The sealing ability and adhesiveness of oval shaped canals versus round shaped canals

obturation using System B heat source with RealSeal system

( An invitro study )

A protocol submitted to the Faculty of Oral and Dental Medicine, Cairo University.

For

Registration to the Master degree in Dental Medicine

( Endodontics )

Presented by:Sami jehad mohammed hassan.

B.D.S. Misr university for science and technology.

2009

Introduction

The primary purpose for using obturating materials is to create a fluid

tight seal apically to prevent failure of root canal treatment. When the root

canal system is not properly cleaned, prepared and obturated will result in

failure of the treatment. Grossman listed that the ideal root canal obturating

material should make hermetic seal and well adapted to the canal walls and its

irregularities.(1)

Root canals have different shapes in cross section including oval and

round shapes. Difficulties in cleaning and shaping and obturating the oval

canals have been noted. Wu et al(2) (2000) found the percentage of long oval

canals was more than 50%. In most cases, the long canal diameter decreased

apically and tended to be rounder in cross section. Long oval canal was

common in the apical 5 mm. In 2001, Wu and Wesselink (3) found that

uninstrumented recesses may be left in many oval canals after instrumentation

using the balanced force technique which was not solved by increasing the

apical flare. Also these recesses can not be completely obturated by cold lateral

condensation of gutta-percha.

There are two new resin based Obturation materials RealSeal and

Epiphany.(4) Epiphany (Sybron Endo, Orange, CA) and RealSeal (Sybron Endo,

Orange, CA) sealers have similar chemical composition with different brand

names and are designed for bonding simultaneously to intraradicular dentin and

Resilon. The new RealSeal Obturation System uses Resilon, which is a ther-

moplastic synthetic polymer-based root canal filling material. It has the same

handling properties as gutta-percha. Resilon can be used with cold lateral con-

densation also with vertical condensation as System B. The Resilon points to-

gether with RealSeal sealer considered as a single entity forming the so called

Resilon monoblock system. These manufacturer claims need to be investigated

especially in such oval shaped canals.

2

Review

Oval shaped canals evaluation:

Wu et al(2) (2000) evaluated the apical root canal diameters of human

teeth to determine prevalence and extent of long oval canals. They used 180

extracted human teeth randomly selected, 20 for each group. All roots were

horizontally sectioned at 1, 2, 3, 4, and 5 mm from the apex. Canal diameters

were measured using microscope. The percentage of long oval canals was more

than 50%. In most cases, the long canal diameter decreased apically tended to

be rounder cross section. Long oval canal was common in the apical 5 mm.

They found that it was impossible to instrument the long and narrow oval

canals without perforating or significantly weakening the roots. They

concluded that care should be taken in cleaning, shaping, and obturating the

oval canals.

Siqueira et al(5) (2000) compared the coronal leakage of saliva into root

canals filled by 3 different obturation techniques. Seventy human mandibular

incisors with straight roots were selected and prepared by step back technique.

Then the teeth were divided into five groups ( 20 root canals were obturated by

lateral condensation technique; 20 root canals were obturated by thermafil

technique; 20 root canals were obturated by using the continuous wave

condensation technique, five teeth obturated by lateral condensation technique

without sealer as the positive control group and five teeth with intact crown as

negative group). The bacterial leakage for all teeth was assessed up to 60 days.

After 30 and 60 days, a significant number of specimens were contaminated.

They found no significant differences when comparing between the three

3

obturation techniques. Neither of the techniques tested could predictably

produce a coronal seal of the root canal after direct exposure to saliva.

Wu and Wesselink(3) (2001) evaluated the uninstrumented recesses in

oval canals after instrumentation and obturation. Twenty mandibular incisors

with a single oval canal were selected and divided equally into two groups

(group 1 where the canals were enlarged to conventional sizes and group 2

where the canals were enlarged more widely up to size 80 3mm short of

working length using Flexofiles). All the canals were prepared using a balanced

force technique. The canals were obturated by a second operator without

knowledge of the preparation technique with cold laterally condensed gutta-

percha. The filled teeth horizontally sectioned at 3 and 5 mm from the apex,

photographed and scanned. They found that uninstrumented recesses appeared

in 13 oval canals. The recesses in five of these 13 canals were obturated with

no visible voids. The recesses in the other canals were either obturated with

visible voids or completely unfilled. The percentage of filled area was higher in

group 1 than in group 2. They concluded that uninstrumented recesses may be

left in many oval canals after instrumentation using the balanced force

technique which was not solved by increasing the apical flare. Also these

recesses can not be completely obturated by cold lateral condensation of gutta-

percha. They found that the long diameter of canals at the level 3 mm from the

apex was less than at the 5 mm level. So, uninstrumented recesses at 3 mm

level appeared less frequently than at 5 mm level.

Van der Sluis et al(6) (2005) investigated the quality of the root canal

filling of mandibular incisors compared with that of mandibular and maxillary

canines using three different techniques of evaluation: radiographs, the fluid

transport test and the percentage of gutta-percha (PGP). First group of 20

mandibular incisors with oval canals and second group of 20 maxillary and 4

mandibular canines were instrumented and obturated by cold lateral

compaction using AH 26 as the sealer. The filled roots were radiographed

bucco-lingually and mesio-distally to measure the quality of the filling. Fluid

transport along the root filling was evaluated. Each root was horizontally

sectioned at 4 and 6 mm from the apex. Images of the cross-sections were taken

to record the percentage of gutta-percha filled areas. They found that

radiographic scores were higher for the mandibular incisors than for the

canines, higher for the mesiodistal radiograph than the bucco-lingual

radiograph for all teeth. The bucco-lingual radiographs were not different

between the mandibular incisors and the canines. The mandibular incisors

showed more fluid transport than the canines. Also, they found that the

percentage of the filled areas was greater in the cross-sections of canines as

compared to the cross-sections of mandibular incisors. The study showed

poorer results of the root fillings in oval canal incisors as it was not possible to

completely instrument the entire oval canal with use of the balanced force

technique. They concluded that the root fillings quality in long oval canals may

be compromised.

De-Deus (7) (2006) compared the sealing ability of the laterally condensed

gutta percha, the vertically compacted warm gutta-percha and thermafil

obturation techniques in single oval canals. Seventy mandibular incisors were

selected radiographically in the buccolingual and mesiodistal directions with

the long:short diameter ratio was ≥ 2.5 at 5 mm from the apex. Sixty of the

prepared teeth were randomly divided into three equal groups according to

obturation technique. Five teeth were used for each of the negative and the

positive control groups. All roots were sectioned at 10 mm from the apex and

coated with two coats of nail varnish on the external surface. All teeth were

placed on a 2 chamber apparatus then exposed to human saliva. The time

required for the entire contamination of the root canals was recorded in days. 5

Each sample was horizontally sectioned 5 mm from the apex to verify the

methodology used to classify the teeth as oval or round. They found no

statistical significant difference between the three techniques. The quality of

the apical seal was similar in the different technique. They considered that

bacterial leakage method was more suitable using human saliva as it simulated

the real clinical situation.

Leakage evaluation for resin based obturation:

Shemesh et al(8) (2006) compared two different experimental leakage

models along root fillings in the presence and absence of smear layer. One

hundred and twenty single rooted teeth were prepared and divided into two

groups for fluid transport model and glucose penetration model. Each group

was subdivided into 3 groups of 20 teeth each. Smear layer was removed in

groups 2 and 3 and left in group 1. In groups 1 and 2 canals were filled with

laterally compacted gutta-percha cones with AH 26, while Group 3 was filled

with Resilon/Epiphany. The coronal portion of the filling was removed leaving

only 4 mm of filling in the canal. Leakage was evaluated using a glucose

penetration model and Fluid transport model. The study showed that Resilon

laterally compacted had the most leakage at all time intervals. For the glucose

model, they found no significant difference existed between the two gutta-

percha groups. But root canals filled with Resilon had more glucose penetration

than gutta-percha with AH 26 during a period of 56 days. While the fluid

transport model showed no significant difference between the three

experimental groups at both time intervals, 1 and 8 weeks, after filling. Also

they found that there was no statistically significant difference in glucose

penetration or fluid transportation observed along the 4 mm apical root filled

with gutta-percha and AH 26 with or without the smear layer removal before

6

obturation. They concluded that the glucose penetration model is a sensitive

method to detect leakage along root fillings.

Biggs et al(9) (2006) compared the sealing ability of the Resilon/Epiphany

obturation technique to that of conventional gutta-percha / Roth or AH plus

sealers using lateral condensation. The root canals were instrumented. The

teeth were randomly divided into eight groups of 12 roots each according to

obturation technique used. Group 1: the teeth were obturated with

Resilon/Epiphany by lateral condensation; group 2: the canals were obturated

with gutta-percha/Roth’s sealer and allowed to set for 3 weeks before checking

for leakage; group 3: the same as group 2 but measured immediately after

obturation; group 4: the same as group 1 but the canals were obturated with a

single cone technique; group 5: the same as group 1 except no primer and no

sealer were used, this group served as positive group, while group 6: the canals

were obturated with gutta-percha and AH Plus sealer using lateral condensation

technique then immediately checked for leakage; group 7: same as group 6 but

sealer allowed to set for 8 hours before leakage testing and group 8: same as

group 1 except the external root surfaces were covered with 3 layers of nail

varnish before leakage testing, this groups served as negative group.

Microleakage was measured using fluid filtration method. They showed that

there was a significant difference between the groups but not for time. They

found that their study did not support the manufacturer’s claim that the

resilon/epiphany system resists leakage significantly better than gutta-percha-

based obturations. They also found that it was necessary to use a sealer to

prevent in vitro leakage.

Belli et al(4) (2008) compared the long-term sealing ability of a new

dual-curable, self-etching, 4-META containing resin-based sealer: Hybrid Root

SEAL (MetaSEAL) and compared with RealSeal and AH Plus sealers. Forty 7

four root canals were instrumented. Four roots were selected and used as

positive and negative control groups (two for each), the rest were randomly

divided into 4 groups (ten for each) and filled as follows: Group 1: AH Plus

with guttapercha; Group 2: Hybrid Root SEAL (MetaSEAL) with gutta-percha;

Group 3: Hybrid Root SEAL (MetaSEAL) with Resilon point; and Group 4:

RealSeal with Resilon point. They evaluated the apical leakage using fluid

filtration model after 1, 4, 12, and 24 weeks. They found that there were no

significant differences between test materials according to the fluid

microleakage values. Yet statistical significance was found among the time

periods especially between 1- and 24- week test periods. They concluded that

Hybrid Root SEAL (MetaSEAL) showed similar sealing performance with

RealSeal and AH Plus sealers when used either with gutta-percha or Resilon at

24 weeks.

Saleh et al(10) (2008) examined the the smear layer effect on the

penetration of bacteria along different root canal obturation materials and

determined the presence of bacteria in the dentine/sealer and sealer/core

material interfaces. One hundred and ten human roots were instrumented. Half

of them were irrigated with a 5-mL rinse of 17% EDTA. Roots with and

without smear layer were then subdivided into six experimental groups fifteen

each and four control groups five each. Group 1: roots were filled with Gutta-

percha and AH Plus. Group 2: Gutta-percha/AH Plus with using EDTA. Group

3: RealSeal core/sealer. Group 4: RealSeal core/sealer with using EDTA.

Group 5: Gutta-percha/Apexit. Group 6: Gutta-percha/Apexit with using

EDTA. Group 7: Positive control. Group 8: Positive control with using EDTA.

Group 9: Negative control. Group 10: Negative control with using EDTA.

After storage in humid conditions at 37ºC for 7 days, the specimens were tested

using a bacterial leakage test model for one hundred and thirty seven days.

Selected specimens were longitudinally sectioned and inspected by scanning 8

electron microscopy for the presence of bacteria at the interfaces. They found

that all sealers leaked more slowly in the presence of the smear layer than in its

absence. In the absence of the smear layer, group 2 leaked significantly slower

than group 4.They concluded that the absence of the smear layer did not impair

bacterial penetration along root canal fillings.

Leakage evaluation for resin based filling using system B as

heat source:

Shipper et al(11) (2004) compared the bacterial leakage through gutta-

percha and Resilon using two filling techniques: lateral and warm vertical

condensation using System B. Streptococcus mutans or Enterococcus faecalis

were tested during a 30-day period. One hundred and fifty six single rooted

teeth were tested. After instrumentation, roots were randomly divided into 8

groups of 15 roots each and 3 control groups of 12 roots each. In all groups

sticky wax was softened and painted over the root surface to seal it except the

apical 2 mm and coronal orifice. In group 1: the roots were filled with cold

lateral gutta-percha and AH 26 sealer, Group 2: Vertical condensation of gutta-

percha with AH 26 sealer using (System B) then backfilled with Obtura II,

group 3: as group 1, but Epiphany sealer was used instead of AH 26, group 4:

as group 2, but Epiphany sealer was used, group 5: lateral condensation of

Resilon with Epiphany sealer, group 6: vertical condensation of Resilon with

Epiphany sealer, group 7: as group 5 except E. faecalis was used to test

leakage, group 8: as group 6 except E. faecalis was used to test leakage.

Control groups were filled with representative samples of techniques, materials

and bacteria but without sealer. In positive control group, sticky wax was

prepared as in group 1, while in negative control, sticky wax completely

covered the surface of the root as well as the canal orifice coronally. At

completion of the leakage study, one Resilon and one gutta-percha specimen

9

were randomly selected, longitudinally sectioned and examined by scanning

electron microscope. They found that all except one positive control leaked

within 24 h, while none of the negative controls leaked. Resilon showed less

leakage than gutta-percha. They found that all Resilon and Epiphany sealer

groups leaked significantly less than all groups that used AH 26 as a sealer. The

study showed that there was no statistical difference in leakage between

Resilon groups using S. mutans and E. faecalis (groups 5–8). They concluded

that Resilon groups were superior to gutta-percha groups.

Epley et al(12) (2006) compared resin based obturation material with

traditional gutta-percha techniques in filling the prepared root canal space.

Eighty single-rooted palatal and distal roots of human first molars were

selected. Teeth were instrumented with hand and rotary files and divided into

four groups of 20 each. Gutta-percha with Roth sealer and Epiphany were used

with lateral condensation or continuous wave obturation. The roots were

sectioned at 1, 3, and 5 mm from the apex then photographed using

steromicroscope. Using software program, the surface areas devoid of the

material were calculated. They concluded that the two obturating techniques

using the resin based Epiphany obturation material were comparable to the

continuous wave Roth sealer technique in preventing voids in the obturated

root canal, while the gutta-percha with lateral condensation method

demonstrated significantly more voids than the other groups.

Pitout et al(13) (2006) compared the micro-leakage of root canals filled

with Resilon or gutta-percha using cold lateral condensation or System B

measured by bacterial and dye penetration tests. One hundred and ten single

root canal teeth had been selected and divided into 4 groups (25 for each) and 5

teeth for each of the positive and negative control group. For both micro-

10

leakage tests, their result showed no significant difference between gutta-

percha and Resilon for both techniques. In the bacterial micro-leakage test, they

found that gutta percha using the Cold Lateral condensation technique showed

the best results followed by Resilon using the Cold Lateral condensation, then

gutta percha or Resilon using System B with the most leakage. While in dye

penetration test, Resilon using Cold Lateral condensation allowed significantly

less dye penetration than gutta percha using System B, but was not statistically

significantly better than Resilon using System B. They suggested that

polymerization shrinkage of the Epiphany sealer was a possible cause of gap

formation leading to apical leakage when using resilon. They concluded that

filling using Resilon and Epiphany sealer was similar to that of gutta-percha

and Roth root canal cement, when using either the Cold Lateral condensation

technique or the System B technique.

kaya et al(14) (2007) compared the sealing ability of gutta-percha and

resilon obturated with different obturation techniques using glucose penetration

model. One hundred and fifty six premolars were selected and instrumented.

The teeth were divided into 12 experimental groups with 12 samples each and 2

control groups with 6 samples each. The root canals were obturated with either

gutta-percha (groups 1-6) or Resilon (groups 7-12) core materials combined

with AH Plus (groups 1, 4, 7, 10), Ketac Endo (groups 1, 5, 8, 11), or Epiphany

(groups 2, 6, 9, 12), using cold lateral compaction (groups 1-3, 7-9) or System

B with Obtura II (groups 4-6, 10-12). The leaked glucose concentration was

measured spectrophotometrically up to 30 days. Percentage leaking of each

group was recorded. They showed that Resilon/Ketac-Endo/cold lateral

compaction (group 8) showed the highest mean values of glucose penetration,

whereas Resilon/AH Plus/cold lateral compaction (group 7) had the least. The

least leaking percentage at the 30th day observed in gutta-percha, Epiphany/cold

lateral compaction (group 3). Glucose penetration was affected by the 11

obturation technique in some groups. Ketac-Endo either with gutta-percha

(group 2) or Resilon (group 8) showed less glucose penetration in warm

technique, whereas gutta-percha/Epiphany (group 3) had significantly less

glucose penetration in cold technique. They concluded that gutta-percha/AH

Plus combinations showed similar patterns of glucose penetration to

Resilon/Epiphany combinations.

Onay et al(15) (2009), compared the short-term sealing abilities of

RealSeal, Hybrid Root Seal and MM-Seal used in combination with either

Resilon or Herofill. They used one hundred and twenty extracted human single-

rooted teeth. The roots were instrumented using crown down technique with

HERO Shaper rotary instruments. The smear layer was removed with 5 mL of

17% EDTA. The roots were divided randomly into eight groups (six

experimental and two control groups of fifteen roots each). Group 1: filled with

RealSeal/Resilon using the warm vertical compaction technique and backfilled

using an Obtura II ; group 2: RealSeal/Herofill soft core; group 3: Hybrid Root

Seal/Resilon using the warm vertical compaction technique and back filled as

in group 1. Group 4: Hybrid Root Seal/Herofill filled as in goup 2. Group 5:

MM-Seal/Resilon filled as in group 1. Group 6: MM-Seal/Herofill filled as in

group 2. Group 7: positive controls (Herofill only with no sealer). Group 8:

negative controls (The roots were left unfilled and totally coated with 3 layers

of nail polish). Microleakage of the filled roots was determined by using a fluid

filtration model. They found that of all the groups, group 6 showed the least

microleakage while group 2 ranked second in this regard. Group 5 showed the

greatest microleakage. . Hybrid Root Seal/Resilon resulted in significantly less

microleakage than Hybrid Root Seal/Herofill. They suggested that the sealing

properties of epoxy-resin-based sealer (MM-Seal) combined with gutta-percha

(Herofill) were superior to those of methacrylate-based sealers (Hybrid Root

Seal and Realseal) combined with Resilon. They concluded that the gutta-12

percha coated carrier technique (Herofill Soft-Core system) combined with

either MMSeal or RealSeal showed significantly better sealing ability when

compared with combinations with Resilon.

Bond strength evaluation for resilon obturation:

Tay et al(16) (2006) evaluated the adhesion of Resilon to a methacrylate-

based sealer using the chemical coupling by bonding to smooth surfaces, and

micromechanical retention by bonding to different surface roughness. Three

Resilon groups were created (thirty Resilon points for each) with different

surfaces roughness and a control group consisting of resin composite disks was

used. A modified microshear bond testing protocol was used to measure the

shear bond strength. Their results showed that the shear bond strength of

Resilon with rough surface was higher than Resilon with smooth surface. They

concluded that chemical coupling of the methacrylate-based sealer to Resilon

was very week.

Ungor et al(17) (2006) evaluated the bond strength of the resin-based

Epiphany–Resilon root canal filling and compared with bond strengths of

different pairings of AH Plus, gutta-percha, Epiphany and Resilon. Sixty five

single-rooted teeth were used. All teeth were instrumented and smear layer was

removed. The roots were divided randomly into five groups of 15 roots each

and one control group of five roots. The canals were filled with different

combinations of core and sealer using lateral condensation. The bond strength

was recorded using push-out test method. The remaining sections were split

longitudinally in buccolingual direction and examined under a

stereomicroscope to determine the nature of bond failure. They showed that the

13

group (Epiphany + gutta-percha) had significantly greater bonding strength

than all the other groups. While the group (AH Plus + gutta-percha) had

significantly greater bonding strength than group (AH Plus + Resilon). They

found that the bond failure was mainly adhesive to dentine for all groups. They

concluded that Epiphany and Resilon combination was not superior to that of

the AH Plus sealer and gutta-percha combination.

Jainaen et al(18) (2007) investigated the push-out bond strength of the

dentine–sealer interface with and without main cone for three resin sealers

(AH26, EndoRez, Resilon sealer). In Thirty maxillary premolar teeth two

separate canals were instrumented and divided into three groups according to

the filling used. In each tooth, one canal was filled with main cone technique,

and other was filled with sealer alone. Teeth were sectioned 1mm thick at the

mid-root dentine for the push-out test. After the push-out bond strength test, the

samples were examined under light microscopy to determine the mode of

failure. They found that the epoxy resin sealer (AH Plus) had a higher push-out

bond strength than the two sealers (EndoREZ and Resilon), which were not

significantly different from each other. The bond strengths after filling with

sealer alone were higher than those with main cone and sealer. They found that

Many resin tags of Resilon sealer were hollow, with only a thin layer of resin

formed around the periphery of the tubule, whereas the tags formed by AH Plus

and EndoREZ appeared solid in cross-section. They concluded that the bond

strengths after filling with sealer alone were higher than those with main cone

and sealer and may reflect different patterns of behaviour when the sealer is

present as a thin layer.

Babb et al(19) (2009), examined the adhesive strengths, interfacial

ultrastructure, and tracer penetration of a non etching (EndoREZ) and two self-

adhesive methacrylate resin–based sealers (MetaSEAL and RealSeal SE) when 14

they were applied to the root dentin with using EDTA as the active final rinse.

They evaluated the dislodgement of core-free sealers using modified push-out

testing design. They used additional specimens to examine the ultrastructure

and nanoleakage within the sealer-radicular dentin interface through

transmission electron microscope. They found that the self-adhesive sealers

MetaSEAL and RealSeal SE exhibited higher push-out strengths than the

nonetching sealer EndoREZ when EDTA was used as the active final rinse.

They showed that all three sealers showed a 1- to 1.5-μm thick zone of partially

demineralized dentin, with the EDTA dentin demineralization effect masking

the true self-etching potential of MetaSEAL and RealSeal SE.

Push-out bond strength evaluation for resin based filling

using system B as heat source:

Nagas et al(20) (2007) determined the push-out bond strength and coronal

microleakage of the Epiphany/ Resilon root canal obturation system using

different light curing methods. Sixty extracted human maxillary central incisors

were used and the length of all roots was adjusted to approximately 16 mm.

The roots canals were instrumented with the ProFile NiTi rotary system. The

specimens were randomly divided into three groups according to the light

curing unit used from the coronal aspect :(1) quartz-tungsten-halogen/40

seconds, (2) light-emitting diode/20 seconds, and (3) plasma arc/6 seconds. The

roots were obturated with Resilon cones using the single-cone obturation

technique. Thirty cured specimens were randomly selected. Three horizontal

sections were obtained from each specimen from coronal-to-apical direction to

measure the push-out bond strength and then examined under a

stereomicroscope. From each group, two specimens were evaluated under a

scanning electron microscope. The remaining thirty cured specimens were

15

checked for the assessment of coronal dye leakage. The roots were sectioned

longitudinally in the buccolingual direction and the extent of dye penetration

was measured on digital images obtained under a stereomicroscope. They

found that both the type of light curing unit and the level of coronal sectioning

had significant effects on push-out bond strength but there was no interaction

between them. The study showed statistical ranking obtained for bond strength

values: quartz-tungsten-halogen more than light-emitting diode and plasma arc

(the least one). Coronal microleakage of specimens cured with the plasma arc

was significantly greater than those of other groups. They concluded that the

tested quartz-tungsten-halogen may be preferable to light-emitting diode and

plasma arc units in terms of better coronal sealing and bonding quality of the

Resilon/Epiphany system. Also, the least amount of dye leakage with

conventional quartz-tungsten-halogen light curing unit does not mean that it

was capable of completely eliminating coronal microleakage.

Onay et al(21) (2009) evaluated the interfacial strengths and failure modes

of new polymeric endodontic obturation systems consisting of different

material combinations. One hundred and five extracted single rooted human

teeth were instrumented using HERO Shaper rotary instruments and grouped

into seven groups obturated with different combinations of core and sealer (six

experimental groups of fifteen roots each and one control group of fifteen

roots). Group 1: Roots were filled with RealSeal/Resilon warm vertical

compaction technique using System B and backfilling with Obtura II unit.

Group 2: filled by RealSeal/Herofill soft core. Group 3: The roots were filled

with Hybrid Root Seal and Resilon core material using the warm vertical

compaction technique. Group 4: The roots were filled with Hybrid Root Seal

and Herofill core material in the same manner as in group 2. Group 5: The

roots were filled with MM-Seal root canal sealer and Resilon using the warm

vertical compaction technique. The root canal filling was completed in the 16

same manner as in group 1. Group 6: The roots were filled with MM-Seal root

canal sealer and Herofill core material in the same manner as in group 2. Group

7 (control group): The roots were filled Herofill core material without any

sealer. The bond strength was determined using push-out test. They found that

group 3 (Hybrid Root Seal/Resilon) had significantly highest bond strength

followed by group 1(RealSeal/Resilon). Group 2 (RealSeal/Herofill) and group

4 (Hybrid Root Seal/Herofill) had the lowest bond strength but were not

significantly different from each other. Failure modes of root slices were

examined with stereomicroscope and scanning electron microscopy after push-

out testing. Most of the groups failed in adhesion. Cohesive failures within the

filling material were mostly observed in group 3. Mixed failures in both

adhesive and cohesive modes were found in group 6.

17

Aim of the study

The present study will compare the quality of obturation for oval-shaped

canals versus round-shaped canals in terms of their sealing ability and

adhesiveness using warm condensed RealSeal system by the System B heat

source.

18

Materials and Methods

Teeth selection:

A total of sixty-two teeth will be selected for this study. Teeth will be

divided into two groups (fifty-eight teeth each) according to the shape of the

canal. Lower anterior teeth will be used for oval canals group and lower

premolars for round canals group. The canal shape will be determined using

periapical radiographs of each tooth in buccolingual and mesiodistal directions.

Teeth with oval-shaped canals will be selected only when the ratio of the long:

short diameter is ≥ 2.5 at 5 mm from the apex. While the rounded shaped

canals, will be selected if this ratio ≈1. Teeth presenting isthmus, lateral and

accessory canals or more than one canal will be excluded from the sample.

Teeth will be stored in normal saline until used.

Teeth preparation:

Standard access cavities will be made and the canal orifices will be

located. The patency of each canal will be confirmed by inserting a size 10 K

file through the apical foramen until it is just visible, and the working length

will be established by deducting 1 mm from that length. The apical portion of

the canal will be instrumented to a size 40 master file using the step back

technique to create a uniform size of canal and to overcome the variation in

natural morphology. A step-back flaring technique will be performed at 1-mm

increments with Gates Glidden burs numbers 2-6 making the taper 0.2

mm/mm. Canals will be irrigated between each file with NaOCl. Each prepared

canal will be then irrigated by EDTA to remove the smear layer followed by

final rinse with normal saline. The canals will be dried with paper points.

19

Canal filling:

All teeth will be filled using RealSeal system using system B heat

source. Primer will be introduced into the canal using a paper point. RealSeal

sealer will be mixed manually and placed into the canal to the full working

length according to manufacturer recommendations. The system B heat device

will be used as recommended by the manufacturer. It will be set to 200°C

during the compaction of the primary resilon cone. Following the

manufacturer’s instructions, the coronal surface of the RealSeal obturation will

be light-cured to create the immediate coronal seal.

Teeth grouping and evaluation:

Teeth will be divided according to canal shape into:

Group1: oval shaped canals (29 teeth).

Group2: rounded shaped canals (29 teeth).

From each group, fourteen teeth will be used for leakage testing and the

other ten teeth will be used for bond strength testing and five teeth for scanning

electron microscope. Leakage of teeth will be evaluated using linear dye

penetration, while bond strength will be evaluated using push out test.

Apical leakage test:

Twenty-eight teeth will be used in this test (14 teeth from group 1 and 14

teeth from group 2). Twenty teeth will be used for leakage assessment (ten

teeth from each group). Eight root canals will be used for control groups (four

teeth from each group). Four teeth will serve as the negative control group, and

four teeth will be instrumented but not obturated to serve as positive control.

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The micro-leakage will be measured using dye penetration technique.

The leakage marker used in this study will be 5% buffered methylene blue dye.

The roots will be coated with a double layer of nail polish to a distance of ½

mm from apical foramen then placed in the dye. Teeth will be then

longitudinally sectioned by cutting 2 longitudinal grooves in the roots with a

separating disk. A chisel will be used to completely separate them into halves

under liquid nitrogen. The extent of leakage will be evaluated by measuring the

extent of visible dye penetration from the apex of each specimen under

stereomicroscope.

Scanning electron microscopic examination:

Five specimens from each group will be taken to examine the different

interfaces between the filling and the dentine.

Push out bond strength test:

Twenty teeth will be used in this test (ten from each group). Each root

will be sectioned perpendicular to its long axis to create slices using a water-

cooled diamond disc. After measuring the thickness of each slice, the filling

material will be loaded with prefabricated cylindrical plunger. The plunger tip

will be sized and positioned such that it touches only the filling material and

does not stress the surrounding root canal walls. Loading will be performed on

a testing machine until bond failure occurs. The bond will be considered to fail

when the filling material is extruded from the root section. The force required

for breaking the bond between the sealer and dentine will be recorded.

Statistical analysis:

Results from all groups for leakage and push out test will be recorded.

All data will be collected, tabulated and statistically analyzed.

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References

1. Ingle J, Bakland L. Endodontics fifth edition. 2002; 579-81.

2. Wu M, R'oris A, Barkis A, Paul R. Prevalence and extent of long oval

canals in the apical third. Oral Surg Oral Med Oral Pathol Oral Radiol

Endod 2000;89:739-43.

3. Wu MK, Wesselink PR. A primary observation on the preparation and

obturation of oval canals. Int Endod J 2001;34:137-41.

4. Belli S, Ozcan E, Derinbay O, Eldeniz AU. A comparative evaluation of

sealing ability of a new, self etching, dual-curable sealer: Hybrid Root

SEAL (MetaSEAL). Oral Surg Oral Med Oral Pathol Oral Radiol Endod

2008;106:45-52.

5. Siqueira JF Jr, Rôças IN, Favieri A, Abad EC, Castro AJR, Gahyva SM.

Bacterial leakage in coronally unsealed root canals obturated with three

different techniques. Oral Surg Oral Med Oral Pathol Oral Radiol Endod

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of root fillings in mandibular incisors and maxillary and mandibular

canines using different methodologies. J Dent 2005; 33:683-8.

7. De-Deus G, Murad CF, Reis CM, Gurgel-Filho E, Coutinho Filho T.

Analysis of the sealing ability of different obturation techniques in oval-

shaped canals: a study using a bacterial leakage model. Braz Oral Res

2006;20:64-9.

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8. Shemesh H, Wu MK, Wesselink PR. Leakage along apical root fillings

with and without smear layer using two different leakage models: a two-

month longitudinal ex vivo study. Int Endod 2006;39:968-76.

9. Biggs SG, Knowles K, Ibarrola JL, Pashley DH. An in vitro assessment

of the sealing ability of Resilon/Epiphany using fluid filtration. J Endod

2006;32:759-61.

10.Saleh IM, Ruyter IE, Haapasalo M, Ørstavik D. Bacterial penetration

along different root canal filling materials in the presence or absence of

smear layer. Int Endod 2008;41:23-40

11.Shipper G, Orstavik D, Teixeira FB, Trope M. An evaluation of

microbial leakage in roots filled with a thermoplastic synthetic polymer-

based root canal filling material (Resilon). J Endod 2004;30:342-7.

12.Epley SR, Fleischman J, Hartwell G, Cicalese C. Completeness of root

canal obturations: Epiphany techniques versus gutta-percha techniques. J

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root-filled with gutta-percha or Resilon root canal filling material. J

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gutta-percha and thermoplastic synthetic polymer-based systems along

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the root canals through the glucose penetration model. Oral Surg Oral

Med Oral Pathol Oral Radiol Endod 2007;104:e66-e73.

15.Onay EO, Ungor M, Unver S, Ari H, Belli S. An in vitro evaluation of

the apical sealing ability of new polymeric endodontic filling systems.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:49-54.

16.Tay FR, Hiraishi N, Pashley DH, Loushine RJ, Weller N, Gillespie WT,

Doyle MD. Bondability of Resilon to a methacrylate- based root canal

sealer. J Endod 2006;32:133-37.

17.Ungor M, Onay E, Orucoglu H. Push-out bond strengths: the Epiphany–

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of Epiphany, Resilon, AH Plus and gutta-percha. Int endod j

2006;39:643-647

18.Jainaen A, Palamara J. E. A, Messer H. Push-out bond strengths of

the dentine–sealer interface with and without a main cone. Int endod j

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19.Babb BR, Loushine RJ, Bryan TF, Ames JM, Causey MS, Kim J, Kim

YK, Weller N, Pashley DH, Tay FR. Bonding of Self-adhesive (Self-

etching) Root Canal Sealers to Radicular Dentin. J Endod 2009;35:578-

82.

20.Nagas E, Cehreli Z, Durmaz V, Vallittu P, Lassila L. Regional Push-out

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Light-curing Methods. J Endod 2007;33:1464-1468.

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21.Onay EO, Ungor M, Ari H, Belli S, Ogus E. Push-out bond strength and

SEM evaluation of new polymeric root canal fillings. Oral Surg Oral

Med Oral Pathol Oral Radiol Endod 2009;107:879-85.

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مقارنة قابلية البيضاوية الجذور قنوات لحشوات وااللتصاق الغلق إحكام الدائرية بالقنوات

بي سيستيم مع ريلسيل بإستخدام

معملية ) ( دراسة

: الطبيب من مقدمة رسالة مشروعحسن محمد ساميجهادواالسنان الفم بكالوريوسطب

والتكنولوجيا للعلوم مصر جامعة

على للحصول توطئةالجذور عالج في الماجستير درجة

واالسنان الفم طب كليةالقاهرة جامعة

2009

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