Penny why don't you do a little research before you make comments about a subject that you clearly don't know. Sadly your comments may prevent children fom obtaining the best possible dental care. Is that really your aim?
See below:

"Removable Appliances
Removable appliances are not as precise as fixed braces, which is why they are only used to move one tooth or a small group of teeth. We have used appliance therapy on many children and a few adults with minimal misalignment of their teeth. Patients are required to wear their appliance all the time during therapy and come in for regular observation and adjustment visits. Therapy can take anywhere from 6-18 months.

Dr. Thomas Kappen can screen your child as early as age seven to see if they may require braces in the future. Sometimes he may choose to have your child wear an appliance before all the adult teeth come in to improve eruption patterns and jaw alignment. This is called "Interceptive Orthodontics". Children may or may not require braces after wearing the appliance; it just depends on the complexity of the case and the growth pattern of your child's teeth and jaw"

Yes this is from Dr Sarah's website, however I suggest you do a search on Interceptive Orthodontics and then comment.