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Endo tips    Better Endo    Endo abstracts    Endo discussions


  Apical preparation size
The opinions and photographs within this web page are not ours. Authors have been credited
for the individual posts where they are. - www.rxroots.com
From: Dr Goodis To: ROOTS Sent: Tuesday, August 09, 2005 12:13 PM Subject: Re: [roots] Attentione Dr. Goodis Thanks for responding Chuck, I always felt that the tapered rotary instruments I used provided no reliable tactile feed back from the apical part of the canal. The greatest constriction along the length of the canal generally is at the orifice. That's why we drill deeper to find canals, we are expecting the canal to open up as we excavate deeper down the root searching for a canal remnant. Since that is the case, the best way to know how large the apex is to use an instrument that doesn't bind at the orifice or the coronal half of the canal like a tapered instrument. A non tapered instrument that cuts only at the apical 1-3mm of the instrument give excellent tactile feel to know what size the canal really is. When the handpiece begins to load up from torque when I'm using LightSpeed, I know it is from the debridement that is occurring at the tip of the instrument because it doesn't cut along the shaft. When the motor loads up from torque when using a tapered instrument it only tells me its cutting but I don't know where its cutting. It could be cutting anywhere along the length of the flutes. In all probability its cutting at the orifice of the canal and we have no idea if it is doing anything in the apex other than spinning against canal wall on the outside of the curve and leaving the rest of the diameter of the canal untouched and undebrided. I find that there are very few canals that are smaller that a final preparation size of a #40 based on tactile feel and listening to the torque on the motor. I find comfort in the anatomic studies and bacterial contamination studies that support my technique of larger preparations. I felt that I was being arbitrary in final instrument sizes when I tried the tapered instrument systems. What indicators or methods are you using to determine the final apical preparation sizes? - Randy I have to ask, what about the research and the literature? Does apical cleanliness matter anymore? I thought that was the entire purpose of instrumentation, to get the canal as clean as possible. - Randy I use ProTapers to length...usually no larger than a F2. I then go back with 0.02 to 0.04 tapered ProFiles and K3's until I get clean shavings at the apex. Seldom does a F2 clean and size the apex and it is a 0.08+ taper, I think, with a size 25 tip. This one was to a F2 and I finished with an 0.02 45 ProFile. I'm assuming that 0.02 taper is turning freely in the rest of the canal except at the apex. Wrong assumption??? Guy Guy, I think your technique is the best way to use tapered instruments in order to have any idea of how large the apical canal diameter is. It makes sense to use a greater taper in the coronal half of the canal and then use an 02 taper in the apical half to get an idea of how large if an instrument is appropriate for each individual canal. A #45 is what I commonly prepare mesial roots of mandibular molars but occasionally I need to go to a #60 especially if the canals merge in the apex. I commonly prepare distal root distal roots to a #55 or larger with LightSpeed. Your radiograph looks good - it's not over prepared in the coronal half yet large enough in the apex to be confident you not only cleaned the debris out of the apex but you also were able to get a large enough volume of irrigant to the apex for it to be effective. "Clean shavings" is an old wives tale from the 60' and 70's, nobody can see if there are bacteria amongst the shavings without a higher powered laboratory microscope and the appropriate stains. I hope that the tapered instrument dentists will consider the solid logic behind your technique. - Randy Hedrick Thanks, Randy. This was the easiest way to do what Bill Watson told me to do. Guy Randy, I don't do alot of extractions, but I've looked at alot of extracted teeth. Next time you take one out, look at the POE's under the microscope. Not that night, not that weekend, not after it has been sitting in whatever solution for who-knows-how-long. Right then. My last extraction was a vital #31. Busted off the distal root end and had to fish it out with the scope, but I got the mesial root out intact. Three POE's. Two were smaller than a #20, one was about a #22. All three were round. I took pictures. I also took pictures and video of what happened when I took a #2 peezo to 6mm from the POE for Barry. LOL! I'm not sure where these large apical sizes are coming from, but I'm not seeing them. I may be blocked. John, my teeth chatter a bit when I argue even a little with you. I'm not shaping my POE's to larger sizes. I'm shaping my apexes to larger sizes. Personally, I think there is a difference. I've extracted several thousand teeth and looked the apex of many a root to see if I left any. I clean that POE getting patent. Usually a 20-25 0.02 handfile is max on that. My larger cleaning size stops slightly short of the EAL reading. I've done a large number of these in my hand...some being fresh. The apical area of the root is simply larger than the POE foramen. OK, kick hell out of me now. - Guy The other perhaps more subltle issue is the interplay between apical size/taper and the termination of intsrumentation. It is a bit of apples and oranges comparison. If I prepare a case with tapered instruments to a #20/.08 to full EAL length (and then a skosh) how big is it at the POE? Compare this to a #40 lightspeed, taken perhaps .5mm short? Or to the "apical constriction?" My problem with a 20/0.08 is that I'm not simply cleaning at the apex. Yea, clean shavings may be an old wive's tale but it sure is better than a bunch of brown/green junk coming out of the apex. My clean shavings have had a dang good soak in sodium hypochlorite before coming off the rotary. - Guy Much of the "bigger is cleaner" lit I was indoctrinated with in gradual school was done without patentcy, and without the number, amount and depth of irrigation that is now routinely done. We were taught at least a 35 MAF...but...this was .5 to as much as 1.5mm back. Versus...Let's see, 20/.08 1mm past the POE=~28/.08 at the POE=~36/.08 1mm short of the POE. More apples and oranges. And which canal do you think got cleaned out better? I look at the apex and POE foramen as different entitities. I clean and shape them separately. I'm not trying to get sodium hypochlorite out the foramen. I'm trying to keep it in so my larger shape stops short of the POE. Another point is that I'm trying to fit a point as exactly as possible at the apex so sizing that exactly is imperative...minize the amount of cement and shrinkage at the apex. Of course I'm boing my point to the canal wall using Epiphany sealer. :-) - Guy David Clark and I have had a number of conversations about this and have both independently come to the same conclusions. Preservation of dentin should be maximized. We believe this means smaller access (appropriately placed and shaped!), and smaller preparations. Less use of uncontrollable instruments like GG's and elimination of Peezo's (for preparation). I compensate by spending more time trying to get down the roots in more places, and more irrigation, and more patency. I occasionally pay the price for this by having to retreat my own case [gratis, of course]. Oh well. I can always cut more. Watching you guys has made me a bit more conservative in removing dentin. Still, I truly feel that a huge number of my failures in old cases was from not cleaning and shaping the apex. Little has changed in my disinfecting and irrigation technique other than utilizing the bonding agent for that sorry ass Epiphany that I use but I know that I simply was not removing the crude from the apex. It is much easier for disinfectant to work in a clean canal than one full of crud and the same goes for the apex. - Guy I initially attempt to cut a shape that appears reasonable and appropriate for the root form. This is Buchanan's SOF (Shaping Objective File). Using untapered (lightspeed) or essentially untapered (NiTi .02 hand files) I assess this shape and apical diameter and make appropriate adjustements to either the taper, diameter or both. When I take out a #20/.08, and the last flutes are full of dentin, how can you explain this if the file is not binding? - John A Khademi In all canals? Wow - Guy John, First I need to say that your discussion is of a generic average root tip. Every root is different even within the same tooth. On a Max 1st molar the MB2 is normally the smallest diameter canal and usually I prepare it to #40 on average. The next largest is the DB which I commonly prepare to a 40 or 50, next is the MB1 which on average I prepare to a 45-55, and finally is the palatal canal. The palatal canal is very large and I find that it usually needs to be prepared to a 55-70. Kuttler was the first to describe apical anatomy in 55. These sizes for maxillary molars were reported in the JOE in 77, 10/99, in Compendium 91, a LightSpeed study in 97, and triple O in 2000. I have a chart that shows these sizes but my Lightyear software upgrade is creating problems which prevent me from posting a apical size chart for all of the teeth. (GRRRR I hate computer problems) I lecture for the UF AEGD program in St. Petersburg, FL and have extensive slides on apical anatomy if ROOTERS want to get involved in a detailed discussion of apical anatomy but I have to get my computer network problems straightened out first. Computer problems aside, this is where "these large apical sizes are coming from". They are coming from science and research which is more highly regarded than personal opinion or personal observation. Based on this established research completed independently over 5 decades with results that are in agreement, I'd have a hard time making a case for small apical preparations. Now I know you are not over extending your tapered rotary instruments 5-8 mm long in order to properly clean palatal roots of maxillary molars but then how can you be sure the apex has been properly debrided. Please don't tell me that you are making that judgment based on the taper and length of your obturation because that is not an accurate indication of proper debridement. The radiographic obturation only tells us where the obturation material is. It could be in the bone through a perforation, in a clean canal, or swimming in a sea of necrotic debris in the canal. At some point we have to acknowledge the truth of the literature or else we are just another craft based on opinion instead of science. At some point the promoters of small apical preparations with tapered rotary instruments are going to realize that they are being overcome by a continuous wave of science. If they refuse to accept it then they will be engaging in cognitive ignorance because they know they are ignoring the truth - Randy Hedrick P.S: I like the bicuspid you posted yesterday, it appears to be a larger apical preparation with 2 nice accessory canals! Excellent! I will say this about those. I got them about 2 weeks ago. And as john stated, they cut. I had previously commented that I wasnít comfortable with the rotaries as they had a tendency to screw into the canal. I decided last week to do an entire case using dr. Goodis Guidance protocol only. When I established a glide path using the #10 .04, .06, and .08 tapers, then went to the rotaries, I did not notice that thread in phenomena at all. The rotary part was quick and easy (there are only 3 of them to use maximally). I was much more impressed with the system when the hand files (I used them in the m4) were used. Perhaps I had an underprepared glide path and the rotaries were augering into the walls? Dr. goodis, feel free to comment. - gary Today, I was watching those rotaries auger out dentin shavings like a drill press would. If rotary too soon, you really have to peck away at it or hold the file back from augering down, but it seems to get easier after a few tries.- Rick Rick, Agree, like all instrument systems, it will have a different feel, but after a few tries it is easy. Thank you - Chuck Chuck, give the sequence we use with the files. I've used them once and got a good result but I think I got the sequence screwed up. It was not as easy as people are reporting. Guy Hello Guy Try this 1) Shape Glide-Path with hand files 10(02) to 10(04) to 10(06) repeat until the 10(02) is at the WL and the 10(04) or 10(06) is at or within 2 mm of WL 2) Shape Coronal 1/2 with rotaries 30(10) to 25(08) to 20(06) In a molar the #30 may only go 2-3 mm into the canal, the #25 may only go 3-5 mm 3) ReGlide-Path with hand files 10(02) to 10(04) to 10(06) repeat until 10(04) or 10(06) is at WL 4) Shape Apical 1/2 with rotaries 30(10) to 25(08) to 20(06) Repeat until file of choice is to the WL If the tooth requires a larger apical prep either 1) Take the instrument long, 2) Use a 02 taper NiTi hand file, 3) LightSpeed, 4) Use a 02 or 04 taper NiTi rotary Enlarging the apical prep is very easy. - Chuck Thanks, Chuck. I'll follow the directions this time. I sort of used them with ProTapers...defeated the purpose of Guidance. Guy The one I just started is filled with caoh2 currently. Will post it upon completion.- gary IMHO this seems quite complicated. 4 steps, 3 instruments per step = 12 instrument changes and that doesn't include "laps" within each step. Does this have to be done one canal at a time or are all canals done simultaneously with the same instruments? Why not use gates gliddens for coronal flaring and LightSpeed for apical preparation. There is a growing mountain of research clearly demonstrates the need for larger apical preparations compared to a relative vacuum of research that shows small apical preparations clean the apex better. Larger apical preparations allow for better disinfection and provides a cleaner canal surface which allows a better seal for the obturation. I've been using LightSpeeds for over 10 years. I've tried other tapered rotary instruments and System B but I keep coming back to LightSpeed because of the simplicity and effectiveness of the system - Randy Hedrick Hi Randy Most people who use the V-Taper system find it much easier and simpler than any other system. Also, it is probably easier to shape all the canals at once and not individually. Personally, I like to break up the shaping into coronal and apical, but it is not required. If you like LS and it works, you should continue. - Chuck Hi Randy, If the canal requires a larger apical prep than a size 30 with a .10 taper then use your LS or NiTi hand file or rotary file, or take the instrument long. Please let me know how you determine your final apical prep size - Chuck I use ProTapers to length...usually no larger than a F2. I then go back with 0.02 to 0.04 tapered ProFiles and K3's until I get clean shavings at the apex. Seldom does a F2 clean and size the apex and it is a 0.08+ taper, I think, with a size 25 tip. This one was to a F2 and I finished with an 0.02 45 ProFile. I'm assuming that 0.02 taper is turning freely in the rest of the canal except at the apex. Wrong assumption??? Guy Chuck, I have to ask, what about the research and the literature? Does apical cleanliness matter anymore? I thought that was the entire purpose of instrumentation, to get the canal as clean as possible.- Randy Bill Watson and Fred Barnett told me to size and gauge the apex until clean. So, that's what I do. Who needs research when Bill and Fred tell me to do it. Guy Hi Randy, Apical size is a hot topic that has been discuss many times. I know you feel very good about LS and do not like tapered instruments. I like tapered instruments, especially an instrument with a decreasing taper along the length of the file. After final shaping to a 25(08) or 30(10), then I will take NiTi .02 hand files, apically clear, and look for debris at 1-2 mm. My usual final apical prep is 25 to 40. I realize this may not be everyone's desired apical size and that is why I would not argue if someone would like it larger. I appreciate and have learned from your emails and position - Chuck Yes, that was a good exchange of info - Randy I had this same dialogue with our good friend ben immediately after our return from monterrey. I tend to favor larger apical preps, ben can show a boatload of stuff dating back to prehistoric times that have stood the test of time with smaller apical diameters. And so the debates continues.- gary What do you think they based their recommendation on? Science + clinical experience - gary Gary, I agree, the hand files really compliment the rotaries. The hand files make a great glide path which allows the rotaries to cut smoothly, please post a case if you have time. - Chuck The only thing I did differently in the cases I complained of augering in vs. this last case was the use of the tapered #10 files which I wanted to try as john k. was raving about them. Prior to that my glide path was established to patency up to a #15 .02. my hypothesis is that the greater taper in the coronal 2/3 reduced the engagement of the cutting edges to a level where it did not advance on its own. I literally had stopped using them for that particular reason. I havenít done enough cases to really give a fair evaluation, but having the hand files available (you didnít have them when I ordered the rotaries) seems to have made all the difference.- gary
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