Histological evaluation of the effectiveness of increased apical enlargement for cleaning the apical third of curved canals

By Fornari VJ, Silva-Sousa YT, Vanni JR, Pécora JD, Versiani MA, Sousa-Neto MD

Date: 01/2010
Journal: IEJ


To evaluate the influence of apical size on cleaning of apical 1/3 of curved canals prepared with rotary instrumentation.


  • n=44 freshly extracted mx M1 teeth
  • inclusion: mature, curvature 20-40 degrees, radius curvature <10mm
  • MB canals instrumented to different apical sizes (30.02, 35.02, 40.02, 45.02) using crown down (Hero 642 rotary system)
  • after instrumenting, apical 1/3 subject to histo analysis at 40x with morphometric analysis


  • % of uninstrumented root canal dentin was higher when apical enlargement performed with instruments 30.02 and 35.02 vs. with 40.02 and 45.02 (P< .05)
  • more debris observed when apical enlargement performed with 30.02, 35.02 (P< .05).
  • significant correlation exists between amount of remaining debris and perimeter of unistrumented root canal dentin (P<.001)

Clinical Significance:

No apical enlargement size allowed root canal walls to be prepared completely. Apical 1/3 cleanliness can be predicted by increasing instrument diameter.