Influence of instrument size on root canal debridement

By Usman N, Baumgartner JC, Marshall JG

Date: 01/2004
Journal: JOE


To compare in an in situ model the efficacy of root canal debridement in the apical 3 mm when instrumenting to a GT size 20 or a GT size 40 at working length.


  • 20 human cadaver teeth with 32 canals were decoronated at the cementoenamel junction and instrumented with rotary Files of GT to either GT size 20 or GT size 40
  • Sodium hypochlorite, EDTA, and RC Prep were chemical aids for debridement
  • The teeth were extracted, decalcified, sectioned at 0.5 mm, 1.5 mm, and 2.5 mm from the apex and prepared for histologic examination and quantification of remaining debris


1.No significant differences were found between each level within each apex size group

2.The GT size 20 group left significantly more debris in the apical third compared with the GT size 40 group.

3.Regression analysis determined that the most important determining factors were the instrument type (GT size 20 or 40) and the working length of the root canal

4.Irrigant volume, number of instrument changes, and depth of penetration of irrigation needle did not explain differences in debridement.

Clinical Significance:

Clinicians should be aware that smaller size instruments may lead to increased debris accumulation.