Pathway by Which Oral Cancers Invade the Mandible

Primary carcinomas of the lip, buccal mucosa, tongue, and floor of the mouth extend along the surface mucosa and the submucosal soft tissues to approach the attached labial, buccal, or lingual gingiva.

From this point, the tumor does not extend directly through intact periosteum and cortical bone toward the cancellous part of the mandible because the periosteum acts as a significant protective barrier .

Instead, the tumor advances from the attached gingiva toward the alveolus.

• In patients with teeth, the tumor extends through the dental socket into the cancellous part of the bone and invades the mandible in that fashion (Figure).

Thus even in patients with early invasion of the mandible, a marginal mandibulectomy is feasible because the cortical part of the mandible inferior to the roots of the teeth remains uninvolved and can be safely spared.

In edentulous patients, however, the feasibility of marginal mandibulectomy depends on the vertical height of the body of the mandible .

• With aging, the alveolar process recedes and the mandibular canal comes closer to the surface of the alveolar process.

  • As shown in the Figure, the resorption of the alveolar process eventually leads to a “pipestem” mandible in elderly patients.

Similarly, in patients who have received previous radiotherapy, a marginal mandibulectomy should be performed with extreme caution.

• The probability of pathological fracture at the site of the marginal mandibulectomy in such patients is very high.

A segmental mandibulectomy also may be required in patients with massive primary tumors with significant soft tissue disease in the proximity of the mandible.