A 16-year-old female patient developed slight tenderness of the gingiva in the left mandibular premolar region, and her dentist referred her to our clinic in April 1992. Oral examination showed erythematous granular swellings that bled easily on the alveolar gingiva involving the area extending from the right second premolar to the left second molar (Fig. 1). The lesion showed extensive, superficial growth but was largely confined to the attached gingiva. Radiographic examination showed notable alveolar bone resorption in the left mandibular premolar region and slight resorption in the right mandibular canine region (Fig. 2). The lesion was biopsied, and histopathological examination showed diffuse unencapsulated proliferation of moderately to poorly differentiated squamoid tumor cells with occasional mitotic figures and keratinization as well as tumor nests comprising intermediate and clear cells. Few duct-like structures were observed, but microcysts were occasionally noted (Fig. 3). The specimen histologically resembled a mucoepidermoid carcinoma, but presented as a rare gingival carcinoma of the mandible. Treatment in May 1992 involved resection of the alveolar ridge between the right and left second molar regions, preserving the right inferior alveolar nerve, followed by bilateral upper neck dissection and transplantation of a lateral tongue flap to cover the alveolar ridge defect (Fig. 4). Histopathological examination of the surgical specimens showed bilateral submandibular lymph node metastases. Two courses of postoperative chemotherapy were performed to prevent local recurrence and distant metastasis.

There was no evidence of recurrence or metastasis at 1 year 3 months after surgery, and an International Team for Implantology (ITI) implant system (Institut Straumann AG, Basel, Switzerland) and prosthetic appliance were provided for cosmetic improvement and recovery of masticatory function. Four implants (three measuring 4.1 × 10 mm, one measuring 4.1 × 8 mm) were placed in the mandible in August 1993 (Fig. 5). Three months later, these implants were connected by three gold U-shaped Dolder bars soldered to gold copings and made to fit passively. The overdenture incorporated three corresponding riders/clips acting as matrices on the intaglio surface, providing attachments to the bar retainer. The implant-supported overdenture was inserted and adjusted until the patient felt no pain (Fig. 6). The patient was given oral hygiene instructions and scheduled for follow-up appointments.