Step 4 – Pulp extirpation
This is only necessary for vital teeth. You can remove the pulp using a barbed broach or by filing the canal with handfiles up to a size 20. A barbed broach is contraindicated in curved or narrow canals.
Step 5 – Pre-Enlargement of Coronal Two-thirds (aka “Coronal Flaring”)
Remember to always irrigate canals with bleach passively. Move the canula up and down and do not lock it into the canal. Never introduce an instrument into dry canals and re-confirm patency frequently.
Clinic Tip: When irrigating the canals with bleach, make sure to have suction ready and place near your access.
Prior to using the WaveOne for coronal flaring, confirm that size 10, 15, and 20 handfiles fit to 2/3 of estimated working length using watch winding or Balanced Force. A glide path of size 20 MUST be confirmed prior to using any WaveOne. Remember to always irrigate between files. These steps will allow the early measurement of the canal and facilitate the establishment of the glide path to the apex.
Step 6 – Establish Working Lengths
Now that you have opened up access to the canals, you must determine your working length. Always use the Apex Locator first, then use the length it gave you to take a radiograph.
Clinic Tip: When using the apex locator, remember to turn on the machine and check that it is working by attaching the file clip to the lip clip. If the apex locator does not read in the red it is not working. Also, the canals should be wet but the pulp chamber should not be overflowing.
Remember to have the curved end on the patient's cheek and probe only touching the file. Use your pre-operative a radiograph to estimate canal length. Make sure that you pre-curve all files before introducing them into curved roots. Watch wind a small file (8 or 10) to patency. This is confirmed by the apex locator reading in the red. Move the file coronally until the apex locator moves into the green. Remove the file and measure it. Subtract 0.5mm and that is your working length. Use watch winding and balanced force with handfiles to size 15 or 20 to working length. Confirm that the apex locator is in the green then take a working length radiograph.
Clinic Tip: The rubber stopper has a black line on it. Line the black mark line up with the curve that you have created. Often times the apical opening of the canal does not exit straight out of the root, but instead it deviates to one direction. You can determine which direction it exits based on the location of the black line after you are at patency.
Step 7 – Shaping the Canals Using Rotary Files (Wave One Files)
The WaveOne motor, handpiece, and files are checked out from the clinic dispensary. Fill out a slip and have your faculty sign it. WaveOnes are taken to full working length. Use your endo motor set to WaveOne mode so the files move in a reciprocating motion. After you have completed your glide path with a size 20 handfile, the WaveOne can be introduced into the canal. The Primary Waveone file, 25/.08 size & taper, should be sufficient in most canals that you work on in the clinic. Remember that you only enter the canals until you meet resistance and then you pull out, repeat three times then clean the rotary file with an alcohol-moistened sterile gauze and then continue. Be sure to mark your working length(s) with the rubber stopper. Make sure that you only use passive pressure and do not push too hard apically to prevent possible damage to the canals or breaking a file in the canal. Also, don't forget to to irrigate and confirm patency when finished with a rotary file.
Clinic Tip: Watch out for the flute loading. This is when the dentin "mud" gets into the flutes of the rotary files. The file should never be fully loaded as this causes too much stress/torque on the file and can lead to the file breaking.
Step 8 – Determine Apical Diameter
If you find using your predetermined working length that the canal is larger than the WaveOne primary, use the green size 35. If that does not cut, use the WaveOne white (tip size 45). If the root canal is larger than size 45, it can be instrumented using handfiles to working length using the Balanced Force Technique (remember to engage the file by twisting 1/4 clockwise, apply apical pressure, then twist 1/2 turn counterclockwise to cut dentin, and repeat the cycle). Every now and then, remove the file with gentle rotations and clean it.
Historically, a master file was about three file sizes larger than the original apical file size. The initial apical file is the first file that cuts when introduced to working length. Typical sizes in molars are #25 for buccal or mesial canals and #35-45 for palatal and distal canals.
Step 9 – Recapitulation
This is the process of removing any debris from the canal using a file after you use the WaveOne file to working length. Introduce the file passively by watching winding to working length and turning clockwise to load the flutes with the debris and dentin chips remaining in the canal before removing it. Don't forget to check for patency with #8 or 10 file 1mm past working length.
Page Updated: April 17, 2019