There really is no real answer to this question. In some instances, particularly those where a child looks very different from his or her classmates, surgery can provide a way to simply fit in. For instance, the child who is struggling with a cleft lip may be teased less when the lip is fixed and they look more natural. The young girl who is developing an overly large chest at a young age may suffer teasing, and that may stop when her chest is reduced to a more natural side.
On the other hand, bullies are what they are, and if there is not a physical feature to tease, they will find something else. So, while plastic surgery can take away a potential source of teasing, parents still need to do their jobs and teach their kids how to deal with bullies, go to school personnel when bullying gets out of hand, and simply give their kids the skills they need to love themselves for who they are.
If you are considering plastic surgery for your child, you just might give her a gift that improves her confidence enough that she can more readily weather teasing. But before you sign up for surgery, make sure your child knows she is beautiful just the way she is.