Classically, tumor surgery of the mandible results in dental, facial, speech, and swallowing deformities. The nature of the deformities varies greatly based on the extent and location of the surgery, and the nature of any surgical rehabilitation.

Obliterative surgery of the mandible has less immediacy in the need for prosthodontic intervention than surgery of the maxilla, but its implications are just as serious. You can’t ethically send a maxillectomy patient home without an obturator, but the defect caused by mandibular surgery can be severely deforming with significant consequences for the patient's speech, swallowing and esthetics.

Removing segments of the mandible, without the loss of mandibular continuity, has little effect on the range of movement of the mandible, other than a possible decrease in the extent of opening. The muscles of mastication usually retain enough attachment and freedom of motion to move the mandible in most of the familiar paths. The nature of the surgical closure, the amount of floor of mouth, tongue, and buccal mucosa removed, as well as the remaining height and movement of the lip and tongue, can greatly affect esthetics and function, however.

Removable dental devices usually rest on mucosa and attached gingiva which are firmly connected to the underlying bone. When this bone is lost and the lip and floor of mouth are connected without the attached mucosa this supporting base is lost. This presents a non-stable, non-supporting base that actually resists prosthesis placement. When a prosthesis is placed, it is not capable of handling a normal functional load and prone to developing sore spots. With adequate tooth or implant support the surgerized soft tissue areas may be bypassed and adequate prosthetic function achieved; But when tooth and/or implant support is lacking, the nature of the soft tissue closure becomes highly significant for prosthetic rehabilitation.

Preparations for all forms of mandibular resection start with a preoperative examination and record taking. With models of the original dentition and arch form, both transitional and final devices will closer approach the patient’s natural oral apparatus. In addition, templates and stents can be constructed to aid in graft location, and soft tissue adaptation intra-operatively, increasing the efficacy of the surgery by making this obliterative phase the first step in the rehabilitation of the patient.

Loss of continuity of the mandible presents it’s own set of rehabilitative problems. In the classic hemi-mandiblectomy, the remaining mandible deviates toward the midline and inferiorly. Scarring increases this as time passes. The more significant the scarring the more difficult it is to reestablish the original tooth relationship, and bring the chin toward the midline. Without reconstruction of the mandible, this deviation is not only deforming, but makes speech and eating difficult. As in all areas, radiation therapy only increases the rigidity of the scars and makes the rehabilitation more difficult.

Even if a secondary reconstruction is planned, it is difficult to reposition the mandible once the scarring is holding the surgerized side inferiorly. To help prevent, or correct this deviation, a guide plane can be constructed driving the lower jaw into tooth to tooth contact during closure. This technique does not correct the rotational deviation of the lower jaw, however. To fight the rotation of the mandible and to align the upper and lower dentitions we construct a device which locks the remaining lower teeth to the upper teeth. This restricts motion but helps prevent rotation while maintaining the midline and enhancing occlusion.

Surgical limitation of tongue function, can be due to peripheral nervous or muscular changes or alterations to the body of the tongue itself. Limited function can be aided by prosthetically altering the shape of the palate and/or narrowing the dental arch. This allows a limited range of motion to bring the tongue into contact with critical structures, improving phonetics and food movement.

It is impossible to make a simple classification of the nature of the mandibular defects caused by obliterative surgery because most patients end up with a combination of anatomic alterations. In planning the surgery, you must look at the surgical results as the first step in the rehabilitation of the patient. Pre-surgical prosthodontic records, preservation of as many remaining teeth as possible (to hold the devices), and proper staging for surgical reconstruction and/or dental implants, all make the highest level of rehabilitation possible. Surgical intervention and Prosthodontic Rehabilitation must be different stages of the same treatment to achieve maximum effect. The better we work together, the better the quality of life our patients can experience.