Phase I, also known as “early intervention,” refers to early orthodontic treatment that is done before a child has all of their permanent teeth. This is carried out between ages 7 and 10. Phase I treatment hardly ever functions as a complete replacement for braces – its purpose is to fix problems that are most easily corrected at an early age and to make the Phase II treatment (braces) easier. In common words, Phase I takes care of the initial structural (skeletal) corrections so that braces can make more refined (dental) corrections and finish the job.