Purpose: To evaluate the influence of apical size on cleaning of the apical third of curved canals prepared with rotary instruments.
•n: 44 Maxillary molars (mesiobuccal root) with specified criteria
•Divided to 4 experimental groups n: 10 (GP 1: 30,.02; GP2: 35,.02; GP3: 40,.02; GP4: 45,.02); rotary system (Hero 642)
•1 endodontist (same file used for 5 canals) using crown down technique •Cervical and middle 1/3 enlarged using file #25, 0.12, 0.10, and 0.08 taper (Micro-Mega)
•MBR were decalcified, cut, embedded in wax, sectioned, stained with H&E, and examined under 40x magnification.
•The percentage of apical debris and uninstrumented canal walls was more significant in in 30,.02 and 35,.04 Table.1
•No significant difference in the amount of apical debris between 40,.02 and 45,.02
•A highly significant correlation between the amount of remaining debris and uninstrumented root canal dentine
Larger files reduces apical debris and uninstrumented canal walls; apical cleanliness can be predicted by the file size