Influence of Instrument Size in Debriding Apical Third of the Root Canal System

Objective: the purpose of this study was to compare the efficacy of root canal debridement in apical 3mm when instrumenting with traditional stainless-steel number 20 k file and traditional stainless-steel number 40 k file at working length with commonly used irrigation solutions. materials & methods: this in vitro comparative study was conducted at operative department,lahore medical & dental college,lahore. data was collected from 2005 to 2006. fifty human mandibular incisor teethwere selected. preoperative radiographs of each tooth were taken and teeth were extracted. teeth were divided in to two groups and,decoronated at cementoe-namel junction. group a was instrumented with stainless steel # 20 k file and group b was instrumented with stainless steel # 40 k file to the working lengths. sodium hypo-chlorite and edta compounds were used as chemical means to debride the canals. all these selected teeth were,decalcified and sliced at 0.5 millimeters,1.5 millimeters,and 2.5 millimeters levels from the root apex and set for histological inspection. results: no dissimilarities were recognized between each level within each root apex size group except at1.5 millimeters level from the apex,open dentinal tubules were seen in group b which was instrumented with the # 40 k type file. conclusion: file size # 40 k is more effective in debris removal from the root canal system as compared to file size # 20 k while preparing the canals.