Plates can be removed after the healed bone cements things into place. Like any foreign material, if there's ever an infection later down the line, the anti-biotics won't be able to get to it. Also, harder to remove-due to bony overgrowth- if there is an infection and they stay in too long. As to materials, titanium is the more bio-compatible (over stainless steel) but also more costly. But still, since removal of plates is suggested after the bone is all healed (for the above stated reason/s) , that applies equally to both materials. So, since both materials can be removed within same/similar time frame, it doesn't matter if the plate is titanium or stainless steel. However, if a metal material actually needs to STAY in the face/body for a lifetime (which these plates don't), then titanium is the preferred material.