Methods : Complex cases of labial teeth were treated by root canal preparation and filling and periapical currettage and immedicate restoration,and the therapeutic efficacy was valued through clinical observation according to success,no change and inefficacy.

Analysis of 205 outpatient intractable cases consultation;

Computerized tomography or panorama film could be used when questionable problem show up on the periapical film of intractable case.

Study on the case difficulty cube and the three stage learning process;

The Reasons and Disposement of Distal Locking Difficulty Occured in the Treatment of Low Extremities Fracture with Interlocking Nail;

Clinical Trial to Solve the Difficulty of Inserting Stomach Vessel;

Clinical analysis and experience of tracheal intubation difficulty(25 cases);