DOH&C; Guidelines on Secondary Care Orthodontics, download as 24 KB WORD document
Orthodontic referral guidelines

Index of Treatment Need

Because orthodontic treatment needs to be justified on either dental health or aesthetic needs, there are two components to this index:-

  • The Dental Health Component (DHC)
  • The Aesthetic Component (AC)

The Dental Health Component of the IOTN has five categories ranging from 1 (no need for treatment) to 5 (great need) which may be applied clinically or to patients’ study casts. The most severe occlusal trait is identified for any particular patient and the patient is then categorised according to this most severe trait. Patients in Grade 5 would include patients with Cleft Lip and Palate, multiple missing teeth or a destructive malocclusion, which would include those with minor tooth displacements where there is little need for treatment.

The Aesthetic Component of the IOTN consists of a ten-point scale illustrated by a series of photographs which were rated for attractiveness by a lay panel and selected as being equidistantly spaced through the range of grades (Evans and Shaw, 1987). A rating is allocated for overall dental attractiveness rather than specific similarities to the photographs. The final value reflects the treatment need on the grounds of aesthetic impairment and by implication the sociopsychological need for orthodontic treatment. Both parents and patients find this easy to apply and there is a high level of agreement between the scores obtained by dentists, parents and children.

There seems to be a general agreement that a DHC of less than 4 and an AC score of below 7 do not justify treatment by a hospital based consultancy except for teaching or research purposes.

The Dental Health Component

Grade 1 No treatment required
  1. Extremely minor malocculsions, including displacements less than 1 mm
Grade 2 Little

2.a Increased Overjet > 3.5 mm but <= 6 mm (with competent lips)

2.b Reverse overjet greater than 0 mm but <= 1mm

2.c Anterior or posterior crossbite with <= 1mm discrepancy between retruded contact position and intercuspal position

2.d Displacement of teeth > 1mm but <= 2mm

2.e Anterior or posterior open bite > 1mm but <= 2mm

2.f Increased overbite >= 3.5mm (without gingival contact)

2.g Prenormal or postnormal occlusions with no other anomalies. Includes up to half a unit discrepancy

Grade 3 Borderline need

3.a Increased overjet > 3.5 mm but <= 6 mm (incompetent lips)

3.b Reverse overjet greater than 1 mm but <= 3.5mm

3.c Anterior or posterior crossbites with >1mm but <= 2mm discrepancy between the retruded contact position and intercuspal position

3.d Displacement of teeth >2mm but <=4mm

3.e Llateral or anterior open bite > 2mm but <= 4mm

3.f Increased and incomplete overbite without gingival or palatal trauma

Grade 4 Treatment required

4.a Increased overjet > 6mm but <= 9 mm

4.b Reverse overjet > 3.5 mm with no masticatory or speech difficulties

4.c Anterior or posterior crossbites with > 2 mm discrepancy between the retruded contact position and intercuspal position

4.d Severe displacements of teeth > 4 

4.e Extreme lateral or anterior open bites > 4 mm

4.f Increased and complete overbite with gingival or palatal trauma

4.h Less extensive hypodontia requiring pre-restorative orthodontics or orthodontic space closure ot obviate the need for a prosthesis

4.i Posterior lingual crossbite with no functional occlusal contact in one or more buccal segments

4.m Reverse overjet > 1 mm but < 3.5 mm with recorded masticatory and speech difficulties

4.t Partially erupted teeth, tipped and impacted against adjacent teeth

4.x Existing supenumerary teeth

Grade 5 Treatment required

5.a Increased overjet > 9 mm

5.h Extensive hypodontia with restorative implications (more than one tooth missing in any quadrant requiring pre-restorative orthodontics)

5.i Impeded eruption of teeth (apart from 3rd molars) due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause

5.m Reverse overjet > 3.5 mm with reported masticatory and speech difficulties

5.p Defects of cleft lip and palate

5.s Submerged deciduous teeth

Aesthetic Component

  • Grade 1 = most aesthetic arrangement of the Dentition
  • Grade 10 = least aesthetic arrangement of the Dentition
  • Grade 1-4 = little or no treatment required
  • Grade 5-7 = moderate or borderline treatment required
  • Grade 8-10 = treatment required

The evaluaton of a plain Plaster model or Black and White Photographs has the advantage that the estimate is not influenced by the oral hygiene, the condition or colour of the gingiva.

Evans R and Shaw WC (1987):Preliminary evaluation of an illustrated scale for rating dental attractiveness. European Journal of Orthodontics; 9:34-318

More about orthodontics:
British Orthodontic Society
American Association of Orthodontists
See also DentalGain information