What are phases one and two of orthodontic treatment?

What are phases one and two of orthodontic treatment?

Phase 1 or interceptive treatment

Aim at detecting and treating mild to severe orthodontics alterations in younger patients, creating a more
favorable ground for the second phase of treatment.
Taking advantage of the rapid growth of younger ages to transform a potential difficult problem into an easier
one to treat (for example eliminating the need of tooth extractions or even surgery and shortening the
duration of treatment in phase 2).
This phase usually starts around ages eight or nine.

Phase 2

Starts when all permanent teeth have erupted and lasts around 18 months.