Carcinomas arising in the maxillary sinus, occasionally present clinically in the oral cavity along the occlusal ridge of the upper alveolus. The mechanism of this spread has not been investigated but it may resemble invasion of the mandible by oral carcinomas, which tend to invade the soft tissues rather than eroding through bone. In Britain, such patients are usually edentulous. This project examines deficiencies in the bony walls of the maxillary sinus to determine possible routes of spread.
Maxillae were obtained from one side of 17 dissecting room cadavers, aged 71-95 years; 15 were edentulous. The roof of the maxillary sinus was removed in all specimens. Five maxillae were each cut into six slices, 0.5 cm thick, in a vertical bucco-lingual plane. In all, soft tissues were removed by treatment in dilute bleach. Histological sections, cut in the horizontal plane, were prepared of a further three maxillae.
Several possible routes were identified by which tumors could spread from the sinus to the oral cavity: 1) directly through foramina in its floor; 2) through numerous foramina in its floor to the marrow cavity of the alveolar process, which mostly contained fat amongst narrow bony trabeculae. (The marrow cavity, in turn, had numerous communications with the occlusal surface); 3) through foramina which carried branches of the superior alveolar nerves and vessels; 4) through deficiencies in the bony walls of the sinus at the neurovascular grooves and elsewhere.