Primary closure

The need for reconstruction of mandibular defects is either due to trauma or tumor resection.

The vast majority of oral cavity tumors are squamous cell carcinoma, and these arise from the mucosa. These tumors are therefore adjacent to the mandible and significant growth frequently leads to invasion of the bone.

A composite resection (segmental mandibulectomy) is the treatment of choice for oral malignant tumors that invade the mandibular cortex and marrow space. It provides an oncologically sound margin for these tumors; however, it disrupts the continuity of the mandible.

Reconstruction of the mandible allows for the restoration of form and function. It must address all the tissue losses in order to provide for the best function.

The general goal of reconstruction is the:

• Restoration/maintenance of airway
• Restoration of mandibular continuity
• Restoration of dentition
• Restoration of chewing (mastication) and swallowing (deglutition)
• Restoration of facial contour
• Consistently obtain a healed wound
• Restoration of a functional temporomandibular joint

However, In cases where the soft tissue loss is relatively minimal or the patient's condition prohibits a more extensive reconstruction, primary closure of the defect may be an option that is considered.

The resection in these cases usually involves the mandible and limited adjacent oral cavity mucosa. Closure of the surgical defect can therefore be accomplished in primary fashion.

This creates the so-called "swinging defect". The mandible shifts to the affected side resulting in a cosmetic deformity, but often allows for acceptable speech and adequate swallowing.

The proposed mandibulectomy margin is marked on the mandible. Care is taken to resect at least 1 cm of normal bone on the medial aspect of the tumor.

The tumor is visualized and palpated intraorally and 1.5 cm soft tissue margins are marked (eg. with an electro cautery) around the tumor in the oral cavity.

In a dentate patient the tooth in the line of the mandibulectomy is extracted.

The bone cut is now carried anterior to the tumor using a saw. Care is taken to resect a 1 cm margin of normal bone anterior to the tumor.

The bone is retracted laterally, thus exposing the previously marked resection margin.

Medially, soft tissue cuts are made through the previously marked resection limits in the floor of mouth, the mylohyoid muscle, and deep tongue muscles if necessary.

Medially, the attachments of the medial pterygoid are released from the ascending ramus and the temporalis muscle is detached from the coronoid process.

Laterally, the buccinator muscle is divided. The masseter muscle will be divided on the lateral aspect of the mandible, as dictated by the tumor.

The lateral pterygoid muscle is divided and the capsule of the temporomandibular joint is entered.

The condyle is retracted inferiorly and the ligaments divided thus freeing the mandible.

The lateral pterygoid muscle is divided and the capsule of the temporomandibular joint is entered.

The condyle is retracted inferiorly and the ligaments divided thus freeing the mandible.

The specimen is submitted en bloc for permanent pathological examination.

Surgical soft tissue margins are now checked with frozen sections to ensure the adequacy of the tumor resection.

The resection in these cases usually involves the mandible and limited adjacent oral mucosa. Closure of the surgical defect can therefore be accomplished in primary fashion. The medial oral mucosa is sutured to the buccal mucosa using interrupted absorbable sutures (eg. 3-0 Vicryl) in vertical mattress fashion.

Pearl: The mandibular edge is rounded to avoid subsequent disruption of the wound closure as some drifting of the mandibular segment is inevitable. This can be done with a rongeur forceps or a rotary burr.