Chin implant after Sliding Genioplasty, possible or not?

I've had Sliding Genioplasty, but despite my chin being moved forward 1cm I feel the deficiency is still too prominent. Would like to have an implant inserted to gain another 1cm. I also feel the Sliding Genioplasty wasn't done well because the labiomental fold now appears to be very, very deep, with the chin below it very pointy, and the tell-tale hourglass deformity on the sides of the chin gives me a "wavy" jawline. Will an implant help, and do you recommend silicone or Medpor? Thank you.