ELYRIA, Ohio -- Thirteen-year-old Marissa Kingery was nervous about undergoing dental surgery, but her father assured her he would be in the waiting room just a short distance away.

Jason Kingery never spoke with his daughter again.

Marissa died Monday in Rainbow Babies & Children's Hospital, two weeks after she fell into a coma after receiving anesthesia for what was supposed to be a routine dental procedure to have two baby teeth and an impacted tooth removed by an oral surgeon in Lorain.

"Her mother and father are crushed," said Michael Czack, a Cleveland lawyer. "She was their only child. The family hired me to find out what happened. Right now, all we have are questions. The first thing that comes to mind is wanting to know how much anesthesia she was given."

The State Dental Board and the Cuyahoga County coroner's office are investigating her death. Three or four dental patients die each year in Ohio while under anesthesia, officials said.

Czack said that he has asked the office of oral surgeon Henry Mazorow for details about what happened during the Dec. 21 surgery but that he has not gotten those answers.

Mazorow, who turns 81 this month, has been a dentist since 1956 and is certified to administer the kind of anesthesia necessary for impacted-tooth removal.

He could not be reached to comment Wednesday.

"We don't know what was used to sedate her," Czack said. "This kind of procedure is done on hundreds of thousands of people every year with no complications. We don't know what happened here."

The coroner's office conducted an autopsy and said the tentative cause of death is a lack of oxygen to the brain. But the manner of death has not been determined. Foul play is not suspected.

Lili C. Reitz, executive director of the Dental Board, said Mazorow has never been disciplined by the board. She said that in these types of cases, the board first determines what happened and then tries to get the dentist and the victim to reach a settlement.

She said one option in a case involving an elderly dentist would be to ask him to retire. If he refuses, she said, the board would proceed with an investigation, which could result in a license revocation.

Czack said that Mazorow was not Marissa's regular dentist but that she was referred to the office on West 21st Street for oral surgery.

She was treated at a Lorain hospital and then transferred to Rainbow Babies & Children's Hospital in Cleveland, where she remained in a coma until her death.

"It's been very difficult for the family," Czak said. "They were there for the last two weeks by her side."

Marissa was an eighth-grader at the Eastern Heights Middle School in Elyria. She lived with her mother, Amber McEwen. Her father lives in Sheffield Lake.

Her family donated her organs for transplant.

To reach this Plain Dealer reporter: msangiacomo@plaind.com, 216-999-4890