May 11, 2020
by Gary Glassman, DDS, FRCD(C)
The main objective of endodontic treatment is the prevention and/or the elimination of apical periodontitis. This is achieved by instrumentation, disinfection, and obturation of the root canal system in three dimensions. Gutta percha is the most widely used and accepted obturation material because of its biocompatibility, inertness, dimensional stability, compactability, plasticity when heated, and ease of removal for post placement or retreatment1 There are a variety of techniques that are used to obturate the root canal system. They can be divided into two basic groups: cold lateral compaction and warm vertical compaction. Warm vertical compaction of gutta percha using the continuous wave of condensation technique is less time consuming, provides less microbial coronal leakage,2 and adapts better to grooves and depressions of the canal walls and lateral canals than cold lateral compaction.3,4
This article will discuss the technique of Continuous Wave of Condensation using the new GuttaSmart™ cordless obturation system. Figs. 1A, B & C.
The Gutta SmartTM cordless Obturation System. 1A. is a cordless obturation system that is easy to use. The Downpack (Pack)
1B. and Backfill (Flow).
1C. devices are available to sit in combined docking station that will recharge the batteries.
The Continuous Wave of Condensation Technique Using the Guttasmart™ Cordless Obturation System
This technique allows a single tapered electric heat plugger to capture a wave of condensation at the orifice of a canal and ride it, without release, to the apical extent of downpacking in a single, continuous movement. Because the tip moves through a viscosity controlled material into a tapered-like canal form, the velocity of the thermosoftened gutta percha and sealer moving into the root canal system actually accelerates as the down packing progresses, moving softened gutta percha into extremely small ramifications. Fig. 2.
Microcomputed tomography 3D reconstruction of a maxillary molar, illustrating the root canal system’s complex anatomy. These areas must be cleaned of their organic debris and bacterial contaminants by thorough irrigation protocols and then subsequently three dimensionally sealed with thermosoftened gutta percha. Courtesy of Dr. Ronald Ordinola Zapata, Brazil.
The continuously tapered root canal preparation facilitates the fit of a suitably sized Conform Fit™ gutta percha cone. (Dentsply Sirona) Figs. 3A & B. The master cone selected should be inserted to full working length and exhibit apical tugback (resistance to displacement) upon its removal. It is simple to fit a master cone into a patent, smoothly tapered, and well-prepared
canal.5-8 The cone may then be cut .5-1mm to accommodate for it apical movement. (distance from apical reference point will vary with canal curvature and size).
Cone Fit. A suitably sized ConformTM Fit gutta percha cone is fit into the tapered root canal preparation making sure that ”apical tug back’’ has been at working length. The cone may then cut .5-1mm to accommodate for it apical movement. (distance from apical reference point will vary with canal curvature and size).
Conformtm Fit Gutta Percha cone and preloaded Gutta Percha cartridges. The ConformTM Fit gutta percha fits intimately at the apical one-third of the root canal and the single use preloaded gutta percha cartridge has enough material to fill an average four canal molar. The cartridge tips are available in 20 gauge, 23 gauge, and 25 gauge sizes with the most popular being the 23 gauge tip size.
The intimacy of diametrical fit between the cone and the canal space may be confirmed radiographically. The heated plugger of the downpack device (most commonly a .04 taper with .5 mm diameter) should fit to within 4 to 7 mm from the apical terminus to allow full thermosoftening of the apical gutta percha plug. When the tip of the plugger contacts dentin (the binding point) in the canal, the rubber stop should be adjusted to its corresponding occlusal reference point. Figs. 4A & B.
Heat Plugger Fit. It is essential that an appropriate Downback (Pack) plugger is prefit into each canal to its binding point. A rubber stop must be placed and adjusted to the appropriate coronal reference point for each canal.
The electric heat pluggers (EHPs) are available in three sizes and are manufactured with annealed stainless steel. The sizes are: Large (60/.06 – Blue; Medium (50/.05 Yellow); Small (40.025 – Black).
Stainless steel pluggers may be prefit into the canals to their binding point in preparation for the backfilling. Rubber stoppers are adjusted on these pluggers to the occlusal reference point corresponding to 2 mm short of the apical binding point. These pluggers are placed aside to be used later in the back fill phase of canal obturation Fig. 5.
Stainless steel and/or NiTi hand pluggers may be prefit into the canals to their binding point. Rubber stoppers are adjusted on these pluggers to the occlusal reference point corresponding to 2 mm short of the apical binding point.
Sealer and Master Cone Placement
The amount of sealer used in this obturation technique should be minimal. The radicular portion of the master cone is lightly buttered with sealer and the cone is gently slid to length. Placing the master cone in this manner will serve to more evenly distribute sealer along the walls of the preparation, and importantly, allow surplus sealer to harmlessly vent coronally.5-8 Figs. 6A & B.
The master cone is seated gently in the canal with sealer placed on its apical one third.
Ribbon ThermaSealTM Plus is an epoxy resin sealer characterized by very good mechanical properties, high radiopacity, low polymerization shrinkage, low solubility, and a high degree of stability during storage.
The activation cuff on the Downpack (Pack) handpiece can be pressed anywhere above the ridge on its 360 degree circumference. A band near the cuff lights blue when the tip is being activated. The tip will remain heated only as long as the activation cuff is being depressed.
The master cone is seared at the orifice of the canals with the activated heated plugger, and then gently “seated” with a larger stainless steel plugger. A small “dimple” may be created in the coronal aspect of the master cone to act as a guide for the activated heated plugger. The activated heated plugger is advanced without interruption through the center of the gutta percha in a single motion (about one to two seconds), to a point about 3-4 mm shy of its apical binding point. Figs 7 & 8. While maintaining pressure on the plugger, the activation cuff on the Pack handpiece is released and the plugger will slow its apical descent as the plugger tip cools (about one second) to within 2 mm from its apical binding point. After the plugger stops, short of its binding point apical pressure on the plugger is sustained until the apical mass of gutta percha has set (five to ten seconds), to minimize any shrinkage that occurs upon cooling Fig. 9.
Initiation of down pack. With the activation cuff depressed on the Gutta SmartTM Downpack (Pack) handpiece, the prefit, preheated plugger is smoothly advanced without interruption through the mass of gutta percha to within 4-6 mm of the binding point.
Sustained apical condensation. The activation cuff on the Pack device should be released once within 3-4 mm of the apical binding point. The plugger should slow and stop within 2 mm short of the binding point. Apical pressure is maintained for a full 10 second ‘’sustained’’ push to prevent the cooling gutta percha mass from shrinking.
After the apical mass has set, the activation cuff on the Pack handpiece is depressed again, for a one second surge of heat. Pause for one second after this separation burst, and then remove the heated plugger along with the middle and coronal gutta percha that adheres to it, leaving behind the 4-6 mm apical plug of gutta percha Figs. 10 & 11. Because these pluggers heat from their tips, this separation burst of heat allows for quick, sure severance of the plugger from the already condensed and set apical mass of gutta percha, minimizing the possibility of pulling the master cone out. Be certain to limit the length of this heat burst, as the goal is separation from the apical mass of gutta percha without reheating.
Separation burst. The Pack activation cuff is depressed for one second then released. The plugger is held in position for one second after the button is released, after which it is removed with the surplus of gutta percha coronal to the apical plug adhering to the cooling plugger, leaving the apical seal intact. All portals of exit may be sealed, primarily with gutta percha or a combination of gutta percha and sealer, and the canal is ready for backfilling.
Clinicians must be very alert during the first second of the downpack so that the binding point is not reached before completion of the downpack. If heat is held for too long, the plugger drops to its binding point in the canal and then cannot maintain condensation pressure on the apical mass of gutta percha during cooling, possibly allowing it to pull away from the canal walls. If binding length is reached by mistake, the heat plugger should be removed immediately and the small end of the nickel-titanium end of a hand plugger may be used to condense the apical mass of gutta percha until set. Once the downpack has been completed in all canals of the tooth being treated as radiograph may be taken to confirm the objective of apical seal.
The GuttaSmart™ Backfill (Flow) handpiece accommodates disposable preloaded cartridges of gutta percha of with dispensing needle tips available in 20 gauge, 23 gauge and 25 gauge diameters. The one most commonly used is the 23 gauge one as it is suitable for most canals being treated. There is enough gutta percha in the disposable cartridges to fill an average four canal molar. Fig. 3B.
Before backfilling, a small amount of sealer is lightly painted on the walls of the root canals with a stainless steel hand file or paper point.
The needle tip is placed into the root canal space until it penetrates the coronal aspect of the apical plug of gutta percha for just a moment, to re-thermosoften it’s most coronal extent. This procedural nuance promotes cohesion between each injected segment of warm gutta percha and the apical plug so the two will seamlessly integrate. Segments of 4 to 7 mm of gutta percha are then deposited. Injecting or dispensing too much gutta percha may lead to cooling shrinkage and/or voids which result in poorly obturated canals within the deeper confines of the root canal space.
As gutta percha is extruded from the applicator tip, the viscosity gradient of the back pressure produced will push the needle tip (and hence the Flow device) coronally from the root canal space. The technique requires a sensitive touch. As the operator feels the pushback from the needle tip of the Flow device, they must maintain contact between the needle tip and the extruding gutta percha. They must also sustain slight pressure on the activation cuff button mechanism to keep the gutta percha flowing as the needle tip moves from the canal. The stainless steel or nickel titanium ends of hand pluggers are then used in sequence to maximize the density and homogeneity of the compressed gutta percha mass. This sequence of thermosoftened gutta percha injection and progressive compaction is continued until the obturation of the entire root canal space is achieved Figs. 12-18.
Back filling. Needle tips for the Gutta SmartTM cordless obturation system are available in sizes #20, #23, and #25 gauges. Additional root canal sealer may be placed in the coronal aspect of the root canal with a hand file or paper point prior to back filling. 4-7 mm increments of gutta percha are injected into the canal space then immediately condensed with the pre fitted stainless steel hand NiTi pluggers in sequence using the sequentially larger pluggers as the coronal aspect of the canal is approached. As thermosoftened gutta percha is deposited in the canal, backpressure is produced and the needle tip (Flow device) is forcibly extruded from the canal space. It is essential that the operator continue injecting as the needle tip is retrieved from the canal in order to avoid inadvertent removal of the newly deposited gutta percha mass prior to condensation.
Even if a post space is to be prepared, the author advises backfilling right to the orifice of the canals to ensure lateral and accessory canals that were not sealed on the downpack but that may be captured on the backfill.
The objective of endodontic obturation is the total three dimensional filling of the root canal system and all of the lateral and accessory canals associated with it. Brothman9 demonstrated that vertical compaction of warm gutta percha (GP) approximately doubled the number of filled lateral canals compared with lateral compaction of GP. The warm vertical technique has shown greater ability to flow into canal irregularities than the cold lateral technique.10,11
Warm vertical compaction was first introduced by Schilder12 in 1967. With this method, GP is heated and packed in 3-5 interrupted waves of compaction. In contrast, the continuous wave of condensation technique was introduced with the goal of simplifying traditional vertical compaction13. This technique allows a single tapered electric heat plugger to capture a wave of compaction pressure at the orifice of a canal and ride it, without release, to the apical extent of the downpack in a single, continuous movement.14 The remainder of the canal is then filled with the backfill Flow device.
The GuttaSmart™ cordless obturation system satisfies the objective of sealing the root canal system in three dimensions and completes the last part of the triad of the imperative of root canal treatment, that being “shape, clean and pack”.
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About the Author
Gary Glassman is the author of numerous publications, lectures globally on endodontics, is on staff at the University of Toronto, Faculty of Dentistry in the graduate department of endodontics. As Adjunct Professor of Dentistry and Director of Endodontic Programming from 2010-2017, Gary helped develop the dental school curriculum for the Oral Health Science programme for the University of Technology, Kingston, Jamaica. Gary is a fellow of the Royal College of Dentists of Canada, Fellow of the American College of Dentists, endodontic editor for Oral Health dental journal, endodontic editor for Inside Dentistry, Faculty Chair for DC Institute and Chief Dental Officer for dentalcorp Canada. His personal/professional website is www.drgaryglassman.com and his office website is www.rootcanals.ca He can be reached at firstname.lastname@example.org.
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