Longitudinal observation of maxillary sinus bony bridges and septa in childhood.

The rate of septum presence in the maxillary sinus has been reported to be over 30%. It was considered that a bony bridge might change to a maxillary sinus septum with growth in a previous study using dry child skulls. In the present investigation, maxillary sinus bony bridges and septa were longitudinally observed using computed tomography (CT). Multislice CT was performed in three patients. A bony bridge was defined as a bony structure between the maxillary sinus wall and dental germ. Also, a septum was defined as a pointed bony structure in the inferior wall of the maxillary sinus. The height and angle of the bony bridge/septum and the distance between the base of the bony bridge/septum and bony palate were measured. In three patients, the bony bridge in the maxillary sinus floor was observed in the second molar on the first CT, and the maxillary sinus septum was observed on the second CT at the same site. In conclusion, it was longitudinally observed that a bony bridge changed to a maxillary sinus septum with growth, such as root formation and tooth eruption.