Objective To estimate the related factors and prophylactic measures of endodontic interappointment emergencies (EIE).Methods The clinical caseswere divided intothree groups. Cases in the routine groupwere treated accordingtothe rou- tine procedures of root canal therapy. Cases in the medicament group took dexamethasone tablets after the instrumentation. Root canals in the drainage group were prepared at the first visit and had been left open for two or three days. The related factors were recorded. The incidences and flare-up index(FUI) value of EIE were statistically analyzed.Results The EIE incidence of the routine group was 19·1%. The EIE incidence and FUI value of the overinstrumented teeth were significantly higher than those of other teeth(P0·05). The FUI value of the medicament groupwas significantly lowerthan that of the routine group(P0·05).Conclusion The occur- rence of EIE was significantly related to overinstrumentation. Taking dexamethasone may relieve EIE.
