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January/february 2016 — Vol. 11, No. 1 www.dental-tribune.com ENDO TRIBUNE The World’s Endodontic Newspaper · U.S. Edition ” See RELIEVED REAMERS, page B2 Clinical opinion By Barry L. Musikant, DMD As a practicing endodontist and man- ufacturer of endodontic instrumenta- tion systems, it is fascinating to me to observe the initial evaluation of greater tapered rotary NiTi instrumentation as a paradigm improvement over tradi- tional manual techniques morph into a far more cautious view where more and more evidence documenting its delete- rious effects on the dentin is becoming increasingly evident. To support that observation, research has found a correlation between the use of greater tapered rotating NiTi and the production of dentinal micro-cracks.1–4 Research has also found a decrease in resistance to vertical fracture as the taper of the preparations increase, sug- gesting there is a clear gap between the actual pulpal anatomy that exists and some of the tools being used to cleanse and shape canals for obturation. At last year’s American Association of Endodontists meeting, the AAE president noted that he has seen a greater number of vertical fractures over the past 20 years, a time consistent with the intro- duction of greater tapered rotary NiTi instrumentation. His observations were supported by a large number of endo- dontists present at the meeting. It is difficult to dismiss the real- ity that rotation of instruments within curved canals leads to torsional stress and cyclic fatigue, the two factors re- sponsible for instrument separation. To reduce instrument separation, dentists have learned to do the following: 1) Establish straight-line access in the mesio-distal plane. 2) Use a crown-down technique that minimizes instrument engagement along length. 3) Employ heat-treated NiTi that are more resistant to cyclic fatigue. 4) Employ the instruments only once. 5) Create a more instrumented glide path prior to the use of rotary NiTi. 6) Remain centered when negotiating to length. 7) Use the instruments in interrupted rotation rather than continuous rotation. 8) Reduce the dimensions of the final canal preparation. The above techniques and strategies are employed to reduce the stresses that occur in the instruments as they rotate within the confines of the canal. Relieved reamers and the 30-degree reciprocating handpiece Save the date AAE16 — the annual session of the American Association of Endodontists — will be held April 6 to 9 at Moscone Center West in San Francisco. Visit the meeting website at www. aae.org/AAE16 for complete information. Photo/Provided by Bev Lloyd-Roberts, freeimages.com I n response to new developments and research indicating the effectiveness of 3-D imaging for endodontic diagno- sis and treatment, the American Asso- ciation of Endodontists and the American Academy of Oral and Maxillofacial Radiol- ogy have issued a revised position state- ment on the use of cone-beam computed tomography in endodontics. The joint statement is an update to a 2010 position on CBCT use in endodontics. An AAE-AAOMR committee reviewed the scientific literature from the past five years and updated the position state- ment to include specific recommenda- tions for the appropriate use of CBCT. The statement emphasizes that CBCT should not be used routinely for endodontic diagnosis or screening purposes in the absence of clinical signs and symptoms, and it provides 11 specific recommenda- tions and supporting evidence for when CBCT should be considered the imaging modality of choice. The statement is con- sistent with principles of ALARA — keep- ing patient radiation doses “as low as rea- sonably achievable,” and notes that the patient’s history and clinical examina- tion must justify the use of CBCT by dem- onstrating that the benefits to the patient outweigh the potential risks. “Endodontists continue to have excellent results with two-dimensional radiogra- phy,” said AAE President Dr. Terryl A. Prop- per. “However, limited-field-of-view CBCT does have a place in endodontics when dealing with more complex cases, which are reflected in the position statement. Our goal is to help AAE members and general dentists determine where it fits for them.” The position statement is available at www.aae.org/guidelines. Position statement on 3-D imaging