Soft Tissue Enhancement and Implant Placement Following Partial Mandibulectomy Due to Squamous Cell Carcinoma
Many dental procedures allow for implant placement in partially or totally edentulous patients. Despite the availability of various implant and abutment types on the market, it often becomes quite challenging to achieve the biological and esthetic goals in a patient who has ridge deficiencies. Problems arise from the lack of adequate bone quality and quantity.1,2 Soft tissue form and maintenance is also a consideration to evaluate.3 Primary reconstructive techniques following segmental mandibulectomy is evolving and improves quality of life. A seldom encountered complication is the discovery and treatment of a malignant process (for example, squamous cell carcinoma). Oral squamous cell carcinoma (OSCC) is one of the most aggressive malignancies worldwide and accounts for more than 90% of all oral cancers.4 It is ranked as the sixth leading cause of cancer mortality worldwide. The most common sites of OSCC are the lateral ventral surface of the tongue, the floor of the mouth and buccal mucosa. For most oral cavity cancers, surgery is the initial treatment of choice (often involving the full or partial removal of bony jaw structure).5 Radiation or chemoradiation is added postoperatively if disease is more advanced or has high-risk features. Successful cancer therapy can affect the quantity and quality of soft tissue in areas where implants are planned, thus affecting the initial placement and the long-term success of the implants. Complications can be numerous; especially difficult is implant treatment in the mandibular anterior area where inadequate alveolar height results in the lingual floor and the vestibule becoming contiguous.6 Further complicating treatment is the presence of scar tissue (often found following cancer surgery and radiotherapy). The present case is a report of the combination of a soft tissue enhancement and implant placement following partial mandibulectomy resulting from the treatment of oral squamous cell carcinoma. A video abstract is available for viewing at https://youtu.be/dZ9t3j4ufOc?list=PLvRxNhB9EJqbqjcYMbwKbwi8Xpbb0YuHI.
Figure 1. Patient presents with leukoplakia of the floor of the mouth. A biopsy of the area confirms oral squamous cell carcinoma. Figure 2. Panoramic radiograph shows poor dentition with no posterior occlusion to stabilize either arch.
The carcinoma was surgically removed with partial floor of mouth dissection. In addition, part of the vestibular portion of the mucosa was removed with a partial resection of the interforaminal portion of the anterior mandible (partial mandibulectomy). A computerized tomography scan shows the extent of removal of the superior cortical section of the mandible.
Figure 4. Following surgery, there was a union of the vestibular floor with the lower lip, resulting in difficulties with speaking, swallowing, and movement of the lower lip. Figure 5. Radiographic studies assisted in the decision for 2 implants in the retroforaminal area (spared at the surgery for partial mandibulectomy) and 2 in the intraforaminal area (site of partial mandibulectomy). Figure 6. Posterior to the foramina, two 6.5 mm in length and 4.1 mm in diameter tapered implants were positioned. Anterior to the foramina, two 8-mm implants were positioned. All implants were placed in an adequate 3D position with insertion torque of at least 35−40 N-cm. Figure 7. An acellular dermal matrix “horse shoe” was tailored to provide addition soft tissue mass in the affected area. Figure 8. Mucosal flaps were sutured with the intention of reducing tension to prevent dehiscence of the wound. Figure 9. At postop day 3: a large wound dehiscence appeared where ADM was widely exposed. The wound was disinfected with hydrogen peroxide and resutured using absorbable suture (Vicryl Plus 4-0). Figure 10. Appearance after 7 days (day 10 after surgery), revealing a large wound dehiscence.
(a) At day 16 postoperative, the dehiscence was visibly reduced. (b) At day 25, postop healing continued, and (c) at day 33 postop, “mucosa bridges” were noted between vestibular and lingual area, with (d) complete re-epithelialization of dehiscence with new tissue formation visible at 39 days postop.
Figure 12. Postoperative day 60 shows a stable wound bed. Figure 13. Biopsies obtained from areas indicated with circles.
Final treatment with a Toronto Bridge was chosen to match the patient's needs. It consisted of a screw-retained mesostructured (a) and a cemented suprastructure (b). The lower image (c) shows the final clinical presentation.
Magnification (×10 original) revealed a healthy incorporation of graft tissue with host tissue and a surface partially covered by viable nonkeratinizing squamous epithelium. The submucosal layer was completely normal.
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