Index of Orthodontic Treatment Need (IOTN)

Index of Orthodontic Treatment Need (IOTN)
Copyright by Department of Orthodontics, UDM

1. INDEX OF ORTHODONTIC TREATMENT NEED INDEX OF ORTHODONTIC TREATMENT NEED
(IOTN)(IOTN)
DR. EI EI HSU HLAING
B.D.S, M.D.Sc (Ygn.)
DEPARTMENT OF ORTHODONTICS
UNIVERSITY OF DENTAL MEDICINE
YANGON
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2. Index of Orthodontic Treatment Need
(IOTN)
The Index of Orthodontic Treatment Need
(IOTN), described by Brook and Shaw (1989) and
modified by Richmond (1990)
The index comprises two parts -
Dental health component (DHC)
Aesthetics component (AC)

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3. DHC records malocclusions in terms of the
significance of tooth irregularities for a personal
dental health
AC records the aesthetics impairment, by
implication, the justification for treatment on
socio-psychological grounds
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4. So, this method not only gives information on
malocclusion traits but also made amenable for
studying the influence of socio - psychologic
effect on the need and demand for orthodontic
treatment
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5. Dental Health ComponentDental Health Component
DHC have 5- grade scale, from grade-1(no need
for treatment) up to the grade-5 (great need for
treatment)
When assessing the DHC, only the worst
occlusal feature was recorded
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6. Dental Health ComponentDental Health Component
Grade 5 (Need treatment)
5•I - Impeded eruption of teeth (except for third molars) due to
crowding, displacement, the presence of supernumerary teeth,
retained deciduous teeth and any pathological cause.
5•h - Extensive hypodontia with restorative implications (more than 1
tooth missing in any quadrant) requiring pre-restorative
orthodontics.
5•a - Increased overjet greater than 9 mm.
5•m -Reverse overjet greater than 3•5 mm with reported masticatory
and speech difficulties.
5•p - Defects of cleft lip and palate and other craniofacial anomalies.
5•s - Submerged deciduous teeth.
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7. Dental Health ComponentDental Health Component
Grade 4 (Need treatment)
4•h-Less extensive hypodontia requiring pre-restorative orthodontics or
orthodontic space closure to obviate the need for a prosthesis.
4•a-Increased overjet greater than 6 mm, but less than or equal to 9 mm.
4•b-Reverse overjet greater than 3•5 mm with no masticatory or speech
difficulties.
4•m-Reverse overjet greater than 1 mm but less than 3•5 mm with recorded
masticatory and speech difficulties.
4•c-Anterior or posterior crossbites with greater than 2 mm discrepancy
between retruded contact position and intercuspal position.
4•l-Posterior lingual crossbite with no functional occlusal contact in one or
both buccal segments.
4•d-Severe contact point displacements greater than 4 mm.
4•e-Extreme lateral or anterior open bites greater than 4 mm.
4•f-Increased and complete overbite with gingival or palatal trauma.
4•t-Partially erupted teeth, tipped and impacted against adjacent teeth.
4•x-Presence of supernumerary teeth.

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8. Dental Health ComponentDental Health Component
Grade 3 (Borderline need)
3•a -Increased overjet greater than 3•5 mm, but less than or equal to 6
mm with incompetent lips.
3•b -Reverse overjet greater than 1 mm, but less than or equal to 3•5
mm.
3•c - Anterior or posterior crossbites with greater than 1 mm, but less
than or equal to 2 mm discrepancy between retruded contact position
and intercuspal position.
3•d - Contact point displacements greater than 2 mm, but less than or
equal to 4 mm.
3•e -Lateral or anterior open bite greater than 2 mm, but less than or
equal to 4 mm.
3•f -Deep overbite complete on gingival or palatal tissues, but no
trauma.

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9. Dental Health ComponentDental Health Component
Grade 2 (Slight)
2•a-Increased overjet greater than 3•5 mm, but less than or equal to 6
mm with competent lips.
2•b-Reverse overjet greater than 0 mm but less than or equal to 1 mm.
2•c-Anterior or posterior crossbite with less than or equal to 1 mm
discrepancy between retruded contact position and intercuspal
position.
2•d-Contact point displacements greater than 1 mm but less than or
equal to 2 mm.
2•e-Anterior or posterior open bite greater than 1 mm but less than or
equal to 2 mm.
2•f-Increased overbite greater than or equal to 3•5 mm without gingival
contact.
2•g-Pre- or post-normal occlusions with no other anomalies (includes up
to half a unit discrepancy).
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10. Dental Health ComponentDental Health Component
Grade 1 (None)
1-Extremely minor malocclusions including
contact point displacements less than 1 mm.
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11. Hierarchial scaleHierarchial scale
When recording the DHC, the hierarchial scale of
occlusal anomalies was used to help identify the
worst occlusal feature
The hierarchial scale is-
1.Missing teeth (including congeninital absence, etopic and
impacted teeth)
2.Overjets (including reverse overjets)
3.Crossbites
4.Displacement of contact points
5.Overbites (including open bites)
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12. Hierarchial scaleHierarchial scale
M O C D O
IOTN 5
Cleft lip &
Palate
Impacted /
Ectopic teeth
Hypodontia >4
missing teeth
> 9mm Overjet
> - 3.5mm
reverse Overjet
IOTN 4
Supernumaries
Hypodontia <4
missing teeth
>6mm Overjet
-2mm to -3.5mm
reverse Overjet
Crossbite with
>2mm
displacement
between RCP and
ICP
> 4mm contact
point
displacement
Deep Overbite +
Trauma
>4mm Anterior
Open Bite
IOTN 3
>4mm Overjet
<-2mm reverse
Overjet
Crossbite with
>1mm
displacement
between RCP and
ICP
<4mm contact
point
displacement
Deep Overbite
(no trauma)
<4mm Anterior
Open Bite
IOTN 2
>2mm Overjet <2mm contact
point
displacement
IOTN 1
Minimal
irregularity
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13. Grading for DHCGrading for DHC
Grades
1 and 2 No need for treatment
3 Moderate/ Borderline need for treatment
4 and 5 Need treatment
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14. Aesthetic Component (AC)Aesthetic Component (AC)
AC consists of a scale of ten colour photographs
showing different levels of dental attractiveness
(Evans and Shaw, 1987)
The patients can be rated their dental attractiveness by
comparing with the standard photographs of Aesthetic
Component of IOTN
Grade-1 represents the most and grade-10 represents
the least attractive arrangements of teeth
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16. Grading for ACGrading for AC
Grades
1 to 4 No need for treatment
5, 6 and 7 Moderate/ Borderline need for treatment
8, 9 and 10 Need treatment
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17. Grade - 1 to 4 (No need for treatment)Grade - 1 to 4 (No need for treatment)
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18. Grade - 5, 6 and 7Grade - 5, 6 and 7
(Moderate/ Borderline need for treatment)(Moderate/ Borderline need for treatment)
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19. Grade – 8,9 and 10 (Need treatment)Grade – 8,9 and 10 (Need treatment)
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21. Digimatic CaliperDigimatic Caliper
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The measurement for overjet

23. The measurement for reverse overjetThe measurement for reverse overjet
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24. The measurement for openbiteThe measurement for openbite
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25. The measurement for contact The measurement for contact
point displacementpoint displacement
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