When Dr. Darren Fee rushed into the surgical suite, he saw a four-year-old girl lying unconscious in a dentist's chair.

Her heart had stopped and she wasn't breathing.

Fee was called to testify Wednesday at a hearing in Edmonton conducted by the Alberta Dental Association and College, which is investigating what happened on Sept. 7, 2016, in the dental office of Dr. William Mather.

The little girl Mather was treating that day, Amber Athwal, suffered permanent brain damage because of oxygen deprivation.

Mather, 68, faces five counts of unprofessional conduct, and has pleaded guilty to three of the charges.

He retired from practice two weeks ago.

During his testimony, Fee told the hearing he was urgently summoned to help that day by Mather's dental assistant.

He rushed from his own office just down the hall.

"I said, 'Let's put the child on the ground,' and asked on my way out the door to make sure 911 was called," Fee, a dentist and dental anaesthesiologist, told the hearing Wednesday.

He told the tribunal that CPR could only be properly administered if the patient was on a hard surface. That's why he told them to move Amber to the floor.

Fee ran into the back hallway shared by both offices to get his nurse and a crash cart. When they returned, Amber was on the ground.

Amber Athwal

Amber Athwal before dental surgery, left, and after. (Supplied, CBC News)

No one was performing CPR, but Fee said Mather was holding an oxygen mask over the child's face. Fee said he quickly discovered the oxygen wasn't turned on.

The hearing has been told Amber was in post-surgical recovery when she went into cardiac arrest.

Fee said it's standard practice for a vital-signs monitor to be attached to a patient in recovery.

Monitor was turned off

"There were no monitors attached to her," Fee testified. "The monitor was turned off and the monitor extensions were rolled up next to the monitor."  

Fee's nurse immediately started CPR. Fee turned on the oxygen and used a bag to deliver it to Amber. Mather continued to hold the mask over the little girl's nose and mouth.

"During the code, I asked Dr. Mather for a health history on the child," Fee said. "If she was healthy, what had happened. He indicated to me the patient had been in recovery for 15 minutes. They'd worked on her for four minutes before they called for me."

It's unclear how long Amber was in medical distress before Mather's registered nurse, Tasneem Ali, noticed something was wrong.  

"I looked at the child, saw that she was looking pale," Ali testified Tuesday. "And I realized the chest was not rising. So immediately I called for help."

The nurse was responsible for monitoring Amber in the recovery room. She was also responsible for operating the vital-signs monitor.

"I personally don't remember turning the monitors off," Ali testified.

During his testimony, Fee said the monitor may have been placed on the child, but it wasn't turned on.

Tasneem Ali

Tasneem Ali was a registered nurse, but no longer has a licence to practice. (John Shypitka/CBC News)

Ali told the hearing she "stopped being a nurse last Monday." She also revealed the College and Association of Registered Nurses of Alberta had launched an investigation of her actions, but said she wasn't sure whether the investigation was ongoing or had concluded.

An association spokesperson said the investigation process is confidential. The college confirmed Ali does not have a current practice permit as a registered nurse.

'I wish I could have been there earlier'

Fee told the hearing that during the height of the medical crisis he suggested bringing Amber's family into the surgical suite.

"I asked Dr. Mather to bring the family in, as this was a serious event," Fee said. "He just said, not at this time."

After paramedics took over, Fee and his nurse walked out through the waiting room of Mather's office.

Amber's father, Ramandeep Singh, had no idea what was going on with his daughter behind the scenes.

"I noticed the child's father sitting in the waiting room on his cellphone, looking very relaxed," Fee said.

Fee became emotional at the hearing when he described what he and his nurse did after they returned to their own office.

Dr. Darren Fee

Dr. Darren Fee has been practising dentistry for 16 years and is an accredited dental anaesthesiologist. (drfee.ca)

"I decided we should write down what we had seen, what we had done, and do it separately," he said. "So that's what we did. We took some time to do that.

"We decided to make a list of things we saw initially we didn't think were being done correctly."

Fee has been a dentist for 16 years. He said he's still haunted by the scene in Mather's office.

"I wish I could have been there earlier, but I'm glad that I could do what I could," Fee told CBC News outside the hearing room. "There isn't a day or an hour that goes by that I don't think about it."

After he finished testifying, Fee approached Amber's father to express his condolences.

The emotional encounter gave Ramandeep Singh the chance to thank Fee.

"It looks like Dr. Fee did what he's supposed to do, and he's the one who saved Amber's life," Singh said.

"Amber is alive because of him. He's a hero."

Fee shrugged off the praise.

"I feel like I just did what I could to try and get her back. And that's all I could do."