Do the usual concerns regarding nose and chin implants (e.g. bone erosion, extrusion, skin thinning, shifting out of place, infection etc) apply equally to implants used for forehead augmentation? Or to a greater or lesser extent. And if so, do these risks also apply when a mallable, soft substance is inserted and kneaded into place by the doctor such as hydroxyapatite or pmma (not sure if I've got those right)?