The World Health Organization said Tuesday that routine, non-essential dental work should be delayed until COVID-19 transmission rates drop sufficiently, cautioning against procedures that produce aerosol spray from patients' mouths.

The WHO said check-ups, dental cleanings and preventive care could be postponed, as it released guidance for dentists on how to minimise the risk of transmission during the coronavirus pandemic.

The United Nations health agency said now that dental services had begun to resume in many countries, several procedures could be done in a way that minimised aerosol, or micro-droplets that hang in the air.

"WHO advises that routine non-essential oral health care -- which usually includes oral health check-ups, dental cleanings and preventive care -- be delayed until there has been sufficient reduction in COVID-19 transmission rates from community transmission to cluster cases," the guidance says.

"The same applies to aesthetic dental treatments. However, urgent or emergency oral health care interventions that are vital for preserving a person's oral functioning, managing severe pain or securing quality of life should be provided."

The WHO said that if possible, patients should be remotely screened before their appointments.

The interim guidance, dated August 3, was aired by the WHO on Tuesday.

- Close proximity -

The WHO said dentists were at high risk of being infected with SARS-CoV-2, the virus that causes COVID-19.

"Oral health care teams work in close proximity to patients' faces for prolonged periods," the organisation said.

"Their procedures involve face-to-face communication and frequent exposure to saliva, blood, and other body fluids and handling sharp instruments. Consequently, they are at high risk of being infected with SARS-CoV-2 or passing the infection to patients."

Aerosol-generating procedures (AGPs) include dental cleaning with an ultrasonic scaler and polishing, work with high or low-speed hand-pieces, surgical tooth extraction and implant placement.

The guidance listed ways in which broken dentures and orthodontic appliances, and extensive dental caries, could be treated while minimising or avoiding AGPs.

The WHO's dental chief Benoit Varenne told reporters that oral disease was a neglected health burden in many countries, affecting people throughout their lives.

"At the global level, last estimates that are available show that 3.5 billion are affected by oral disease, he said.

"Untreated dental caries in permanent teeth is the most common health condition in human beings."

He said that in a a survey, 75 percent of WHO member states said dental services had been completely or partially disrupted during the pandemic.

Varenne also voiced concern about the availability of personal protective equipment for dentists working during the pandemic.