Searching for the Best Obturation System

[drmithila]

INTRODUCTION
A cursory glance at the title of this article brings to mind for many dentists an immediate answer that of course, there is a “best” obturation system; it is obviously the one I am using. However, we must begin by defining the word “best” before we can really answer this question. “Best” does not mean the prettiest results on x-ray and all that goes into how one subjectively determines what a pretty fill in endodontics should look like.

In the last 60 years, a “beautiful” endodontic obturation has rapidly and greatly changed appearances. For example, a “beautiful” obturation has gone from thin silver points and sealer to a .02 tapered preparation, and a single gutta-percha (GP) point and sealer to laterally condensed GP and sealer, to Chloropercha with puffs of sealer and GP, and then to GP on a metallic or plastic carrier with sealer to larger tapered preparations (> .06 taper) with hot GP and sealer. As we used each different technique to obturate the canal, our subjective idea of what a good endodontic fill should look like changed with the use of that new obturation technique over time.

Ultimately root canal treatment is a treatment for a series of diseases that affect the tooth. Therefore, in the author’s opinion, the “best” obturation technique is the technique that gives us the best clinical outcome for our treatment. In other words, the technique with the highest clinical success rate is the technique that we should use for our patients.

A DIFFICULT PROBLEM
The problem is that determining which obturation technique yields the best clinical outcome (highest success rate) becomes very difficult, because there are so many variables which can affect the outcome of treatment. An interesting example can be found in the Toronto study by Farzaneh, et al.1 In this study, they linked a different type of obturation with a different type of instrumentation. They found that in teeth with apical periodontitis (AP), the flared canal preparation and vertical compaction of warm GP, as described by Herbert Schilder2,3 gave a higher success rate than modified step-back preparation and lateral compaction of GP. In teeth with no AP, the techniques gave statistically the same clinical outcome. Was it the flaring that increased the healing of AP, or the vertical compaction of warm GP, or both? This is the type of research that is very hard to draw conclusions from when thinking about formulating one’s desired clinical technique.

WHAT DOES RESEARCH SAY?
Research has asked the ultimate question: Do you need a root filling material at all? In other words, do we need to obturate the canal in order to achieve clinical success? In a study on dogs, Sabeti, et al4 found that there was no difference in healing of apical periodontitis between the instrumented and obturated, and instrumented and nonobturated root canal system. They stated, “The success of endodontic treatment ultimately depends on the elimination of the microorganism, host response, and mechanical closure (coronal seal) of treated root canals that may provide a potential for future bacterial contamination.” So basically, as long as one has eliminated most of the bacteria, and sealed the tooth so that no bacterial contamination was apparent from the saliva, clinical success is achieved. This seemed to indicate that obturation of the canal space was not a factor in clinical success. This is an incredible result in dogs, but what can we say is happening in humans?

Let’s look at the worldwide dental literature for some clues as to what is going on in the realm of obturation. Tamarut, et al, in an endodontic practice, clinically tested periapical healing when using obturation done by the GP/euca-percha method up to the apical constriction.5 Overall, the result of therapy success was approximately 95%. Peng, et al6 did a meta-analysis of 10 clinical studies evaluating the success of warm GP versus cold lateral condensation (CLC). The results suggest that the 2 obturation techniques are not significantly different, except in overextension. In conclusion, warm GP obturation demonstrated a higher rate of overextension than CLC.

Postoperative pain prevalence, long-term outcomes, and obturation quality were similar between the 2 groups. In a retrospective study done by Zmener and Pameijer,7 295 root canals were treated with laterally condensed GP cones in conjunction with a methacrylate-based endodontic sealer (EndoRez). Results were assessed clinically and radiographically, 14 to 24 months postoperatively. The overall success rate was 91.3%. A retrospective study by Cotton, et al8 shows that root canal systems obturated with GP and Kerr Pulp Canal Sealer, or Resilon (Pentron Clinical Technologies) and Epiphany sealer (Pentron Clinical Technologies), had statistically indistinguishable differences in clinical outcome. Ozer and Aktener9 concluded in their study that the Soft-Core obturation technique did not result in a significantly different treatment outcome when compared with cold lateral compaction after 3 years. Lipski10 compared Thermafil (DENTSPLY) obturators with GP lateral condensation. Evaluation of immediate results of treatment demonstrated no differences between both techniques. A positive result after one year was found in 94.2% of laterally condensed GP fillings and in 90.2 % of Thermafil fillings. After 2 years, the respective figures were 93.7% and 90.0%.

Within the last few years, a new filling technique and material have been studied and used clinically. Conner, et al11 evaluated the clinical outcomes of root canal treatment in private practice and filled with Resilon. Their evaluation revealed that 90% of the teeth that were healthy at the initial reading maintained the condition at the follow-up evaluation. The results support the idea that regardless of different treatment protocol, healing rates for Resilon-filled teeth in private practice were similar to the range of success rates for studies with uniform treatment protocols in university settings with GP root filling. In a retrospective study conducted in a private endodontic practice by Deutsch, et al12 a 94.1% clinical success rate was achieved. The authors used the SafeSiders (Essential Dental Systems) reciprocating instrumentation system and obturated with EZ-Fill epoxy cement (Essential Dental Systems) and a single GP master cone.

Therefore, when looking at the literature, we are starting to get the idea that regardless of the obturation technique or the composition of the filling material, the clinical success rate will generally be somewhere between 90% to 95%.

Haapasalo, et al have indicated that current research suggests instrumentation (cleaning and shaping) of the root canal is the most important factor in preventing and treating endodontic diseases, and it is difficult to give obturation the same primary importance. As no single approach can unequivocally boast superior evidence of healing success, decisions may be based on such factors as speed, simplicity, economics, or how it feels in the hands of the operator. For some, there may be other issues at stake such as the desire to: keep up to date, demonstrate mastery, keep ahead of referring colleagues, and/or enliven the working day by the “thrill of the fill” as unexpected canal ramifications are demonstrated more consistently.

        

[drmithila]

IMPORTANCE OF DYE LEAKAGE STUDIES
Oliver and Abbott, in a very interesting study, examined whether a correlation exists between apical dye penetration and the clinical performance of root fillings. They measured apical dye penetration into 116 roots of human teeth that had been root-filled at least 6 months prior to extraction. Endodontic treatment was classified as clinically successful, or unsuccessful, and results for these groups were compared using analysis of variance and the students’ t-tests. Overall, dye penetrated 99.5% of the specimens, indicating that the presence of dye in the canal is a poor indicator of whether the technique/material will succeed. Clinically placed root canal fillings do not provide an apical seal that prevents fluid penetration. The outcome of treatment cannot be predicted from the results of apical dye leakage studies.

THERMOPLASTICIZED GUTTA-PERCHA
Some clinicians have stated that unless the root filling is a thermoplasticized technique, it is not worth doing, and anyone who advocates other techniques should not be given credence. In the author’s opinion, this narrow-minded view is contrary to both the dental literature and the clinical outcomes. Keçedi, et al18 compared CLC with continuous wave of obturation with System B (SybronEndo). They reported that the distribution of filling materials was similar in all combinations of instrumentation and obturation techniques.
In a recent study, De-Deus, et al compared the percentage of GP filled area achieved in oval-shaped canals after filling with 3 thermoplasticized techniques and lateral condensation. Thermafil system, wave of condensation, and thermomechanical compaction produced significantly higher percentages of GP filled area than lateral condensation (P < .05); however, in the present study no significant differences among these techniques were detected (P > .05). Therefore, a limited ability to fill oval- shaped canals was achieved in the 3 thermoplasticized techniques tested.
In the present study, a common finding among all 3 thermoplasticized techniques and the lateral condensation technique was unfilled areas. This can be seen in Figures 1 and 2. Even though all 3 warm GP techniques and the CLC demonstrated GP voids in oval-shaped canals, all these techniques have about the same clinical success rate in practice.
In another study, De-Deus, et al20 tested lateral condensation, System B and Thermafil. They concluded there was no significant difference in apical seal of the anal-filled area in oval canals among the 3 filling techniques. No significant correlation was found between the quality of the apical seal and the filled-area of the root canal space. Even though there were voids, the canal was still sealed about the same in all 3 techniques. Clinically, we know that these 3 techniques all enjoy similar success rates even though there are voids and large areas of sealer.
In a study by Hata, et al,21 they compared sealing ability of EZ-Fill single point GP obturation with System B technique and with conventional GP points, lateral condensation and sealer. A one-way analysis of variance showed that there was no significant difference among the groups (P = .289). Root canals obturated with the EZ-Fill technique showed the least dye penetration. It should be noted that EZ-Fill is a single-cone technique and yet was statistically equivalent in sealing ability to System B, a thermoplasticized GP technique. Similarly, in a study by Dalat and Spångberg,22 they compared leakage for single point, lateral condensation, vertical condensation, and the thermoplasticized techniques of Thermafil and Ultrafil (Coltène Whaledent). All techniques were statistically the same, but the single point technique had the least deviation in results. Whitworth16 has stated that many warm, vertically compacted root canal fillings may comprise of a single, minimally distorted cone in the apical few millimeters. In a study by Deutsch, et al23 the apical one-mm obturation was found to be composed of a single GP cone and sealer in the 3 techniques tested. The techniques were EZ-Fill (a single GP point and sealer technique), cold lateral condensation of GP, and Thermafil. All techniques statistically sealed the canal the same (Figures 3 to 5). In the Thermafil group there was more plastic core material in the apical one mm than GP.
Taking all this evidence together we can see that there is much doubt as to which obturation technique gives consistently the highest clinical success rate. Warm GP techniques do not seem to outperform any of the older simpler techniques. Bergenholtz, et al24stated, “The warm GP techniques have much to commend them and undoubtedly the resultant root filling appears to be homogeneous and, from radiographs, seem to fill the root canal space well. Yet there is no evidence to show that these techniques result in higher clinical success than, for instance, cold lateral compaction.” As was discussed earlier, a recent meta-analysis review was unable to prove that the outcome of the root canal treatment is affected by the use of the warm GP filling technique.6
Whitworth in his article has drawn several interesting conclusions: (1) Although the importance of root canal filling should not be diminished within a package of infection-controlling care, clinical trials have failed to identify filling methods as significant in endodontic outcome. Most critical may be the elements of care which are not seen; the integrity of the operator in securing infection control at every step, rather than the details of materials and methods.
(2) The clinical science of root canal filling is weak, and weighted toward laboratory studies, often of questionable clinical relevance and with little standardization of method. There is a need to translate daily practice into research data to provide stronger evidence to support our care of patients.

CONCLUSION
Looking at the totality of data, we start to form the clinical impression that no obturation technique to date fills the canal totally. We see that all techniques give us about the same clinical success rate of somewhere between 90% to 95%. No one technique seems to be better than any other as far as clinical success is concerned. So, if all the obturation techniques give approximately the same clinical results, we would like to use the easiest operator-friendly technique that gives the most predictable results clinically. This has taken me full circle in 35 years of practice. We have been using a single-cone and sealer technique, which has given us a published success rate of 94.1% in our practice.12 Radiographically, because of the high radiopacity of the epoxy sealer, the results appear similar to all other techniques. We are relying on the sealer (EZ-Fill) to seal the accessory and lateral canals, which gives us a 3-dimensional (3-D) obturation (Figure 6). There is no magic to GP. The epoxy sealer is much less viscous than even warm GP and flows into all the irregularities of the 3-D root canal system. The proof is in the pudding, as they say; all obturation techniques give about the same clinical success rate.
The answer to our hypothetical question is that there is no one “best” obturation technique/material yet. Even the new bonded root canal fillings, which are much more operator sensitive, give no increase in clinical success rate. If you are like me, you go back to the easier and proven technology that is less operator-sensitive and yet yields very predictable results. If you are happy with what you are currently doing, then you may opt to wait for the next technological breakthrough, “regenerative pulp biology,” before you change obturation techniques.

        

[drmithila]

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