The present investigation had as an objective to determine the relationship between the thickening of maxillary sinus mucosa and the presence of periapical lesions studied with cone beam CT in a virtual file, that had CTs from 2017-2021 period, of a private radiologic center in Iquitos, the sample was formed by 125 patients, in whom CT scans were made, (44% of masculine sex and 56% of feminine sex), of them 64% (80) were adults (27 to 59 years). The average age was 46,19 years (STD ±15,62 years), applying the inclusion and exclusion criteria, we observed 203 hemimaxilla (53,2% right side and 46,8% to the left side), the molar tooth was the most observed (88,2%) The periapical lesions were categorized according the CBCT-PAI y we observed 14,8% (30) of the total, and maxillary mucosa thickening was found in 51,2% (104) cases in total. 24.1% (49) of the maxillary mucosa thickening cases sh...