Long-term sealing ability of resin-based root canal

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Long-term sealing ability of resin-based root canal

fillings

J. Santos1, L. Tjaderhane2, C. Ferraz1, A. Zaia1, M. Alves3, M. De Goes4 & M. Carrilho4,5

1Department of Restorative Dentistry, Endodontic Area, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil;2Institute of Dentistry, University of Oulu and Oulu University Hospital, Oulu, Finland; 3Department of Morphology, Piracicaba

Dental School, State University of Campinas, Piracicaba; 4Department of Restorative Dentistry, Dental Materials Area, Piracicaba

Dental School, State University of Campinas, Piracicaba; and 5Department of Restorative Dentistry GEO, Bandeirante University

of Sao Paulo, School of Dentistry, Sao Paulo, Brazil

Abstract

Santos J, Tjaderhane L, Ferraz C, Zaia A, Alves M, De

Goes M, Carrilho M. Long-term sealing ability of resin-based

root canal fillings. International Endodontic Journal, 43, 455

460, 2010.

Aim To evaluate the ability of two resin-based filling

materials to provide immediate and long-term sealing

of the root canal.

Methodology A total of eighty-two human roots

were instrumented and filled with AH Plus/gutta-percha

or Epiphany/Resilon. Root filled teeth were sealed

coronally either with Coltosol or Clearfil SE Bond/Filtek

Z250 or were left unsealed. The quality of root canal

sealing was assessed by a fluid filtration method

performed at immediate and 180-day time intervals.

Mean fluid filtration rates were analyzed by three-way

repeated measures anova and Tukey post hoc test.

Results Specimens filled with Epiphany/Resilon

exhibited higher leakage than specimens filled with AH

Plus/gutta-percha (P < 0.05), regardless of the coronal

sealing condition and period of evaluation. No difference

was detected between coronal restorative materials

(P > 0.05), whilst leakage in teeth without any coronal

restoration was significantly higher (P < 0.05). After

storage, a significant decrease in leakage (P < 0.05) was

observed in all experimental groups.

Conclusions AH Plus/gutta-percha provided supe-

rior root canal sealing at both immediate and 180-day

time periods. The presence of a coronal seal reduced

leakage significantly. Storage of root filled specimens did

not disturb the sealing ability of the tested materials.

Keywords: endodontic filling materials, fluid filtra-

tion, resins, sealing.

Received 3 November 2008; accepted 15 December 2009

Introduction

Along with cleaning and shaping procedures, root

canal filling with impermeable and biocompatible

materials is thought to be essential for the long-term

outcome of root canal treatment (Hommez et al. 2002).

However, once exposed to saliva and/or other oral

fluids, root fillings will tend to leak (Sly et al. 2007),

with an obvious impact on prognosis (Imura et al.

2007). Therefore, the achievement of an effective

coronal seal following root canal treatment is consid-

ered of major importance in preventing post-treatment

disease (Schwartz 2006).

Adhesive dentistry concepts have increasingly been

applied to endodontics to prevent coronal leakage

(Economides et al. 2004). The rationale for using

so-called adhesive root fillings is based on the premise

that because of the intimate contact with dentine, these

materials could remain micromechanically retained,

reinforcing tooth structure and preventing root recon-

tamination (Teixeira et al. 2004). Undoubtedly, an

effective bond between root filling materials and root

dentine would improve long-term root canal sealing. In

Correspondence: Marcela R. Carrilho, DDS, PhD, Rua Alagoas,

475 ap.13B, CEP 01242-001, Sao Paulo, Brazil (Tel.: +55 11

83974904; fax: +55 11 30917840; e-mail: marcelacarrilho@

gmail.com).

doi:10.1111/j.1365-2591.2010.01687.x

2010 International Endodontic Journal International Endodontic Journal, 43, 455460, 2010 455


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this sense, a polymer-based root canal filling material,

Resilon (ResilonTM; Research LCC, Madison, CT, USA),

associated with a dentine primer (EpiphanyTM primer;

Pentron Clinical Technologies, Wallingford, CT, USA)

and a resin cement (EpiphanyTM sealer; Pentron

Technologies), has been introduced as a root canal

filling system that is claimed to bond to root dentine,forming a monoblock and thus providing an efficient

seal (Shipper et al. 2004, Teixeira et al. 2004). How-

ever, the results related to the performance of this

resin-based, adhesive endodontic filling system are

controversial (Pitout et al. 2006, Raina et al. 2007,

Gogos et al. 2008), indicating the need for additional

investigation, especially concerning its ability to pro-

vide a long-term seal.

This study evaluated the ability of two resin-based

filling materials to provide an immediate and long-term

seal with root dentine. In addition, the contribution of

adhesive versus non-adhesive restorative materials

used as coronal restoration in the overall sealing of

the root canal was assessed. The tested hypotheses

were (i) the sealing ability of non-adhesive, resin-based

root filling materials is not different from that of

adhesive resin-based filling materials; (ii) the presence

of a coronal restorative material does not affect the

overall seal of the root canal system and (iii) the seal

provided by both systems is not disturbed after

180 days of laboratory storage.

Materials and methods

Specimen preparation

A total of 82 extracted single-rooted human maxillary

anterior teeth were collected under a protocol reviewed

and approved by the Ethics Committee for Human

Studies, Piracicaba School of Dentistry, UNICAMP,

Brazil. After extraction, teeth were stored in 0.1%

thymol solution for no more than 1 month. Organic

debris and calculus were detached with scalers, and the

crowns were removed leaving 13-mm long root spec-

imens. A crown-down root canal preparation was

performed using Gates-Glidden drills sizes 5, 4, 3 and 2

(Dentsply Maillefer, Ballaigues, Switzerland) placed to a

length where resistance was met in the coronal and

middle thirds of the root canal. This was followed by

step-back instrumentation of the apical third to create a

size 45 apical stop. Root canals were irrigated during

instrumentation using 5 mL of 5.25% sodium hypo-

chlorite (NaOCl) solution and rinsed with 3 mL of 17%

ethylenediaminetetraacetic acid (EDTA) for 5 min to

remove the smear layer. Subsequently, a final flush

with 10 mL of distilled water was performed to wash

out the EDTA solution, and root canals were then dried

with paper points (Dentsply, Petropolis, Brazil).

Canal filling procedure

Teeth with prepared root canals were randomly divided

into two experimental groups according to the filling

material employed. Roots were filled using the cold

lateral compaction technique with either AH Plus

sealer (Dentsply De Trey, Konstanz, Germany) and

gutta-percha points (AH Plus/gutta-percha) or Epiph-

any sealer and Resilon points (Epiphany/Resilon).

Depending on the assigned experimental group, a

medium-size pre-fitted master gutta-percha or Resilon

point was coated with either AH Plus or Epiphany

sealer, mixed according to the manufacturers instruc-

tions and inserted into the root canal at working

length. Lateral compaction was performed by a size C

finger spreader (Dentsply Maillefer, Ballaigues, Switzer-

land) and fine-medium accessory gutta-percha or

Resilon points. According to the manufacturers

instructions, Epiphany primer was applied throughout

root canal walls before the insertion of Epiphany sealer

and Resilon points. After filling the root canal, material

excess was removed with a heated instrument 3 mm

below root canal orifices. The coronal third of Epiph-

any/Resilon specimens was light-cured for 40 s, using

a quartz-tungsten-halogen curing-light unit (XL 3000;

3M/ESPE, St. Paul, MN, USA) with an output of

500 mW cm)2

, as suggested by the manufacturer. AHPlus/gutta-percha specimens were not submitted to

light-curing.

After filling, AH Plus/gutta-percha and Epiphany/

Resilon specimens were divided into three subgroups

each (n = 12), according to the coronal restoration. In

subgroup A, the coronal portion of the roots did not

receive any sealing material. In subgroup B, a tempo-

rary, non-adhesive sealing material (Coltosol; Coltene

G, Altstatten, Switzerland) was condensed to form a

coronal plug of 2 mm. Root canals in subgroup C were

sealed with a self-etching dentine adhesive (Clearfil SE

Bond; Kuraray, Kurashiki, Japan), applied according to

manufacturers instructions, and resin composite

(Filtek Z250; 3M/ESPE) that was inserted into two

1-mm increments to form a coronal plug of 2 mm.

Each resin increment was light-cured for 40 s using a

quartz-tungsten-halogen curing-light unit with an

output of 500 mW cm)2. All specimens were stored

at 37 C in a humid atmosphere for 14 days to allow

Sealing ability of endodontic fillings Santos et al.

International Endodontic Journal, 43, 455460, 2010 2010 International Endodontic Journal456


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the sealers to set. The positive control group consisted

of five specimens that received root canal preparation

and were filled with a gutta-percha cone without

sealer. Another five roots were filled and entirely coated

with two layers of nail varnish and served as the

negative control group. These specimens were also

submitted to the same testing protocol.

Microleakage measurement

Microleakage of roots was evaluated after the sealers

were set (immediate); and after 180 days of storage in a

humid environment. A laboratory fluid filtration model

was used to measure fluid penetration induced by

hydrostatic pressure, following the general guidelines

reported by Wu et al. (1993). A connection platform

was constructed by inserting an 18-gauge stainless

steel tube into a centre hole created in a Plexiglass slab

(1.8 1.8 0.7 cm). Each root was then glued to this

device with viscous cyanoacrylate cement (SuperBon-

der Gel; Loctite Adesivos, Itapevi, Brazil), so that the

coronal root canal orifice was centred over the metal

tubing. This assembly was connected with a fluid

filtration apparatus as described by Wedding et al.

(2007). The fluid flow in the system was recorded

under a constant pressure of 10 psi, as the linear

movement of an air bubble read every 2 min in an

8-min interval and converted in lL min)1. The spec-

imens were then removed from the fluid filtration

apparatus and stored in a 100% humidity environment

at 37 C for 180 days. Afterwards, they were re-

mounted in the system and tested for microleakage asdescribed earlier.

Statistical analysis

Fluid flow rates obtained from all samples at both time

intervals were compared by three-way repeated

measures anova, considering filling material, coronal

restoration and storage period as factors. Multiple

pairwise comparisons were performed using Tukeys

post hoc test. The level of significance was set at

P < 0.05.

Results

The specimens used as controls for the method behaved

as expected at both time intervals. Negative controls

did not reveal any fluid movement, whereas in the

positive controls, the fluid flow rate was too high to be

recorded.

The mean fluid flow rates measured in the experi-

mental groups at both observation time points are

shown on Fig. 1. The effect of root filling material was

independent of the coronal restoration and storage

period, i.e. there was no significant interaction between

them. Specimens filled with Epiphany/Resilon had

significantly higher fluid filtration rates than thosefilled with AH Plus/gutta-percha (P < 0.05). The

differences in fluid flow between the coronal restoration

were also statistically significant (P < 0.05). The

groups without any coronal restoration had higher

fluid flow rates than the groups filled with either

Coltosol or composite resin (Tukeys post hoc,

P < 0.05), but there was no difference between the

two types of filling materials (Tukeys post hoc,

P > 0.05). In addition, a significant decrease in fluid

flow rates after 180-day storage was observed for all

experimental groups (P < 0.05) (Fig. 1).

Discussion

The results demonstrate that mean fluid flow rates of

Epiphany/Resilon were higher than AH Plus/gutta-

percha regardless of coronal restoration type or period

of evaluation. Thus, the first null hypothesis can be

rejected. The second hypothesis should be also rejected,

as there were differences in fluid flow values between

different restorations. Finally, the third null hypothesis

can be accepted, because the leakage rates obtained

Epiphany/Resilon AH Plus/Gutta-Percha

0.2

0.25

0.3

0.35

a

ba

(a) (b)

a

b

0

0.05

0.1

0.15

Wi th ou t C olt oso l R esin Wi th ou t C olt oso l R esi n

Leakage(L/min1)

* ** *

a

bb

b

b

a a b

Immediate 180/days

Figure 1 Fluid flow rate (lL.min)1) at immediate and 180-day

measurements of Epiphany/Resilon and AH Plus/gutta-percha

associated to different coronal sealing conditions. Error bars

indicate standard deviations. Capital letters indicate statistical

differences between storage periods (3-way anova, p < 0.05).

Lower superscript letters indicate statistical differences be-

tween root filling materials (3-way anova, p < 0.05). Bars

marked with (*) represent groups that showed significant

higher fluid flow rates among coronal sealing conditions

(3-way anova followed by Tukey, p < 0.05). WITHOUT =

groups that received no coronal sealing.

Santos et al. Sealing ability of endodontic fillings



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after 180 days of storage decreased, indicating that the

sealing was not disturbed.

Even though bond strength tests are widely

employed to compare resin-based materials, microleak-

age studies are considered more valuable to predict the

behaviour of root fillings (Schwartz 2006). A good root

filling material might not necessarily yield high bondstrength levels to dentine; on the other hand, none of

the currently available adhesive materials is able to

provide a leak-proof seal (Schwartz 2006). The fluid

filtration model is one of the most suitable methods to

assess microleakage, because it allows a quantitative

measurement of fluid penetration along potential voids

within the root filling (Wu et al. 1993). Although the

pressure applied to force water trough gaps is higher

than physiological values (Verssimo & Vale 2006), no

damage to the specimen is expected, because the

reading interval employed in this study was short

(2 min). In addition, it was demonstrated that loading

pressures above physiological levels are necessary to

produce relevant leakage measurements (Dobo-Nagy

et al. 2003). Therefore, the fluid filtration methodology

permits non-destructive repeated measurements in the

same specimen over time.

The higher fluid filtration in Epiphany/Resilon spec-

imens is in agreement with other studies that also

included dye, computerized filtration and bacterial

leakage models (Onay et al. 2006, Baumgartner et al.

2007, Munoz et al. 2007). The combined general

outcomes of these studies indicate that there is no

apparent advantage in using Epiphany/Resilon over

more conventional gutta-percha techniques in terms ofits seal. The highly unfavourable cavity configuration

factor (C-factor) inside the root canal has been sug-

gested as the main reason for the suboptimal perfor-

mance of Epipahny/Resilon (Ungor et al. 2006, Sly et al.

2007). Previous reports have already highlighted the

role of the C-factor in maximizing the polymerization

stress of adhesive resinous materials along the root

canal walls (Ferracane 2005, Tay et al. 2005). The

present results, along with evidence currently available,

clearly demonstrate that the development of adhesive

strategies for root canal surfaces is yet to overcome the

challenging influence of root canal anatomy.

The differences in fluid flow values between the

various restorative conditions for both root filling

materials indicated that the presence of a coronal

restoration influenced significantly the leakage rates.

These findings support the concept of an immediate and

effective coronal seal to prevent leakage (Schwartz

2006, Imura et al. 2007). Although both temporary

and resin-based materials reduced leakage, it must be

emphasized that, under clinical conditions, temporary

restorative materials have limited mechanical proper-

ties (Galvan et al. 2002), and they should not be

recommended as a long-term restorative solution.

The finding that leakage rates diminished after

180 days of storage was considered somewhat unex-pected, because it has been repeatedly demonstrated

that long-term storage of root filled specimens causes a

significant decrease in sealing ability (Paque & Sirtes

2007, De-Deus et al. 2008). However, those results are

in concert with previous reports that also failed to

demonstrate a negative effect of time on sealing (Biggs

et al. 2006, Shemesh et al. 2006, Bouillaguet et al.

2008). Some previous studies (Paque & Sirtes 2007,

De-Deus et al. 2008) employed longer periods of storage

(over 1 year) and extended application of pressurized

water through root fillings (28 h), which might

disturb the seal obtained initially, thus explaining the

reported increase in leakage throughout time.

Root filled specimens left without a coronal restora-

tion were exposed directly to a humid environment.

Once exposed to moisture, both AH Plus and Epiphany

sealers are prone to water sorption (Donnelly et al.

2007, Bouillaguet et al. 2008). This phenomenon leads

to expansion (Kazemi et al. 1993, Ruyter 1995), which

in turn might explain the reduced leakage over time in

those groups. It might also be speculated that at the

moment of the first measurement (immediate), the

sealers had not yet reached their final set and optimal

mechanical properties, meaning that the apparent set

of the material might not correspond to the completionof the process. Indeed, some studies have stated that the

setting time of endodontic sealers is usually higher than

that claimed by manufacturers (Allan et al. 2001).

Expansion of gutta-percha has also been reported

(Wu et al. 2000) and might have contributed to some

extent to the decrease in leakage rates. Once again, the

decreased leakage rates observed for composite resin

restored root specimens confirm the ability of a coronal

restoration to enhance the seal in root filled teeth,

as previously stated (Schwartz 2006, Imura et al.

2007).

Although interesting, the performance of endodontic

filling materials after 180-day storage should be

interpreted carefully. Whilst being prone to water

sorption, such materials are also susceptible to solubil-

ity (Donnelly et al. 2007). As far as longer periods of

evaluation are concerned, dissolution of sealers would

allow gap formation, and leakage might increase

(De-Deus et al. 2008).




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Conclusions

Under the conditions and limitations of the current

study, AH Plus/gutta-percha root fillings provided a

better seal than Epiphany/Resilon. The presence of a

coronal restoration reduced significantly the leakage

rates of the specimens. Storage of root filled specimensfor 180 days did not cause any loss of sealing ability of

the tested materials.

Acknowledgements

The authors gratefully acknowledge the valuable

assistance given by Dr David Pashley for his scientific

advice and Mr Marcos B. Cangiani for his laboratorial

support. This manuscript is a partial fulfillment of

requirements for the PhD degree of Juliana Santos,

Piracicaba School of Dentistry, University of Campinas,

Brazil. This study was supported by grants from CAPES

(P.I. Juliana Santos), CNPq (#300615/2007-8 and

473164/2007-8, P.I. Marcela Carrilho), FAPESP (#05/

53996-0, P.I. Alexandre Zaia) and the Academy of

Finland (#111724, P.I. Leo Tjaderhane).

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Long-term sealing ability of resin-based root canal

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