A Tory MP's call for child migrants arriving in the UK from Calais to have their teeth tested to verify their age has been condemned by dentists.
Several unaccompanied children have arrived to join relatives in the UK - amid suggestions they could be adults.
Monmouth MP David Davies said mandatory teeth checks would reassure people, but the British Dental Association said it was unethical.
The Home Office said additional checks on their ages would be made.
Once in the UK, it is understood further checks will include interviews with their relatives and fingerprinting to cross check with other records which may contain details of their age.
The BBC understands 39 children with links to Britain have arrived this week, after French authorities ratified a list drawn up by the charity Citizens UK, which is working with the government to bring unaccompanied minors over from Calais.
However, photographs of some of the children have been printed on the front pages of some national newspapers, along with headlines questioning their ages.
Mr Davies, chairman of the Commons Welsh Affairs Select Committee, said that one of the migrants arriving had "lines around his eyes and looks older than I am".
He said: "If they are jumping on lorries, they are not going to be adverse to lying about their ages. We should do the tests."
"We don't want to vilify anyone... but if we don't raise these questions we are not going to be able to help the people who need our help," he added.
The MP has been backed by his Tory colleague, Jacob Rees-Mogg, who is also calling for more stringent checks.
Mr Rees-Mogg said it was "very worrying" that "older migrants are reported to be pushing children out of the way".
He added: "For the public to have confidence in the process and to feel that it is genuinely children that are being rescued, it would not be unreasonable to make detailed checks, and if that includes dental checks, I think that would be perfectly sensible."
But the BDA, which represents dentists and dental students in the UK, disputed claims that dental radiographs could accurately determine whether someone was under 18 or not.
Clinical tests are not used by the authorities to assess migrants' ages.
If they have no birth certificate, passport or other documentation, officials make an assessment of their age based on "physical appearance and demeanour".
- In the year ending September 2015, 590 asylum applicants had their age disputed
- Of those 574 were recorded as having an age assessment and 371 were found to be adults
- Since 2006 there have been 11,121 age disputes. Of those, 4,828 were found to have been adults
Home Office sources said it was extremely unlikely that any migrants found to be an adult would be returned to Calais as they would be able to claim asylum in the UK, regardless of the age.
So far this year, 140 children have been accepted for transport to the UK - including 80 from France in the last month - according to the Home Office, but it would not say how many were already on British soil.
A BDA spokesman said it was "vigorously opposed" to the use of dental X-rays to try to determine the age of asylum seekers.
"It's not only an inaccurate method for assessing age, but it is both inappropriate and unethical to take radiographs of people when there is no health benefit for them," he added.
Doctors of the World UK also called the idea "unethical and unnecessary", saying "healthcare workers are not border guards".
Judith Dennis, policy manager for the Refugee Council, said she was concerned by media coverage questioning the appearance of those admitted to the UK.
"It is not possible to judge how old someone is by looking at them, and most people understand that teenagers' appearances vary widely."
Diane Abbott, Labour's shadow home secretary said it was "an outrageous demand, which would further violate the human rights of vulnerable refugees".
"They have suffered insanitary and dangerous conditions and should have been admitted long ago," she said.
"This is a vile, reactionary clamour. It distracts from the government's responsibilities to these refugees, which it has largely neglected to date."
French authorities have said they will close the Jungle camp - situated near the port of Calais, and close to the 31-mile Channel Tunnel - by the end of the year.
UK officials in Calais have been focusing initially on unaccompanied minors who have the right to join relatives in the UK under EU legislation, known as the Dublin regulation.
Under the EU-wide regulation, asylum claims must be made in the first safe country a person reaches, but children can have their claim transferred to another country if they have family members living there.