A lawmaker on Friday suggested that public dental clinics should require patients to arrive at least an hour in advance to deal with no-shows.

The Department of Health launched its online registration for public dental services on Monday in a bid to avoid residents queuing overnight.

With 151 slots available, it recorded an overall absentee rate of 26.5 percent during the first two working days since the service was launched.

A majority of them were residents aged 65 or above.

The department said it would keep monitoring the operation and effectiveness of the new system and carry out suitable remedial measures, such as setting up a waiting list mechanism.

Election Committee lawmaker Chan Hoi-yan said patients might not show up due to various reasons, including illness or they simply forgot about the appointment.

"I think that - for instance - we can ask them to come in for registration an hour or so before the appointment. I think the public understands that the government has tried its best to avoid long queues," she told an RTHK radio programme.

"Coming in earlier to make sure you'll show up enables medical workers, or the Department of Health, to contact people on the waiting list and ask them to come in."

She said absentees should not be penalised.

Speaking on the same programme, Tsuen Wan District Councillor Ng Chun-yu suggested that officials should also phone elderly patients to notify them they have been allocated a spot at a public dental clinic.

The no-show rate at the Tsuen Wan clinic was 33.3 percent - the highest among all surveyed.

Ng suspected this was because some older people living outside the area were reluctant to travel a long distance for dental appointments.

"Apart from notifying elderly by SMS, the government could also use pre-recorded phone calls and can call the elderly twice," said Ng.

"If they don't pick up both calls, then it's likely that they won't show up, right? If half of the 40 people who've been allocated a slot aren't picking up the phone, maybe there's a high number of people not showing up? At least [health workers] can be prepared."

Responding to media enquiries, the health department said some patients did not show up due to other engagements, or they forgot about the appointment.

It added that some residents were not aware that the clinics only provide emergency dental services.