OBJECTIVEThe purpose of this study was to investigate the proper site for enlarging maxillary natural ostium during ESS, and to compare the draining mode of mucociliary transportation system.

METHODSThree groups were designed to observe the differences of tracer agent transported from maxillary sinus to nasal cavity. Normal control group: 30 cases; Trial group A:30 cases, the maxillary natural ostium were radically enlarged by all sides; Trial group B: 30 cases, the maxillary natural ostium were enlarged by reservation of whole inferior edge and cut away anterior and/or posterior edge. The patients in two trial groups were after nasal endoscopic sinus surgery for more than 12 months and the maxillary ostium were well open.

RESULTSTracer agent was drained from maxillary sinus to nasal cavity by inferior edge (s) of natural ostium in control group. The core area was posterior part of inferior edge. In trial group A, tracer agent was drained out by inferior edge in 4 cases (13.3%), tracer agent drained out by posterior and/or superior edge(s) and then dispersed to ethmoid sinus in 17 cases (56.7%),tracer agent stacked and/or circularly flowed in the maxillary sinus, and could not be transported out in 9 cases (30.0%). In trial group B,tracer agent drained out by inferior edge to middle meatal in all subjects (30/30,100%), and there was no redirection of the mucociliary transportation.

CONCLUSIONSThe inferior edge of natural ostium is the main passage of mucociliary transportation system of maxillary sinus. If the inferior edge of maxillary natural ostium reserved, the post-operative drainage of maxillary sinus would be the same as normal ones. Radical removal of all edges of maxillary natural ostium could lead to redirection of mucociliary transportation, only few cases could drain out by inferior edge, most cases drained out by posterior and/or superior edge and then dispersed to ethmoid sinus. In some cases, tracer agent often stacked in the maxillary sinus and could not be drained out. When there was a need to enlarge the maxillary natural ostium in ESS, it should be done in the anterior and/or posterior edge of natural ostium, the inferior edge should not be damaged so as not to interfere the passage of mucociliary transportation system of the maxillary sinus.