A 15-year-old girl died after she stopped breathing while undergoing routine dental surgery so she could have a brace fitted, an inquest heard. Denisa Alexandra Stefanoaia, known as Alex, died at Great Ormond Street hospital in London in February after complications during a 19-minute procedure to have four teeth removed. St Pancras coroner’s court heard that Alex, from Watford, Hertfordshire, was “severely obese”, with mild asthma and sleep apnoea. Despite being a higher risk patient, neither the teenager nor her family were warned about the risk of death before the operation. Alex was told the surgery would take no longer than an hour, was given a general anaesthetic, and was said to be pleased that it would eventually result in fixing her smile, the inquest heard. Experts told the coroner, Mary Hassell, that the chance of Alex dying during the operation on 14 February was “less than one in 100,000”, and that the risk was therefore deemed so low that Alex and her family were not warned. The procedure was deemed by the surgeon to have been “very straightforward”, but medics discovered Alex had bitten down on the endotracheal tube and had stopped breathing, the inquest heard. She was taken to intensive care but was pronounced dead five days later, her brain having been starved of oxygen. Giving evidence remotely on Thursday, Dr Atheer Ujam, the senior registrar at Great Ormond Street hospital who carried out the surgery, told the coroner that while the patient was a higher risk, he had no qualms about proceeding with the surgery and would not do anything differently were he to be faced with a patient similar to Alex. Ujam described the procedure as “uncomplicated” but said he later noticed there was a problem when Alex had turned blue and a short time later he could see blood coming from her mouth. It was at that point, he said, that he could not find a pulse and a colleague said they had to start CPR. Dr Akane Iguchi, a consultant anaesthetist at Great Ormond Street hospital, was also in the operating theatre at the time and said she began to become concerned when she was unable to ventilate Alex’s lungs after the procedure. “We were trying to improve her lung capacity,” she said. “I looked over at Alex’s face and she was biting the ET [endotracheal] tube and she was becoming blue.” Iguchi told the coroner that Alex’s obesity meant she may have been deprived of oxygen for only “a matter of seconds” before turning blue. “Less than one minute – much, much less than healthy children. In her case, because of her severe obesity, her oxygen consumption is very high. All the factors combined make her very risky.” In a statement to the PA Media news agency, Alex’s mother, Angelica Stefanoaia, described how the death of her daughter – her “best friend” – had affected her life. “I have cried every day since she died, desperate to bring her back,” she said. “I begged them on my knees to do everything they could for her and save her and they simply said she wouldn’t wake up. When they told me she was poorly after the surgery, I never for one moment thought she would die. “Please, no other family should have to go through this terrible pain.” Mark Bowman, a partner at Fieldfisher, which is supporting the family at the inquest, said: “Going through an inquest investigating the death of your daughter is a horrific experience. “The hope is that the family will receive some answers which will allow them to properly grieve for Alex.” The inquest continues.