White spots after braces?

that's sign of demineralized enamel(outermost layer of tooth). enamel should have strong content of mineral so that it can protect tooth. but, if mineral get leaked out due to acid or plague that's not cleaned for some time, that area is prone to decay. sometimes, there is already decay under that whitish weakened enamel layer. i know it's hard to clean around bracket, but you should make sure you clean every corner.