Introduction: The incidence of oral sinus communications (OSC) following the extraction of an upper third molar remains uncertain.
Objectives: The purpose of this study was to determine the incidence of OSC following the extraction of 389 consecutive upper third molars during 2003 in the Master of Oral Surgery and Orofacial Implantology (Barcelona University, Spain).
Patients and method: Different variables were recorded, including patient age, sex, molar angulation, surgical technique and radiological sinus proximity, to determine the relation between third molar extraction and the incidence of OSC.
Results: Only 5.1% (95% CI: 2.2-7.3%) of the upper molar surgical extractions produced OSC, the risk of which was found to be similar in all age groups and increased with the depth of third molar inclusion, the complexity of the surgical technique and the performance of an ostectomy.