The council heard that Tse implanted two teeth for Yeung Pak-keung on May 3, 2006. Yeung experienced intense pain during the operation, but Tse told him it was normal.

Yeung told the council yesterday that he had not experienced pain during two similar operations performed by Tse in 2001 and 2005.

'The drilling started out normal. But as it reached a particular depth, I felt that something had been drilled open. I felt intense pain,' he said.

A CT scan carried out by a doctor showed Yeung's nerve had been damaged. One implant had penetrated the nerve, while another had touched it. He went back to Tse, who removed the tooth that had penetrated the nerve, but said there was no need to remove the other one.

'He told me to believe him, that there was no need to ask for a second opinion,' Yeung told the council.

Tse eventually elevated Yeung's second implant by about 2mm.

Yeung said his ability to sense cold and heat had been harmed since the implant surgery and that he felt fatigued after talking for long periods.

'Four years on, I still feel that something is stuck in my mouth, or that a plaster is pulling my jaw,' he said.

The defence said Yeung had demanded Tse pay him compensation of HK$5 million. Yeung told the council yesterday that he could not remember the exact amount he had asked for, but that Tse had rejected it.

The legal officer called on an expert witness, Dr Edward To Wai-hei.

To said Tse did not assess the patient properly prior to the surgery. One X-ray he used, which was taken one day before the operation, did not show the nerve clearly, To said. The only other X-ray Tse used to determine the implant's position was taken in 2004.

'Even a primary school pupil would know that this is not the proper procedure,' he said.

To said Tse used only a guide pin to test the depth of the implant. The correct procedure should be supported by a series of X-rays.

Tse originally pleaded guilty, but changed his mind 15 minutes before the hearing started. The hearing was adjourned until next Thursday.