Preventing a potential orthodontic anomaly at the youngest age is always better than addressing the problem when it already occurs. A good orthodontist will, in a timely manner, recognize a possible anomaly and prevent or minimize subsequent anomaly (such as dealing with premature loss of a second premolar by a so-called placeholder).
Orthodontics in children is of the utmost importance as mobile devices can influence both the position of the teeth and the direction of bone growth and development (eg, in the case of a more narrow upper jaw than lower jaw, which causes a deep overbite.)
For adults, the best choice for correcting the position of the teeth is a fixed brace.