IOTN classification

Question 1

What is IOTN?

Answer 1

Index of Orthodontic treatment need - used to rank occlusal disharmonies according to their severity and to determine the effect of the malocclusion on the dental health and psychological wellbeing of the patient.

Question 2

What are the components of the IOTN?

Answer 2

1 Aesthetic component

2 Dental Health component

Question 3

What is the aesthetic component?

Answer 3

Used to assess the degree the malocclusion affects aesthetics and therefore the likeliness it affects the patients psychological wellbeing

Question 4

What is the scale of the aesthetic component?

Answer 4

1 (most aesthetically pleasing) - 10 (least aesthetically pleasing)

Question 5

What score for the aesthetic component allows for treatment)

Answer 5

1-2 = no need
3-4 - slight need
5, 6, 7 - some need
8, 9, 10 - definite need

Question 6

What is the dental health component?

Answer 6

Single worst feature of malocclusion is noted and categorised into one of five grades

Question 7

What are the grades for the dental health component?

Answer 7

Grade 1 = no need 
Grade 2 = little need 
Grade 3 = moderate need /boderline 
Grade 4 = great need for tx 
Grade 5 = very great need for tx

Question 8

Grade 1 criteria

Answer 8

1 Minor malocclusions including displacements <1mm

Question 9

Grade 2 criteria (7)

Answer 9

2a - increased overset >3.5mm but <6mm and competent lips
2b - reverse overjet >0mm but <1mm
2c - Anterior or posterior cross bite with <1mm discrepancy between RCP and ICP
2d - displacement of teeth >1mm but <2mm
2e - anterior or posterior open bite >1mm but <2mm
2f - increased overbite >3.5mm (without gingival contact)
2g - Paranormal or postnormtl occlusion with no other anomalies

Question 10

Grade 3 criteria (6)

Answer 10

3a - increased overset >3.5mm but <6mm and incompetent lips
3b - reverse overjet >1mm but <3.5mm
3c - ant or post cross bite with >1mm but <2mm discrepancy between ICP and RCP
3d - displacement >2mm but <4mm
3e - lateral or anterior open bite >3mm but <4mm
3f - increased or incomplete overbite without gingival or palatal trauma

Question 11

Grade 4 (11)

Answer 11

4a - inc overjet >6mm but <9mm
4b - reverse overjet >3.5mm but no functional or speech difficulties
4c - ant or post cross bite with >2mm discrepancy between RCP and ICP
4d - severe displacement >4mm
4e - lateral or anterior open bite >4mm
4f - inc or complete overbite with gingival or palatal trauma
4h - less extensive hypodontia
41 - posterior lingual cross bite with no functional occlusal contact in one or more buccal segments
4m - reverse overjet >1mm but <3.5mm
4i - partially erupted teeth, tipped and impacted against adjacent teeth
4x - supernumerary teeth

Question 12

Grade 5 criteria (5)

Answer 12

5a - increased overset >9mm
5h - extensive hypodontia with restorative implications - more than one tooth missing in any quadrant requiring pre-resto orthodontics
5i - impacted tooth due to crowding, displacement, supernumerary teeth, retained primary etc
5m - reverse overjet >3.5mm with functional and speech difficulties
5p - defects of cleft lip and palate
5x - infra occluded teeth