Objective: A large maxillary odontogenic cyst could intrude into the maxillary sinus. The traditional approach following surgery for such a cyst is the Caldwell-Luc procedure However the traditional CDL procedure is associated with more complications and damage of the sinus mucosa. The purpose of this study was to assess a new method with easier operation, which not only prevented postoperative infection but also caused less damage to the maxillary sinus mucosa.Methods: A large odontogenic cyst in the maxillary sinus of 40 patients was diagnosed through radiographic imaging and postoperative histopathology. Twenty patients were treated with maxillary sinus saline irrigation after cyst resection surgery, while 20 patients underwent the traditional Caldwell-Luc procedure. The therapeutic efficacy was evaluated by clinical examination and radiographic imaging; the longest follow-up was 36 months.Results: The postoperative recovery of the 20 patients treated with sinus irrigation. Six patients had mild swelling (30%), 12 had moderate swelling (60%), and 2 had severe swelling (10%); 16 had mild pain (80%), 4 had moderate pain (20%), and 0 had severe pain (0%). Among the 20 patients treated by the Caldwell-Luc approach. Immediately postoperatively, 2 patients had mild swelling (10%), 12 had moderate swelling (60%), and 6 had severe swelling (30%); 10 had mild pain (50%); 6 had moderate pain (30%), and 4 had severe pain (20%). On the second day after surgery, a mild temperature elevation (38.0°C-39.0°C) was noted in 8 patients (40%) treated with the Caldwell-Luc procedure and 1 patient (5%) treated with saline irrigation.Conclusion: Sinus irrigation following large odontogenic cyst surgery involving the maxillary sinus can serve as an alternative to standard CDL and has the advantages of fewer complications, reduced trauma, restoration of the mucosa and more satisfactory results.