A retired dentist in China was stabbed to death by a former patient whose teeth had been left yellow after a procedure 25 years ago. The man, who has not been named, stabbed the dentist 38 times in what was seemingly an act of revenge.

The 60-year-old dentist, Chen Zhongwei, died from the attack after 43 hours of emergency surgery to try and save him. He had been stabbed in the head, chest, abdomen and arms. Zhongwei's wife was also injured but survived.

The attacker jumped from a balcony to his death after the attack last week. The hospital in Guangzhou said that the killer had undergone dental work from Zhongwei in the 1990s and had confronted him last month demanding compensation for his teeth's discolouration. The hospital said that the man had a history of mental illness.

According to the China Daily newspaper, China has a problem with the worsening relationship between patients and medical practitioners. "There have been too many similar cases in which patients attack, even kill, medical staff because they believe they have not received the proper treatment," said the paper.

Last month, a man in Indiana sought to file a malpractice suit after attending a dentist to have four teeth taken out and waking up to discover that all of his teeth had been removed. Donny Grisby, 36, suffered cardiopulmonary arrests twice in an ambulance while being taken to hospital after the procedure. "I am so ashamed now. I have no teeth," he said.