Barry Musikant
 |
 ECENTLY,
a local endodontist distributed a newsletter quoting research from an article
by Pommel et al stating that obturation
with a single gutta-percha point produces the greatest amount of leakage.
From their conclusions he extrapolated the further conclusion that the
EZ-Fill® Obturation System (Essential
Dental Systems, Inc. S. Hackensack, NJ) would perform badly because it
too is a single-point obturation system. The quoted authors conducted their
research using a zinc-oxide-eugenol cement as the interface. They
noted that zinc oxide, unlike the epoxy resin used in EZ-Fill, hydrolizes
in water. The authors conjectured that zinc oxide would be prone
to cement washout over time because the setting reaction is reversible
in the presence of water, resulting in a degradation of the material and
leaching of hydrolized eugenol and unreacted zinc oxide. They concluded
that the large volume of sealer used for the single-cone technique is more
prone to shrinkage than the small volume used for compaction techniques.
However, epoxy resin’s setting reaction is not reversible in the presence
of water, and because it is a polymer it is far tougher than the particulate
zinc-eugenol cement. The endodontist would not have come to the erroneous
conclusion he reached if he had been aware of the differences in cement
interfaces between zinc oxide eugenol and epoxy resins.
Furthermore, several studies comparing single-cone
techniques using epoxy-resin cements have attained different results. Wu,
Ozok and Wesselink compared the sealer-coated canal perimeter at 3
mm and 6 mm from the apex and found significantly better seals after the
single-cone obturation (with no condensation) than after vertical or lateral
condensation. Antonopoulous, comparing
lateral condensation with lateral condensation, found similar sealing abilities. Spangberg
tested single-cone, lateral-condensation, vertical-condensation Thermafil
and Ultrafil and found them all statistically the same, with the single-cone
technique having the least deviation in results. In a study published
this year, Hata et al compared
the apical sealing ability of System B, lateral condensation, and the EZ-Fill
obturation technique, using a one-way analysis of variance, and found no
significant difference among the groups. However, the authors stated
that the root canals obturated with the EZ-Fill technique showed the least
dye penetration. Baumann et al
compared the leakage of five different single-cone techniques with lateral
condensation and concluded that some single-cone techniques with thermoplastic
gutta percha and sealer or cold gutta percha and a new sealer application
tool (EZ-Fill) can be an alternative to lateral and vertical condensation. Cohen
et al compared the leakage of single-point fills using epoxy resins
to lateral condensation and Thermafil and found them all statistically
equal, with the single-point fill having the least leakage in absolute
terms.
In a study that addresses the long-term sealing
ability of an epoxy-resin cement interface, Kontakotis,
Wu, and Wesselink compared the performance of five sealers before and
after storage in water for two years. They concluded that Roth and
Pulp Canal Sealer, both zinc-oxide-eugenol cements, allowed more leakage
in thick layers than thin, whereas no significant difference was found
between the thin and thick layers for the epoxy-resin cement. Cohen
et al confirmed the weakness of zinc-oxide-eugenol cements compared
with epoxy-resin cements. The shear bond strength of the zinc-oxide-based
cement was literally zero, while that of the EZ-Fill epoxy-resin was 323.9
psi. No more-adhesive endodontic cement exists.
Furthermore, Cohen
determined that the free eugenol found in all zinc-oxide cements prevents
the polymerization of composites and their bonding agents by scavenging
the free radicals that initiate the polymerization process10. From a clinical
point of view, using the EZ-Fill Obturation System, Deutsch
et al reported a success rate of 94.1 percent over two-and-a-half years.
A body of research has determined that the use of
an epoxy-resin cement as an interface of varying thicknesses over at least
two years is at least as effective as every other method of obturation.
From a mechanical point of view, one may believe that a single-point fill
cannot obturate accessory canals. Yet, obturating with EZ-Fill often
shows lateral canals filled. Unlike thermoplastic obturation, in
which the canals are filled with gutta percha, the EZ-Fill technique predictably
fills these canals with epoxy-resin cement. The filling of these
canals is clearly observed because the epoxy-resin cement is radiopaque.
The canals have been debrided both mechanically and chemically with NaOCl
and are sufficiently open to allow the extrusion of material into these
spaces.
There is no innate superiority of gutta percha over
epoxy-resin. In fact, Lee
has demonstrated that thermoplastic gutta percha contracts as it cools
from a minimum of 45 minutes to 10 hours, shrinking approximately 4 percent
in the process. Epoxy-resin, on the other hand, goes into the canal
at room temperature and expands approximately 1.75 percent as it warms
from room to body temperature. Not only does shrinkage continue far
longer than the 10 seconds popularly believed, but very little cement can
even be used during thermoplastic obturation. Because the coronal
escape route is closed off when obturating thermoplastically, any excess
cement in the canal would be forced over the apex under significant pressure.
The single-point technique allows the safe coronal extrusion of excess
cement and, consequently, cement can be used liberally both in the canal
and on the point itself. Hall
demonstrated that at best 62.5 percent of curved canal spaces are coated
with cement with the traditional applicators, obviously less when thermoplastic
techniques are used. Therefore, combining a thermoplastic technique
with an inadequate cement interface produces a result far removed from
the three-dimensional claims made for it.
To understand the EZ-Fill obturation system, you
must appreciate the mechanics behind the bi-directional spiral. The
coronal spirals drive the cement apically while the three apical spirals
drive the cement coronally. These two cement flows collide and are
driven laterally. The spiral is used with an up-and-down hand motion,
driving the cement against the canal walls and any accessory canals that
may reside there, along its entire length. The cement is driven further
laterally when the coated tapered gutta-percha point is placed into the
canal. The EZ-Fill SafeSider instrumentation system rapidly shapes
the canal to a minimum of an .08 mm/mm taper, which corresponds to a medium
gutta-percha point. The greater the taper of the gutta percha, the
more the cement interface is driven laterally, which is why so many lateral
canals are filled with this instrumentation and obturation system.
Some other points to be considered: Floren
et al noted that System B represented a narrow window of success because
it is possible to cause thermal damage to the ligament if the temperature
rise exceeds 10 degrees C, something that is more likely in canals with
thin roots. Saw et al demonstrated
that thermoplastic techniques not only caused a temperature rise in the
tooth and ligament, but that this rise created dentinal stress and could
lead to premature fracture. Jurcak
et al reported that Touch N Heat produced increases in temperature
from 8 to 67 degrees C and that this was a concern. E.
M. Hardie reported on similar concerns for the same reasons.
To further appreciate the utility of the EZ-Fill
system, consider the following research: Zidan
et al state that it appears that leakage is independent of the method
of obturation when an adhesive sealer is used. This can be attributed
to the ability of the adhesive sealer to wet the walls of the canal, bond
to the dentin, and seal the residual volume between gutta percha and the
canal wall. In fact, the literature shows that an epoxy-resin has
strong adhesion to dentin and the gutta-percha point without the need of
a dentinal bonding agent. Opening the dentinal tubules of the canal
with EDTA significantly increases the bond strength of the epoxy-resin
cement to the dentinal walls. Gettleman
et al compared the adhesion of three cements—AH-26, Sultan, and Sealapex—to
dentin with the smear layer intact and the smear layer removed. AH-26
has the highest adhesion to dentin when the smear layer is removed.
Limkangwalmongkol et al compared
the sealing abilities of four root-canal cements, including Apexit, Sealapex,
Tubli-Seal and AH-26. AH-26 demonstrated a significantly better apical
seal than the other sealers. The authors note that from the findings
of other studies AH-26 appears to have many advantages over other sealers.
It mixes easily, flows well, has ample working time, good radiopacity,
comparable solubility, good adhesion and good biocompatibility. It
has also been shown to adhere to dentin that has been maintained in a moist
state. Of the materials tested in this study, AH-26 had the best
working characteristics. Wu et al,
in comparing the leakage of four sealers stored in water for one year,
determined that AH26, Ketac-Endo, and Tubli-Seal showed a reduction in
leakage over time and gave significantly less leakage than Sealapex. The
authors also noted that AH26 gave a long-lasting seal when used as the
sole material, showing its possible multiple applications.
Those dentists who try the EZ-Fill Instrumentation
and Obturation Systems will quickly find that they have the ability to
produce the highest quality results more easily, quickly, simply, and far
less expensively. I hope that this detailed response to wayward conclusions
sets things straight. The research and our seven years of clinical
results speak for themselves. In the past you may have felt that
you had to invest in complex, complicated, and expensive endodontic systems,
but you can bring about a major reduction in your level of stress and financial
costs if you adopt the EZ-Fill SafeSider Instrumentation and Obturation
systems.
References
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Pommel L, Camps J. In Vitro Apical Leakage of System B
Compared with Other Filling Techniques. J Endodon 2001;27:449-51.
[BACK]
-
Wu M-K, Ozok R, Wesselink P R. Sealer distribution in root
canals obturated by three techniques. International Endodontic J 2000;33:340-345.
[BACK]
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Antonopoulos K G, Attin T and Helwig E. Evaluation of the
apical seal of root canal fillings with different methods. J Endodon 1998;24;655
[BACK]
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Dalat D M, Spangberg LSW. Comparison of apical leakage
in root canals obturated with various gutta-percha techniques using a dye
vacuum tracing method. J Endodon 1994; 20:315-9.
[BACK]
-
Hata G, Imura N, Matsuda T, Kato A, Souza F J, Toda T.
Apical sealing ability of the EZ-Fill obturation technique. J Endodon 2002;
28:260. [BACK]
-
Baumann M A, Loy R, Behrens O. Dye penetration of five
different single cone techniques compared to lateral condensation. Abstract
IADR/AADR/CADR 80th General Session March 2002
[BACK]
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Cohen B I, Pagnillo MK, Musikant B L and Deutsch A S. The
evaluation of apical leakage for three endodontic fill systems. Gen Dent.1998;
Nov-Dec: 618-23. [BACK]
-
Kontakiotis E G, Wu M-K, Wesselink P R. Effect of sealer
thickness on long surface of the tooth during the thermo-mechanical compaction
technique of root canal obturation. International Endodontic J. 1986; 19:73-77.
[BACK]
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Cohen B, Volovich S, Musikant B and Deutsch A. Shear bond
strength for four endodontic sealers. Endodontic Practice; 3:9-14.
[BACK]
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Cohen BI, Volovich Y, Musikant B L and Deutsch A S. The
Effects of Eugenol and Epoxy-Resin on the Strength of a Hybrid Composite
Resin. J Endodon; 2:79-82.
[BACK]
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Deutsch A S, Cohen B I, Musikant B L, Kase D. A study
of one-visit treatment using EZ-Fill root canal sealer. Endodontic Practice
2001 4:29-36. [BACK]
-
Lee C Q, Chang Y, Cobb C M, Robinson S, Hellmuth E M.
Dimensional Stability of Thermosensitive Gutta-Percha. J Endodon; 23:579-582.
[BACK]
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Hall M C, Clement D J, Dove S B, Walker lll W A. A Comparison
of Sealer Placement Techniques in Curved Canals. J Endodon 1996; 22: 638-642.
[BACK]
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Floren J W, Weller R N, Pashley D H, Kimbrough W F. Changes
in Root Surface Temperatures with In Vitro Use of the System B HeatSource.
J Endodon 1999; 25:593-595.
[BACK]
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Saw L-P, Messer H H. Root Strains Associated with Different
Obturation Techniques. J Endodon 1995; 21:314-320.
[BACK]
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Jurcak J J, Weller R N, Kulild J C, Donley D L. In Vitro
Intracanal Temperatures Produced during Warm Lateral Condensation of Gutta-percha.
J Endodon 1992; 18:1-3.
[BACK]
-
Hardie E M. Heat transmission to the outer surface of
the tooth during the thermo-mechanical compaction technique of root canal
obturation. International Endodontic J. 1986; 19:73-77.
[BACK]
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Zidan O, Al-Khatib Z, Gomez-Marin O. Obturation of root
canals using the single cone gutta-percha technique and dentinal bonding
agents. Internatinal Endodontic J 1987; 20:128-132.
[BACK]
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Gettleman B H, Messer H H, ElDeeb M E. Adhesion of Sealer
Cements to Dentin with and without the Smear Layer. J Endodon 1991; 17:15-20.
[BACK]
-
Limkangwalmongkol S, Burtscher P, Abbott P V, Sandler
A B, Bishop B M. A Comparative Study of the Apical Leakage of Four Root
Canal Sealers and Laterally Condensed Gutta-percha. J Endodon 1991; 17:495-499.
[BACK]
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Wu M-K, Wesselink P R, Boersma J. A 1-year follow-up study
on leakage of four root canal sealers at different thicknesses. International
Endodontic J 1995; 28:185-189.
[BACK]
September-October 2002
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A
body of research has determined that the use of an epoxy-resin cement . . .
is at least as effective as every other method of obturation.
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