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clinical opinion Endo Tribune U.S. Edition | January/February 2016 B2 Publisher & Chairman Torsten Oemus t.oemus@dental-tribune.com President/CEO Eric Seid e.seid@dental-tribune.com Group Editor Kristine Colker k.colker@dental-tribune.com Editor in Chief ENDO Tribune Frederic Barnett, DMD barnettF@einstein.edu Managing Editor ENDO Tribune Fred Michmershuizen f.michmershuizen@dental-tribune.com Managing Editor Sierra Rendon s.rendon@dental-tribune.com Managing Editor Robert Selleck, r.selleck@dental-tribune.com Product/Account Manager Humberto Estrada h.estrada@dental-tribune.com Product/Account Manager Maria Kaiser m.kaiser@dental-tribune.com business development manager Travis Gittens t.gittens@dental-tribune.com Education DIRECTOR Christiane Ferret c.ferret@dtstudyclub.com accounting coordinator Nirmala Singh n.singh@dental-tribune.com Tribune America, LLC 116 West 23rd Street, Suite 500 New York, NY 10011 Phone (212) 244-7181 Fax (212) 244-7185 Published by Tribune America © 2016 Tribune America, LLC All rights reserved. Tribune America strives to maintain the utmost ac- curacy in its news and clinical reports. If you find a factual error or content that requires clarification, please contact Managing Editor Fred Michmershuizen at f.michmershuizen@dental-tribune.com. Tribune America cannot assume responsibility for the validity of product claims or for typographical er- rors. The publisher also does not assume responsibil- ity for product names or statements made by adver- tisers. Opinions expressed by authors are their own and may not reflect those of Tribune America. Editorial Board Frederic Barnett, Editor in Chief Dr. Roman Borczyk Dr. L. Stephen Buchanan Dr. Gary B. Carr Prof. Dr. Arnaldo Castellucci Dr. Unni Endal Dr. Frnando Goldberg Dr. Vladimir Gorokhovsky Dr. Fabio G.M. Gorni Dr. James L. Gutmann Dr. William “Ben” Johnson Dr. Kenneth Koch Dr. Sergio Kuttler Dr. John T. McSpadden Dr. Richard E. Mounce Dr. John Nusstein Dr. Ove A. Peters Dr. David B. Rosenberg Dr. Clifford J. Ruddle Dr. William P. Saunders Dr. Kenneth S. Serota Dr. Asgeir Sigurdsson Dr. Yoshitsugu Terauchi Dr. John D. West Tell us what you think! Do you have general comments or criticism you would like to share? Is there a particular topic you would like to see articles about in Endo Tribune? Let us know by emailing feedback@dental-tribune.com. We look forward to hearing from you! If you would like to make changes to your subscription (name, address or to opt out) please send us an email at c.maragh@dental-tribune.com and be sure to include which publication you are referring to. Also, please note that subscription changes can take up to 6 weeks to process. ENDO TRIBUNE “ RELIEVED REAMERS, Page B1 Corrections Endo Tribune strives to maintain the utmost accuracy in its news and clinical reports. If you find a factual error or content that requires clarification, please report the details to Managing Editor Fred Michmershuizen at f.michmershuizen@dental-tribune. com. The emphasis is placed on maintaining the integrity of the instrument with minimal thought given to the impact they have on the integrity of the re- maining root structure. Straight-line access is purchased at the expense of removing additional amounts of coronal tooth structure. Crown-down preparations signifi- cantly increase the amount of coronal dentin removed so the instruments will contact a reduced amount of ca- nal length at any one time. Heat treat- ment is a technique that increases the life span of the instrument without a comparable increase in the life span of the dentin, a tissue that is not ame- nable to technological improvements at present. The instruments may be used once, but the impact of stress on dentin is cu- mulative whether new instruments are employed or not. A single instrument will simply work longer in a canal to achieve its goals of cleansing and shap- ing than any one instrument used with a multiple sequence technique. Keeping instruments centered in canals that are highly oval, anatomy that is more the rule than the excep- tion, keeps the instruments intact at the expense of compromised cleansing most often in the bucco-lingual plane. The new single file interrupted rotary systems are prone to instrument sepa- ration because they are still generating a minimum of 200 full rotations per minute. As a single instrument they are now doing the complete shaping after glide path creation and suffer from the same need to remain centered within the confines of the canal despite the presence of significant buccal and lin- gual extensions of pulpal tissue. By instrumenting the canal to small- er tapers, the rotary systems — either continuous or interrupted — remove less tooth structure and are less prone to breakage. However, they are still con- fined to centered preparations with lit- tle lateral brushing occurring, leaving untouched buccal and lingual exten- sions of tissue. If we go back to an earlier time prior to the introduction of greater tapered rotary systems, we basically relied on the use of K-files to shape the canals. From the start, these instruments are poorly designed to shape and cleanse canals. Their main defect in design is the in- corporation of 30 predominantly hori- zontal flutes aligned along the 16 mm of working length. Horizontal flutes can only shave dentin away with the pull stroke be- cause it is only then that the cutting edges of the flutes are more or less at Fig. 2: Tango Endo. Fig. 1: 02 tapered stainless steel relieved reamers. Photos/Provided by Barry L. Musikant, DMD right angles to the plane of motion, a requirement for the removal of den- tin. This same flute alignment unfor- tunately is designed to impact dentin at the tip of the instrument when it is directed apically. Losing length when using K-files is familiar to most dentists, especially when curves exist in the apical third. Rather than employing instruments with predominantly horizontal flute orientations as our initial tools, we should be using instruments with pre- dominantly vertical flute orientations, similar to the designs incorporated into most rotary systems. A predominantly vertical flute orien- tation will shave dentin from the canal walls with the first clockwise stroke. When the instrument is removed and reintroduced into the canal, the verti- cally oriented flutes will tend to glide past any debris present rather than im- pacting it apically. These instruments are defined as reamers. Essentially, we are using a watch- winding motion, similar to that used with K-files, but with far greater ef- ficiencies and far less likelihood for apical blockage. We further improve the mechanics by incorporating a flat along the length of the reamers, fur- ther reducing engagement and creat- ing an instrument that now has two columns of cutting chisels that work in both the clockwise and counter- clockwise motion. A watch-winding motion eliminates the full rotations that lead to excessive torsional stress and cylic fatigue that produce the instrument separations we want to avoid. The hand fatigue as- sociated with the use of K-files is com- pletely eliminated when generating the watch winding motion in a 30- to 45-degree reciprocating handpiece. The speed of the procedure is signifi- cantly increased because the recipro- cating handpiece has the added advan- tage of oscillating at 3,000 to 4,000 cycles per minute.5 For those dentists using greater ta- pered rotary NiTi systems, the goal of the K-files was limited to creating a glide path producing an 02 tapered centered space up to at most a 20. The relieved reamers also have that func- tion, but with the power of a reciprocat- ing handpiece generating oscillations of 3,000 to 4,000 cycles per minute, the instruments have the added ability to vigorously work the buccal and lin- gual extensions of highly oval, sheath- like pulpal anatomy. One need not be concerned about the reduced flexibility of stainless steel re- lieved reamers. In their smaller dimen- sions they are easily flexible enough to negotiate complex curved canals. As the thinner, highly flexible instru- ments faithfully enlarge the original canal anatomy free of distortions, they are defining a pathway that the some- what larger and less flexible relieved reamers will then faithfully follow. The goal in most situations is to produce an apical preparation of 30 applied to all the walls of the canals, be they round or not. Please realize that this goal will ultimately produce a larger version of the original canal anatomy rather than the imposition of a large conical shape that bears little relationship to the original anatomy. For the most part, we do not want to exceed a taper of 04. Such a conserva- tive preparation preserves coronal den- tin and in combination with the relieved reamers allows us to remove tissue from those thin extensions that are off limits to rotary NiTi instrumentation.6 The sys- tem we are defining is based primarily on 02 tapered stainless steel relieved ream- ers (Fig. 1). After the glide path creation using the relieved reamers (SafeSiders), crown-down preparations are no longer necessary. Rather the final preparation is a simple extension of instrumenta- tion that widens the canal from a 20/02 preparation to a maximum of 30/04 in most situations (Tango Endo, Fig. 2), a final result that requires only two more instruments after the 20/02 preparation has been achieved. Given our clinical experience, along with the insights that are being docu- mented from recent research, we can make the following conclusions regard- ing the use of this approach to endodon- tic instrumentation: 1) Instrument separation is virtually eliminated, producing a much more fa- vorable mindset for the dentist. BarryLeeMusikant, DMD, FICD, is a mem- ber of the American Dental Association, American Associa- tion of Endodontists, Academy of General Dentistry, the Dental Society of New York, First District Dental Society, Academy of Oral Medicine, Alpha Omega Dental Fraternity and the American Society of Dental Aesthetics. He is also a fellow of the Amer- ican College of Dentistry (FACD). He is a partner in the largest endodontic practice in Manhattan. Musikant’s 35-plus years of practice experience have established him as one of the top authorities in endodontics. To find more information from Musikant, visit www.essentialseminars.org, email info@essentialseminars.org or call (888) 542-6376.