The forehead can be contoured to look smoother and less sloping or to fill in localized depressions or irregularities using bone cement applied directly to the skull.
Bone cement has been safely employed for decades in orthopedic surgery to help anchor artificial joints and even longer to fill in breaks or gaps in the skull. The main ingredient is polymethylmethacrylate (PMMA), the same thing as Plexiglas or Lucite. It is extremely durable, biocompatible, and turns transparent after hardening.
The bone of the forehead is exposed in a manner similar to that made during coronal forehead lifting (upper facelift) using a wide incision rimming the forehead but hidden in the hair.
The bone cement is created by mixing a dry PMMA powder and a liquid. The viscosity of the cement changes from runny into a dough-like paste that is applied much like putty. Hardening is slow enough that the cement can be carefully sculpted on its bed of bone.
Not as soft or flexible as silicone implants, the plastic cement feels similar to natural bone. The augmentation effect is permanent but can be surgically reversed by removing the solid implant.
While easier to use and less time-consuming, the end result is seldom as precise as with silicone implant.