Authors: Goerig AC, Michelich RJ, Schultz HH.
Title: Instrumentation of root canals in molar using the step-down technique.
Journal: J Endod
Date: Dec 1982
Citation: 8(12):550-4
Category: Access and Canal Instrumentation
Evidence-based Ranking: 5
Purpose/Objectives: To introduce a technique for manual instrumentation of molar teeth.

Summary: The author separates endodontic preparation into 3 processes – coronal access, radicular access, and apical instrumentation.

Step 1 – Coronal Access Initial access is made into the pulp chamber and a straight line path to the canal orifices is created. The chamber should be completely unroofed and any obscuring ledges or walls removed. An instrument should enter the canal without any interference and minimal bending.

Step 2 – Radicular Access, The Step-Down Technique

This step focuses on opening and flaring the radicular one-half to two-thirds of the canal system. The step-down technique provides the following advantages:

v Straighter access to the apical region v Eliminates dentinal interferences in the coronal two-thirds of the canal v Bulk of pulp tissue, debris and microorganisms are removed before apical instrumentation v Allows deeper penetration of irrigating solutions v Less likely change in working length due to less canal curvature

All filing and flaring in this step is directed away from the furcation and to the areas of greatest bulk to minimize the possibility of perforation. Also, continuous and copious irrigation is used throughout the procedure.

I. Hedstroem #15 Placed to 16-18 mm or to where the file binds in the canal II. Hedstroem #20 Placed 0.5mm less than previous file III. Hedstroem #25 Placed 0.5mm less than previous file IV. Gates-Glidden #2 Placed 14-16 mm V. Gates-Glidden #3 Placed 11-13 mm

Additional instructions ü No files or burrs are ever forced or screwed apically ü With short roots lengths should be decreased accordingly ü With small and calcified canals a #10 K-file is used to negotiate and maintain patency ü With larger canals a Gates-Glidden #4 can be used Step 3 – Apical Instrumentation, The Step-Back Technique

The remaining apical one-third is now instrumented following the traditional step-back technique.