IOTN Grade 4 (Great)
This grade indicates a severe need for treatment and can be classified as follows:
4h | Less extensive hypodontia requiring pre-restorative orthodontics or orthodontic space closure to obviate the need for a prosthesis. |
4a | Increased overjet greater than 6mm but less than or equal to 9mm. |
4b | Reverse overjet greater than 3.5mm with no masticatory or speech difficulties. |
4m | Reverse overjet greater than 1mm but less than 3.5mm with recorded masticatory or speech difficulties. |
4c | Anterior or posterior crossbites with greater than 2mm discrepancy between retruded contact position and intercuspal position. |
4l | Posterior lingual crossbite with no functional occlusal contact in one or both buccal segments. |
4d | Severe contact point displacements greater than 4mm. |
4e | Extreme lateral or anterior open bites greater than 4mm. |
4f | Increased and complete overbite with gingival or palatal trauma. |
4t | Partially erupted teeth, tipped and impacted against adjacent teeth. |
4x | Presence of supernumerary teeth. |