A Sydney dentist says he may have accidentally rubbed his crotch against patients while performing procedures in his clinic.

Bassem Magdy El-Badrawy Fouad agreed it was common sense not to touch the breasts of female patients during a procedure or deliberately press his crotch against clients.

However, under questioning from crown prosecutor Daniel Noll, Fouad acknowledged he may have inadvertently pressed his genitals against the thigh, head or arms of patients while operating in his Mascot clinic.

"Everything was covered," Fouad told the jury at his District Court trial on Thursday.

"If that happened accidentally while I'm doing the procedure, but I'm focusing on the mouth. Never did I think about anything else."

He said he also understood the patients never consented to being exposed to the dentist's thigh or crotch area when they had dental procedures being performed.

The 55-year-old has pleaded not guilty to nine counts of aggravated sexual touching, indecent assault under authority, and intentionally sexually touching a child. All five complainants are women.

Presented with diagrams showing the "up-to-date" best practice positioning for dentists performing procedures, Fouad said they were guidelines.

"There's a significant distance between the head and what would be described as the crotch of the dentist," Mr Noll said.

Fouad said the diagram presented "the basic, standard position".

"The dentist has to refine the position as per the treatment needed," he said.

It's alleged Fouad would frequently press himself against his patients and would place his dentistry tools on their breasts.

He said it was possible he could have accidentally touched patients' breasts when reaching for his instruments but clarified they would generally be placed on the area just beneath the neck.

He has told the jury his medical conditions - deep vein thrombosis and a fungal infection - forced him to sit in such a way to put him in closer proximity to his patients.

Fouad said CCTV footage showing him putting his hand near his crotch after it came in contact with his patient was not a sign he was sexually aroused, but rather it showed him putting pressure on lesions near his thigh caused by his ailments.

The jury heard Fouad sometimes worked alone but it was not his preference.

Rather, he was often obliged to work without an assistant due to staffing issues with dental nurses.

The dentist operated at two clinics at Mascot where the alleged assaults against five complainants, who cannot be named, took place.

The trial before Judge Phillip Mahoney resumes on Monday, with the jury set to deliberate on the evidence next week.