The NHS requires a patient to meet one or more of the follow criteria to qualify as exempt.

“You do not have to pay for NHS dental treatment if, when your treatment starts, you are:

• Under 18
• Under 19 and in full-time education
• Pregnant or you’ve had a baby in the 12 months before treatment starts
• Staying in an NHS hospital and the hospital dentist carries out your treatment
• An NHS Hospital Dental Service outpatient (although you may have to pay for your dentures or bridges)

You can also get free NHS dental treatment if, when the treatment starts or when you’re asked to pay:

• You’re included in an award of income support, income-based job-seeker’s allowance, income-related employment and support allowance or pension credit/guarantee credit
• You’re named on, or entitled to, a valid NHS tax credit exemption certificate
• You’re named on a valid HC2 certificate

If you’re named on a valid HC3 certificate, you may not have to pay for all your NHS dental treatment.

You will not be exempt from paying for NHS dental treatment because you receive one of the benefits below when paid on their own:

• Incapacity benefit
• Contribution-based job-seeker’s allowance
• contribution-based employment and support allowance
• Disability living allowance
• Council tax benefit
• Housing benefit
• Pension credit savings credit

(From NHS Dental)