Abstract: Objective　To investigate the characteristics of maxillary sinus mucositis adjacent to teeth with apical periodontitis (AP) and evaluate its resolution after endodontic treatment with cone beam computed tomography(CBCT). Methods 25 maxillary sinuses in patients who had AP associated with maxillary posterior teeth were scanned with CBCT. When mucositis was found, its resolution was evaluated with CBCT imaging 3 months after endodontic treatment, and periapical healing was assessed by the periapical index(PAI) after 6 months. Results Excluding 2 sinusitis, mucositis was found in 14 of 23 sinuses (61％). Three months after therapy, mucositis was fully resolved in 5 of 14 patients (35.7％), partially resolved in 6 of 14 patients(42.9％), unchanged in 3 patients(21.4％). Six months after treatment, a total of 3 of 14 teeth (21.4％) were healed, 4 of 14 teeth(28.6％) were healing, 7 of 14 teeth(50％) had persistent AP. Conclusions Endodontic treatment is an effective therapy for posterior teeth associated with AP which can easily trigger maxillary sinus mucositis. CBCT can accurately assess the resolution of maxillary sinus mucositis before and after endodontic treatment, which has important clinical reference value.

Key words: Maxillary sinus mucositis Apical periodontitis Endodontic treatment CBCT