A dentist accused of groping a teenage girl after giving her gas and air has gone on trial at Bradford Crown Court.

Dr Muzzafar Zaman, 40, is alleged to have told the youngster that he was trying out a new technique when he called her into his surgery for an after-hours appointment in January last year.

Richard Newbury, prosecuting, said that Zaman rubbed the 16-year-old's breasts as she sat in his dentist's chair, conscious but under the influence of nitrous-oxide.

The prosecution alleges Zaman was grooming the girl - "trying her out" in the hope of progressing further.

The jury were told that Zaman had phoned the girl, who cannot be identified for legal reasons, a few days earlier to change her appointment to 5.20pm - 20 minutes after the surgery on High Street, in Brighouse, closed.

Mr Newbury told the court that Zaman, who denies assaulting the girl, knew that he would be alone and had contrived the situation "to con her into allowing him to do what he was doing at the time."

The girl was dropped off for her appointment by her father and Zaman opened the locked door, sat her in the chair and asked her if he could try out a new technique which involved giving her gas and air.

The court was told that once the mixture started to take effect, Zaman started rubbing her hand and arm saying, "are you all right?"

The jury heard that she was struggling to keep her eyes open and Zaman told her that she could close them if she liked. He is then alleged to have rubbed her stomach before moving his hand up and rubbing her chest.

Mr Newbury said that it was the Crown's case that Zaman had deliberately engineered the situation and was grooming the girl.

"The prosecution say that he was trying her out," Mr Newbury told the jury. "It may well be that having been successful in his eyes on the Thursday he may well have wished to repeat it or progress a little bit further on a subsequent occasion.

"The events you are concerned with may well be some sort of grooming procedure testing this young lady out to see his subterfuge had worked."

Zaman, of Central Park, Savile Park in Halifax, has pleaded not guilty to a charge of sexual assault and denies that he was acting inappropriately, claiming that he only touched the girl's hand and arm.

He told police that he was by himself in the surgery because his secretary had gone home sick.

Zaman admitted that he had kept no record of the girl's appointment and had breached the rules governing administering gas and air despite going on a training course just a few months prior to the alleged incident.

"This was a wholly unnecessary procedure this man was carrying out," Mr Newbury said.

"He was trying to keep it as quiet as he possibly could and his objective was that he had decided that he was going to try and see how far he could get with this young lady by touching her and seeing what her reaction was."

The young complainant was expected to give evidence today.

The trial continues.