The HSE provides orthodontic treatment to those who have been assessed and referred for treatment before their 16th birthday. Where a course of orthodontic treatment commences while a child is in primary school the necessary treatment will continue after the child enters secondary school. Orthodontic referrals are generally received via the Public Dental Service primary school screening programme. Those who attend private schools or are home schooled are also included. An individual's access to orthodontic treatment is determined against a set of clinical guidelines called the Modified Index of Treatment Need. Patients with the greatest level of need, i.e. Grade 5 or Grade 4 are provided with treatment by the HSE.