Assessing mental capacity

Assessing dental patients' capacity to consent is a vital part of the treatment process. Here's what you need to know.

A person may not have mental capacity because of a problem with the way their brain functions, for example:

  • a serious brain injury
  • an illness, such as dementia
  • severe learning difficulties.

Mental capacity can come and go, as with dementia and some mental health conditions. A person can also recover mental capacity - for instance, following a severe stroke.


For people 16 years old and over who lack capacity, the Mental Capacity Act 2005 (MCA) provides a legal framework in England and Wales. The Act is supplemented by a detailed Code of Practice, with which dental professionals are expected to comply.

In Northern Ireland, the relevant legislation is the Mental Capacity Act (Northern Ireland) 2016.

In Scotland, the relevant legislation is the Adults with Incapacity (Scotland) Act 2000. Under the Act, a suitably trained health professional will make an assessment of a patient's capacity to consent to treatment. If the patient is deemed unable to consent, the health professional will complete a 'section 47' certificate to allow them to provide treatment.

As 16 is the legal age for capacity in Scotland, a 16 or 17-year old without capacity to consent is treated as an adult without capacity.

Assumption of capacity

  • You should assume all adult patients have the capacity to consent to treatment, unless you determine they lack that capacity.
  • If you decide an adult lacks capacity to consent, you should then decide if it's in their best interests to proceed with treatment.
  • The fact that a person has a mental health condition or learning difficulties is not, on its own, grounds for deciding that person does not have capacity.
  • If you decide a patient lacks capacity to consent, you should be able to justify your decision.

You should not assume the patient lacks capacity by making judgments about their behaviour or appearance.

You should take all steps practicable to help patients make decisions about their treatment before concluding they lack capacity.

If a patient appears to make an unwise or irrational decision, this is not sufficient reason to treat them as lacking capacity.


When you are assessing a patient's ability to make a decision, the patient must be able to do the following:

  • understand the information relevant to the decision; this includes information about the reasonably foreseeable consequences of deciding one way or another, or failing to make a decision
  • retain that information
  • use or weigh up that information as part of the process of making the decision
  • communicate their decision; this may be through talking, using sign language or other means of communication.

A patient's capacity may vary depending on the complexity of the decision to be made. It may also fluctuate with time.

Lack of capacity

If an adult patient lacks capacity and you are faced with providing treatment without consent, you should take into account:

  • the views of relatives, and/or
  • the views of carers, and/or
  • anyone named by the patient, and
  • the patient's present and previously expressed wishes in helping to determine if the treatment is in their best interests.

When assessing whether treatment is in the patient's best interests, you should consider whether the patient may regain capacity later.

If a patient has fluctuating capacity, it would be very unusual for dental treatment to be appropriate while the patient lacks capacity, when it could be left until the patient regains capacity and can consent.

Top tips

  • Make sure the patient has the information they need to make a decision about treatment.
  • Present the information in a way that is easy for the patient to understand - for example, by using simple language or visual aids.
  • Record in the clinical notes the processes you went through in determining capacity.
  • If the patient lacks capacity, record in the notes the basis on which a decision to treat, or not treat, was in the patient's best interests, and the steps you took to establish that.

This page was correct at publication on 17/02/2022. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.