People who have their tongue pierced risk developing a gap in their front teeth as a result of ‘playing' with the tiny barbell-shaped stud, US researchers have said.

According to the team from the University of Buffalo's School of Dental Medicine, even a fraction of an inch gap can cost hundreds or thousands of euro in orthodontic bills to repair.

A previous study by the same team found that people with tongue rings tended to push the metal stud up against their upper front teeth, a habit commonly referred to as ‘playing'.

This happened in a ‘very high percentage of cases', they noted.

In their latest study, they looked at a 26-year-old female patient who complained that a large space had developed between her upper central incisors (upper front teeth). The patient also had a tongue piercing that held a barbell-shaped stud.

The tongue was pierced seven years earlier and every day for seven years, she had pushed the stud between her upper front teeth, creating the space between them and, subsequently, habitually placing it in the space. The patient did not have a space between her upper front teeth prior to the tongue piercing.

"The barbell is never removed because the tongue is so vascular that leaving the stud out can result in healing of the opening in the tongue, so it makes perfect sense that constant pushing of the stud against the teeth - every day with no break - will move them or drive them apart," explained lead researcher Prof Sawsan Tabbaa.

The patient provided the research team with photos that demonstrated she had no space prior to having her tongue pierced. For the purposes of treating this patient's space, it was assumed that positioning of the tongue stud between the maxillary central incisors or ‘playing' caused the midline space.

Her treatment involved fixed braces to push the front teeth back together.

The researchers pointed out that tongue piercings can result in serious injury, not just to teeth. They have also been associated with hemorrhage, infection, chipped and fractured teeth, trauma to the gums and, in the worst cases, brain abscess.

"The best way to protect your health, your teeth and your money is to avoid tongue piercing," Prof Tabbaa insisted.

Details of these findings are published in the Journal of Clinical Orthodontics.