The patient was a 49-year-old female, who initially visited the Department of Otolaryngology, Iwate Medical University Hospital, for an evaluation of oral complaints in January 2002. She was subsequently diagnosed with adenoid cystic carcinoma of the mouth floor. A total glossectomy, bilateral radical neck dissection, segmental resection of the mandible, and immediate reconstruction using a rectus abdominal muscle flap were performed in February 2002. In May 2002, the patient consulted the Clinic of Maxillofacial Prosthodontics for functional and esthetic recovery of the introverted lower lip. We devised and applied a mandibular prosthesis to extend the denture border which was placed on the free skin graft to establish stability of the prosthesis, and improve the masticatory and swallowing functions by placing the maxillary appliance. The patient was very satisfied with the mandibular prosthesis which restored lip-support, masticatory and swallowing functions with the placement of the maxillary appliance. This case report shows that placement of a mandibular prosthesis on the free skin graft area as supplemental equipment in order to extend the denture border, together with placement of a maxillary appliance, is an effective strategy for assisting the movement of food towards the pharynx by masticatory motion.