Dr. Andrei Zoryan dispels some of the common myths surrounding carrier-based obturation
Carrier-based gutta percha
Carrier-based obturation (such as Thermafil®, GT® obturator, ProTaper® obturator [Dentsply Tulsa Dental Specialties]) is one of the most popular techniques of root canal filling worldwide, which enjoys deserved recognition from leading authorities in the field of endodontics, including Drs. L. Stephen Buchanan, Giuseppe Cantatore, Julian Webber, Pierre Machtou, James L. Gutmann, and others.
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This simple and effective procedure significantly reduces dentists’ working time while ensuring high-quality obturation, especially in narrow root canals and anatomically complex canals (Buchanan, 2009; Christensen, 1991; Dummer, et al., 1994; Cantatore, 2001) (Figures 1 and 2).
However, many dentists are still prejudiced against the use of obturators, preferring lateral or vertical condensation instead. The main reason for this is the existence of various myths about carrier-based obturation, which often contradict each other.
Myth one: Application of obturators causes periodontal tissue damage, manifested by postoperative sensitivity. Therefore, endodontic treatment will inevitably end in failure
In fact, research suggests that temperature rise on the external surface of the root in the use of obturators is an average of 3.87°C, whereas for periodontal tissue damage, it is necessary to increase the temperature at least 10°C (Lipski, 2004). The postoperative pain that can occur in some cases is caused by extrusion of the air from the root canal space into the periapical tissues during insertion of the obturator. Such sensitivity resolves spontaneously, without subsequent development of any complications.
Myth two: When obturators are used, there is a high risk of gutta-percha extrusion beyond the apex
Despite its simplicity, the carrier-based gutta percha obturation technique requires strict adherence to the rules of root canal preparation. An important stage is the gauging of the apical foramen, since using an obturator of a smaller diameter than that of the apical foramen may indeed lead to gutta- percha extrusion into the periapical tissues. Yet when the root canal is prepared correctly, and the instructions for carrier-based root canal obturation are followed accurately, the probability of extrusion is virtually ruled out.
Myth three: Only the obturator’s carrier reaches the apex. The gutta percha and sealer stay in the coronal and middle thirds of the canal
This is actually a real possibility if the canal preparation, irrigation, and carrier-based obturation guidelines are not observed. There are several key factors to avoid this problem:
1. The root canal orifice must be sufficiently widened (“funnel shape”) for the obturator to enter freely, without losing gutta percha at the canal entrance.
2. The root canal must be properly disinfected. A vital condition for high-quality irrigation is the use of sodium hypochlorite and chemicals removing smear layer created during canal preparation, such as a 15% to 17% EDTA (aqueous solution) or citric acid. This approach allows high-quality obturation of the main canal to be achieved, as well as enabling the practitioner to fill its ramifications (lateral canals, apical delta system, anastomoses between canals).
3. The coronal and middle thirds of the canal should be filled with sealer, ensuring that the obturator slides smoothly along its walls. At the same time, the sealer’s consistency should not be too dense. Epoxy-resin-based sealers are the ideal option, such as AH Plus® (Dentsply), Adseal (Meta Biomed), etc.
4. The obturator must be inserted into the root canal slowly and smoothly. Thermafil® obturators, with .04 taper, are inserted into the canal over 3 to 4 seconds. Obturators with a larger taper (such as GT, ProTaper, and WaveOne®) are inserted during 6 to 8 seconds.
Using carrier-based gutta percha allows predictable, successful results in root canal obturation to be achieved, as confirmed by numerous studies (Beatty, et al., 1989; Dummer, et al., 1993; Gençoglu, et al., 1993; Gençoglu, et al., 2002; Xu, et al., 2007; Inan, et al., 2007; Gençoglu, et al., 2007; Saunders, et al., 1994; Gutmann, et al., 1993; Dalat, et al., 1994; Pathomvanich, et al., 1996; Abarca, et al., 2001; Kontakiotis, et al., 2007).
Myth four: It is hard to remove obturators from the canal for retreatment
Many clinicians encounter certain problems when a carrier-based gutta-percha obturation needs to be removed. These problems are most often caused by the dentist lacking the appropriate tools. The relevant literature attests that removing an obturator filling from a canal takes even less time than retreatment of a canal filled with gutta percha (Frajlich, 1998; Royzenblat, Goodell, 2007). The optimum solution for these purposes is using nickel-titanium rotary instruments (ProFile®, GT, etc.). In my own practice, I use ProTaper Retreatment files (D series) (Figure 3). Using these instruments, it is possible to extract the obturator’s plastic carrier within 1 minute, after which removing gutta-percha residue from the canal walls becomes a fairly easy task.
Myth five: A plastic obturator carrier impedes proper preparation of the post space
When preparing the canal for a post, it is essential, before using the appropriately sized post preparation bur, to remove the obturator’s carrier to the necessary depth. To this end, practitioners often use diamond burs (which is not really a very safe approach), ultrasonic tips, and electrically heated pluggers (System B™ [SybronEndo], Calamus® DUAL [Dentsply Tulsa Dental Specialties], Beefill® [VDW Dental], etc). However, in my opinion, the most predictable option is application of dedicated Post Space Burs (Dentsply Maillefer) (Figure 4). This bur is used in a turbine handpiece without water cooling; it allows removal of the plastic carrier from the root canal to the full length of the post planned in one movement.
Features and usage of the GuttaCore® (Dentsply Tulsa Dental Specialties) system
Based on the prejudices set out previously, the main claim of dentists against obturators, one way or another, is the presence of the plastic carrier in them. The GuttaCore system demonstrates an all-new application in the concept of carrier-based gutta percha (Figure 5). The GuttaCore obturator carriers are not made from plastic, but from a gutta-percha elastomer with intermolecular cross links (cross-linked gutta percha). Thus, the obturator is made entirely of gutta percha in two different forms (Figure 6). This makes for not only rapid and high-quality three-dimensional root canal obturation, but also for an easy post space preparation and root filling removal, in case retreatment is required. The carrier can be removed from the root canal just as easily as gutta percha, since it also is gutta percha. Consequently, for these purposes, we can use the same instruments as in canals filled using lateral or vertical condensation.
Working with the GuttaCore system is very easy, but there are a series of key factors that should be considered to avoid procedural errors. Here is a stage-by-stage sequence for the use of GuttaCore obturators:
1. The root canal must be properly shaped and disinfected.
The GuttaCore system is universal, meaning it can be used regardless of which instruments were used to prepare the root canal. However, according to research, root canals should have either no less than .06 taper or a large apical diameter after preparation. This is essential in order to ensure high-quality irrigation and three-dimensional obturation (Boutsioukis, et al., 2010). When using the GuttaCore system, the root canal must be widened to at least size 20.06 or 25.04.
2. Select the right GuttaCore obturator diameter.
If .06 or larger instruments were used to prepare the root canal, then select an obturator of the same size as the final nickel-titanium file. If .04 instruments were employed, then select obturator one size smaller.
Under no circumstances should any gutta percha be cut off from the obturator, as this may damage the carrier.
3. Gauging the root canal is a very important stage in ensuring predictable, high-quality, three-dimensional obturation.
To this end, each GuttaCore blister pack, besides five obturators, has a verifier of corresponding size and taper (Figures 7 and 8). This is a manual instrument that is passively inserted to the working length of the root canal. If the verifier does not passively fit to working length, it can be used as a finishing file for apical enlargement.
4. When using GuttaCore obturators, a thin layer of sealer is applied to the coronal or, in case of long root canals, the coronal and middle thirds of the canal.
To apply the sealer, a paper point, a probe, or in case of using AH Plus Jet sealant, a special mixing tip can be employed (Figure 9). The preheated obturator, in the process of insertion into the root canal, evenly distributes the sealer along its walls. If there is excess sealer, or it was applied to the full working length, there is a very high risk of sealer extrusion into the periapical tissues.
5. The working length is set on the oburator, after which it is placed into a holder of one of the ThermaPrep® 2 (Dentsply Tulsa Dental Specialties) oven’s heating elements (Figures 10 and 11).
The distinguishing characteristics of the ThermaPrep 2 oven are rapid three-dimensional heating of obturators, while maintaining the properties of the gutta percha carrier, as well as the option of having both heating elements operating simultaneously.
When working with the GuttaCore system, unlike obturators with a plastic carrier, a minimum heating level of 20-25 is set on the operating panel of the oven, regardless of the obturator size (Figure 12).
The obturator is placed into the ThermaPrep 2 heating element by gently pressing down the holder. Immediately, the operating cycle is automatically activated, and an indicator light is switched on. The option of having both heating elements operating simultaneously makes it possible to heat up two obturators at the same time, if necessary. When the heating is complete, the oven makes a sound signal, and the indicator light starts blinking. Pressing on the holder releases it; the obturator is removed (Figure 13), and slowly, without rotation, inserted into the root canal to the working length.
With cases that have difficult access to root canals, especially in posterior teeth in a patient with limited oral opening, the GuttaCore obturator carrier may be inserted with pliers (Figure 14), after the obturator handle has been removed by bending it from side to side (Figures 15 and 16).
6. After the obturator is inserted into the root canal, the heated gutta percha can be condensed with a plugger in the coronal part of the root canal.
This generates additional hydrodynamic pressure, enabling the gutta percha to fill the ramifications of the main canal, such as lateral canals, apical delta system, anastomoses between canals, etc., even better. During the condensation process, the obturator should be held firmly by the handle, preventing any displacement.
7. The final stage of obturation is the removal of the handle and the excess carrier above the orifice level.
When using the GuttaCore system, there is no need to use special Thermacut® burs for this purpose. The carrier can be cut off at the orifice using a regular round bur or sharp hand excavator, or simply broken off using gentle lateral motions.
To clean off the gutta percha and sealer residue from the access cavity, a cotton pellet soaked in chloroform or ethanol can be used.
Conclusion
Development of the GuttaCore obturation system is indeed a step forward in the evolution of endodontics. This system allows optimal three-dimensional obturation to be achieved, quickly and without special effort, in situations where the dentist may encounter certain problems when applying other obturation techniques (Figures 17-19).Endodontics is evolving with simplification of technical procedures, reducing the dentist’s work time needed to perform them. There are new instruments, materials, devices, and accessories being developed in order to reduce the number of working stages and make endodontic treatment less labor intensive. At the same time, great attention must certainly be paid to ensure a simultaneous increase in the predictability of results and overall treatment success.
References
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