A man was taken to hospital with his brace embedded into his lip following a seafront brawl in the early hours.
Officers were called to the junction of Kings Road and West Street following reports of several men fighting outside the Beach Hut cafe.
The incident took place at about 3.30am on Sunday but police have just released details now.
A 23-year-old from Kent and a 19-year-old from Surrey were taken to the Royal Sussex County Hospital in Brighton after the incident.
PC Darren Robertson, of Sussex Police, said: “This was a nasty incident between a group of men culminating in one [the 19-year-old] losing a tooth and another [the 23-year-old] being knocked unconscious and having his orthodontic brace embedded into his lip.
“We are continuing to view CCTV from the area but would really like to hear from anyone who witnessed the fight or has any information that could assist us with the investigation.
Three teenagers from Hampshire were arrested at the scene for various offences including assault and carrying false ID.
They have been bailed with the condition not to enter Sussex until May 22 pending further enquiries.
Anyone with information is asked to call police on 101 or the independent charity Crimestoppers on 0800 555 111.
