Apical and coronal patency

Aug. 1, 2002
Two types of patency are important when performing a root canal: apical patency and coronal patency. Apical patency is the concept of using a small hand file to keep the apical constriction open. Think how many times you have blocked yourself out when doing a root canal.

Dennis Brave, DDS
Kenneth Koch, DMD

Two types of patency are important when performing a root canal: apical patency and coronal patency. Apical patency is the concept of using a small hand file to keep the apical constriction open. Think how many times you have blocked yourself out when doing a root canal. Maintaining patency circumvents this problem. We recommend using a No. 08 or a No. 10 stainless-steel hand file. You take it to length and extend it .5 mm past the apical constriction. Doing this after every working file will prevent you from creating a blockage. This is particularly helpful on vital teeth because they are most susceptible to blockage. Using small files and extending only .5 mm past the constriction helps prevent postoperative problems. This concept applies to both hand filing and the use of rotary instruments. Keep in mind, however, that when using rotaries, you can use a patency hand file after every other rotary. Maintaining apical patency also helps when doing curved canals because it will help you stay centered.

Coronal patency is when you confirm (establish) that the root canal is open in the coronal third. Calcification occurs crown down (coronal to apex), so if the canal is patent in the coronal half it will be open all the way to the apex. We always recommend establishing coronal patency first when doing a root canal. Take a No. 10 stainless-steel hand file, with lubrication, and work it halfway down the canal. If the canal is open to this point, it means the canal is patent to the apex. You may now begin your crown-down preparation with your rotary files. We almost never determine our final working length until we have used two rotary files and opened the coronal half of the canal. We do this to take advantage of the benefits offered by a crown- down preparation - less binding of the hand file, and, therefore, more tactile awareness when determining final working length.


Here are our top five recommendations for performing serious endodontics:

Rotary file system - Nickel titanium rotary instrumentation has changed the way we do endodontics. You should be using a rotary technique. Once you understand how the design features affect the performance of a file, you will be better able to choose the correct file for you situation. We strongly recommend a unit with a noncutting tip and radial lands as they are the safest. Examples are the K3 by SybronEndo, and GT's by Dentsply.

Quality apex locator - This is an absolute must due to the accuracy of the new third-generation units.

These units use advanced microtechnology to achieve their outstanding results. Some of the units we like are the Root ZX by J. Morita, the AFA by SybronEndo, and the Endex Plus by Osada.

Electrice engine - Due to their constant RPM, less vibration, and noise reduction, electric engines are superior, in our opinion, to air turbines.

We recommend a torque-control engine for most GPs who do not perform endo 24/7. We recommend evaluating many engines before making a final selection. Real World tip:Find an engine that is easy to use!

Touch 'N Heat - Formerly made by Analytic Technology, now SybronEndo, this piece of equipment is a great time saver. It can be used to sever gutta percha points, helps in thermo-plastic obturation techniques, and is the best way to create post preparations.

Piezo-electric ultrasonic - Ultrasonics have many uses in endodontic therapy, 90 percent of which is nonsurgical. Piezo-electric is preferable because it creates a linear motion with the ultrasonic tips, rather than the figure eight we get with maganostrictive units. Among others, some of the models we like are the mini Endo (by SybronEndo) the Spartan unit, and the P-5 by Satelec.

Dr. Dennis Brave is a diplomate of the American Board of Endodontics and was the senior managing partner of a group specialty practice for 27 years.

Dr. Kenneth Koch is the founder and past director of the new program in postdoctoral endodontics at the Harvard School of Dental Medicine. Drs. Koch and Brave together are Real World Endo, an endodontic education company. They can be reached at (866) RWE-ENDO, or visit their Web site at RealWorldEndo.com.

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