Aim: To evaluate the effects of the expansion of maxillary sinus ostium towards anterior-inferiorly and the posteriorly by endoscopic sinus surgery, on the mucociliary clearance and normal sinus physiology in a rabbit model.

Materials and method: Twenty New Zealand healthy rabbits weighting between 2-2,5 kg were used in the study. Left maxillary sinuses of the rabbits were used as the control group (group 1). The study group comprised right maxillary sinuses of the rabbits. Of the 20 right maxillary sinuses chosen as the study group, anterior-inferior widening was performed in 10 (group 2) and posterior widening was performed in the other 10 rabbits (group 3). On the first and the 14th day of operation, one drop of indiaink was applied to the base of maxillary sinuses. Mucociliary clearance time, the route of mucociliary clearance, whether indiaink has passed through the ostium and reached the nasal cavity or not and the development of infection were determined.

Results: The decrease in mucociliary clearance time was more prominent in the ostium expanded group than the controls. The direction of mucociliary clearance was regular in all of the control group. The irregularity was most prominent in the group in which the ostium was widened posteriorly. The indiaink passed through the maxillary sinus ostium and reached to the nasal cavity in all cases of the control group. However study groups showed delayed maxillary sinus passage. This failure of passage was more frequent in the subjects with posterior widening. These results were statistically significant (P<0.05).

Conclusion: It was found that the widening of the ostium anterior-inferiorly disturbed the maxillary sinus functions less than the posteriorly widening and operating on the ostium decreases the mucociliary clearance so that, it would be better not to expand the ostium if it is patent but posteriorly widening should be performed if the ostium is stenotic, during endoscopic sinus surgery.