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ePaper created 2017-09-12, 09:26:18 | version 1.38.0
instrumentation and obturation CE article | While these vary by instrument, a set of common rules applies to root canal preparation. Root canal systems are best prepared in the following sequence: · Analysis of the specific anatomy of the case. · Canal scouting. · Coronal modifications. · Negotiation to patency. · Determination of working length. · Glide path preparation. · Root canal shaping to desired size. · Gauging the foramen, apical adjustment. Obturation of the endodontic space A well-shaped and cleaned canal system should create the conditions for intact periapical tissues. On the other hand, this root canal system is inaccessible to the body’s immune system and therefore it cannot combat coronal leakage. Accordingly, best practices dictate that root canals should be filled as completely as possible to prevent ingress of nutrients or oral mi- croorganism. None of the established techniques for root canal filling provides a definitive coronal, lateral and apical seal.24 Basic strategies in root canal obturation Ideally, root canal fillings should seal all foramina leading to the periodontium, be without voids, adapt to the instrumented canal walls and end at working length. There are various acceptable materials and techniques to obturate root canal systems, including: · Sealer (cement/paste/resin) only. · Sealer and a single cone of a stiff or flexible core material. · Sealer coating combined with cold compaction of core materials. · Sealer coating combined with warm compaction of core materials. · Sealer coating combined with carrier-based core materials. Several of these techniques have shown compara- ble success rates regarding apical bone fill or healing of periradicular lesions, so a clinician may choose from a variety of techniques and approaches that works best for him or her. Existing research directs clinicians toward preparation and disinfection of the root canal as the single most important factor in the treatment of endodontic pathosis, and no particular sealing technique can claim superior healing success.25 Current developments in root canal obturation materials After the introduction of mineral trioxide aggre- gate (MTA) as a material for perforation repair and apical surgery more than two decades ago, materials with similar bioactive properties now are available as root canal sealers. Bioceramic root canal cement (BC Sealer, Brasseler) has clinically acceptable radi- opacity and flow.26 Moreover, it is well-tolerated in cell culture experiments.27 However, there is no clinical evidence that using this cement leads to better out- comes. In fact, most research has indicated the type of cement used has comparatively little impact.28 In contemporary practice, heat generators are used to plasticise gutta-percha. Additionally, cordless heat- ing devices are available. Another recent addition is a carrier-based material, GuttaCore (Dentsply Sirona), which uses modified gutta-percha materials instead of plastic as its base. Early data indicate that obtura- tion with this new material is similar to warm vertical compaction or lateral compaction.29 Fig. 3: Root canal treatment of tooth #19 with four canals diagnosed with irreversible pulpitis and acute apical periodontitis. A second canal in the distal root of a mandibular molar is not infrequent. Note multiple apical foramina in both the mesial and the distal apices. Prior to temporisation, the orifices were protected with a barrier of light-curing glass ionomer. (Case courtesy of Dr Paymon Bahrami) Fig. 3 roots 3 2017 19