The purpose of the present study was to evaluate the relationship between the maxillary sinus floor and the upper posterior root tips in the Colombian population using cone-beam computed tomography.A total of 1656 roots were analyzed (1104 molars and 552 premolars), classified as types I (outside the maxillary sinus) and II (inside the maxillary sinus).The results showed that the palatal root of the maxillary first molar was most frequently found inside the antrum.Understanding the relationship between the maxillary sinus floor and the upper posterior root tips is important to the clinician when performing conventional or surgical endodontic treatment and conventional surgery procedures in order to minimize or avoid the risk of damaging the maxillary sinus.