Which of the following is NOT a requirement of a mucoperiosteal flap?

The requirement that is not necessary for a mucoperiosteal flap pertains to the careful separation of the mucous membrane from the periosteum. While it is essential to separate these layers to ensure that the flap can be elevated and positioned correctly for healing, it is not a strict requirement within the definition of a mucoperiosteal flap itself.

In surgical practice, the focus is more on maintaining the integrity and blood supply of the flap for successful healing and adequate coverage over the underlying bony defect. The design of the flap typically ensures that the base is wider than the free margin, promoting blood flow and viability. It also needs to provide adequate coverage for the bony defect while allowing for sufficient vascularity from the base throughout the flap. Overall, the primary importance lies in the flap's successful integration and blood supply rather than the meticulous separation of mucous membrane from periosteum at all times.