Searching for the Best Obturation System

[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.