Assessment Of Accuracy And Effect Fact Of Electronic Apex Locators In Dental Clinical Practice

Objectives TO evaluate the accuracies of the electronic method(EM),the handing method(HM) and the x-raying method(x-RM) in measuring working length of root canal.To analyse the influence of the clinical situations such as the periapical bone resorption,root canal in dry or wet conditions,root canal contained with some electrolytes on the accuracy of the electronic apex locators(EAL).Methods 37 teeth(provided with 58 root canals) were choosen with the characteristics of being in chronic periapical or paradentosis condition accompanied byâ…¢.loosening or owning residual root and residual crown,or healthy but orthopaedics. Each root canals' working length was measured in vivo by three examing methods:HM, x-RM and EM(by the electronic apical locators-Root ZX and Raypex-5 respectively), and each root canal was measured in the dry or wet conditions or electrolytes(3%H₂O₂ or 0.9%NaCl) sunk surroundings with the instrument of Root ZX,Raypex-5 to detect the working length of root canals.The root canal lengths that were measured from the sectional view's constrictions of the extracted teeth were definited to gold criterion.The accuracy rate of different methods in measuring working length and the accuracy of EAL in measuring working length of root canals with some certain influential elements could be worked out by compared with gold criterion.SAS software was carried out to analyse the different data of working lengths measured in different examing methods and the different data of working lengths measured by Root ZX,Raypex-5 as canals being in the dry or wet conditions or electrolytes(3%H₂O₂ or 0.9%NaCl) sunk surroundings or with periapical bone resorption or not. Results The accurate rate of the data measured by Raypex-5,Root ZX,HM,x-RM was 84.48%,79.31%,32.59%,44.83%respectively.The accuracy between EM and HM,x-RM had significant difference(p＜0.01),While the accuracy between inter-group (Root ZX/Raypex-5,HM/x-RM) showed no significant difference(p＞0.05).In the canal without periapical bone resorption,the accuracy rate of data measured by Raypex-5, Root ZX was 93.55%,87.10%,whereas with periapical bone resorption was 74.03%, 70.37%respectively.The accurate rate of the canal with periapical bone resorption measured by Raypex-5 was much lower than that of the canal without periapical bone resorption and the difference had statistic meaning.No statistic difference was found as an indication of the impact of root canal surrounding conditions(dry or wet conditions, or electrolyte sunk surroundings—3%H₂O₂ or 0.9%NaCl) on the accuracy of EALs, but the electrolyte sunk surroundings the canal with periapical bone resorption—3% H₂O₂ or 0.9%NaCl had significantly statistic differences in the higher data of accuracy rate measured by Root ZX(p＜0.05),but no higher data could be worked out by Raypex-5(p＞0.05).Conclusions The accuracy of working length of root canal measured by EM is higher than that measured by HM and that measured by x-RM.Thus,the three devices conjugated could raise the accurate in a big margin.Periapical bone resorption has influence on EALs,then other influential elements:wet condition or electrolyte surroundings has no.The root canal with periapial bone resorptionis in wet condition or electrolyte surroundings has improved periapex's conductivity in vivo and consequently the accurare rate of data measured by EAL could be raised.