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clinical opinion Endo Tribune U.S. Edition | March 2015B2 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 Marketing director Anna Kataoka a.kataoka@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 © 2015 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. Joseph S. Dovgan 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 “ RECIPROCATING, Page B1 Fig. 4: SafeSiders have 16 flutes compared to 24 flutes for files. Fewer flutes means less engagement with the walls of the canal, which means less resistance and binding, and virtually no instrument separation. • Preservation of tooth structure in what is often the thinner mesio-distal plane. • There is no longer a need for crown- down greater preparations that exag- gerate the amount of tooth structure removed coronally. • Hand fatigue is eliminated, starting with the first instrument through the fi- nal sequence. With the knowledge that the width of preparations should be a minimum of 30 for effective irrigation, we can prepare an effective, well-cleansed space by using just two more instruments after prepar- ing the glide path to a 20. By taking the 30/04 relieved NiTi instrument to within 3 to 4 mm of the apex and then follow- ing that up with the 30/02 relieved stain- less-steel vertically fluted instrument to the apex, we can fit with precision a fine point that when the canal is flooded with epoxy resin cement creates a three- dimensional seal. If desired, we can go up one size to a fine-medium point if we then take the 30/04 to the apex. In both cases the seal is created by the epoxy resin interface present along length via its application with a tool called the bi-directional spiral that gives the dentist the ability to flood the canal while at the same time prevent- ing the extrusion of cement beyond its confines (see Figs. 3a, b). If one takes a close look at the bi- directional spiral, one sees coronal flutes that drive the cement apically as it rotates. The apical three threads have the opposite orientation as the coronal flutes and drive the cement coronally. The result is two flows of cement that collide 3 mm from the applicator’s tip driving the cement laterally. The dentist uses the applicator with an up and down motion as it rotates in the slow-speed handpiece. Most often, nothing more than a single point is required to produce a three-dimensional fill. This method of obturation is dependent upon the bidi- rectional spiral and the properties of the cement, including: • Physical and chemical bonding to both the gutta-percha and the canal walls; • Its dimensional stability as it polym- erizes; • Being a polymer, its resistance to hy- drolytic degradation; • Being a room-temperature obtu- ration system, the cement and gutta- percha point expand 1.75 percent as it warms from room to body temperature; • Is an effective seal in both thin and thick layers; • A far lower level of viscosity than the most thermoplasticized gutta-percha; • Great penetration of the cement into the dentinal tubules; • Its well-documented antibacterial properties; • More than 70 years of usage that at- test to its effectiveness as an endodontic seal. From a procedural standpoint, the ob- turation procedures recommended here do away with: • The application of excessive force via lateral and vertical condensation that can lead to over extension of the point, the expansion of already existing den- tinal defects that in turn can lead to ver- tical root fracture; • The application of heat that can lead to the over extension of obturation mate- rial, damage to the periodontal ligament via exposure to excess prolonged heat; • The creation of voids as overly com- pacted gutta-percha rebounds to its orig- inal shape after the interface cement has been displaced. It should be noted here that I am not against the use of lateral or vertical condensation, only the degree of force applied. When creating a space for the placement of auxiliary points, I will nev- er use more force on a spreader than the weight of my hand. I do not want to apply sufficient pressure to distort the gutta- percha, knowing as it rebounds it will create a void. In addition, I do not want to add significant stress to the root that may already have preexisting defects or new ones as a result of rotating NiTi in- strumentation. If we consider the two aspects of end- odontics, instrumentation and obtura- tion, we can see where techniques can be simplified while adding safety and precision to the procedure. This is the true paradigm shift that has been ob- scured by the constant introduction of newer rotating NiTi instruments. All the new rotating NiTi entries require some degree of crown down prepara- tion even if a so-called single instru- ment is used. The result will predictably be exces- sive removal of tooth structure in the mesio-distal plane and inadequate preparation in the bucco-lingual plane exacerbated by the dentist’s concern that any deviation from the centered position increases the incidence of in- strument breakage. To further alleviate separation anxi- ety, difficult apical curves are to be first negotiated to a 20 with K-files, a holdover from an earlier time period making initial pathway a tiresome hand-fatiguing proposition. Vertically fluted instruments unre- lieved through a 10 and relieved there- after with a flat long length used in the 30-degree reciprocating handpiece os- cillating at 3,000 to 4,000 cycles per minute eliminate hand fatigue from the start. In the smaller dimensions, stainless-steel 02 tapered vertically flut- ed instruments are quite flexible while retaining enough body to effectively remove dentin when directed against all the walls. In these thin dimensions, NiTi by contrast would be way too flex- ible for effective shaving of dentin when pressed against these walls. As we work ourselves up to a 30 prepa- ration, one might think that particularly in curved canals the stainless-steel in- struments are too stiff to negotiate with- out distortion. To understand why this is not a problem, one must realize that the pathway has already been well-defined by the previous use of thin, highly flexi- ble, stainless-steel instruments that have widened the canal space beyond their own dimensions, creating a pathway that less flexible instruments can follow. Furthermore, the instruments used to negotiate the canals are relieved with a flat starting with a 15, making them more flexible just when unrelieved compa- rably sized instruments might become excessively stiff. Most important, the amplitude of motion confined to 30 de- grees keeps the instruments centered on the down stroke preventing distortion and can then be applied to all the walls on the upstroke. The idea is to replace complex with simple, unpredictable with predict- able while preserving as much tooth structure as possible, maintaining the integrity of the dentin and virtually eliminating instrument separation as a concern, thus making the procedures safer, less stressful and more effective and ultimately costing far less in their applications. 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. Figs. 3a,b: The bi-directional spiral (left) thoroughly coats the walls of the root canal and lateral canals without significant cement being forced apically.