I'm glad LightSpeed will be available to India soon. It's a great instrument and there is a solid foundation of independent research to support it. I should tell you that I have a close affiliation to the people who own and operate LightSpeed. I have given 4 LightSpeed presentations for LS, 2 of which were to the 04 & 05 AEGD residents at the University of Florida Clinic at St. Petersburg, FL where I volunteer 1/2day per month. I am not a stock owner and have no financial interest in LS. I am compensated for some lectures but the compensation is not enough to cover my time out of the office. I do it because research indicates it is the best instrument available for cleaning the apex. I feel more people should be aware of it and use it. It's like promoting microscope use but not receiving any significant compensation from the microscope manufacturers.
I was in my residency at San Antonio when the first prototypes were introduced and I was using it a year before it went to market in 1993 or 1994. Dr Senia was my mentor for the first 6 months of my residency at which time he retired but we have maintained the friendship over the years. I should say that no one should expect this to be a "magical instrument". It requires some practice and experience but it's worth it and the literature supports it. Here is my technique which deviates somewhat from the manufacturers recommended technique. Sorry for the length of the post.
After establishing access, I get the canal up to a #12 or 15 hand file before using a #2 gates followed by a #4 gates to have a smooth path from the margin of the access opening into the orifice of the canal. There are other instruments that can be used instead of gates but I prefer to keep things simple whenever possible. It's a matter of personal preference. My last hand file is normally a #17 Flex-O-file. After that I only use LightSpeeds for the remainder of the preparation. If the canals are sharply curved with a tight radius of curvature I use the LightSpeed instruments by hand to avoid breakage. Occasionally when a LightSpeed instrument wonít get past a sharp curve or obstruction I use larger pre-curved stainless steel hand files to smooth out the path to the apex. I use 2 cordless handpieces. It's really nice for the assistant to hand you a big, fat handpiece loaded with the next file instead of a tiny file that has to be put into the handpiece. This speeds up the procedure substantially as we exchange the cordless handpieces. Rotary speed is about 1500RPM for LS1( the original design) and 2000-2500 for the newer LSX design.
LightSpeed teaches to use liquid EDTA for the entire instrumentation process and a final irrigation with hypochlorite. I prefer to alternate liquid EDTA and 5.25% NaOCl after every 3 instruments. It seems to me that when I use only EDTA or only NaOCl, debris accumulate in the canal. With only EDTA I think the debris are composed primarily of organic remnants of the dentin filings. With only NaOCl the debris are probably inorganic remnants of the dentin filings. When I alternate I get less debris on the instrument at the final recapitulation with the master apical rotaries. This approach probably minimizes smear layer accumulation. After I have finished apical preparation I recapitulate with the master apical rotary file in each canal with EDTA. Then I flood the canal with NaOCl and get a curved .06 to explore the isthmus and apical areas for "catches". I continue to change the hypochlorite during this process.
Apical preparation size selection does require some experience. The starting point is the 12 peck rule, the first instrument that takes 12 pecks to get to the apex is the master apical rotary. It seems to me that dentin can have different degrees of hardness which affects the 12 peck rule. Consequently you must keep in mind the range of sizes that are appropriate for each root. That is where the anatomic studies are important and should not be ignored. One of the indicators I use is to notice the length measurement at which the instrument starts to engage the canal walls as indicated by a resistance to apical advancement of the instrument. Ultimately I want to end up with a larger apical preparation diameter that is prepared as a parallel sided tube for the apical 4-5mm. I like to be at least a size 50 4-5mm from the working length to make sure I can get the 23gauge Obtura needle deep enough to touch the Simplifil plug to reduce voids between the Simplifil plug and the backfill.
In preparation for obturation I follow the NaOCl with a rinse of EDTA. I like to leave it in the canal for at least a minute and change the EDTA fluid at least once during that minute. Then I rinse thoroughly with distilled water, suction the canals with a needle and dry with paper points. I put paper points soaked in Epiphany primer into each canal and then fill the chamber with primer from a pipette and leave in the canals for one minute. I usually pump the paper points up and down to agitate and freshen the primer in the canals. I suction the canals with a needle and dry the excess primer with paper points then apply a lot of sealer with paper points. I coat the Simplifil with sealer and push it to place. The handle is turned counter clockwise to release the Simplifil plug and removed. The plug is an .02 taper that is being pushed into a parallel tube preparation. Works like a cork in a bottle. This provides vertical and lateral condensation at the same time and can pop a few accessory canals if present. If the plug comes out on the carrier when it is removed take scissors and cut 2mm off the plug. If it comes out again go to the next larger size. After the plug releases I like to use a 5-7 condenser to further condense the plug. The 5-7 plugger is used cold but was heat treated once when it was new to soften the metal which allows it to go around curves for condensation. I then use Obtura to backfill and while the material is still warm I push the cold 5-7 plugger into the warm Resilon with a single sustained push for about 3-5sec then wobble the plugger, in a circumferential manner, to release the plugger from the Resilon. I then fill the plugger void with the Obtura. This gets an occasional lateral canal.
Sorry about the length of this post but I wanted to be thorough. There are many ways to skin a cat but this is what I have settled on at this point. I am open to change when worthy innovations are supported by good research. If you have any questions Iíd be happy to answer them. I won't be back in the office until Monday morning but I will try to arrive early to reply to questions.
Here is are some suggested apical preparation sizes from LightSpeed derived from anatomical studies. I find it interesting and validating that these studies were done independently and decades apart but came essentially to the same conclusions.
Excellent job randy, but your post brought up 3 questions in my mind.
why #2 gates then #4. why not, say the way I do it, #4, then a #3, then a #2, each one prepping a little deeper for the next instrument. Not major, but Iím curious as to your thought process. I too have been trained with ls, but Iíve never heard the always edta thing. Iíve always alternated, and being anal retentive, I alternate after every file. You go back further than I do and you were in ls back yard for your residency, so maybe it predated my ls experience of say 5 years ago. this I guess is not a question but just a statement, with the new lsx, there is no 12 peck rule, and in fact pecking is out. I know you know, but I want others who may not be in the know to know, you know?
And donít even tell me your diving this weekend while I am freezing my derriere off (yes, there is plenty of that to freeze off) up here.- Gary
1. After a #12 or #15 the #2 will be able to enter the canal better than a #4. The depth I go is dependent on resistance to advancement and root anatomy. If it goes easy, I go deeper. Cuspids, maxillary centrals, palatal roots of Max molars and distal roots of mandibular molars are generally larger and straighter and I can go deeper safely. I don't use the #3 because the #4 blends smoothly into the #2 prepared portion of the canal. I do use a #3 after I use an 80-LS because it is equivalent to a #90 and the flaring is usually in the coronal 1/3 by then.
2. I believe LS is advocating irrigation after every LSX instrument since they don't have half sizes. I still am using LS1, the original instrument. I have used one of their initial prototypes, LS2 which was replaced with the LSX which tracks down the canal better and is less impeded by obstructions than the LS2. I have used one set of LSX instruments and it did track down the canal better than the LS2. As for the irrigation protocol with LS1 I just experimented myself and found I get less debris by alternating between liquid EDTA and 5.25% NaOCl.
3. The 12 peck rule is the starting point the technique with LS1. I've used many LS2 and only one set of LSX and have not used the LSX enough to advise you. LS may have better guidance on the LSX but I believe they have determined that the clinician should notice when the instrument begins to engage the canal walls and then provides steady moderate resistance to advancement to the apex. When that steady, moderate resistance occurs in the last 4-5mm that should be the master apical file size. Maybe at some point Dr. Senia will do a guest day on ROOTS and we can find out the latest. - Randy Hedrick
If you go lsx, you absolutely want to loose pecking, which most advanced clinicians have already done, and two, I strongly suggest kicking the rpmís up to at least 2500 rpm. I thought the lsx was terrible at 2000, but much more efficient and less chatter at 2500. I reported that to steve during beta testing, and they agree. Some are cranking them up to 3000. - Gary
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