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ePaper created 2017-04-26, 11:33:32 | version 1.38.0
I C.E. article_ instrumentation and obturation that an appropriate amount of sealer is deposited. If the master cones are the carrier for the sealer, they should be removed and inspected for a complete coating with sealer and then replaced in the canal. The master cones are placed close to working length using a slight pumping motion to allow trapped air and the excess sealer to flow in a coronal direction. The marking on the cone should be close to the coronal reference point for working length determination. For lateral compaction, a preselected finger spreader is then slowly inserted alongside the master cone to the marked length and held with measured apical pressure for about 10 seconds. Dur- ing this procedure, the master cone is pushed laterally and vertically as the clinician feels the compression of the gutta-percha. Rotation of the spreader around its axis will disengage it from the gutta-percha mass and facilitate removal from the canal. The space created by the spreader is filled by inserting a small, lightly sealer-coated accessory gutta-percha cone. Using auxiliary cones larger than the taper of the spreader will produce voids or sealer pools in the filling and should be avoided. The pro- cedure is repeated by inserting several gutta-percha cones until the entire canal is filled. For vertical compaction, electrically heated plug- gers are used to melt a master cone fitted to length. Tapered gutta-percha cones optimize the hydraulic forces that arise during compaction of softened gutta-percha with pluggers of a similar taper. After fitting the master cone as before, different hand pluggers and heated pluggers are placed into the root canal to verify a fit to within 5 to 7 mm of the apical constriction. For both lateral and vertical compaction the gutta-percha mass in each canal should end about 1 mm below the pulpal floor, leaving a small dimple. In cases where placement of a post is planned, gutta- percha is confined to the apical 5 mm.31 All root canals that do not receive a post may be protected with an orifice barrier (Fig. 3) to protect from leak- age prior to placement of a definitive restoration.32 This has been shown to promote healing of apical periodontitis.33 Materials that are suitable for such a barrier include light-curing glass ionomers, flowable composites or fissure sealants. In order to facilitate retreatment if necessary, such a barrier should be thin so that the gutta-percha fill is just visible. _Radiographic appearance of filled root canal systems Prepared and filled canals should demonstrate a homogenous radiopaque appearance, free of voids and filled to working length. The fill should approxi- mate canal walls and extend as much as possible into canal irregularities such as an isthmus or a c-shaped Fig. 4 Fig. 4_Root canal treatment of •Fillingtheapicalportion(lateralandvertical tooth #15 with four canals, compaction). diagnosed with irreversible pulpitis and acute apical periodontitis. The tooth was restored with a crown immediately after finalizing the root canal treatment. Case courtesy of Dr. Reza Hamid. •Completingthefill. •Assessingthequalityofthefill. The root canal system should be assessed before choosing an obturation technique. In the presence of open apices or procedural errors such as apical zip- ping and also for teeth with apices in close proximity to the mandibular canal, there is significant potential for overfills. In order to avoid such mishaps, these cases may be better obturated with cold lateral con- densation to avoid overfilling, or in some cases, MTA may be placed as a barrier. In general, canals should be filled only when there are no symptoms of acute apical periodon- titis or an apical abscess, such as significant pain on percussion or not dryable due to secretion into the canal. Gutta-percha cones first should be dis- infected by submerging them in an NaOCl solution for about 60 seconds. In addition to a solid filler such as gutta-percha, a sealer or cement should be used. Most sealers are toxic in the freshly mixed state, but this toxicity is reduced after setting. When in contact with tissues and tissue fluids, zinc oxide eugenol-based sealers are absorbable while resin-based materials typically are not absorbed.30 Some by-products of sealers may adversely affect and delay healing. Therefore, sealers should not be routinely extruded into the periradicu- lar tissues. The appropriate amount of sealer is then de- posited into the canal system. This may be done using a lentulo spiral, a K-file or the master cones themselves; each method is acceptable, provided 10 I roots 1_ 2017