RESUMEN
PURPOSE: To analyze the anatomical findings and alterations of the maxillary sinus in asymptomatic patients observed by cone beam computed tomography. MATERIALS AND METHODS: A cross-sectional retrospective study of the anatomical variations and alterations of the maxillary sinus was made in 160 patients-71 males (44.3%) and 89 females (55.6%), with an age range of 18 to 74 years-measuring the thickness of the Schneiderian membrane and the cortical thickness of the lower margin of the maxillary sinus (in its most caudal portion), and correlations among the different study variables were assessed. RESULTS: Sinus pneumatization was the most frequent anatomical finding (81.3%). A negative correlation was observed between the thickness of the Schneiderian membrane and the presence of Underwood septa (P < 0.005). Mucosal thickening of more than 2 mm was directly correlated with the presence of maxillary sinus lesions (opacification, discontinuity of the floor of the sinus, polypoid lesions, or air-liquid levels). CONCLUSION: The presence or absence of septa seems to be related to the thickness of the Schneiderian membrane.