Forehead augmentation and foreign materials implanted or inserted.

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)?