The American Association of Orthodontists recommends that all children get a check-up with an orthodontist no later than age seven. Although only a few orthodontic problems need to be corrected at that age, an early exam allows the orthodontist to offer advice and guidance as to when the appropriate age to start treatment would be. Let your orthodontist guide you as to when to start treatment.
Many patients begin treatment just before they loose the last baby tooth which is around age 11 or 12. Adults can always start treatment as long as their gum is healthy.