Anatomical Changes in a Case with Asymmetrical Bilateral Maxillary Sinus Hypoplasia

Background and Objectives: The maxillary sinus hypoplasia (MSH) is an occasional variation of the maxilla, occurring either unilaterally or bilaterally. Previous studies dealing with MSH have not detailed the consequent anatomical changes of the maxilla and adjacent fossae. Materials and Methods: A 58-year-old female case was scanned in Cone Beam Computed Tomography and found to have asymmetrical bilateral MSH, who was then further evaluated anatomically. Results: The maxillary sinuses were hypoplastic and had mild mucosal thickenings. The orbital floors were curved. The uncinate process and the ethmoidal infundibulum were laterally displaced beneath the orbit floor. On each side, the lateral nasal wall protruded within the respective maxillary bone to reach above the vestibular cortical plate of the alveolar process. This expansion of the lateral nasal walls was limited to the premolar and first molar regions. The inferior turbinates were laterally curved. The perpendicular palatine plate was building a postero-lateral nasal wall in front of the pterygopalatine fossa. Conclusions: The classification systems of MSH should be detailed to indicate whether the normal uncinate process is medial or inferior to the orbit. The lateral expansion of the lateral nasal wall in MSH is limited to the anterior part of that wall. The laterally expanded nasal fossa could reach anterior to the pterygopalatine fossa in MSH. Seemingly, CBCT is a better tool than CT to evaluate the detailed anatomy of the modified anatomical structures in MSH; as such, it could be of help in a surgical approach.