his 80th birthday on Monday.
Edge Hill station was on the world's first passenger train line, and George Stephenson's Rocket passed through when the Liverpool to Manchester line opened in 1830.
The station provided the backdrop for Thursday's performance of Different Trains, performed by the London Contemporary Orchestra.
The work was inspired by Reich's own childhood train journeys across the US and trains that transported Jews to World War Two concentration camps around the same time.
"If I had been born in Stuttgart or in Brussels or Budapest, you and I wouldn't be having this conversation," he told BBC 6 Music.
Artist and film-maker Bill Morrison used archive film from the era to create a film to accompany the Edge Hill show, which was staged by arts organisations Metal and the Liverpool Biennial.
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Two men who set off a canister in a fast-food restaurant have been jailed for 10 months each.
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The world's oldest active train station has hosted a live performance of composer Steve Reich's Different Trains, as real trains rumbled past.