KeystoneExplorer | Fall 2023 11 dentistry issues Q is associated with post-operative pain13,14. I would argue that continually recapitulating into the foramen is a sure way to increase the foramen diameter and to introduce smear layer debris into the periodontal ligament. After establishing the working length, it is imperative rotary instruments do not go beyond the working length and therefore violate the apex. 1. Establish an obturator size at least 2 sizes (0.10”) larger than the foramen diameter. This seems intuitive but I have attended a few courses that advocate the final size of the gutta percha is the size of the first file to achieve an apical seal. Just because you plug the end, doesn’t mean you have an apical seal. 2. Treat the apical third differently. Always establish the lower glide path after establishing the working length. The glide path is a smoother shape to the apex than the original anatomical tortuous and narrow route. It is necessary in the beginning of accessing the canals to extirpate the pulp in the coronal portion of the canals in order to achieve hemostasis and be able to investigate for additional canals, but the mistake I often make is in getting overzealous about using rotary files to get to the finished product faster. The initial opening of the coronal portion of the canal with rotary instruments and correcting for better access angulation is part of creating the glide path but the final shaping of the apical third of the glide path is different from preparing the coronal glide path. Introducing rotary files into the apical third of the root system too early is a prescription for a variety of failures such as separated files, smear layer compaction into lateral canals or isthmuses, and transporting the apex to name a few and are beyond the scope of this discussion. If you treat the apical third differently, it will reward you. If there are two things I want to prevent in my endodontic therapy, they are: Don’t use rotary instruments beyond the apex, and don’t compact the apical third of the root with debris. The following method will help with both goals: METHOD After you establish the apical diameter, you can determine the final working length by subtracting a millimeter (or more) and you can determine the final diameter by adding two sizes. For example, if I bring a #10 file to a length of 21.5mm, and then a #15 goes to length, but a #20 does not go to length, then I will measure the #15 file at the length it exits the tooth then subtract a millimeter. My final rotary file will likely be a #25 file at 20.5mm, but I need to do a little more work before that goes to length. First, I make sure my #20 hand file will go to 20.5mm and that it measures to an ideal electronic reading (“doctors choice” according to my J.Morita RootZX). If my #20 file suddenly goes out the apex, then I will assume that my final file will now be a #30 and I will subtract another half millimeter. If I struggle to get my #20 file to the 20.5mm then I can assume the final diameter rotary instrument will be a #20. Once I establish what I determine to be the final rotary choice, then I can establish the apical portion of the glide path. (If we are going to keep with the flight terminology, *Footnote… Semantics: Regarding apical limit, foramen, [radiographic] apex, and working length, there is a great article by Stephane Simon et al that describes the use of electronic “apex” locators in defining these terms in endodontic therapy. For sake of brevity in this article, I would defer to the definitions and descriptions of these terms in that article. I will try to remain consistent in my terminology. To be clear though, ALL “apex” locators are foramen locators. They do not determine the radiographic nor anatomical apex. #21 previous endodontic treatment... is this failed endodontic treatment a result of overfill, underfill, overreliance on sealer, incomplete instrumentation of the canal walls, hyperocclusion, poor apical seal, C-shaped canal, coronal microleakage, or just ‘idiopathic’ apical root resorption?
RkJQdWJsaXNoZXIy MTY1NDIzOQ==