Cone-beam computed tomography assessment of palatal-nasal recess of maxillary sinus in dentulous and edentulous subjects.

Background: Implant placement in the posterior maxilla is challenging in the case of maxillary sinus pneumatization. Increasing the vertical dimension by grafting the sinus floor is a common surgical modality. Cone-beam computed tomography (CBCT) scans are used to assess the presurgical anatomic variations of the maxillary sinus and determine the difficulty that might be encountered while performing sinus elevation. The sinus membrane is elevated from both the lateral and mesial walls of the sinus. The location and angulation of the palatal-nasal recess (PNR) on the medial wall of the sinus could complicate the elevation of the sinus membrane in this region. This study aimed to assess the angulation of the PNR and its position with respect to the alveolar crest in dentulous and edentulous subjects in the 1^st molar region on CBCT scans.

Materials and methods: One hundred and fifty-two scans were selected from the department database. Sagittal sections including the 1^st molar region were selected and measurements made. The PNR height was measured from the alveolar crest in millimeters and angulation in degrees and compared between the dentulous and edentulous groups.

Results: The dentulous group showed a statistically significant greater distance (10.4 ± 2.8 mm) between the alveolar crest and PNR as compared to the edentulous group (8.08 ± 3.1 mm). The edentulous group showed a statistically significant greater PNR angle (139.6^o ± 13.6^o) as compared to the dentulous group (133.4^o ± 16.4^o).

Conclusion: Maxillary sinuses with acute-angled PNR and lesser distance from the alveolar crest should be carefully evaluated to avoid complications such as membrane perforation during their elevation from the bony wall of the sinus.