01/29/2021
Tales From the Chamber
To Scan or Not to Scan, that is the question!
By Doug Kase
First let me start by saying I hope all my readers are safe and healthy and may 2021 be a better year for all of us as we deal with the aftermath of 2020, because it was a doozy of all doozies! So on with the show.
When it comes to the need for root canal a diagnosis can be made without a scan by symptoms alone if they are severe enough and specific enough, but certainly a CBCT can help to illuminate the not so obvious. However, the one thing in endodontic treatment we must all remember, is never assume when it comes to canal anatomy. The first assumption we all make starts when we look at our final image and see a wonderful dense mesio-distal obturation, that this is a perfect fill and ultimately be a successful root canal. The reality is, this final look doesn’t really take into consideration the buccal -lingual dimensions that we all know do exist and our ability to cleanse and instrument the naturally occurring fins and isthmuses. This is particularly true when utilizing a self centering rotary technique that can’t possibly move into the buccal and lingual nooks and crannies and mechanically clean them. Depending on irrigation only to free up the organic matter can’t be 100%, thus combining reciprocation with thin flexible .02 tapered stainless steel instruments and targeting these areas to mechanically debride (targeted instrumentation using internal routing) insures a better truly three dimensional obturation and more guaranteed success rate. So wouldn’t it be nice to have a preoperative CBCT to know where to target buccal lingual anatomy more efficiently. Obviously it’s not going to show it on microscopic level, but it certainly will give you a better anatomical view of the shape the canal.
Now onto other assumptions that might not be completely accurate and will obviously effect your success rate more dramatically. Canal anatomy and the number of canals is a perfect reason to get a preoperative or working scan. There are some teeth such as maxillary central incisors where you can assume all you have is one canal. But there are many teeth that have varied divergent anatomy such as 2 canal lower incisors, maxillary second bicuspids, and lower first bicuspids not to mention a lower cuspid with 2 canals as well. Then of course there is the clinicians nightmare, the dreaded MB2 which is present in about 65% of all maxillary 1st molars and 45% of maxillary 2nd molars. My thought is if it’s there I’m obligated to find it, if it’s not I don’t want to undermine good tooth structure looking for it rendering the tooth more susceptible to fracture. Canal splits, lateral canals if large enough and of course extra canals and roots can be verified on a 3-D scan!
When I was in my residency my attending taught me, if you see 2 canals look for 3, if you see 3 look for 4 and if you see 4 you sometimes might find 5. So the scan takes all the guesswork out of the equation.
Thus I present Kase’s case of the month. Typical tooth number 19. Two, three or four roots, three or four canals, right! Easy peasy! (X-ray 1) Well I was almost right. After gaining access I found two mesial canals and one large distal canal. Great, established measurement control and started instrumentation using SafeSider instruments in a reciprocating hand piece. Did my preliminary debridement with consistent irrigation alternating between sodium hypochlorite and EDTA under the microscope, but the orientation of the canal or***ces just seem a bit skewed. Positionally the ML canal seemed a bit centered when compared to the distal. This was a bit of an eyebrow raiser so closed the access with cotton and cavit and off to the scanner we ran! After a quick painless CBCT the mystery was solved and canal anatomy was confirmed. I had found the MB and the MM ( middle mesial) canals and had yet to find the ML which was actually in the correct anatomical position (X-ray 2). Back in the chair with the rubber dam back in place I swept to the lingual with a purple muntz bur in a slow speed hand piece I found, measured and instrumented the actual ML canal. The tooth was ultimately filled with single point gutta percha and EZFILL epoxy resin cement (X-ray 3). So I was correct it was a four canal first molar, just the canals weren’t in the assumed position.
Thus the CBCT scan like the microscope, is an invaluable tool when performing endodontics eliminating anatomical guesswork that could change the long term prognosis for a tooth! See you next TALES!
