A) Full mucoperiosteal (i.e., sulcular) incision. The horizontal incision is into the sulcus, accompanied by one (i.e., three-corner) or two (i.e., four-corner) vertical components. This represents the classic trapezoidal flap with the base broader rather than the peripheral edge. (B) In comparison, by making the vertical-releasing incision(s) along the long axis of adjacent teeth, the length of the flap in nonkeratinized tissue is decreased, which reduces pain and accelerates the healing.