[Clinical application of endoscope on removal of broken root from maxillary sinus]. 
The broken root dislocated into the maxillary sinus is a common complication during the teeth extraction.  This article reported broken roots of four patients dislocated into maxillary sinus were removed successfully by endoscope under local anesthesia through windowing in inferior nasal meatus.  It is an efficient method, which has less wounds and shorter surgical time.