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ePaper created 2016-03-11, 23:13:06 | version 1.38.0
62 — issue 2016 Endodontics Article MATCHING GUTTA-PERCHA CONES — to NiTi rotary instrument preparations — Gianluca Gambarini is Professor of Endodontics at the Sapienza University of Rome’s dental school in Italy. He is an international lecturer and researcher, and actively collaborates with a number of manufacturers all over the world to develop new tech- nologies, operative procedures and materials for root canal treatment. Prof. Gambarini also works in a private endo- dontics practice in Rome. Prof. Gianluca Gambarini, Dr. Gianluca Plotino, Dr. Nicola Maria Grande, Dr. Simone Staffoli, Dr. Federico Valenti Obino, Dr. Lucila Piasecki, Dr. Dario di Nardo, Dr. Gabriele Miccoli & Prof. Luca Testarelli, Italy Introduction With the widespread use of rotary nickel- titanium (NiTi) instruments, matched- taper gutta-percha (GP) cones of greater tapersweredevelopedtomakerootcanal obturation techniques easier and more predictable, and possibly to the improve quality of 3-D fillings. Nowadays, many manufacturers produce matched-taper GP cones intended for use with a specific instrumentation technique. Consequently, the single-cone technique has regained popularity, since a single matched-taper cone can produce a satisfactory 3-D fill, andwarmverticaltechniquesbenefitfrom the use of a matched-taper master cone by a reduced risk of voids inside the filled endodontic space. However,thelargernumberofandvari- ability in design and dimensions of com- mercially available NiTi instruments and GP cones of greatertapers can easilycre- ate confusion among practitioners, espe- ciallyifusinginstrumentsandconesofdif- ferentbrands.IftheGPconesselecteddo not precisely match with the NiTi instru- ments used, the whole concept fails and in many cases the GP cones do not reach the desired working length or do not pre- cisely fill the apical preparation. In order to understand how matched- taper GP cones should work, it is impor- tant that clinicians be aware of the differences in size, taper, design and manufacturingprocessoftheseproducts. Even if these factors are usually taken in account when a manufacturer produces matched-taper GP cones to be used with a specific instrumentation technique, the goal of the present paper is to discuss all ofthesevariablesandgivecliniciansabet- ter understanding of the possible clinical problems they may encounter in cone fit- ting and practical solutions to these. Size, tolerance and manufacture of GP cones Conventionally, GP cones are hand rolled, a manufacturing process that is neither veryprecisenorconsistent.Therefore,ac- cordingtoISOstandards,thetoleranceal- lowed for GP cones is 0.05 mm, much larger than the tolerance allowed for en- dodontic instruments produced by grind- ing or twisting (0.02mm). This has always been a problem in endodontics and it ex- plains why correct fitting of the master cones in all techniques (single-cone, lat- eral condensation, warm vertical conden- sation,continuouswaveofobturation)has always been described as a fundamental step in the procedure. WiththeconventionalISO0.02-tapered cones, the problem was mainly related to the lack of precision of the tip of the GP cones. Therefore, GP tips needed to be manually adjusted to fit the apical prepa- ration with good retention (tug-back) in order to avoid underfilling or overexten- sion of cones through the apical foramen. The same procedure was needed for non- Article_Gambarini_00-00.qxp_Layout 1 02.03.16 20:48 Seite 1 Article_Gambarini_00-00.qxp_Layout 102.03.1620:48 Seite 1