1. Index of Orthodontic Treatment Need modified for use in Epidemiological Surveys : Modified IOTN

2. Written by Donald Burden and Cynthia Pine with assistance from the BASCD Working Party on Orthodontics

3. Modified IOTN consists of two components:
1. Aesthetic Component
2. Dental Health Component

4. Aesthetic Component Grades 1-7 No Definite Need for treatment

6. Recording the Aesthetic Component
Ask subject to close on their back teeth
Retract lips
Grade the dental attractiveness of the anterior teeth

7. Recording the Aesthetic Component
The grade awarded is for overall dental attractiveness rather than specific morphological similarity to the photographs
First impressions are usually correct
Main aim is to differentiate those at
8 - 10

8. Dental Health Component
IOTN has been simplified to two
categories:
 Definite Need for Treatment
 No Definite Need for Treatment
The subject is examined for specific conditions and if one is found, a Definite Need for Treatment is recorded and no further conditions are sought.

9. Recording the DHC Examine each subject for: Missing teeth Overjets
Crossbites
Displacement of contact points
Overbites
= MOCDO

10. Recording the DHC Examine the subject using the ‘MOCDO’ scale
As soon as a definite treatment need threshold is reached, then the examination is stopped

11. ‘MOCDO’
Missing teeth
Overjets
Crossbites
Displacement of contact points
Overbites

12. Missing Teeth (teeth not visible)
Congenital absence/traumatic loss
Ectopic teeth
Impacted teeth

13. Missing Teeth Palatally ectopic canines
Is the canine palpable in the buccal sulcus?
If not, it is ectopic = Need for Treatment

14. Missing Teeth
IMPACTED if 4mm or less space is available between adjacent teeth
Impacted = Need for Treatment

16. Missing Teeth
(Congenital absence/traumatic loss)
In your opinion, is orthodontic treatment required to open or close the space?
If yes = Need for Treatment

17. Displacement of contact points Overbites
Original Slide No.15
‘MOCDO’
Missing teeth
Overjets
Crossbites
Displacement of contact points
Overbites

18. Measuring Overjets
Increased overjets (Class II) and reverse overjets (Class III) are measured using the metal ruler

19. Second line (red) – 6mm
Positive overjets

21. Measuring Overjets
Measure to the labial aspect of the most prominent incisor
Only record Need for Treatment if the overjet extends beyond the 6mm line

24. Measuring Reverse Overjets
All four incisors must be in lingual occlusion

25. Measuring Reverse Overjets
If the reverse overjet falls exactly on the 4mm (white line) record in the Definite Need for Treatment category

26. First line (white) – 4mm
Crowding
Reverse overjets
Open bites

28. ‘MOCDO’
Missing teeth
Overjets
Crossbites
Displacement of contact points
Overbites

29. Crossbites Can be anterior or posterior, but mostly posterior.
Check for displacement on closure.
If displacement on closure = Need for Treatment

30. ‘MOCDO’
Missing teeth
Overjets
Crossbites
Displacement of contact points (crowding)
Overbites

31. Crowding Only applies to crowding between permanent teeth
Measure between the contact points of the two most crowded teeth

32. First line (white) – 4mm
Crowding
Reverse overjets
Open bites

34. ‘MOCDO’
Missing teeth
Overjets
Crossbites
Displacement of contact points
Overbites

35. Deep overbite Open bite

36. Deep overbite causing gingival or palatal traumatic injury
= Definite Need for Treatment

38. Other Points of the Modified IOTN
Generalised spacing is not recorded in the Dental Health Component