Index for orthodontic treatment needs is/are:
SCAN index
ICON index
DAI index
All of the above
SCAN index is the synonym for Index for Orthodontic Treatment Needs (IOTN). IOTN index was developed by BROOK and SHAW to link dentofacial variation to perceive esthetic impairment.
Key Concept:
The other Orthodontic treatment need indices are:

Handicapping Labio-lingual Deviation Index (HLD) (Draker)
Dental Aesthetic Index (DAI) (Cons et al)
Index of Complexity, Outcome and Need (ICON) (Daniels & Richmond)