Development and Application of Nasal Spine-Guided Classification for Maxillary Sinus Pneumatization

<b>Background/Objectives</b>: The aim of this study was to develop a novel Nasal Spine-Guided Classification for assessing the alveolar vertical extension of the maxillary sinus and to evaluate its anatomical relationship with the roots of the posterior teeth using CBCT in a Saudi subpopulation. <b>Methods</b>: Maxillary sinus pneumatization was measured using cone-beam computed tomography for 380 patients. The assessment was performed along a horizontal plane extending between anterior and posterior nasal spine. In addition, pneumatization was evaluated in edentulous areas, and between the roots of multi-rooted teeth. Maxillary sinus membrane thickness was also measured. The results were expressed as mean, median and interquartile range, and considered statistically significant at a <i>p</i>-value < 0.05. <b>Results</b>: The mean maxillary sinus pneumatization on the left side was 8.8 ± 4.32 mm, and 8.58 ± 4.85 mm on the right side, with no statistically significant difference. The median of pneumatization in the edentulous area and between the roots on left side were 5.1 and 3.8 mm respectively, while on the right side, the median pneumatization was 5.03 and 3.04 mm. In addition, the proximity of the maxillary root apices to the sinus floor revealed a zero distance in 80.49% of the roots on the left side and in 79.48% on the right side. Furthermore, the results indicated no statistically significant association between maxillary sinus membrane thickness and pneumatization in the edentulous area. <b>Conclusions</b>: CBCT analysis revealed a predominance of advanced maxillary sinus pneumatization (Class III) and a high frequency of direct contact between posterior maxillary root apices and the sinus floor in the studied population. Additionally, no significant association was identified between maxillary sinus membrane thickness and sinus pneumatization in edentulous areas.