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Zahid`s Study Notes IOTN Ruler Modified IOTN*

IOTN have two components: A. Aesthetic Component (AC) B. Dental Health Component (DHC)

A. Aesthetic Component (AC)

Grade 1-7: NO treatment (NT)

Grade 8-10: Definitive need of treatment (DNT)

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Method of recording aesthetic component:

1, Ask pt to close teeth on posteriors 2. Retrected lips 3. Grade overall attractiveness of anterior teeth rather then specific morphological similarities to photographs 4. Ist impression is usually correct

5. Focus is to differentiate those at 8-10 then DEFINITVE NEED OF TREETMENT

B. Dental Health Component (DHC)

For DHC again IOTN has been simplified in to two categories:

1. DEFINITVE NEED OF TREETMENT

2. No DNT

The Subject is examined for 5 specific conditions and if one is found a DNT is recorded and no further condition is sought

Method: Examine each subject for: MOCDO

Missing Over jet Cross bite Displacement of �Contacts Points� (of two most imbricate teeth) Overbite

Recording the DHC 1. Examine using mocdo Scale 2. As soon as DNT reached examination stoped 3. IOTN Ruler is required

It has a white line at 4mm and a red line at 6mm.

White line is for reverse over jet Crowding Open Bite Reverse over jet (ROJ)

Red line is at 6mm represent positive over jet Over jet (if greater then red) = Need for Treatment (DNT)

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sApplication of MOCDO SCALE

1 . Missing Teeth(Invisible)

A. Congenitally/Traumatically absent: If less then white line is the space left, if in your opinion treatment is required to open or close the

space then DEFINITVE NEED OF TREETMENT B. Ectopic Canines Is canine palpable on bucal sulcus if not DEFINITVE NEED OF TREETMENT

C. Impacted If at or less then white line space available, then DEFINITVE NEED OF TREETMENT

2.Over Jet Measure oj up to labial aspect of the most prominent incisor

A. Increased (Class 2)

if >6 more then red line DEFINITVE NEED OF TREETMENT

B. Reversed (Class3) All four incisors must be in lingual occlusion.

If ROJ fall on white line (4mm) DEFINITVE NEED OF TREETMENT

3. Cross Bites

Can b anterior or posterior but mostly posterior

Check for the displacement on closure if yes DEFINITVE NEED OF TREETMENT

4.Displacement of contact pointsOnly applies to crowding in permanents Measured between contact points of two most crowded anterior teeth

If the most crowded tooth is beyond white line DEFINITVE NEED OF TREETMENT

5. Overbite:

C. Deep Causes trauma to gingival or palatal tissue

D. Open

If beyond white line then DEFINITVE NEED OF TREETMENT

Note : Generalised spacing is not recorded in DHC.

Ref: pcwww.liv.ac.uk written by Donald Burden and Cynthia Pine with assistance from BASCD working party on orthodontics with thanks.

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Reading a ruler:

Upper left half: positive over jet=a 0-2 over jet upto 3.5mm up to normal grade 1 3-i overjet 3.5-6 mm incompetent lips grade 3 since positive over jet=a so 3a 2-c - do- compitent lip grade 2 -do- so 2a 4 6-9mm 4a 5 > 9mm 5a

Lower left half: now reverse overjet =b and reverse overjet with maticatory/speech defect=m 1 up to 1mm = 2 since reverse overjet =b so 2b 3 >1 but < 3.5mm -do- 3b 4 >1 but < 3.5mm with masticatory and speech defect 4m 4 > 3.5 with no m 4b 5 >3.5 with masticatory or speech defect 5m

Right side is for contact displacement Displacement of �Contacts Points� (of two most imbricate teeth) =d 1 displacement <1 mm minor grade 1 2 >1 to < 2 grade 2 2d 3 >2 to < 4 mm grade3 3d4 >4 grade4 4d

Middle Open bite e; or deep bite f

4f

4e

3f

3e

2e

2f all other are self explanatory

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MOCDO

Missing teeth (I= impacted ,h= hypodotia) 5i=

5h=

4h=

Over Jet a/b or m

5 a =

4.a =

3.a=

2.a=

5m=

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4m=

4 b=

3.b=

2.b=

(d)

4 d=

3d=

2.d=

(c)

Check for the displacement on closure if yes definitive need for treatment 4c=

3.c=

2c=

(e=open&f=deep) 4.f=

3.f=

2.f=

and 4e=

3.e=

2.e=

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Clinical Significance:

Example: