How misaligned do a child's teeth have to be for her to need braces at age 9?

Early treatment: There are several factors. If the child's teeth are crowded, the upper or lower jaws are not in alignment, muscle attachments are preventing proper alignment, etc are all factors. Early treatment can prevent more complex treatment at a later age. Consult your dentist

Individual decision: Age nine and ten are too often referred to as the ugly duckling stage of tooth development. All kind of changes going on in the mouth. Evaluation of the tooth sizes to arch lengthen, a skeletal analysis, and the eruption pattern. What looks awful now may not be so bad as it looks. Two stage ortho is common enough. Early treatment can have advantages is some cases, but not routinely.

Standard of Care is that ALL children have (free) Initial Orthodontic Examination by Age 7. Statistically approximately 1 of 15 children that will require Orthodontic treatment would benefit from early intervention. For best understanding, see a qualified Orthodontic Specialist for a growth and development review.