Backbencher David T.C Davies told Heat Street he is suspicious about the number of young men who have recently been given an automatic right to join their relatives in Britain simply having told officials they are under the age of 18.
Since 2006 there have been 11,121 age disputes.
Home Office documents say if a refugee does not have a birth certificate, a Home Office screening officer can certify them as a child based on "physical appearance" or "demeanour".
A spokesman said the United Kingdom uses "a number of determining factors" to establish age.
He called for tests on teeth to determine exactly how old child migrants are.
But according to the British Dental Association (BDA), carrying out such dental checks would be unethical.
That's why David Davies, MP for Monmouth, said mandatory teeth checks would reassure people the United Kingdom was not being exploited.
BBC assistant political editor Norman Smith said it was understood they will undergo further interviews about their background and their finger prints will be taken to cross check with other records which may contain their age details.
A spokesman said: "X-rays taken for a clinically justified reason must not be used for another goal without the patient's informed consent, without coercion and in full knowledge of how the radiograph will be used and by whom".
Leigh Daynes, executive director of Doctors of the World agreed, saying: 'Health staff are not border guards; and in any event such tests have been shown to be unreliable'.
She added: "Such is the seriousness of Mr Davies's unethical and divisive remarks that we are asking his party chairman to consider disciplinary action".
"We must not be naive about this".
"You know, Lily Allen style, with tears in our eyes - we're not actually going to be able to help the people who need our help".
Condemning Mr Davies' comments, journalist Caroline Gregory, who spoke to the programme from the Calais "Jungle", said the children had been through rigorous checks.
"The tests are perfectly ethical if people are coming here who look clearly like they are over 18".
Separately, in an angry exchange with Good Morning Britain presenter Piers Morgan, Davies said he was committed to helping child refugees - but wanted to make sure the right people were being assisted. "They could disappear and be put in a very vulnerable situation trying to survive outside the community".
It states that Britain will take in "vulnerable unaccompanied child refugees" who arrived in the European Union before March 20, even if they do not have relatives in Britain.
Child migrants from the Calais "Jungle" camp will not face dental checks in the United Kingdom to verify their age, the government has insisted.
Just before bulldozers arrive to dismantle the Calais jungle migrant camp, the first busload of migrant children that are to be settled in the United Kingdom arrived Monday, crossing the Channel to be reunited with family members in the country.
Conservative MPs have raised concerns that the photographs of the migrants arriving in the United Kingdom appear to depict people above the age of 17.
He said: "It would be a way of reassuring the public that the system is not being abused. We need to show those values now by warmly welcoming these young refugees". "At the moment we have not been advised that any children will staying here".
"We do not use dental x-rays to confirm the ages of those seeking asylum in the UK. The British Dental Association has described them as inaccurate, inappropriate and unethical". However, one peer, Lord Roberts, said at the present rate of intervention there would be more than 1,000 children marooned when the demolition started. "This means there will be cases where such reports should be given considerable weight - for example because the applicant's claimed age is within the possible range".