The Index of Orthodontic Treatment Need was developed as a result of a government initiative. The purpose of the index was to help determine the likely impact of a malocclusion on an individual’s dental health and psychosocial well-being. It comprises two elements.

Dental health component
This was developed from an index used by the Dental Board in Sweden designed to reflect those occlusal traits, which could affect the function and longevity of the dentition. The single worst feature of a malocclusion is noted (the index is not cumulative) and categorized into one of five grades reflecting need for treatment

Grade 1 — no need

Grade 2 — little need

Grade 3 — moderate need

Grade 4 — great need

Grade 5 — very great need.

A ruler has been developed to help with assessment of the dental health component , and these are available commercially.

Aesthetic component
This aspect of the index was developed in an attempt to assess the aesthetic handicap posed by a malocclusion and thus the likely psychosocial impact upon the patient — a task fraught with potential pitfalls . The aesthetic component comprises a set of ten standard photographs , which are also graded from score 1, the most aesthetically pleasing, to score 10, the least aesthetically pleasing. Colour photographs are available for use with a patient in the clinical situation and black-and-white photographs for scoring from study