The image of the hard palate/nasal fossa floor in panoramic radiography: The controversy is over

Objective. The aim of this investigation was to obtain further information about the anatomic structures involved in the formation of the upper image of the hard palate/nasal fossa floor (HP/NFF). Study design. Three dry human skulls underwent ostectomies along the HP mid line (ie, the area of the junction of the nasal septum with the nasal fossa floor) and along posterior portions of the HP/NFF (ie, the horizontal plat es of the palatine bones and part of the palatine processes of the maxillae ). The radiographs were digitized and preostectomy and postostectomy optica l densities were measured. Preostectomy and postostectomy optical densities were also measured. Results. Partial disappearance of the upper image occurred after ostectomy of the junction of the nasal septum with the NFF. Total disappearance occur red only after bilateral ostectomy of the posterior portions of the HP/NFF. The mean increases in regional optical density in terms of pixel gray leve l after the ostectomies were 70.44%, 72.27%, and 51.40%. Conclusions. The junction of the nasal septum with the NFF and the posterio r portions of the HP/NFF form the upper image of the HP/NFF. Most of the im age is real, although a small part is a ghost image of the horizontal plate s of the palatine bones and of the posterior region of the palatine process es of the maxillae.