File Delivery by Drs. Allen Ali Nasseh and Anne Lauren Koch

A 36-year-old patient presents with a chief complaint of needing a root canal in his upper tooth. The patient had a previous formocresol pulpotomy to address pain and discomfort; upon examination, it was noted that the tooth had a severely curved mesial buccal root in addition to the previous pulpotomy.

Note: The presence of a prior pulp cap can complicate the procedure if there is any coronal calcification associated with the previous pulp therapy. This is something to be mindful of as one begins the procedure.

A CBCT was obtained to fully evaluate the root anatomy and to formulate an endodontic treatment plan to manage the 90-degree curvature on the mesial root. The axial section shows the presence of an MB2 canal, while the coronal section through the MB root demonstrates that MB1 and MB2 join somewhere midroot.

Note: The vast majority of mesial buccal canals (MB1 and MB2) do join together. This is why, for many years, molar endodontics worked, even though we weren’t fully aware of the prevalence of additional canals.

Following access through the original temporary filling, access is modified to gain straight-line access to the orifice of each canal before creating straight-line access to the body of each root. The use of ball-shaped ultrasonic tips can be a great help along with regular tapered tips.

Note: It’s important to remember that proper straight-line access is imperative for instrumenting a severely curved canal. Good access is key for clinical success.

Higher magnification shows the isthmus connecting the MB1 and MB2 canals. Even though MB2 joins MB1 in this case, it’s important to instrument this portion of the root canal to ensure proper cleaning and disinfection.

Note: Ultrasonics are a great help in this part of the procedure, because of their ability to clean in a three-dimensional manner.

Once coronal access has been adequately prepared to allow straight-line access to each orifice, coronal flaring is achieved using an orifice opener such as a 16-millimeter 20/.08 EndoSequence file in each canal.

Note: Coronal flaring at this point in the procedure will facilitate rotary instrumentation by effectively opening the canal in the coronal third.

After initial preparation of each canal to a Size 15/.06 EndoSequence CM, a finishing file was used in each canal, based on its determined size after apical gauging. The palatal and DB canals were quite large, and a single EndoSequence 35/.04 file was used in these straighter canals.

Note: Heat-treated files such as the EndoSequence CM, with their inherent flexibility, will do all the “hard work,” but we like to complete the preparation with a non-heat-treated file because the instrument will not distort and, consequently, will ensure a better match with the gutta-percha master cone.

The severely curved MB roots had to be prepared to a smaller apical diameter, using heat-treated files to address the flexibility necessary to instrument such curvatures. Consequently, the MB roots were instrumented to only Size 20/.06 EndoSequence CM.

Note: While this size initially may seem small, we must consider the fact that with a .06 taper, the canal size 1mm back from the apex is 26mm in diameter. MB2 canals that join the main MB1 canal generally are narrower than a stand-alone MB2 canal.

After our irrigation protocol and smear layer removal, we can readily see both the MB1 and the MB2 canals.

Note: Notice how good straight-line access facilitates entry to the orifices.

After a bioceramic sealer was placed in the individual canals, matching well-fitted master cones were fully seated to the respective apices and were confirmed. In the more oval-shaped palatal
canal, additional cones were placed alongside the master cone: Two additional Size 25 gutta-percha cones were passively placed next to the master cone to prevent pooling of the sealer. The gutta-percha cones were seared off at the level of the individual orifices and vertically compacted using a Size 10 plugger.

Note: The additional cones placed in the palatal canal were not laterally condensed. They were simply placed as supplemental or “confirmation cones” to occupy space and to properly disperse the sealer.

The pulp chamber is cleaned of sealer, using the water spray from an ultrasonic, and subsequently dried.

Note: Water will not have a deleterious effect on the bioceramic sealer because BC Sealer is hydrophilic not hydrophobic..

BC Liner was then placed with a thickness of 3mm to seal the chamber and the orifices. The immediate sealing of the root-canal system will help reduce coronal leakage from the  provisional restoration.

Note: If a surgical microscope (with a high-powered light) is used during the procedure, an orange filter is recommended to prevent premature setting of the BC Liner.

After waiting 30 seconds for the material to self-etch and bond to dentin, it can be light-cured to expedite the process. Higher magnification shows the seamless bond to the walls, which provides an excellent seal under the provisional restoration.

Note: This can act as a base under a final restoration and has a compressive strength of over 260 megapascals.

This angled postoperative image shows the high degree of curvature and the joining of the MB1 and MB2 canals in this root.

Note: This tooth has not only been treated in a proper endodontic manner, it has also been treated in such a way as to allow a good final restoration, thereby ensuring long-term success. After an endodontic procedure has been completed, it is critically important to have the tooth restored properly and in a timely manner.

3D imaging of the final fill shows the high degree of curvature.

Note: The challenging anatomy in the apical 5mm is addressed through proper access and using heat-treated files as “scouts” in this area.

Patient was seen for a one-year recall and the tooth was completely asymptomatic. The tooth was restored with a well-sealing coronal restoration.

Note: The long-term prognosis of this tooth is excellent!