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The Patency Technique for Root Canal Therapy

Learning Objectives:

After hearing this podcast, the listener should:

  • Understand the patency technique for root canal therapy
  • Know the tools and materials needed to perform this technique

Dr. Peter Velvart, DMD*

An important aspect of endodontic therapy is the mechanical cleansing and shaping of the root canal system. In order to maximally clean the canal, its shape must be maintained in all dimensions. To achieve the ideal preparation of the root canal, the dentin should be evenly removed in all directions and at all levels in the canal. Unfortunately, when curved canals are treated, the instrumentation methods can transport the apical, or root-ward, portion of the canal toward the outside of the curve and the coronal portion toward the inside.

This study indicates that the patency instrumentation technique with files of variable taper and non-cutting tip is a superior technique. Both the push/pull and balanced-force techniques that used cutting tips caused a clinically unacceptable degree of canal length loss. While the design of endodontic instruments continues to be refined, additional studies must be completed to determine the most effective manner of utilizing these tools during root canal therapy.


*Private practice, Zurich, Switzerland

Related Reading:

  1. Grossman LI. Endodontic Practice. 10th ed. Philadelphia, PA: Lea & Febiger; 1981:200-236.
  2. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974;18(2):269-296.
  3. al Omari MA, Dummer PM, Newcombe RG, Doller R. Comparison of six files to prepare simulated root canals. 2. Int Endodont J 1992;25(2):67-81.
  4. Lentine FN. A study of torsional and angular deflection of endodontic files and reamers. J Endodont 1975;5:181-191.
  5. Pettiette M, Metzger Z, Phillips C, Trope M. Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel titanium hand files. J Endodont 1999;25:230-234.
  6. Miserendino LJ, Moser JB, Heuer MA, Osetek EM. Cutting efficiency of endodontic instruments. Part I: A quantitative comparison of the tip and fluted regions. J Endodont 1985;11(10):435-441.
  7. Miserendino LJ, Moser JB, Heuer MA, Osetek EM. Cutting efficiency of endodontic instruments. Part II: Analysis of tip design. J Endodont 1986;12(1):8-12.
  8. Powell SE, Simon JH, Maze BB. A comparison of the effect of modified and nonmodified instrument tips on apical canal configuration. J Endodont 1986;12(7):293-300.
  9. Roane JB, Powell SE. The optimal instrument design for canal preparation. J Am Dent Assoc 1986;113(4):596-597.
  10. Weine FS, Kelly RF, Lio PJ. The effect of preparation procedures on original canal shape and on apical foramen shape. J Endodont 1975;1:255.
  11. Abou Rass M, Frank AL, Glick DH. The anticurvature filing method to prepare the curved root canal. J Am Dent Assoc 1980;101(5):792-794.
  12. Walton RE. Current concepts of canal preparation. Dent Clin North Am 1992;36(2):309-326.
  13. Goerig AC, Michelich RJ, Schultz HH. Instrumentation of root canals in molars using the step-down technique. J Endodont 1982;8(12):550-554.
  14. Roane JB, Sabala CL, Duncanson MG Jr. The "balanced force" concept for instrumentation of curved canals. J Endodont 1985;11(5):203-211.
  15. Stoeckel D, Yu W. Superelastic NiTi wire. Wire J Int 1991;3:45-50.
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