Grade 1 (none)
Extremely minor malocclusions, including displacements <1 mm
Grade 2 (little)
2a Increased overjet >3.5 mm but <6 mm with competent lips
2b Reverse overjet >0 mm but ≤1 mm
2c Anterior or posterior crossbite with ≤1 mm discrepancy between retruded contact position and intercuspal position
2d Contact point displacements >1 mm but ≤2 mm
2e Anterior or posterior openbite >1 mm but ≤2 mm
2f Increased overbite ≥3.5 mm without gingival contact
2g Pre-normal or post-normal occlusions with no other anomalies. Includes up to half a unit discrepancy
Grade 3 (borderline need)
3a Increased overjet >3.5 mm but ≤6 mm with incompetent lips
3b Reverse overjet greater than 1 mm but ≤3.5 mm
3c Anterior or posterior crossbites with >1 mm but ≤2 mm discrepancy between the retruded contact position and intercuspal position
3d Displacement of teeth >2 mm but ≤4 mm
3e Lateral or anterior openbite >2 mm but ≤4 mm
3f Increased and incomplete overbite without gingival or palatal trauma
Grade 4 (treatment need)
4a Increased overjet >6 mm but ≤9 mm
4b Reverse overjet >3.5 mm with no masticatory or speech difficulties
4c Anterior or posterior crossbites with >2 mm discrepancy between the retruded contact position and intercuspal position
4d Severe displacements of teeth >4 mm
4e Extreme lateral or anterior open bites >4 mm
4f Increased and complete overbite with gingival or palatal trauma
4h Less extensive hypodontia requiring pre-restorative orthodontics or orthodontic space closure to obviate the need for a prosthesis
4l Posterior lingual crossbite with no functional occlusal contact in one or more buccal segments
4m Reverse overjet >1 mm but <3.5 mm with recorded masticatory and speech difficulties
4t Partially erupted teeth, tipped and impacted against adjacent teeth
4x Existing supernumerary teeth
Grade 5 (treatment required)
5a Increased overjet >9 mm
5h Extensive hypodontia with restorative implications (more than one tooth missing in any quadrant requiring pre-restorative orthodontics
5i Impeded eruption of teeth (apart from 3rd molars) due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause
5m Reverse overjet >3.5 mm with reported masticatory and speech difficulties
5p Defects of cleft lip and palate
5s Submerged deciduous teeth