Step 3 Subperiosteal Dissection of the Mandible

The mentalis muscle is stripped from the mandible in a subperiosteal plane. Retraction of the labial tissues is facilitated by stripping them off the inferior border of the symphysis. Subperiosteal dissection of the mandibular body is relatively simple compared to that of the symphysis because there are fewer Sharpey's fibers inserting into the bone. Controlled dissection and reflection of the mental neurovascular bundle facilitate retraction of the soft tissue away from the mandible. The periosteum is totally freed circumferentially around the mental foramen and nerve. Retracting the facial tissues laterally will gently tense the mental nerve. Using a scalpel, the surgeon then incises the stretched periosteum longitudinally, paralleling the nerve fibers (Fig. 8-7), in two or three locations. The sharp end of a periosteal elevator teases the periosteum away from the mental foramen and nerve. Any remaining periosteal attachments are dissected free with sharp scissors. This stripping allows mobilization on the branches of the mental nerve, facilitating facial retraction and augmenting exposure of the mandible. Dissection can then proceed posteriorly along the lateral surface of the mandibular body/ramus. The surgeon should stay within the periosteal envelope to prevent lacerating the facial vessels, which are just superficial to the periosteum (see Fig. 8-2).

Buccal Fat Exposure
FIGURE 8- 7 Dissection of the mental nerves. The periosteum is incised and the periosteum is stripped laterally to expose nerve branches.

Subperiosteal dissection up the anterior edge of the ascending ramus strips the buccinator attachments, which allows the muscle to retract upward, minimizing the chance of herniation of the buccal fat pad (see Fig. 8-4). Temporalis muscle fibers may be easily stripped by inserting the sharp end of a periosteal elevator between the fibers and the bone as high on the coronoid process as possible, and stripping downward (Fig 8-8). A notched right-angle retractor (Fig. 8-9) may be placed on the anterior border of the coronoid process to retract the mucosa, buccinator, and temporalis tendon superiorly during stripping. Stripping some of the tissue from the medial side of the ramus will widen the access. After stripping of the upper one third of the coronoid process, a curved Kocher clamp can be used as a self-retaining retractor grasping the coronoid process.

Anterior Ramus Retractor

While the buccal tissues are retracted laterally with a right-angle retractor, the masseter muscle is stripped from the lateral surface of the ramus (see Fig. 8-8). Sweeping the periosteal elevator superoinferiorly cleanly strips the muscle from the bone. Although direct visualization may be poor, the posterior and inferior borders of the mandible are readily stripped of the pterygomasseteric fibers using periosteal elevators, J-strippers, or both. Dissection can continue superiorly, exposing the condylar neck and the entire sigmoid notch. To maintain exposure of the ramus, Bauer retractors (Fig. 8-10) inserted into the sigmoid notch and/or under the inferior border are useful (Fig. 8-11). The LaVasseur-Merrill retractor is another useful device that slides behind and clutches the posterior border of the mandible to hold the masseter in a lateral position.

Right Angle Retractor
FIGURE 8- 9 Notched right-angle retractor. The V-shaped notch is posittioned on the ascending ramus and the retractor is pulled superiorly to retract tissues.
Inferior Border Retractor
FIGURE 8- 10 Bauer retractors. The flanges at right angle to the shaft are used to engage the sigmoid notch and/or inferior border of the mandible, allowing retraction of the masseter muscle.
Inferior Border Retractor
FIGURE 8- 11 Exposure after insertion of Bauer retractors. Note that the flange of one retractor is in the sigmoid notch and the flange of the other is under the inferior border of the mandible.

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