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ePaper created 2015-03-18, 11:28:53 | version 1.33.01
March 2015 — Vol. 10, No. 1 www.dental-tribune.com ENDO TRIBUNE The World’s Endodontic Newspaper · U.S. Edition ” See RECIPROCATING, page B2 Clinical opinion An update on non-rotating reciprocating endodontics By Barry L. Musikant, DMD T here is an important distinction to be made between systems that involve 360-degree rotations, be they interrupted or continuous, and systems that purposely minimize rotation to 30 degrees. While a system that undergoes interrupted full rotations is less vulnerable to instrument separa- tion than continuous rotations, it is still a problem and both are associated with the production of dentinal defects where con- cern exists that they may propagate and coalesce into vertical fractures over time. Dentists acknowledge separation anxi- ety by using these rotating systems with a light touch, staying centered with min- imal deviation from the conical shapes these instruments impart to the canal (see Fig. 1). By limiting the amplitude of motion to 30 degrees, the torsional stress and cyclic fatigue associated with full rotations is reduced to the point where it virtually is no longer a factor in instrument separa- tion. What this means in practice is the dentist’s ability to use the thinnest 02 ta- pered stainless-steel instrument in his/ her arsenal without fear of breakage. For most dentists, this immediately leads to the use of K-files, instruments that with their horizontally oriented flute design are inclined to impact debris apically when the push stroke is employed, lead- ing to loss of length. Fig. 1: Endo-Express 30-degree reciprocating handpiece. Photos/Provided by Barry L. Musikant, DMD Many of us are familiar with the loss of length that occurs when shaping curved canals with K-files, thinking it is our fault when in fact a good deal of the blame is associated with the instruments’ design. We can drastically reduce the incidence of blockage, minimize resistance along length and shave dentin away far more efficiently if we employ 02 tapered in- struments with fewer and more verti- cally oriented flutes that incorporate a flat along their working length starting with a 15. After the tightest most tortuous ca- nals are negotiated to the apex using our thinnest 02 tapered 06 tipped stainless- steel vertically fluted instrument manu- ally, the same instrument is attached to a 30-degree reciprocating handpiece oscillating at 3,000 to 4,000 cycles per minute to widen the canal to a diam- eter larger than the instrument being used without distortion and creating a space where the next instrument in the sequence used in the reciprocating hand- piece can reach the apex with minimal resistance. This capability is utilized because the dentist quickly learns that separation simply will not occur, giving him/her the confidence to work these instruments against all the walls of the canal with special attention given to what is often the wider bucco-lingual plane. With each instrument widening the canal signifi- cantly beyond its own dimensions, the sequence to any desired dimension is rapid, risk-free and without hand fatigue. From the point of view of dentin pres- ervation, most of the instrumentation is done with 02 tapered instruments minimizing the amount of coronal tooth structure that is removed when greater tapered instruments are used. Straight- line access, a requirement for rotating NiTi that further compromises coronal dentin, is not a requirement when us- ing the vertically fluted instruments in 30-degree reciprocation, further pre- serving tooth structure. Where rotating NiTi prepares a conical shape along length even when the canals are highly oval and sheath-like, the thin 02 tapered stainless-steel relieved verti- cally fluted instruments will produce a space that reflects the original canal anatomy in larger form. If the canal was oval to begin with, the final shape will be oval, preserving tooth structure in the mesio-distal plane and extending the preparation to include the buccal and lingual tissue extensions that are pres- ent in sheath-like pulpal configurations. By confining motion to 30 degrees, a number of advantages become available to the dentist: • There is a reduction in procedural stress because breakage is no longer a concern. • Knowing the instruments are virtu- ally free of breakage, they can be used with vigor against the canal walls, as- suring a greater degree of cleansing into areas that rotating NiTi does not cleanse effectively. • The instruments can be used several times with substantial savings. • Short amplitudes of motion are not associated with dentinal defects. Fig. 2: Vertically fluted SafeSiders instrument in an Endo-Express 30-degree reciprocating handpiece. AAE to meet in Seattle R egistration is now open for AAE15, the annual meeting of the American Associa- tion of Endodontists, taking place May 6 to 9 at the Washington State Convention Center in Seattle. The AAE’s annual meeting is billed by the association as “the most comprehensive endodontic education summit, vendor exhibition and net- working opportunity in the world.” “AAE15 will provide our members and guests with outstanding education, entertain- ment and networking events,” said AAE President Dr. Robert S. Roda. “Our program will focus on future trends and growth to help practitioners prepare for the next generation of advancements in the art and science of endodontics.”