The goal of first phase treatment or also known as interceptive treatment is to develop the jaw size in order to accommodate all the permanent teeth and to relate the upper & lower jaws to each other. Children sometimes exhibit early signs of jaw problems as they grow and develop. An upper & lower jaw that is growing too much or not enough can be recognized at an early age. If children after age 6 are found to have this jaw discrepancy, they are candidates for early orthodontic treatment.
Because children grow so rapidly, they can benefit enormously from an early phase of orthodontic treatment utilizing appliances that direct the growth relationship of the upper & lower jaws and providing adequate room for eruption of all permanent teeth. This early correction may prevent later removal of permanent teeth to correct overcrowding and/or surgical procedures to align the upper & lower jaws. Leaving such a condition untreated until all permanent teeth erupt could result in a jaw discrepancy too severe to achieve an ideal result with braces.
After first phase treatment is completed, the patient will be placed in a "resting period". In this phase, the remaining teeth are allowed to erupt. Retaining devices are not usually recommended since they may interfere with eruption. It is best to allow the existing permanent teeth some freedom of movement while final eruption of teeth occurs. A successful first phase will have created room for teeth to find an eruption path. Otherwise, they may become impacted or severely displaced.
In other words, at the end of the first phase of treatment, teeth are not in their final positions. This will be determined and accomplished in the second phase of treatment. Selective removal of certain primary (baby) teeth may be in the best interest of enhancing eruption during this resting phase. Therefore, periodic recall appointments for observation are necessary, usually on a six-month basis.