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 midline (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 plates of the palatine bones and part of the palatine processes of the maxillae). The radiographs were digitized and preostectomy and postostectomy optical 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 occurred only after bilateral ostectomy of the posterior portions of the HP/NFF. The mean increases in regional optical density in terms of pixel gray level after the ostectomies were 70.44%, 72.27%, and 51.40%.

CONCLUSIONS

The junction of the nasal septum with the NFF and the posterior portions of the HP/NFF form the upper image of the HP/NFF. Most of the image is real, although a small part is a ghost image of the horizontal plates of the palatine bones and of the posterior region of the palatine processes of the maxillae.