Topographic Analysis of Maxillary Posterior Teeth and Maxillary Sinus in the Mongolian Population

The relationship between the maxillary posterior teeth and the level of the maxillary sinus varies across different populations and can significantly impact the success of endodontic, prosthodontic, orthodontic, and surgical treatments. This study aimed to evaluate the alveolar bone anatomy of maxillary posterior teeth and the vertical relationship to the maxillary sinus in Mongolian adults using cone-beam computed tomography (CBCT) images.

The study was designed as a retrospective study. We selected 30 CBCT images and examined a total of 202 maxillary posterior teeth using these CBCT images. We measured the alveolar bone thickness at six different distances (L1-L6) by millimeter scale, and the vertical relationship between the maxillary sinus and the maxillary molars was classified into five categories according to Kwak's classification. Statistical analyses were done using IBM SPSS Statistics for Windows, Version 27 (Released 2020; IBM Corp., Armonk, New York).

The average distances measured were 1.66±1.10 mm at L1, 2.13±1.00 mm at L2, 3.03±2.21 mm at L3, 6.04±3.50 mm at L4, 2.41±3.54 mm at L5, and 0.74±2.09 mm at L6, with statistical significance (p<0.001). According to Kwak's classification, the most commonly observed types are Type I (82.1%) at the maxillary first premolars, Type III (63.3%) at the maxillary second premolars, Type II (43.3%) at the maxillary first molars, and Type I (43.3%) at the maxillary second molars (p<0.001).

The horizontal distances between the buccal and palatal roots to the alveolar plate were shorter in molars than in premolars due to root numbers, indicating a narrower bone structure that may limit implant stability. Additionally, the vertical distance between the root apex and the maxillary sinus was shortest in second molars, increasing the risk of sinus perforation during implant placement.