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Dental Tribune Middle East & Africa Edition | January-February 2016 9 mCME < Page 8 > Page 10 solutions (hydrogen perozide, chlorhexidine, 17 percent aque- ous EDTA, MTAD, etc.) can also be used alternately, depending on operator preference. Close observation with an SOM will clearly indicate complete cleaning of the canal system when no debris is flushed out during the irrigation process. During the evacuation with the capillary tip, it becomes appar- ent if there is a joining of the canal systems within the root. For example, if using the SOM as the MB1 canal is being evacu- ated and it is noted that fluid is simultaneously being drawn from the MB2 canal, there is a good indication that the system is complicated and does join at some point (Figs. 4a,b). There are occasions, especially in lower molars, where the me- sial root canal system unexpect- edly joins with the distal root ca- nal system. On occasion, the maxillary canal system will have the DB or MB canal system connected to the palatal system. These “surpris- es” are important to be aware of, before obturation of the canal system, especially when using either carriers or injectable GP. Drying canals with F•I•R•E The canal(s) are Flooded with 95 percent ethanol (Everclear, available at local liquor store), agitation of the fluids are Initi- ated with an activator for the tsunami effect, then Re-irrigated with the 95 percent ethanol, and then Evacuated with the capil- lary tip. The canal(s) are then best dried by using a Stropko Ir- rigator on a dedicated, air-only syringe (DCI), but if a three-way syringe is used, be sure to ex- press all water from the line first (Fig. 5). Next, with a 27- or 30-gauge notched or sidevented nee- dle (Monoject), fit- ted to the tip of the Stropko Irrigator and bent as neces- sary, to easily dry the canal system (Fig. 6). Important note: It is essen- tial to regulate the air pressure to the syringe at 1 to 3 psi and use a side-vented or notched needle, to prevent any possibility of in- advertently forcing air through the apical foramen. This is easily achieved with an in-line regula- tor, the Chapman-Huffman Reg- ulator & Gauge, Part #17-050-00 (Fig. 7). As dentists, we are accustomed to a “blast” of air while using the usual air/water syringe tip and high air pressure to the A/W sy- ringes.Withaproperlyregulated Stropko Irrigator fitted with an appropriate small gauge needle, only a “kiss” of air is necessary to create the flow necessary for thorough air drying of the canal. On occasion, one has to direct the air to a sensitive area on himself or herself to be sure the air is even flowing. Just watch- ing the evaporation that occurs within the canal, while using the SOM, is enough to convince any operator that there is indeed a flow of air. There is enough physiologic back pressure of the apical envi- ronment (1.5 mm Hg) to prevent movement of the air past the terminus in the correctly shaped canal. In almost 20 years, with many different doctors using the Stropko Irrigator to “air dry” ca- nals, the author has only heard of one unfavorable incident. In that one case, the doctor did not use a side-vented needle and did not regulate the air pressure to the air syringe. To repeat, when the Stropko Ir- rigator is used with the properly regulated air pressure (1 to 3 psi) and the appropriate 27- to 30-gauge, side-vented/notched needle is used, there is no fear of forcing air into apical tissues. Sealer application To the SOM user, the ineffective- ness of drying the canal with a paper point is soon realized. It is also easy to observe how differ- ently the Kerr Pulp Canal Sealer EWT (SybronEndo) acts when the canal is in fact dry, not just blotted. After blotting with a pa- per point, the sealer tends to act like a drop of oil when placed on the canal wall. But when the sur- face is dried, using alcohol and air as described above, the seal- er readily spreads onto the canal wall, much like a coat of paint. The complete dryness of the ca- naltothedesiredworkinglength is checked with a clean absor- bent point that fits to length. This also gives the operator an excellent chance to recheck the working length and dryness of the canal. Any sealer (Kerr EWT, Roth, AH Plus, etc.) can be used as long as the heat of the warm GP does not cause a “flash set.” The end 3 mm of a sterile paper point is coated with the sealer of choice and placed into the canal to the working length. The author uses Kerr Pulp Canal Sealer EWT, mixed per usual di- rections, but a little “on the thin side.” Using short, rapid apical- coronal movements, the walls of the canal are completely coated with sealer. The use of the SOM is a great aid for observing when the coating of the canal wall by the sealer is complete. Then, a sterile absorbent point is used, in the same manner, to remove any excess sealer that may re- main. Depending on the amount of sealer placed at the beginning, more than one absorbent point may be necessary to get the “blotchy appearance” on the final point (Fig. 8). Only a thin coat of sealer is necessary for lu- brication, so very little remains on the walls of the canal (Fig. 9). One of the most common mis- takes, made at first, is using too much sealer. When this hap- pens, the excess sealer will be extruded back into the cham- ber, or apically when the warm GP is placed. In some cases, the GP may be prevented from completing the desired “flow” apically. Typically, only one or two points are normally needed once the operator achieves pro- ficiency at applying the correct amount of sealer to begin with. Thermoplastic GP techniques are not sealer-dependent and depend more on the sealer as a lubricant and facilitate the flow of the thermoplastic GP. Important consideration be- tween using injection or carrier- based obturation Essentially, there is one very significant dif- ference between the two tech- niques. The injection technique fills the canal system from the apical to the coronal, whereas the carrier-based techniques fill from coronal to the apical. This is important to take into account, especially in cases in which the operator does not want to fill the canal to the orifice or needs to control the “depth” of the fill. A good example would be in the case of treatment of a per- foration repair. Using injection, the “fill” can be accomplished rather easily, and both the sealer and GP can be confined apical to the perforation. MTA can then be added to the repair in a very controlled manner (Figs. 10a–c). When a post space is required, the GP can be injected to any level in the canal, but it is bet- ter to obturate the entire canal first, so unknown anatomy more coronally in the canal won’t be missed. Injection of thermo-plasti- cized GP with a Calamus or Obtura After using the Obtura for more than a decade for thermo-plasti- cized GP obturation, the author switched to the Calamus when it was introduced many years ago. After thousands of canals were obturated using both of them, several advantages were noted when comparing the two units (Table 1). Both units are available as a sin- gle unit, or a dual unit combined with a thermal handpiece for convenience (Figs. 11a,b). The consistent flow of the Calamus unit does make the learning curve quicker and easier to mas- ter than the Obtura, because the relatively large muscle action of squeezing the trigger could vary from patient to patient, or day to day. The much smaller muscle action of using a finger to press the collar of the Calamus is sig- nificantly less, and the resulting flow of the GP can be pre-set for consistency. The size of the needle used in the Calamus or Obtura (20 vs. 23 gauge) is generally a matter of preference and can also de- pend on what the canal wants. It does not make any difference, in the scheme of things, how far apically into the canal the nee- dle is placed, as long as it is non- binding.4 For example, a straighter and larger canal will take a larger needle. On some occasions, the 20-gauge needle will not be far enough apical to the orifice of the canal before binding. If the canal preparation is narrower, this is an indication to use the smaller, 23-gauge needle. As long as it is not binding and the canal has the correct shape, the GP will flow to the apex. Note: If the canal is parallel in shape, the canal then becomes an ex- tension of the needle and apical control is severely handicapped. Shape is of the utmost impor- tance, especially in these tech- niques. The settings on the Calamus are checked to assure the de- sired set temperature has been achieved (the author uses 160 C), and the flow rate is set cor- rectly (the author prefers 100 percent). When the unit reaches the set temperature, it will stop blinking. Note: As a safety fea- ture, until the unit has achieved the pre-set parameters, the mo- torized plunger will not initiate and GP is not ejected. When all is ready, the collar is pressed un- til the initial GP is extruded and then the collar is released. The slight amount of GP at the tip is removed. The needle is then placed into the canal apically, just short of binding,andthecollarispressed to reactivate the plunger and initiate the flow of GP. It is good practice to barely move the tip, in a very slight apical-coronal direction as the GP is flowing. The moment there is a sensa- Fig. 6. When drying canals with air, needles must be notched or sidevented (arrows). Fig. 11a. The Calamus Dual unit with a thermal handpiece. (Photo/ Courtesy of Dentsply Tulsa Dental Specialties). Fig. 12. The plugger is pre-fit, short of binding, to avoid unnecessary con- tact with the canal walls during deep compaction of the softened GP. (Im- age/Courtesy of Arnaldo Castellucci, Florence, Italy). Fig. 11b. An Obtura III Max Pack Dual also has the thermal handpiece. Fig. 13. The GuttaCore carriers are just one of many popular products for carrier-based GP. (Photo/Courtesy of Dentsply Tulsa Dental Specialties). Fig. 7. The Chapman Huffman in-line air regu- lator and 0-15 psi gauge works well. Fig. 10a. A furcal perforation in the distal root of a mandibular first molar. Fig. 10b. Canal filled just apical to furcal perforation. Fig. 10c. MTA placed to repair the perforation. Fig. 8. Fresh absorbent points are used to remove excess sealer until ‘blotchy. Fig. 9. Only a very thin layer of sealer needs to coat the walls for lubrication. (Photo/Courtesy of Bob Sharp, Sacra- mento, Calif.) Dental Tribune Middle East & Africa Edition | January-February 20169