A sharp blade of the proper size should be used.This detachment results in the formation
of a small hematoma increasing postoperative oral swelling, and the
organization of the blood clot results in the loss of depth in the buccal sulcus?In addition, torn, split, and macerated tissue heals more slowly
than a cleanly reflected full thickness flap
Vertical-releasing incisions should cross the free gingival margin at the line angle of a tooth
and should not be directly on the facial aspect of the tooth nor directly in the papilla.So, vertical releasing incisions in the posterior
aspect of the palate should be avoided, because they usually sever
the greater palatine artery within the tissue, which results in
bleeding that may be difficult to control.11- The vertical relaxing incision should not extend beyond the depth of the
mucobuccal fold to avoid detaching the alveolar attachment of muscles (e.g.
buccinator muscle) from the bone.This
angle produces squared wound edges that are both easier to re- approximated properly
during suturing and less susceptible to necrosis of the wound edges as a result of ischemia,
and overlapping of the edges during closure.Because the goal of the surgery 
is to remove or reshape the bone, all overlying tissue must be reflected from it. In 
addition, full-thickness flaps are necessary because the periosteum is the primary tissue
responsible for bone healing, and replacement of the periosteum in its original position
hastens that healing process.8- Incisions should not be made in an area of thinned mucosa e.g. over an
exostosis or bony protuberances because the blood supply is reduced, suturing is
difficult, and the rate of dehiscence is high.The base of the flap must be broader than the free gingival margin,
and width of the base should be greater than the length, to ensure
adequate blood supply and to promote healing.If the pathologic condition has eroded the
buccocortical plate, the incision must be at least 6 or 8 mm away from it. In addition, if
bone is to be removed over a particular tooth, the incision must be sufficiently distant 
from it so that after the bone is removed, the incision is 6 to 8 mm away from the bony
defect created by surgery.If the incision line is unsupported by sound bone, It tends to
collapse into the bony defect, which results in wound dehiscence, infection and delayed
healing .The flap should be designed to avoid injury to local vital structures in the 
area of the surgery
The greater palatine artery, which emerges from the greater
palatine foramen.The nasopalatine nerves and arteries exit the incisive foramen to
supply the anterior palatal gingiva.If the anterior palatal tissue must
be reflected, both the artery and the nerve can be incised at the level
of the foramen without much risk.Incisions that cross the gingival papilla damage the papilla unnecessarily and increase the
chances for localized periodontal problems; such incisions should be avoided.A sharp blade
allows incisions to be made cleanly, without unnecessary damage
caused by repeated strokes.Bone and ligamental tissues dull blades more rapidly than does
buccal mucosa.Incisions
that cross the free margin of the gingiva directly over the facial aspect of the tooth do not heal
properly because of tension; the result is a defect in the attached gingiva.The incisions that outline the flap must be made over intact bone that will be present
after the surgical procedure is complete.This means that the flap
includes the surface mucosa, submucosa, and periosteum.Because the facial
bone is frequently quite thin, such incisions will also result in vertical clefting of the bone.Sharp corners tend to
slough because of poor circulation and this causes excessive scarring.?