One of the concerns about plastic surgery on adolescents is that their bodies are still maturing. In addition to development that may occur in the late teens. This is why plastic surgery shouldn't be introduced teens this is because they have little knowledge about this concept they totally don't know what will happen after the procedure.

is this correct check my grammar

Second sentence doesn't make sense. Third sentence is three sentences run together.

Please study this:

http://grammar.about.com/od/rs/g/runonsentenceterm.htm

One of the concerns about performing plastic surgery on adolescents is that their bodies are still maturing, especially during the late teens. This is why it is not advisable to introduce plastic surgery to teenagers, as they typically have limited knowledge about the concept and are often unaware of the potential outcomes and consequences of the procedure.