RESUMEN
This retrospective analysis assessed a possible correlation of perforation of the maxillary sinus floor during apical surgery of maxillary molars and the distances from the treated apices/periapical radiolucencies to the sinus floor. The material included 168 apical surgeries of maxillary first or second molars performed from 1999 to 2016. In 22 (out of 33) perforation cases, a preoperative cone beam computed tomography (CBCT) was available. These cases were defined as the test group. From the pool of operated cases without sinus floor perforation, matching cases - that is, same treated tooth, similar age and same gender - were selected as a control group (N = 26). Mean linear distances from root apices or radiolucencies to sinus floor were significantly shorter in the test group compared to the control group. In conclusion, perforation cases were significantly closer to the sinus floor than cases without perforation.