Bernadette Mitchell had both jaws broken to achieve the perfect smile.

The 18-year-old suffered for six years with dental braces to try to correct her underbite.

But as she put up with constant trips to the dentist, the problem continued.

After watching her two younger brothers get rid of their braces while she was still persevering, the Hove Park sixth form student knew the time had come for drastic action.

During a visit to the Royal Sussex County Hospital in Brighton she was offered pioneering treatment to correct her bite, meaning she could throw away her braces for ever.

Consultant maxillofacial surgeon Keith Altman proposed an operation to break both jaws and reposition them.

Instead of using fixed metal plates, the broken bones would be fixed with a biodegradable alternative which would start dissolving within two to three months.

They would be completely gone after four years, by which time Bernadette's bones would have knitted themselves back together.

The teenager would not need another painful operation to remove the plates.

Bernadette, of Portland Road, Hove, said: "My bottom jaw was in front of my top jaw - only a couple of millimetres but I really wanted it corrected.

"I'd worn braces from the age of 12 but they hadn't worked and I was told this was the best age to have the operation."

It was performed in February and at first she suffered severe swelling and could eat only liquidised food.

She said: "My mum took a week off work to look after me.

"I couldn't chew so I lived on soup, ice cream, jelly and very strong painkillers."

After a few weeks all was well, however, and the gap year student hopes to travel around Europe with a friend before deciding on a career.

Mr Altman said traditional permanent titanium implants were not universally popular and 20 per cent of patients needed a second operation to remove the plates, often after developing an infection.

Mr Altman has been using the dissolving system for about 18 months.

More than 50 patients have benefited thanks to the pioneering surgeon, who had to qualify as a dentist and a doctor.

The plates, made by Finnish company Inion, are made from acids found naturally in the body.

They are mixed with other substances into a plastic, which becomes pliable when warm.

Many of Mr Altman's patients are aged 15 and over and, like Bernadette, have undergone orthodontic treatment.

Mr Altman, who also works at Eastbourne District General Hospital, said the system worked in a similar way to soluble stitches.

He said: "They dissolve through hydrolysis. It's a chemical action.

"It's only carpentry. You are just using plates and screws, just a different material."