A dentist on trial on three charges of sexually assaulting a trainee dental nurse told a court he opened all the buttons on her uniform tunic top but denied any sexual intent.

He said the nurse had bought a new tunic with buttons down the front and he wanted to check them as his other nurse had problems with the buttons falling off a similar uniform.

"I said I would check the buttons. I undid five buttons on the tunic. It took 30 or 40 seconds and she made no request to me to stop," said the dentist.

He claimed that nurses who previously worked for him always wore a roundneck t-shirt under their tunics and he expected the same but she was only wearing a bra underneath.

"I was not focused on it [her bra]. I was literally looking at the buttons. I know it does not make sense but I made no attempt at sexual assault, sex or any sexual contact at all," he said.

He pointed out that his other nurse was walking back and forth on the corridor and a patient was due to come in at any minute.

"I was only checking the uniform, there was no other intent, it's difficult to explain. Now with hindsight I can see how inappropriate it was. It's hugely regrettable," said the defendant.

He said he was "shocked and devastated" when he heard the allegations that had been made against him and said that at no point did he force himself on the nurse.

He is denying three counts of sexual assault on the 23-year-old nurse at his dental practice in April and June of 2008.

The trainee nurse claimed that the dentist put two of his fingers on her sternum between her breasts during while checking the alignment of her teeth.

She claimed that on a second incident, the defendant was photographing her tattoos with a micro-camera which he then put inside her pants.

And in a third incident, the nurse claimed that her employer opened the buttons on her tunic exposing her bra.

Cork District Court heard yesterday that the nurse left the dental practice after the third incident and went on sick leave. She had only been working there for six weeks in total.

Judge Tim Lucey adjourned the case to next Thursday to fix a date for hearing.