Endodontic-sinus communications: a 10-year retrospective observational study on maxillary posterior teeth

To describe the clinical characteristics, anatomical distribution, and long-term outcomes of unintended endodontic-sinus communication involving maxillary posterior teeth that occurred during endodontic treatment.

This retrospective observational study reviewed clinical records collected over approximately 10 years of routine clinical practice. Among 10,345 maxillary premolars and molars treated endodontically, cases presenting intraoperative endodontic-sinus communication were identified. Preoperative periapical radiographs were obtained in all cases, with cone-beam computed tomography (CBCT) available in selected patients. Endodontic treatment was performed under rubber dam isolation using electronic apex locators and rotary nickel-titanium instruments. The Valsalva maneuver was systematically performed intraoperatively to detect communication. Root canal obturation was completed in one or two visits using bioceramic techniques. Clinical and radiographic follow-up was scheduled at 3, 5, and 10 years.

Thirty-one patients (18 males, 13 females) presented an endodontic-sinus communication, corresponding to an incidence of 0.30% (31/10,345). The affected teeth included 14 maxillary second molars, 15 maxillary first molars, and 2 maxillary second premolars. A total of 32 root-level communications were identified. Vital primary treatments accounted for 22 cases (70.97%), retreatments for 7 cases (22.58%), and necrotic teeth for 2 cases (6.45%). The Valsalva maneuver was positive in all cases. The mean follow-up duration was 48 months (range: 36-120 months). All evaluated teeth remained functional, with no persistent sinus-related symptoms and no need for surgical intervention.

Unintended endodontic-sinus communication is a rare intraoperative event during treatment of maxillary posterior teeth. Early recognition, strict apical control, and conservative management may allow favorable long-term outcomes without the need for surgical intervention. However, these findings should be interpreted cautiously in light of the retrospective design, limited sample size, and absence of a control group.