I have a horizontal line in my chin, which looks like split skin and is creating a groove. How can I get rid of it?

The least invasive technique would  be to use a filler like  Radiesse to plump up the line . I also use Botox injection (2.5 units) in the mentalis PRIOR to the Radiesse.An other option is subincision . Using a special needle I go "under" the line to sever the sub dermal attachments to "release" the line. Keep in mind that none of those options are permanent. Good luck!