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Materials for root canal filling in permanent teeth




Technics of root canal filling in decidui teeth.

When a ZOE mixture is used, several filling techniques may be employed. For large canals, as in primary anterior teeth, a thin mixture can be used to coat the walls of the canal, followed by a thick mixture that can be manually condensed into the remainder of the lumen. An endodontic plugger or a small amalgam condenser is useful for compacting the paste at the level of the canal orifice. Also the creamy mix of filling ZOE paste can be coated around the walls of the canals with the last-used file or a spiral root-canal filler. Care should be taken not to overfill the canal. In primary molars, some of the canals may be quite small and difficult to fill. Commercial pressure syringes have been developed for this purpose. An alternative technique is to use a disposable tuberculin syringe or a local anesthetic syringe, in which the anesthetic capsule is emptied, after which the canal is dried and filled with ZOE paste.

When the root canal is filled with a resorbable paste such as Kri, Maisto, or Endoflas, a spiral lentulo mounted on a low-speed turbine can be used, facilitating introduction of the material into the canal. The spiral root filler should be one size smaller than the last file used and cut with sharp scissors to half its length. This makes it easier to use in a child's mouth but also prevents the filling material being pushed through the apices of the primary tooth. When the canal is completely filled, the material is compressed with a cotton pellet. Excessive material is rapidly resorbed.

Vitapex is packed in a very convenient and sterile syringe, and the paste is injected into the canal with disposable plastic needles. This tech­nique is particularly easy to use for primary incisors but less practical for narrow canals of primary molars.

1. Cements, based on zinc oxide-eugenol.

2. Calcium hydroxide sealers

3. Plastics and resins.

4. Glass ionomer cements.

5. Materials, based on formaldehyde and phenol. But these materials are toxic and are not recommended to application in children.

Gutta-percha is the universal filler for root canals, but it applyes only with sealers. Sometimes silver points use as a filler.

There are many methods of root canal obturation. The most commonly used are:

1. Obturation by single paste. This method is useful for temporarii teeth.

2. Obturation by the single gutta-percha point with sealer.

3. Lateral compaction of gutta-percha points and their variations.

4. Obturation with canal-warmed gutta-percha (vertical compaction).

5. Obturation with thermoplasticized gutta-percha (syringe insertion or solid-core carrier insertion such thermafil).

Obturation by paste performs with application of spiral filler (Lentulo).

Obturation by the single gutta-percha point with sealer is similar to obturation by singly paste, but the fit gutta-percha point must be placed in canal after inserting of paste into canal.

Lateral compaction of gutta-percha points.

The lateral compaction of cold gutta-percha points with sealer has long been the standard against which other methods of canal obturation have been judged. This technique encompasses first placing a sealer lining in the canal, followed by a measured primary point, that in turn is compacted laterally by a plugger-like tapering spreader to make room for additional accessory points. The final mass of points is severed at the canal's coronal orifice with a hot instrument, and final vertical compaction is done with a large plugger. If executed correctly, solid canal obturation will totally reflect the shape and diversions of the canal network.

Before embarking on the filling process, however, several important steps in preparation must first be completed: spreader size determination, primary point size determination, drying the canal, and mixing and placement of the sealer.

Before trying in the trial point, it is mandatory to fit the spreader that will reach to within 1.0 to 2.0 mm of the true working length. Again, spreaders have been numbered to match the instrument size. Therefore a spreader of the same-apical instrument size or one size larger is chosen so that it reaches to within 1 mm but will not penetrate the apical orifice.

A rubber stop should be placed on the shaft of the spreader to mark true working length minus 1 mm. It is then set aside for immediate use.

Gutta-percha points have been standardized in size and shape to match the standardized instrument sizes. They have even been color-coded to match the instrument's color. But, leaving nothing to chance, the primary point selected to match the size of the last instrument used at the apex, should be tested in place.

The working length of the tooth must be correct, and the point must go completely to position. The size of point is comply with the size of apical master file.

The sealer inserts into the dried canal by file or reamer, or spiral filler. The premeasured pri­mary (or master, or initial) point must be coated with cement and slowly moved to full working length. The sealer acts as a lubricant. After this multiple-point obturation with lateral compaction performs. The premeasured spreader is then introduced into the canal alongside the primary point, and with a rotary vertical motion is slowly moved apically to full penetra­tion, marked on the shaft with a silicone stop. Weine recommends that the initial spreader be left in place a full minute to allow the primary gutta-percha time to reconform to this pressure. The spreader is then removed with the same recipro­cating motion and is immediately followed by the first auxiliary point inserted to the full depth of the space left by the spreader. This point is followed by more spreading and more points until the entire root cavity is filled.

To ensure a cohesive filling, additional sealer may have been added with each point, although many find this not necessary. Obliteration is considered complete when the spreader can no longer penetrate the filling mass beyond the cervical line.

At this time the protruding points are severed at the orifice of the canal with a very hot instrument. Vertical compaction with a large plugger will then ensure the tightest possible compression ol the gutta-percha mass. All of the sealer and gutta-percha should be removal from the pulp chamber and a final radiograph taken. Either a final or temporary coronal filling should follow.

Method of vertical compaction of gutta-percha includes the heating of gutta-percha point in the canal with hot spreader and vertical pressure (compaction) of softened gutta-percha with plugger.

Obturation with thermoplasticized gutta-percha may be performed with special syringe or with application of solid-core carriers such thermafil. Thermafil is endodontic obturator consisting of flexible central carrier, sized and tapered to match standard endodontic files, that are uniformly coated with a layer of refined and tested alpha-phase gutta-percha. The plastic-core carrier-obturator can only be heated in a special oven. Immediately after the sealer is applied, the warmed obturator is removed from the oven and carried slowly to full working length in the canal.

Technique of root canal filling in permanent teeth after apexification.

The immature canal is complicated by a gaping foramen. The apical opening is either a nonconstrictive terminus of a tubular canal or a flaring foramen of a "blunderbuss,, shape.

Every effort should be made to attain the genetically programmed closure of the foramen that remains open because of early pulp death. This can be accomplished by apexification, a method of recharging the growth potential and restoring root growth and foramen clo­sure.

If apexification fails or is inappropriate, special methods must be employed to obturate the canals with­out benefit of the constrictive foramen serving as a con­fining matrix against which to condense.

These rather straightforward cases respond well to the use of an enormous primary gutta-percha point compacted by lateral pressure of additional gutta-percha. On the other hand, the softened gutta-percha technique, with heavy vertical pressure, could lead to gross overfilling.

It goes without saying that the canal preparation is shaped to receive the filling material best suited for total obliteration of the space.

The large tubular canal with little constriction at the foramen may best be filled with a "coarse" primary gutta-percha cone that has been blunted by cutting off the tip. Sometimes the canal is such that a large "tailor-made" point must be used. In either case, the "trial point" should pass the tests of proper fit.

The objective of the primary point is to block the foramen, in so far as possible, while auxiliary points are condensed to complete the filling. The length of tooth must be marked on the spreader so it will not be forced out the apex. With care, a well-compacted filling may be placed without gross overfill­ing of either cement or gutta-percha.

Inverted pointtTechnique. The particular type of canal for which this method of filling is most applicable is the tubular canal found in the tooth that suffered earlv death of the pulp, or one that has been "resurrected" by apexiflcation as cited above.

As a primary point, a "coarse" gutta-percha cone is selected and the serrated butt end of the point is care­fully removed with a scalpel. The point is inverted and tried in the canal, that is, it should visibly go to full depth, but stop dead just short of the apex. It should exhibit "tugback" when an attempt is made to remove it. Finally, it should appear in the radiograph to be in optimum position to obliterate the foramen area of the canal.

If the inverted point is thought to fill correctly the requirements of a primary point, the canal is liberally coated with cement and the cement-coated point is slowly pushed to full position. This point may act as a plunger because of the shape of the canal and the tight fit of the point.

When the primary inverted point is in place, addi­tional gutta-percha points should be carefully added by lateral condensation with the spreader. It is most important at this time to mark the length of the tooth on the spreader, so the instrument will not penetrate into the periradicular tissue. The spreader is used repeatedly, followed by auxiliary gutta-percha points until the canal is totally obliterated. The common error in this technique is an outgrowth of fear of overfilling. Insufficient pressure is applied during lateral condensation, resulting in poorly con­densed filling. This in turn allows subsequent leakage and invites failure.

Tailor-made gutta-percha roll. If the tubular canal is so large that the largest inverted gutta-percha point is still loose in the canal, a tailor-made point must be used as a primary point. This point may be prepared by heat­ing a number of gutta-percha points and combining them, butt to tip, until a roll has been developed much the size and shape of the canal. The roll must be chilled with a spray of ethyl chloride or ice water to stiffen the gutta-percha before it is fitted in the canal. If it goes to full depth easily but is too loose, more gutta-percha must be added. If it is only slightly too large, the outside of the gutta-percha can be flash-heated over the flame and the roll forced to proper position. By this method, an impression of the canal is actually secured.

The outer surface of the stiffened point may also be softened by “flash”-dipping the point in chloroform, eucalyptol, or halothane. By repealing this exercise, one can essentially take an internal impression of the canal. A mark is made on the buccal of the cone, and it is dipped in alcohol to stop the action of this solvent. Alcohol can also be used to assist in diving the canal prior to filling. The rolled gutta-percha should be tested for tugback and by means of the radiograph. If satisfactory, it should be cemented into place. The gutta-percha pro­truding from the crown should then be severed at the base of the pulp chamber with a hot spoon excavator so the spreader can be introduced. The spreader should be marked just short of the working length of tooth as described above. Lateral compaction is neces­sary in conjunction with the tailor-made gutta-percha roll to ensure obliteration of the canal space.

Simpson and Natkin have suggested a specialized fill­ing technique for those teeth with tubular canals but closed apices. These are the roots that were origi­nally blunderbuss in shape, but have been induced to complete their growth by the introduction into the root canal of a biologically active chemical, such as calcium hydroxide.

The canal is initially filled with a warmed and soft­ened tailor-made gutta-percha roll cemented to place and severed at the canal orifice with a hot spoon excava­tor. Using a heavy plugger, the gutta-percha is forced to the apex and compacted to place. Pres­sure with the plugger will leave a void in the center of the mass when the plugger is removed with a twisting motion. It may be necessary to hold the gutta-percha in place with an explorer when removing the plugger. The plugger is dipped in oxyphosphale of zinc powder to prevent sticking, and then used to collapse the gutta-percha into the space created by the initial plugging. If the gutta-percha begins to set, the plugger is heated to better compact the filling. With heavy vertical pressure, the entire canal is obturated and the excess gutta-percha seared off at the gingival level.

One popular technique successfully combines the thermal adaptation of gutta percha in the apical portion of the canal with cold lateral condensation more coronally. A master point is first selected and tried in the canal. This is usually the widest point which will reach the canal terminus, and may be inverted in the widest canals. After drying the canal and lightly coating its walls with a slow setting sealer, the tip of the master point is softened by passage through a flame. Without delay, the point is inserted to the apical limit of the canal; pressed gently against the calcine barrier to adapt the softened gutta-percha. Cold lateral condensation then follows by the insertion of a spreader within 1 mm of the apical limit of the canal and the addition of accessory gutta-percha cones lightly coated with sealer. Condensation continues until the spreader is able to reach no further than 2 or 3 mm into the canal. A check radiograph may then be exposed to assess the quality of fill before removing excess gutta-percha with a hot instrument and vertically condensing the warm gutta-percha at the canal entrance. Further cold or warm condensation may be under-taken at this stage if required to obtain a uniformly dense obturation. Other warm gutta-percha techniques, notably the injection-moulded thermoplastic systems may equally well be applied to the obturation of immature root canals, and offer the possibility of extremely rapid and dense obturation of the most irregularly shaped spaces.

After obturation a final or temporary coronal filling should follow.

 




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