Perth dad faces court accused of brushing his teenage son's teeth too violently.

A Perth father has appeared in court on assault charges after allegedly brushing his son’s teeth with so much force the boy’s gums bled.

Steve Lawrence has pleaded not guilty to three counts of common aggravated assault.

The 36-year-old allegedly grabbed his 16-year-old son by the scruff of his neck and steered him toward the bathroom where he grabbed his toothbrush, brushed the teenager’s teeth aggressively and made him use mouth wash, according to Seven News.

The Port Kennedy father did not deny the claim, but said the teen refused to brush his teeth and he had acted with reasonable force, something permissible for parents disciplining their children in Western Australia.

Mr Lawrence is also charged with allegedly dragging his eight-year-old son to his room and locking him in after a tantrum.

His lawyer Nicole Young said they would "vigorously defend" the charges.

"We believe it is one of those instances where this is reasonable discipline by a father of his children and needed to be done," Ms Young said.

Mr Lawrence was granted bail, on the condition he stays at least 50 metres away from his two sons.

He will face court again on March 7.