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I 43 industry report _ Calamus Dual 3D Obturation System I roots1_2011 and to contact the previously down-packed master cone. Calamusdown-pack In preparation for initiating the down-pack, the clinician should select the Calamus EHP that fits passively through the straightaway portion of the preparation and optimally to within 5 mm from the terminus of the canal. When the EHP cannot reach thisdesiredlevel,inawell-shapedcanal,theCalamus bending tool may be utilised to place a suitable curvatureonthemoreapicalportionofthe40/03EHP that matches the curvature of the prepared canal. A silicone stop may be placed on the EHP to monitor its maximum depth of insertion safely. Because of the thermo-molecular properties of gutta-percha,theCalamusEHPwillgenerateabouta 5 mm heat-wave through gutta-percha, apical to its actual depth of placement. Following the placement of the sealer-buttered master cone in a canal with an irregular cross-section, it is beneficial to inject heat- softenedgutta-perchalateraltothemastercone.This methodwillservetoinitiallythermo-softenthemas- ter cone, maximise the volume of gutta-percha and effectively increase hydraulics when commencing with the down-packing phase of obturation. The Calamus EHP is activated and utilised to sear off the master cone at the cemento-enamel junction in single rooted teeth or at the orifice level in multi- rooted teeth (Fig. 7a). In order to capture the maxi- mumcushionofwarmrubber,theworkingendofthe large-sized, pre-fit plugger is methodically stepped aroundthecircumferenceofthecanal.Thispluggeris used with short, firm vertical strokes to scrape warm gutta-percha off the canal walls and flatten the material coronally. The working end of the plugger is used to press vertically on this flattened platform of warm gutta- percha for five seconds (Fig. 7b). This action serves to automatically fill the root-canal system, laterally and vertically, over a range of a few millimetres and is termed a wave of condensation (WOC).4 Specifi- cally, a WOC moves thermo-softened gutta-percha into the narrowing cross-sectional diameters of the preparation, generates a piston effect on the en- trapped sealer and produces significant hydraulics. During this heating and compaction cycle, the oper- ator will tactilely feel the warm mass of gutta- percha begin to stiffen as it cools. Importantly, using a plugger to press on warm gutta-percha during the cooling cycle has been shown to offset shrinkage completely. In order to generate a progressively deeper heat- wave along the length of the master cone, the Cala- musEHPisactivatedandallowedtoplunge3to4mm into the previously compacted material. Following the plunge, the EHP is deactivated and the operator shouldhesitateforabriefsecondbeforeremovingthe coolinginstrumentalongwithabiteofgutta-percha (Fig. 8a). Removing a bite of gutta-percha results in the progressive apical transfer of heat another 4 to 5mm along the length of the master cone and facili- tates the placement of the medium-sized, pre-fit plugger deeper into the root-canal preparation. This pluggerisused,asdescribedabove,tocompactwarm gutta-percha into this region of the canal, producing a second WOC (Fig. 8b). Depending on the length of the canal, only two, threeorfourheatingandremovalcyclesarerequired until the pre-selected EHP can be placed within 5 mm of the canal terminus (Fig. 9a). Owing to multi- ple heatings, thermal cycling progressively transfers heat into the apical one-third of the gutta-percha master cone. Advantageously, the temperature of gutta-percha only has to be elevated 3°C above body temperature to become heat-softened and readily mouldable. Utilising this technique, obturation tem- peratures within the gutta-percha have been shown to be clinically safe and generate working tempera- tures that range from 40 to 45°C. Fortuitously, the temperature produced on the external root surface is less than 2°C. This minor transfer of temperature is Fig. 9a_The EHP is activated and plunged deeper into the gutta- percha, deactivated, then the cooling EHP removed along with another bite of gutta-percha. Fig. 9b_The working end of the small-sized, pre-fit plugger scrapes the walls of the canal clean, maximises the volume of gutta- percha and generates the final WOC. Fig. 10_Following the down-pack, a working film demonstrates 3-D corkage and filled lateral canals coronal to the more apical mass of gutta-percha. Fig. 9a Fig. 9b Fig. 10