Prosthetic Management

Prosthetic management of the radical maxillectomy defect is the traditional method of rehabilitation. Clinical experience using prosthetic devices for this purpose is significant and it has become clear that certain factors are favorable with regard to prosthesis retention and function. These include the presence of an intact opposite hemipalate, retention of healthy teeth adjacent to the palatal defect, retention of the majority of the soft palate, and formation of a linear contracted scar around the cheek facilitated by the placement of a skin graft at the time of the extirpative surgery. The size of the defect is proportional to the likelihood of excessive prosthesis movement and failure. The presence of stable teeth, especially next to the defect, significantly improves this relationship. Using a prosthesis after maxillectomy nonselec-tively will result in several patients experiencing difficulties that include leakage and poor mastication. Approximately 70% of patients describe their swallowing and speech as fair to good. To avoid these complications, certain surgical defects should either be prepared with osseointegrated implants or left for flap reconstruction.

Prosthesis retention and stability are major determinants of successful obturation and mastication. An unstable prosthesis is more likely to leak and be unable to withstand the forces of mastication. Stability and retention are intimately related. In m

Figure 28 Typical tissue-borne prosthesis consisting of an obturator portion that extends into the maxillary defect and a denture portion that conforms to the remaining hard palate (a). The tissue-borne prosthesis in place (b).

general, stability increases as the size of the opposing hard palate increases. The cantilever effect of vertical prosthesis movement within the cavity secondary to mastication is lessened when the opposite normal palate extends beyond the midline. If there is significant remaining normal hard palate, it is possible that a tissue-borne prosthesis will work (Fig. 28). A tissue-borne prosthesis is one that depends only on the underlying tissues for support, much like a denture. With less remaining hard palate it is possible to extend the obturator into the cavity to engage the bony elements, including the proximal stumps of the buttresses. After engaging these bony surfaces, the prosthesis is retained over the lateral scar band at the junction of the skin graft and oral mucosa. The prosthesis can also be attached to healthy teeth in the remaining alveolus to improve its stability and retention when the hard palate defect extends across the mid-line. This tooth-borne prosthesis can be quite stable since the teeth assist to retain the prosthesis and to limit the cantilevering effect of mastication. The prosthesis attaches to the teeth with clasps similar to a partial denture. If teeth are not present in the remaining alveolus and the prosthesis is unstable, the patient may be a candidate for osseoin-tegrated implants. These implants are best placed along the remaining alveolus and are essentially tooth substitutes that act to secure a full denture. This implant-borne prosthesis can be snapped out for cavity inspection and cleaning.

Preparation of the surgical cavity to accept a prosthesis is an important aspect of treatment. During resection, healthy teeth in the remaining alveolus should be preserved. The abutment teeth are most important. To ensure the survival of abutting teeth, the osteotomy should be done through the adjacent tooth socket instead of the space between the teeth. This will preserve a stabilizing shelf of bone around the last tooth. The radical maxillectomy cavity is skin-grafted to enhance healing and facilitate the formation of a scar band inferolaterally that will be important to help retain the final prosthesis. An initial (surgical) prosthesis is used to hold the bolster in the cavity against the skin graft. It also facilitates speech and swallowing in the immediate postoperative period and after the bolster is removed. This prosthesis is created preoperatively by the prosthodontist. A new interim prosthesis is created by the prosthodontist after the acute postoperative period that will better fit the defect and minimize leakage. The patient usually uses this prosthesis through radiation therapy. Once the cavity has stabilized, the final prosthesis will be fitted. This prosthesis will be modified as needed to enhance function and comfort.

Prosthetic management of soft palate defects is more difficult because of the mobility and intricate muscular coordination of this structure. A significant defect in the soft palate may leave an orphaned area of soft palate (a band of tissue); this defect is difficult to obturate effectively. Removal of the remaining soft palatal band of tissue may be needed to improve the ability of the obturator to create an effective seal. This is especially true if the posterior band is foreshortened and not able to reach the posterior pharyngeal wall. A notable exception to this is in a patient that has undergone a maxillectomy and a large cavity is created above the level of the hard and soft palates. In such a case, the soft palatal band of tissue will assist in retaining the prosthesis.

Certain size-related and configuration-related factors may be present after maxillectomy that impede the successful use of a prosthesis. Large-volume defects including radical maxillectomy associated with orbital exenteration and/or removal of cheek skin are difficult or impossible to obturate effectively. Facial contour problems arise when the resection approaches the medial zygomatic bone and inferior orbital rim. Due to the limitations of local flap tissue design, periorbital reconstruction including the inferior orbital rim requires the use of nonvascularized bone grafts and titanium mesh. These implants require envelopment in vascularized flap tissue for survival and integration. When the resected palate includes the pre-maxilla (including the canines and nasal spine), prosthetic rehabilitation is difficult and movement of the prosthesis with mastication is common. Vascularized bone reconstruction is essential to provide a stable base for a prosthesis or osseointe-grated implants and to maintain the contour and projection of the upper lip and nasal base.

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