“A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ...

“A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ANALYSIS OF GUTTA

PERCHA IN CONTACT WITH VARIOUS CONCENTRATIONS OF ZINC- OXIDE

EUGENOL SEALER & RESIN BASED SEALER USING MICRO COMPUTED

TOMOGRAPHY-AN INVITRO STUDY.”

By

Dr. CYNTHIA .P

Dissertation Submitted to the

Rajiv Gandhi University of Health Sciences, Karnataka, Bangalore

In partial fulfilment of the requirements for the degree of

MASTER OF DENTAL SURGERY

In

CONSERVATIVE DENTISTRY AND ENDODONTICS

Under the guidance of

DR. RUPALI KARALE

Professor and Head

DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS

K.L.E SOCIETY’S INSTITUTE OF DENTAL SCIENCES

BANGALORE -560022, KARNATAKA.

2016-2019

III

LIST OF ABBREVIATIONS

CBCT Cone beam computed tomography

CEJ Cemento enamel junction

CT Computed tomography

CLC Cold lateral condensation

EDTA Ethylene diamine tetra-acetic acid

EWT Extended working time

GF Gutta flow

GP Gutta percha

HBSS Hanks balanced salt solution

HT Hybrid technique

LCT Lateral compaction technique

MCT Micro computed tomography

MTA Mineral trioxide aggregate

NAOCL Sodium hypochlorite

NITI Nickel titanium instruments

PA Periapical radiograph

PCS Pulp canal sealer

P/L Powder liquid

POV Percentage of obturated volume

RACE Reamers with alternative cutting edge

SC Single cone

SCT Spiral computed tomography

SPSS

Statistical Package for the Social Sciences

UDMA Urethane dimethacrylate

VII

VOI Volume of interest

VP Volume percentage

WVC Warm vertical condensation

ZOE Zinc-oxide eugenol sealer

LIST OF TABLES

SL NO TITLE PAGE NO

TABLE 1 The obturated mean volume of root canals and standard

deviation after 7, and 30 days. [paired t test] 33

TABLE2 Comparison of Expansion of Gutta-percha when using

different sealers after 7 days 34

TABLE 3 Comparison of Expansion of Gutta-percha when using

different sealers after 30 days 35

TABLE 4

Tukey’s post hoc test for multiple pairwise

comparison

For 7 days

37

TABLE 5

Tukey’s post hoc test for multiple pairwise

comparison

For 30 days

39

GRAPH 1 Mean volumetric expansion of Gutta-percha at 7days

interval 40

GRAPH 2 Mean volumetric expansion of Gutta-percha at 30days

interval 40

GRAPH 3

Comparison of Mean volumetric expansion of Gutta-

percha during 7 days and 30 days intervals.

41

VIII

LIST OF FIGURES

IX

SL NO TITLE PAGE NO.

FIG 1 ARMANTERIUM 66

FIG2 40 PREMOLAR SAMPLES 67

FIG 3 SAMPLES GROUND WITH DIAMOND DISK 67

FIG 4 STANDARDIZATION OF SPECIMENS 68

FIG 5 CLEANING AND SHAPING USING M2 ROTARY FILES 68

FIG 6 IRRIGANTS USED IN STUDY 69

FIG 7 MICRO CT SCANNER 70

FIG 8 SAMPLES SUBJECTED TO MICRO CT SCANNING 71

FIG 9

MCT IMAGE SHOWING CANALS OBTURATED WITH SINGLE

CONE GUTTA-PERCHA AND ZOE BASED SEALER AT 1:1 & 1:2 AT

7-DAY INTERVAL AND 30 DAYS INTERVAL 72

FIG 10


CONE GUTTA-PERCHA AND ZOE BASED SEALER AT 1:3 & AH

PLUS AT 7-DAY INTERVAL AND 30 DAYS INTERVAL 73

FIG 11


CONE GUTTA-PERCHA AND NO SEALER AT 7-DAY INTERVAL

AND 30 DAYS INTERVAL

74

ABSTRACT

“A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ANALYSIS OF GUTTA

PERCHA IN CONTACT WITH VARIOUS CONCENTRATIONS OF ZINC- OXIDE

EUGENOL SEALER & RESIN BASED SEALER USING MICRO COMPUTED

TOMOGRAPHY-AN IN VITRO STUDY.”

Background and objective:

One of the keys to a successful root canal therapy is to adequately obturate the prepared root canal

space to create a fluid tight seal .Gutta-percha which is commonly used for obturation has shown

a reduction in leakage overtime indicating an increase in volume. Eugenol which is a principal

component in ZOE based sealers produces a volumetric expansion of GP. AH plus an epoxy resin

based sealer has also shown continuous expansion of GP in a liquid environment over time.

Thus, the purpose of this study was to compare the 3D volumetric changes of GP at various

powder/liquid ratios of ZOE-based sealer & AH Plus sealer using Micro CT.

Material and Method: A sample of forty extracted mandibular premolars were decoronated at

the level of CEJ followed by access opening and cleaning and shaping was performed in all the

teeth with M2 rotary instruments (35/06). Teeth were randomly divided into five groups of 8 teeth

each. Group 1,2,3 were obturated with ZOE sealer in 1:1,1:2,1:3 ratio respectively, and group 4

with AH plus sealer and GP. Obturation was performed with single cone GP points (35/04) by

dipping it in sealers for 5 seconds while in the control group, no sealer was used. MCT scan was

performed to calculate the mean volume of GP and sealer in all groups after 7 and 30 days of

obturation. Data were statistically analyzed using one‑way ANOVA. Inter‑group comparisons

were done using Scheffe post hoc multiple comparisons test.

Results: Increasing the ratio of eugenol in sealer resulted in significant increase in volumetric

expansion of GP in a 7 days and 30days time interval. ZOE 1:1, ZOE 1:2, ZOE 1:3 and AH plus

showed statistically significant more expansion compared to control group. AH plus showed more

expansion compared to ZOE 1:1 & ZOE 1:2 , and less expansion compared to ZOE 1:3

XI

Conclusion:

Within the limitations of this study it is concluded that increasing concentration of eugenol causes

expansion of GP. AH plus also causes expansion of GP which is lesser than ZOE 1:3 which might

have a role in reducing apical leakage over time.

Keywords: Eugenol; Gutta‑percha; Micro computed tomography; volumetric expansion; Zinc

oxide‑eugenol sealer; AH plus sealer

XII

“A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ANALYSIS OF

GUTTA PERCHA IN CONTACT WITH VARIOUS CONCENTRATIONS OF

ZINC- OXIDE EUGENOL SEALER & RESIN BASED SEALER USING MICRO

COMPUTED TOMOGRAPHY-AN INVITRO STUDY.”

INTRODUCTION:-

One of the keys to successful root canal therapy is to adequately obturate the

prepared root canal space. Root canal obturation aims to provide a complete filling of the

root canal in all dimensions to create a fluid-tight seal to prevent ingress of bacteria and

their toxins and their flow into periapical tissues. The objective of root canal filling

procedure, therefore, should be the total three-dimensional (3D) filling of the root canals

and all the accessory canals.1

Obturation of the canal system has historically been achieved with gutta-percha

and an appropriate sealer to obtain a tight seal.2The use of sealer is necessary to fill voids

and gaps between the main material and the root canal walls. Without a sealer, canal

obturations exhibit greater leakage.3Development and maintenance of the seal are

essential to optimize the outcome of root canal treatment.4

The success of a clean, well-prepared root canal system will be compromised if

the root canal system is not properly obturated.Epley et al and Schilder suggested that the

ideal root canal obturating material should be well-adapted to the canal walls and its

irregularities and that the entire length of the canal be densely compacted with a

homogeneous mass of gutta-percha.4

Most root canal fillings do not completely fill the root canal system. Teeth with

inadequate obturation, unfilled root canals, or under extended root fillings might require

retreatment before coronal restoration. These unfilled areas might create problems

because they might contain bacteria that can multiply when in contact with nutrients via

the periapical region or lateral canals.4

The material used for root canal obturation is one of the critical determinants for

the success or failure of endodontic treatment. The sealing properties of root canal filling

materials constitute another important factor that can influence the success of treatment.5

Suitable physical properties of Gutta-percha (GP) as the most common root canal

obturation material, allow it to apply in several obturation techniques. Its physical

properties have made it possible to use it in several different techniques with differing

opinion regarding the effective sealing of root canals.6 It is used as a root canal core

material, which exhibits the necessary properties for root canal treatment, namely,

minimal toxicity and ease of insertion.7Adhesion of a root canal sealer to both GP and to

root dentin would be desirable in stabilizing the apical seal. An ideal endodontic sealer

should, in part, adhere firmly both to dentin and to GP.8 Differences in the adhesive

properties of endodontic sealers may be expected, because their interaction with either

dentin or GP may vary with their chemical composition.8

Zinc oxide-eugenol cements are widely used root canal sealers because of their

plasticity, slow setting time in the absence of moisture, and small volumetric change on

setting.9

Zinc oxide-eugenol (ZOE) sealer firmly bonds to dentin and GP. Setting reaction

of ZOE mixture is a chelation reaction occurring with zinc ion of the zinc oxide. This

reaction may also occur with the zinc oxide phase of GP, which ranges from 50% to 70%

according to the manufacturer as well as with the calcium of mineral phase of dentin.8

Eugenol, which is the main constituent of oil of cloves, is weakly ionized and has

a dimeric structure with both inter and intra-molecular hydrogen bonds.10

In addition, eugenol is a solvent of GP that may soften it during setting reaction

and increase bonding of sealer to GP.8 Eugenol in the sealer can react with zinc oxide in

the gutta-percha to create a chelate bond, because the two materials share common

ingredients and because eugenol, in excess, may soften gutta-percha, increasing the sealer

gutta-percha interface.8 Powder/ liquid ratio may vary from 2 to 4 for the same root canal

sealer. Since some essential properties, such as disintegration and setting time are under

the control of the powder/liquid ratio of the zinc oxide–eugenol-based sealers, preparing

the root canal sealer with varying consistency may result in variations in the properties of

the set root canal sealer.10

Root canal fillings may be prone to bacterial penetration along their entire length.

Dimensional changes of root canal sealers over time may introduce gaps and channels

along the sealer/GP or sealer/dentin interface, channels which may be large enough to

permit micro-organisms to pass along the spaces. 11

Wu et al. Found that when canals were obturated with just sealer alone, there was

a dramatic increase in leakage over time as a result of sealer dissolution. They also

demonstrated that with and without sealer gutta-percha had a reduction in leakage over

time, which indicated an increase in volume, with the expansion of gutta-percha

compensating for sealer dissolution, resulting in decreased leakage of the canal system.2

Free eugenol component of freshly mixed ZOE sealer can seep out and cause

various cytotoxic effects on gingival fibroblasts, periodontal ligament cells, and

osteoblast‑like cells.12 However, it was found that leakage of eugenol into periapical

tissues is very low, and it dramatically decreases over time.13

AH Plus, (DentsplyMaillefer,Ballaigues,Switzerland) is an epoxy-based

endodontic sealer that is used with gutta-percha in vertical or lateral compaction

techniques with high tissue compatibility, low solubility and a relatively short setting

time.7 It contains dibenzyldiamine, aminoadamantane, and tricyclodecane-diamine.

These polyamines act as initiators and react with the resins, resulting in polymerization. It

does not release formaldehyde and is thus more biocompatible and highly radiopaque.14

.Epoxy sealers show microretention to root dentin and low sensitivity to moisture.8

Various experimental methods have been used to assess the quality of root

fillings, such as: radioisotope, dye penetration, fluid filtration, bacterial leakage,

microscopic analysis, clearing techniques and micro-computed tomography (micro-CT)

.15In endodontics, micro-CT has been used for evaluation of root canal anatomy and

morphology following instrumentation. This method has the advantages of being highly

accurate and being nondestructive.15

Micro-CT which is rapid and noninvasive technology, has been used in

endodontics for evaluating details such as master or accessory gutta-percha cones, sealer,

recesses or voids etc.16. Micro-CT analysis provides objective data. Specimens can be

examined both quantitatively and qualitatively. Volumes can be calculated with dedicated

software, while it is also possible to localize specific details with visual image analysis.17

Very few comparative studies are done to assess effect of different sealers on GP by

differentiating exact volume of GP and sealer using micro-CT.

Therefore the Aim of study was to compare the 3D volumetric changes of GP at various

powder/liquid ratios of ZOE-based sealer & AH Plus sealer using MICRO CT.

NULL HYPOTHESIS:-

The null hypothesis considered in this study was that there will be no difference in

volume of GP after obturation using various concentrations of ZOE sealer & AH Plus

sealer.

OBJECTIVES OF THE STUDY:

• To evaluate three dimensional volumetric changes of gutta-percha in contact with

Zinc Oxide Eugenol sealer with Powder/Liquid Ratio of 1:1, 1:2, 1:3 after 7 days

and 30 days.

• To evaluate three dimensional volumetric changes of gutta-percha in contact with

AH plus sealer after 7 days and 30 days using Micro CT

• To compare and analyze the volumetric changes of gutta-percha in contact with

Zinc Oxide Eugenol sealer and AH plus sealer after 7 days and 30 days using

Micro CT.

• To assess and compare presence of voids at sealer GP interface.

REVIEW OF LITERATURE:

1. A study compared the impact of the quality of root canal treatment versus the

quality of coronal restoration in treatment outcomes. Thorough cleaning and shaping of

root canals are essential for periapical healing. Restoration of endodontically treated teeth

is also required for them to function and prevent coronal leakage. Articles that evaluated

the effect of the quality of root filling and coronal restoration or both on the success of

root canal treatment were selected. Nine articles were identified and were reviewed by 3

investigators. Data were collected based on predetermined criteria. Percentages of teeth

without apical periodontitis were recorded for each category: adequate root canal

treatment (AE), inadequate root canal treatment (IE), adequate restoration (AR), and

inadequate restoration (IR). Data were analyzed using meta-analysis for odds ratios.

Results showed that on the basis of the current best available evidence, the odds for

healing of apical periodontitis increase with both adequate root canal treatment and

adequate restorative treatment. Although poorer clinical outcomes may be expected with

adequate root filling–inadequate coronal restoration and inadequate root filling–adequate

coronal restoration, there is no significant difference in the odds of healing between these

2 combinations. 18

2. A study was done to evaluate the association between the technical quality of the

root canal filling and treatment outcome. In 234 teeth (268 roots) that underwent root-

canal treatment, the quality of the root canal filling as well as the outcome of the

treatment were assessed with both Periapical radiograph [PA] and cone-beam computed

tomography (CBCT) 2 years after treatment. Satisfactory root filling on PA was defined

as 0–2 mm within the radiographic apex without voids; on CBCT scans, the apical end of

the canal replaced the radiographic apex. The outcome predictors were analyzed using

multivariate logistic regression. Results showed that complete absence of post-treatment

periapical radiolucency was observed in CBCT scans in 81% and 49% of satisfactory and

unsatisfactory root fillings, respectively, as compared to 87% and 61% revealed by PA.

Satisfactory root fillings were associated with a favorable outcome, confirmed by both

PA and CBCT. The outcome of root canal treatment is improved once the filling is 0–2

mm from the apex, and no voids could be detected. Technical skills and performance of

root canal filling procedures should be emphasized, and suitable methods should be

developed in order to achieve more compacted filling materials without voids and at the

correct length.19

3. A study was done to observe sealer distribution in root canals filled by different

root filling techniques.AH26 (0.05 mL) dyed with carbon black powder was placed into

the prepared root canals of maxillary central incisors using a lentulo spiral. Thereafter the

canals were obturated using three different gutta-percha root-filling techniques.

Horizontal sections were cut in the apical and middle portions of the filled canals. Images

of the cross sections were scanned and the percentage of sealer coated canal perimeter

(PSCP) was measured using a computer digital imaging system. Results showed that

sealer may also serve as a lubricant to assist in the thorough seating of the core filling

material during compaction. A better adaptation to the canal wall will reduce the width of

gaps between GP and the canal wall, as well as the leakage. Sealer with a thinner film

thickness should be used with the GP condensations techniques. 20

4. A study was done to investigate the long-term seal of gutta-percha (GP) without

sealer. Extracted human maxillary central incisors were prepared and obturated using

heat-or chloroform-softened GP only or GP in combination with a root canal sealer.

Leakage along root fillings was measured at 48 h and after a period of 6 months using a

fluid transport model. Results showed that at 48 h the GP-filled roots without sealer

leaked more than the control roots filled with GP and sealer. At 6 months a significant

reduction in leakage was found in the GP-only groups for both heat- and chloroform-

softened GP. After 6 months, roots filled by vertical condensation of GP-only had similar

leakage as vertically condensed GP with a sealer .Results showed that the long-term seal

of root fillings is affected by the volume change of both GP and sealer. Leakage

reduction due to expansion of GP may compensate to a certain extent for leakage that

may occur from sealer dissolution.21

5. A study was done to investigate the effect of a particular variable, that of powder

particle size, on the setting time, compressive strength, solubility, and abrasion resistance

of zinc oxide-eugenol cement. In addition, variables of powder liquid ratio and the effects

of certain additive agents were included. Five particle sizes of zinc oxide (0.11, 0.18,

0.30, 0.93, and 8 microns) were obtained. Preliminary tests were initially required in

order to determine something of the working qualities of these materials. These

experiments revealed that it would be necessary to employ an accelerator in order to

secure a reasonable setting time. Thus 30 mg. of zinc acetate were added to all of the

mixes. If the role of particle size, per se, was to be investigated, a common powder-liquid

ratio would be required. The 0.30-micron powder represented somewhat of a middle

range in the selected particle sizes and hence was used in establishing the test ratios. A

slump test carried out in accordance with A.D.A. Specification Number 8 for zinc-

phosphate cement disclosed that 1.23 gm. of zinc oxide mixed with 0.5 milliliter of

eugenol provided a mix of standard consistency. A thicker mix containing 1.5 gr. of

powder and another thinner mix utilizing only 0.9 gr. were also investigated. Only one

powder-liquid ratio, 1.5gm/0.5ml, was employed in these tests. Where hydrogenated

rosin was added the powder consisted of 90 per cent zinc oxide and 10 per cent rosin, and

when o-ethoxy benzoic acid was used, the liquid was composed of 37.5 per cent eugenol

and 62.5 per cent o-ethoxy benzoic acid. Result states that smaller particle sizes set more

rapidly than did the larger particle sizes. Neither particle size nor powder-liquid ratio

affected the strength of zinc oxide eugenol. O-ethoxy benzoic acid and rosin markedly

improved the strength of all materials. The highest strengths were obtained with the

smallest particle sizes.22

6. A study was undertaken to determine the amount of free eugenol as a function of

consistency after mixing. A number of batches of ZOE were made, using 20 percent

eugenol and 80 percent zinc-oxide. Each batch weighed approximately 3 kg and was

compounded by using a small bakery mixer and a roller mill to ensure that each particle

of powder was coated with eugenol. For each determination to be described, 100 Gm. of

the mixture was used. The quantitative determinations of free eugenol were made by

extraction. Results showed that Agitation of the ZOE mixture during the extraction of

eugenol affected the rate of reaction. The greater the amount of agitation, the less free

eugenol was present. The effect of zinc-salt accelerators and water increased the amount

of free eugenol extracted immediately after hardening. Eventually, the amount of free

eugenol to approximately the same amount found when the accelerators were not present.

Since free eugenol is always present even in small amounts, changes in the tooth

structure and tissue can be expected when ZOE cement is used.23

7. A study was undertaken to determine the pH of six rosins, both natural and

synthetic, and to assess the effect of these rosins on setting time. The pH of the rosins

was determined in the following manner. One gram of rosin was crushed to a fine

powder, and placed in a 15-ml centrifuge tube. Deionized water (9ml) was added. The

tubes were stoppered and centrifuged in a Sorval Super speed RC2B centrifuge at 5,000

rpm for five minutes. The pH of the supernatant fluid was determined with a London no.

26 pH meter .Approximately 35 mg of each of the powders was mixed slowly with 0.8

mg of eugenol to obtain a smooth mixture, which would conform to the consistency tests.

Dorman spacers (1 mm thick) were fixed to a polished glass plate and filled to the top

surface of the spacers with each of the cements. The mixing time was recorded for each

of the cements. The glass plate supporting the cements was placed in an incubator at 37

ºC with 100% humidity. Tests for setting cements were made every half hour for a total

of eight hours. The tests were made with a 100-gm weight attached to a sharp, pointed

instrument. The instrument was placed on the surface of the cements, and it was noted

whether it made an indentation. Cement was considered hard-set when the instrument

could no longer make an indentation. All tests were made at least five times and then

averaged. Results showed that root canal sealer cements vary considerably in respect to

ph. Those having a pH of 7 or above, retarded or interfered with the setting properties of

the cements. Zinc oxide-eugenol cement without rosin did not set hard in 24 hours and

was friable when it did set. The additional of rosin to zinc-oxide powder gave it body and

coherence, and allowed it to set in a reasonable time. The biologic effect of grossly acidic

rosins should be investigated.24

8. A study was done to examine this phenomenon further and to determine under

what conditions, and to what degree eugenol diffuses into and through dentin when ZOE

is applied to human teeth Tritium-labeled eugenol was released from mixtures of zinc-

oxide eugenol (ZOE) into aqueous solution at rates which declined exponentially with

time, and which were directly proportional to the liquid-powder ratio. The release pattern

was consistent with a model of progressive hydrolysis of zinc eugenolate in a limited-

thickness ZOE surface layer. Intervening dentin had a profound effect on this pattern of

release. In human teeth in vitro containing ZOE as a base or temporary filling, peak

eugenol release at the pulpal surface of dentin was of the order of a thousand-fold less

than that at the salivary surface. In such teeth, eugenol reached concentrations in excess

of 1 -2 M in dentin just beneath ZOE, and 10-4 M or less adjacent to the pulp space. Both

pulpal outflow and dentin concentrations of eugenol remained relatively constant for

more than a week, unlike release into aqueous solution. Results showed that there is

intervening dentin, the rate of release into pulp tissue can be expected to be about a

thousand-fold less; even allowing for some differences between the in vitro and in vivo

situations, it appears that there are major differences in eugenol availability. It is unlikely

that eugenol would reach concentrations in excess of 104 M in pulp tissue, and cells are

able to survive prolonged exposure to that concentration.25

9. A study was done to determine a long-term sealing ability of five root-canal

sealer and a dentine bonding agent, at thicknesses of 0.05 mm (thin layer) and 0.3 mm

(thick layer), in 212 standard human root specimens, before and after storage in water for

2 years. Canals were filled, using sealer in combination with standard gutta-percha

cylinders of 1.0 or 1.5 mm diameter, so that the layer of sealer between the gutta-percha

and the root canal wall was about 0.3mm or 0.05 mm .Results showed that thick layers of

Roth and Pulp Canal Sealer EWT (PCS-EWT) allowed more leakage than did thin layers

for Roth and PCS-EWT, respectively) whereas no significant difference was found

between the thin and thick layers for AH26, Ketac-Endo, Sealapex and J&J Bonding

Agent. J&J Bonding Agent showed less leakage than the other five agents.26

10. A study was done to investigate the amount of eugenol released from a zinc oxide

eugenol based sealer at the apex of teeth filled according to two techniques: the single-

cone and the Thermafil. The crown of 10 maxillary central incisors was removed, and the

canal was prepared with ProFile to a size 30 under NaOCI irrigation. The patency of the

apex was checked with a #8 K-file between each ProFile. Five roots were filled with a

Thermafil#30 and 0.03 g of Sealite; five roots were filled using a Lentulo with 0.07 g of

sealer and a gutta-percha cone #30. The powder/liquid ratio of the sealer was of 5/1. The

concentration of eugenol released in phosphate-buffered saline was spectro

fluorimetrically determined immediately after sealing, after 1 day, and after 1 month of

storage. The roots filled with the single-cone technique released significantly more

eugenol than these filled with Thermafil immediately after sealing; but, after 1-day or 1-

month storage, there was no difference. For both techniques, eugenol concentration

decreased over time: the immediate concentration was higher than the 1-day

concentration .Eugenol concentration after 1-month storage was undetectable. The results

of this work show that the level of eugenol released from a zinc oxide-eugenol-based

sealer beyond the apex is very low and decreases over time.13

11. A study was done to evaluate the dimensional changes of endodontic sealers and

to assess the dimensional changes of 11 commercial sealers after prolonged storage in

water. Method for linear dimensional changes described in draft standard for endodontic

sealers was applied to 11 different types of endodontic sealers. Materials were followed

for dimensional changes over 48 weeks. Results showed that greatest dimensional

changes took place within 4 weeks .ZOE sealers showed shrinkage ranging from 0.3 -

1%.Procosol exhibited expansion exceeding 6% after prolonged storage .Epoxy based

sealers AH 26, AH 26 silver free exhibited a large initial expansion of 4-5 %.AH plus

expanded from 0.4 % after 4 weeks up to 0.9 %.Apexit plus showed minor variation.

Bacterial penetration may be a real threat from sealer shrinkage as little as 1%. 11

12. A study was done to investigate the effects of modifications of the powder/liquid

ratio by endodontists on the physical properties recommended by ISO standards as well

as on other clinically relevant properties of zinc oxide–eugenol-based root canal sealers.

The powder/liquid ratio of two zinc oxide–eugenol-based root canal sealers (Cortisomol

and Pulp Canal Sealer EWT) was recorded by 10 endodontists. The materials, prepared

according to the different consistencies, were tested according to ISO standards to

evaluate their physical properties. Their sealing efficiency and the release of eugenol

were also evaluated on 20 single rooted teeth. Results showed that variations in the

powder/liquid ratio of zinc oxide–eugenol-based root canal sealers have a limited

influence on the properties of the sealers. The endodontists can prepare the zinc oxide–

eugenol-based root canal sealers at their chosen consistency according to the filling

technique they use10.

13. A study was done to evaluate the long-term sealing ability of four contemporary

endodontic sealers [Pulp Canal Sealer (PCS), AH-Plus, GuttaFlow and Epiphany] using a

fluid filtration technique. The palatal roots of 40 human maxillary molar teeth were

selected and the root canal was prepared using a crown-down technique (apical size 40,

6% taper). Roots were irrigated with 3% NaOCl, 17% EDTA solution and rinsed with

distilled water. Canals were filled with either PCS, AH-Plus, GuttaFlow or Epiphany

using a single-cone technique (n ¼ 8). Twenty-four hours after filling, the roots were

connected to an automatic flow-recording device (Flodec System) filled with double-

distilled water under pressure (0.2 bar) to measure leakage and flow along the interface

between the sealer and the dentine. Flow rates were assessed at 6, 12 or 24-h and after 1-

year of storage. Results showed that none of the materials fully prevented fluid flow.

Fluid flow decreased after 6 h and decreased further after 12 h. After 24 h, PCS and AH-

Plus allowed significantly more fluid flow than GuttaFlow and Epiphany. After 1 year,

PCS allowed significantly more fluid flow than the other materials. No significant

changes in leakage occurred between 24 h and 1 year. GuttaFlow and Epiphany allowed

less fluid movement along filled straight roots.27

14. A study was done to evaluate both the precision of filling and the extension of

voids in main root canals as well as filling of lateral canals after using a two phase filling

technique with two sealers. Twenty-four maxillary and 26 mandibular molars were

selected and randomly assigned to two groups. Root canals were instrumented and then

filled using the vertical compaction with the apical backfilling technique, with Pulp Canal

Sealer (EWT) in group “A” and AH Plus in group “B.” After clearing, voids within the

filled main canals were measured by using a stereomicroscope. In addition, visible lateral

canals were counted, each unfilled space was measured, and five ratings (0 – 4) were

fixed. Results showed that when using the vertical compaction with the apical backfilling

technique with either AH Plus or PCS (EWT), the apical gutta-percha cold compaction

provided lesser voids than the middle coronal thermo mechanical compaction as well as

lower filling scores in the apical lateral canals. The same technique, when used with AH

Plus rather than PCS (EWT), provided lesser voids in the apical third and, regardless of

the canal third, better filling scores in the lateral canals.9

15. A study was done to compare the volumetric expansion of gutta-percha in the

presence of eugenol or physiologic saline over time. One hundred eighty sections of

gutta-percha cones were scanned to determine their total volume and surface area. They

were placed in sealed test tubes with either 2 µl eugenol or 2 µl saline and allowed to

soak for 24 hours, 7 days, or 30 days. The results were scanned again to determine the

volumetric changes in material after placement in the test solutions. Results showed that

specimens soaked in eugenol showed a dramatic increase in volumetric expansion versus

saline group at all time periods. Sealers that incorporated eugenol could have attributed to

gutta-percha volumetric expansion there by creating a better seal of obturation material.2

16. A study was done to evaluate the three dimensional expansion of gutta-percha at

various powder/liquid ratios of ZOE- based sealers by using spiral computed

tomography. Fifty freshly extracted premolars with single canal were decoronated and

instrumented by using RACE rotary instruments (35/06). The teeth were divided into 5

groups of 10 each, and volume of the canal was measured by using SCT. The teeth were

then obturated with gutta-percha cones (35/04) in groups ZOE 1:1 to ZOE 1:4 with Pulp

Canal Sealer EWT (ZOE-based) with powder/liquid ratio of 1:1, 1:2, 1:3, and 1:4,

respectively, and gutta-percha alone in control group (no sealer group). The filled volume

in each canal was measured by using SCT 1 day, 7 days, and 1 month after obturation,

and percentages of obturated volume and of volume changes in groups over time were

calculated. Results showed that increasing the ratio of eugenol in sealer resulted in

volumetric increase of gutta-percha.28

17. A study was done to evaluate the sealing ability of a new urethane methacrylate

resin-based sealer, EndoRez, was evaluated using a fluid-filtration model. Sixty-four

single-rooted lower bicuspids were decoronated, instrumented, and divided into 3 groups

of 20 each with 4 teeth used as controls. In group A, the roots were obturated with

EndoRez and a single cone of gutta-percha, group B with AH Plus and a single cone of

gutta-percha, and group C was obturated using gutta-percha with warm vertical

compaction and AH Plus sealer. All specimens were allowed to set for 7 days in 100%

humidity at 37°C.Results showed that EndoRez, when used as a sealer with a single,

gutta-percha cone, is not as effective at sealing the apex as AH plus when used with a

single cone or warm vertical compaction. Warm vertical compaction and the single-cone

method with AH Plus showed no statistical difference in ability to seal the canal.29

18. A study was done to analyze volumetrically the efficacy of various techniques to

fill root canals using spiral computed tomography (SCT). The teeth were divided into

four groups of 10 each and roots were filled by lateral compaction, Thermafil, Obtura II

and System B techniques, respectively. AH plus was used as sealer with all techniques.

The filled volume in each canal was measured using SCT and the percentage of obturated

volume (POV) was calculated. Results showed that the greatest POV was obtained with

System B and Thermafil. Voids were seen in all root fillings. Limitation of SCT is that it

is difficult to differentiate GP and sealer.30

19. A study was done to use the fluid transport model to evaluate the ex vivo short-

and long-term micro leakage along root canals filled with Gutta-flow or AH-Plus using

the cold lateral compaction technique. A total of 38 single-rooted human teeth were used

for the assessment of micro leakage. The crowns of the teeth were sectioned below their

cementoenamel junctions to adjust the length of the roots to approximately 15 mm. The

root canals were instrumented using the step-back technique and filled using cold lateral

condensation. The sealer employed was either Gutta-flow (Group A) or AH-Plus (Group

B). Micro leakage along the root canals was evaluated using a fluid transport model after

periods of 1 week and 3 months. Fluid filtration is a dynamic, quantitative and

nondestructive technique appropriate to assess micro leakage of root filling systems over

time (Wu &Wesselink1993, Wu et al. 1994). However, fluid transport demonstrates the

existence of one continuous void along a root filling; blind voids within the material

cannot be detected (Souza et al. 2008).Results showed that there was no significant

difference between AH-plus and Gutta-flow in terms of sealing ability.31

20. A study was done to investigate nondestructively the percentage of 3D voids and

marginal gaps in a pre-defined interface volume of interest (VOI) within root fillings

produced by Thermafil Obturators with either a hydrophobic epoxy-resin-based sealer

(AH Plus) or a hydrophilic flowable calcium-silicate sealer [mineral trioxide aggregate

(MTA) Flow]. Sixteen single root canals from extracted premolar teeth were prepared

with ProTaper rotary instruments, randomly allocated into two groups (n = 8) and filled

with size 30 Thermafil Obturators in association with AH Plus or MTA Flow sealers. The

filled roots were stored at 37 °C in 5 mL of Hank’s balanced salt solution (HBSS) used to

represent body fluids and scanned after 7 days and 6 months using a high-resolution

micro-CT. From each root, images of 3000 sections were analyzed in 3D and binarized

using a high-resolution Micro-CT (4-l resolution). The 3D distribution of voids (porosity

and marginal gaps) at the gutta-percha-sealer-dentine interface was detected through a

threshold grey level and expressed as percentage of the 40-l-thick pre-defined interface

VOI (20 l of interface dentine and 20 l of gutta-percha sealer). A method of analysis

based on the root canal segmentation was used, and coronal, middle and apical thirds

considered separately. Environmental Scanning Electron Microscope with Energy

Dispersive X-ray (ESEM-EDX) analysis was performed on the surface of both sealers

after soaking in HBSS. Results showed that Micro-CT proved to be a powerful

nondestructive 3D analysis tool for visualizing the porous internal microstructure of

dental/endodontic materials at the interface with dentine. The proportion of voids was

least in the apical third of root canals. Voids reduced over time in the presence of

simulated body fluid.32

21. A study was done to evaluate in-vitro the quality of root fillings completed by two

gutta-percha techniques – lateral condensation and single cone technique. Two sets of

maxillary and mandibular teeth were selected (up to second molar). Root canals were

prepared with ProTaper instruments and then randomly divided into two groups. In group

1 canals were filled with lateral condensation technique and in group 2, canals were filled

with single cone technique. AH-Plus sealer was used in all groups. After obturation the

quality was assessed by subjecting the samples through spiral CT using an innovative

technique having pixel frames. Percentage of root canal filled and unfilled space was

calculated and compared using obturation index. Both techniques produced comparable

results in terms of percentage of root canal filling. Void distribution was found to be

different in both groups. External voids were found to be more common in single cone

technique and internal voids were found mostly with lateral condensation technique. The

Obturation Index (as proposed by the authors) may find its applications in daily clinical

practice for judging the efficacy of obturation techniques, so that a technique with an aim

to create void less obturation space may be devised.33

22. A study was done to investigate the ability of BioRoot RCS, a tricalciumsilicate-

based root canal sealer and AH Plus to effectively fill the root canals of contralateral

teeth using three evaluation methods, and to investigate also the correlation between the

methods. The prepared root canals of ten pairs of contralateral mandibular premolar teeth

were filled with gutta-percha and sealer using lateral compaction. The percentage of

voids within the root canal was assessed by micro-computed tomography, whilst sealing

ability was investigated by fluid transport and leakage of fluorescent microspheres. The

interaction of sealer with dentine, and sealer penetration were assessed by confocal

microscopy. The void volume, fluid flow, microsphere leakage and sealer interaction

with dentine for both materials were compared. Results showed that Micro CT analysis

revealed a higher void volume for BioRoot RCS. The other techniques did not show a

difference between the sealing ability of the sealers. The correlation between the three ex

vivo methods of assessment was weak demonstrating their complementarity rather than

their concordance.34

23. A study was done to evaluate and compare the presence of voids in oval root

canals filled with different root canal sealers (EndoSequence BC Sealer, Smart paste bio,

Activ GP) and to compare those with root canals filled with AH Plus sealer using Micro-

CT. 40 freshly extracted human single-root maxillary premolars were used. Specimens

instrumented with the EndoSequence NiTi rotary instrument were assigned randomly into

four groups. In each group, root canals were filled with single-cone gutta-percha and one

of the tested sealers. Each specimen was then scanned using Micro-CT at a voxel

resolution of 13.47mm. Proportions of sections with voids in cross-sectional images and

void volumes for each sealer were calculated in the apical, middle, and coronal thirds.

The analysis showed a decrease in void formation in the apical third, with a significant

difference between the apical and coronal thirds among bio ceramic sealers, Activ GP,

and AH Plus but no significant difference between the apical and middle thirds or

between the middle and coronal thirds was found for the sealers tested . All root canal

sealers tested resulted in voids. The bio ceramic sealers (EndoSequence BC Sealer,

Smartpaste bio) produced similar voids which had the fewest in the apical third of root

canals among the sealers tested which can be related due to root canal anatomy

variations.35

24. A study was done to compare apical sealing ability of lateral compaction and

single cone gutta-percha techniques in root canals obturated using three different resin-

based root canal sealers. Seventy single-rooted human premolars were endodontically

treated using hand ProTaper. The samples were divided into three groups, that is, group I

(n = 20): AH Plus sealer; group II (n = 20): MetaSEAL sealer and group III (n = 20):

GuttaFlow2. On the basis of obturation technique, each group was further subdivided into

two subgroups of 10 each: subgroup A: single cone and subgroup B: cold lateral

condensation. All the specimens were immersed in methylene blue dye for 24 h, and then

the teeth were sectioned longitudinally. Apical leakage was measured under a

stereomicroscope. Result showed that the apical sealing ability of lateral condensation

was better than the single cone technique. GuttaFlow2 showed superior sealing ability as

compared to MetaSEAL and AH Plus in both lateral compaction and single cone

technique.36

25. A study was done to evaluate the value of Micro-computed tomography (MCT)

for use in endodontic research. Four periodontally involved highly calcified maxillary

first molars were extracted and then scanned for evaluation by a MCT system. The teeth

were then instrumented, and 2 of the 4 obturated before rescanning for comparison

evaluation. Several capabilities of the MCT to advance endodontic research significantly

were observed. Results showed that the ability of the MCT to present accurately the

external and internal morphologies of the tooth without tooth destruction; the possibility

of showing changes over time in surface areas and volumes of tissues; the ability to

assess area and volume changes after instrumentation or obturation; and the capability of

evaluating canal transportation following instrumentation or instrumentation and

obturation. The tremendous potential of this scientific tool was discussed. MCT

evaluation will continue to expand our understanding pertaining to endodontics. Not only

does it have potential as an advanced system for research, but it also provides the

foundation as an exciting interactive educational tool .37

26. A study was done to examine the potential and accuracy of Micro-computed

tomography (micro-CT) for imaging of filled root canals. The root canals of five

extracted maxillary teeth were shaped manually with K-files & filled by lateral

condensation using gutta-percha cones and AH plus sealer. The filled root canals were

examined by Micro-CT at resolutions <11μm. The roots were sectioned histologically

and standard photographs of the sectioned surfaces were taken. Digitized photographic

images and the corresponding micro-CT sections were correlated qualitatively by

superimposition. Results showed that the micro-CT technique was a highly accurate and

nondestructive method for the evaluation of root canal fillings and its constituents. The

fillings were clearly differentiated from the root canal walls. Individual gutta-percha

cones and sealer were discernable.16

27. A study was done to measure the percentage of volume of voids and gaps in root

canals obturated with different obturation materials by using Micro-Computed

Tomography (micro-CT). Root canals were prepared by using rotary files. The roots were

randomly allocated into 4 groups, and each group was obturated by using cold lateral

compaction with a different material (gutta-percha and TubliSeal sealer, EndoRez points

and EndoRez sealer, Real Seal points and Real Seal sealer, and a gutta-percha point and

GuttaFlow sealer). Roots were scanned with micro-CT, and volume measurements for

voids and gaps in the obturated roots were carried out by using specialized CT software.

Results showed that roots filled with gutta-percha showed less voids and gaps than roots

filled with the remaining filling materials.4

28. A study was done to evaluate ex vivo the quality of root fillings completed by two

thermo plasticized gutta-percha techniques(Thermafil and System B) and a cold gutta-

percha technique (single point) by 𝜇CT analysis.A total of 30 freshly extracted human

single-rooted permanent teeth were selected. Root canals were prepared with ProTaper

Universal instruments and then randomly divided into three groups (n = 10) depending on

the filling technique. In group 1, canals were filled with a single-point technique; group 2

was filled with Thermafil; in group 3 System B was used. In group 1 and group 3, the

root filling was performed using ProTaper Universal gutta-percha points, in group 2

Thermafil Obturators were used; AH-Plus sealer was used in all groups. Assessment of

the root filling was carried out by 𝜇CT, using a desktop X-ray micro focus CT scanner.

Percentage of root canal filling materials and voids was calculated for each specimen.

Results showed that all techniques produced comparable results in terms of percentage of

filling and void distribution.17

29. A study was done to compare the presence of voids in root fillings performed in

oval and ribbon shaped canals with two root filling techniques, lateral compaction

technique (LCT) or hybrid technique (HT), a combination of a gutta-percha master point

and thermoplastic gutta-percha. Furthermore, the obturation time for the two techniques

was evaluated. Sixty-seven roots with oval and ribbon-shaped canals were prepared using

Profile Ni-Ti rotary files. After preparation, the roots were randomly allocated to two

groups according to root filling technique. All roots were filled with AH plus and gutta-

percha. Group 1 was filled using LCT (n = 34) and Group2 was filled using HT (n = 33).

The obturation time was measured in 30 cases evenly distributed between the two

techniques. Voids in relation to the root canal fillings were assessed using cross-section

images from Micro Computed Tomography scans. Results showed that using the Micro-

CT technique as the validation method, voids were present in all root fillings. The present

study found no statistically significant difference in percentage of voids between two root

filling techniques. A 40% reduction in obturation time was found for the HT compared to

the LCT.38

30. A study was done to analyze the formation of voids and gaps in root canals

obturated with different sealer materials in combination with warm gutta-percha vertical

compaction technique by using BeeFill® 2in1[warm gutta-percha systems. Twenty-four

single-rooted teeth were collected, and root canals were prepared by using rotary files.

All teeth were randomly allocated into three groups. Each group was obturated by using

the BeeFill® 2in1 system in combination with Seal apex (non-eugenol, calcium

hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal

(polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin

based sealer; VDW, Germany). Following preparation, all teeth were scanned with a

micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the

obturated root canals was performed to analyze the volume of interface voids and gaps in

the obturated teeth. Results showed that demonstrated that the silicon based sealer

RoekoSeal induced significantly less voids and gaps than other tested materials. The

amount of voids and gaps significantly was higher in the apical region. These data

indicate that none of the root canal filled teeth were free of gaps. Teeth obturated with

RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation

in combination with the BeeFill® 2in1 obturation system.39

31. A study was done to compare the quality of four different root canal obturation

techniques: cold lateral condensation (CLC), warm vertical condensation (WVC), Obtura

II (OII) and Gutta Flow (GF) by using micro-computed tomography (micro CT). A total

of 20 extracted maxillary first molars prepared with ProTaper files, were randomly

divided into four groups. Micro CT was used to measure the internal volume of root

canals. Following application of AH26 sealer to canal obturation, new micro-CT images

were taken and the volume percentage (VP) of voids, gutta-percha and sealer at different

levels were calculated with CT software. Results showed that the present in vitro study

demonstrated that none of the root canal filled teeth were gap-free; GF and CLC

obturation techniques had the highest and the lowest VP of obturation materials,

respectively.15

32. A study was done to assess the percentage volumes of filling materials and voids

in oval‐shaped canals filled with either cold lateral compaction or warm compaction

techniques, using micro‐computed tomography (micro‐CT).Twenty‐four single‐rooted

maxillary premolar teeth with oval‐shaped canals were selected and the root canals

prepared and assigned to two groups (n = 12), according to the filling technique: cold

lateral compaction (CLC) or warm vertical compaction (WVC). Each specimen was

scanned using a micro‐CT device at an isotropic resolution of 12.5 μm. Percentage

volumes of root filling materials and voids were calculated, and data were statistically

analyzed using Student's t‐test and Friedman's test, with a significance level of 5%.

Results showed that no root fillings were void free. Warm vertical compaction produced

a significantly greater volume of gutta‐percha and a significantly lower percentage of

voids than those achieved with cold lateral compaction. Distribution of sealer and voids

within the root canal space after root filling was unpredictable, irrespective of the

technique used.40

33. A study was to apply Micro Computed Tomography to quantitative evaluation of

voids and to test any specific location of voids in root canal obturations. Twenty root

canals were prepared and obturated with gutta-percha and TubliSeal sealer using the

thermoplastic compaction method (System B + Obtura II). Roots were scanned and three-

dimensional visualization was obtained. The volume and Feret’s diameter of I-voids (at

the filling/dentine interface) and S-voids (surrounded by filling material) were measured.

Results revealed that none of the scanned root canal fillings were void-free. For I-voids,

the volume fraction was significantly larger, but their number was lower, than for S-

voids. Both types of voids occurred in characteristic regions. I-voids occurred mainly in

the apical third, while S-voids in the coronal third of the canal filling. Results indicate

that micro tomography, with proposed semi-automatic algorithm, is a useful tools for

three-dimensional quantitative evaluation of dental root canal fillings. In canals filled

with thermoplastic gutta-percha and TubliSeal, voids at the interface between the filling

and canal dentine deserve special attention due to of their Periapical location, which

might promote apical microleakage.41

34. A study was done to evaluate and compare the volume percentage of root canals

obturated with gutta-percha (POV), with various techniques using spiral computed

tomography (SCT).Forty-five mandibular first premolar teeth were instrumented using

RACE files and randomly divided into three groups of 15 teeth each (n = 15). The

volume of root canal space was measured using SCT and the root canals were obturated

as follows: Group 1–lateral condensation, Group 2–single-cone obturation and Group 3–

thermo plasticized gutta-percha technique. The filled volume of root canals was measured

using SCT and POV was calculated in total and at apical, middle and coronal third

individually. Results showed that all the groups showed 100% POV at the apical third.

Group 2 showed least POV at the middle third of the root canal.6

35. A study was done to investigate voids in different root canal sealers using micro-

CT and Nano- CT, and to explore the feasibility of using Nano-CT for quantitative

analysis of sealer filling quality.30 extracted mandibular central incisors were randomly

assigned into three groups according to the applied root canal sealers (Total BC Sealer,

Sure Seal Root, AH Plus) by the single cone technique. Subsequently, Micro-CT and

Nano-CT were performed to analyse the incidence rate of voids, void fraction, void

volume and their distribution in each sample. Results showed that Micro-CT evaluation

showed no significant difference among sealers for the incidence rate of voids or void

fraction in the whole filling materials, whereas a significant difference was found

between AH Plus and the other two sealers using Nano-CT. All three sealers presented

less void volume in the apical third; however, higher void volumes were observed in the

apical and coronal thirds in AH Plus using Micro-CT while Nano-CT results displayed

higher void volume in AH plus among all the sealers and regions 7.

MATERIALS AND METHODS

ARMAMENTARIUM USED

Airotor handpiece (NSK )

Endodontic access burs No.2 (Dentsply Maillefer, Ballaigues, Switzerland)

K- Files

M2 ROTARY FILES [DENTSPLY INDIA]

Micro CT scanner [Skyscan 1072]

Glass beaker

Storage glass bottle

MATERIALS USED:

40 extracted single rooted human premolars

5.25% Sodium hypochlorite [VIP Vensons India, Dental Division,

Karnataka]

Saline[Otsuka pharmaceutical company]

EDTA [RC-prep premier dental, India ERC/114]

Sterile paper points [Dentsply Maillefer]

GP points[Dentsply 35/04]

ZOE-based root canal sealer [Pulp canal sealer EWT, Sybron Endo]

AH plus sealer [Dentsply 1308000717]

Wax blocks made of modelling wax

TABLE 1 Composition of materials used

AH plus sealer [Dentsply)

Epoxide paste Amine paste

Diepoxide 1-adamantane amine

Calcium N,N-dibenzyl-5-oxa-nonandiamine-1,9

Zirconium oxide TCD-diamine

Aerosol Calcium tungstate

Pigment Zirconium oxide

Aerosil

Silicone oil

Pulp canal sealer [Sybron endo)

POWDER LIQUID

Zinc oxide Oil of cloves

Precipitated molecular silver Canada balsam

Oleoresins[white resin]

Thymol iodide

METHODOLOGY FLOW CHART

Forty freshly extracted single rooted human premolars with closed apices, extracted for orthodontic

reasons were used for this study.

Sample teeth were decoronated at cementoenamel junction to obtain standardized length of 17mm in

all the groups.

Cleaning and shaping of root canals was performed in all the teeth with M2 ROTARY FILES

[DENTSPLY INDIA] as per manufactures instructions up to # 35/06.

Constant irrigation with 5.25% sodium hypochlorite and EDTA (RC Prep Premier Dental, India) as

a lubricant was performed.

.Ethylene diaminetetraaceticacid (RC-Prep, Premier Dental,India) will be used as the irrigant once

complete cleaning and shaping will be done followed by rinsing with saline.

After root canal preparation, teeth were randomly divided into five groups of 08 teeth each.

Group 2 -

Powder/liquid ratio

of ZOE sealer 1:2

and GP

Group 3 -

Powder/liquid ratio

of ZOE sealer 1:3

and GP

Group1-

Powder/liquid

ratio of ZOE

sealer 1:1 and

(GP)

Group 4-AH plus

sealer and GP

Control Group –

Only GP and no

sealer was used.

METHOD:

This study was carried out in the Department of Conservative Dentistry and Endodontics,

K.L.E Society‘s Institute of Dental Sciences and Hospital, Bangalore.

SOURCE OF DATA:

Forty freshly extracted contralateral single rooted human mandibular premolar samples

were collected from Department of Oral and Maxillofacial Surgery, K.L.E Society’s

Institute of Dental sciences, Bangalore.

Sample size –40 extracted human mandibular premolars

INCLUSION CRITERIA:

Single rooted contralateral human Mandibular premolars with single canal and

closed apices confirmed radiographically.

EXCLUSION CRITERIA:

Premolars with incompletely formed apices, calcified canals, fractures or

Resorption.

Obturation was performed with GP points (35/04) and ZOE-based root canal sealer [Pulp canal sealer EWT,

Sybron endo] in different powder-liquid ratios & AH plus sealer [Dentsply].

Micro-Ct Scanner

SAMPLE PROCESSING:

The selected teeth were cleaned thoroughly of any debris or calculus using

ultrasonic scalers (Suprasson, Statellec) and stored in saline solution at room

temperature until subjected to use.

SAMPLE PREPRATION:

Forty freshly extracted single rooted human Mandibular premolars with closed apices,

extracted for orthodontic reasons were used for this study. The sample teeth were

decoronated at cementoenamel junction to obtain standardized length of 17mm in all the

groups. Conventional access to the root canal system was performed using high-speed

Airotor handpiece (NSK PANA Airotor, contra angle handpiece, Japan) and endodontic

access bur no.2 (Dentsply Maillefer, Ballaigues, Switzerland). Patency of each canal was

established by placing a size 10 K-file (Mani Inc. Tochigi, Japan) until it is visible in the

apical foramen. Working length was derived by subtracting 0.5mm from the measured

length. Cleaning and shaping of root canals was performed in all the teeth with M2

ROTARY FILES [DENTSPLY INDIA] as per manufactures instructions up to # 35/06.

Constant irrigation with 5.25% sodium hypochlorite and EDTA (RC Prep Premier

Dental, India) as a lubricant, were performed. Ethylene diamine tetra-acetic acid (RC-

Prep, Premier Dental India) were used as the irrigant once complete cleaning and shaping

were done followed by rinsing with saline.

After root canal preparation, teeth were randomly divided into five groups of 08 teeth

each. Before obturation, root canals were dried with a #35 paper point. Obturation was

performed with GP points (35/04) and ZOE-based root canal sealer [Pulp canal sealer

EWT, Sybron endo] in different powder-liquid ratios & AH plus sealer [Dentsply].

Samples were divided in following groups:

TEST GROUPS -

GROUP 1: (n=08) Powder/liquid ratio of ZOE sealer 1:1

Consisted of 08 samples, were obturated with Gutta-percha in contact with zinc-Oxide

eugenol Sealer with powder/ liquid Ratio of 1:1.

GROUP 2: (n=08) Powder/liquid Ratio of ZOE sealer 1:2


eugenol Sealer, powder/ liquid Ratio of 1:2.



eugenol Sealer, powder/ liquid Ratio of 1:3.

GROUP 4: (n=08) AH Plus sealer & GP

Consisted of 08samples, were obturated with Gutta-percha using AH Plus sealer

GROUP 5: (n=08) No sealer was used. (Control group)

Consisted of 08 samples, were obturated with Gutta-percha without using sealer

For the purpose of standardization, sealers were not applied onto the canal walls. The GP

cones were individually coated uniformly with the sealer by dipping for 5 seconds. The

obturations were performed by sealer coated single cone GP (35/04). Teeth were kept

moist throughout the test by covering with wet gauze and stored in airtight containers.

Specimens were scanned using high resolution micro-CT scanner, to determine the

volume of GP and sealer in all five groups after 7 days of obturation. Obturated volumes

of root canal in each tooth were calculated. The second micro CT scans were taken 30

days after obturation. The mean volume and percentage volume of GP per group were

calculated. Presence of Voids were also assessed.

SAMPLE SIZE ESTIMATION:

• The sample size for the present study was estimated using G*Power Software

version 3.1.9.2. The test family selected was F tests, and number of measurements

were two. By keeping the Power of the study at 90%, Alpha (α) at 5% and Effect

Size (f) at 0.25 the total sample size was calculated as 40, that is 8 samples in

each group. The Sample size of this study is derived from following formula:

• N = �

��

�∗ �

�

� Where,

• Z= 1.96, when alpha is 0.05

• σ2 = Pooled Variance taken from previous studies (0.00000511) (give reference)

• d = Precision of measurement = 0.001

• Therefore N= 39.3 which is rounded off to 40.

RESULTS

The present in-vitro study was done to compare the 3D volumetric changes of GP

at various powder/liquid ratios of ZOE-based sealer & AH Plus sealer using MICRO CT

after 7 and 30 days.

TEST GROUPS -




GROUP 4: (n=08) AH Plus sealer & GP

GROUP 5: (n=08) No sealer was used. (Control group)

Method of Statistical Analysis

The sample size for the present study was estimated using G*Power Software

version 3.1.9.2.

The data was compiled using Microsoft Excel Spread sheet and subjected to

statistical analysis using Statistical Package of Social Sciences (SPSS).version 20

One Way Analysis of Variance (ANOVA) for repeated measures was used to

compare the difference between four groups.

Tukey’s post hoc test for multiple pairwise comparisons.

Shapiro Wilk’s test was done to determine normality of the data.

Data was found to be normally distributed, thus parametric tests were done.

Paired Samples T test was done to determine whether there was any statistically

significant difference in the mean expansion of Gutta-Percha on using the same

sealer when measured at 7 days and 30 days.

*P <0.001 was considered statistically significant for all tests.

Table 1 shows comparison of mean obturated volume of root canals after 7 days and 30

days using different sealers.

The Groups 3and 4 have the highest mean obturated volume values during the period of

30 days and were statistically significant compared with Groups 1, 2 and control group

[p<0.001].

The test results showed that mean volumetric expansion of Gutta-percha in Group 1

[ZOE 1:1) at 30 days was higher [1684] as compared to7 days [1664] with the mean

difference of 27.1. This Mean difference was statistically significant at [p<0.001].

The mean volumetric expansion of Gutta-percha in Group 2 [ZOE 1:2 ]at 30 days was

higher[1754] as compared to 7 days [1728, ZOE 1:2], with the mean difference of 38.11.

This Mean difference was statistically significant at [p<0.001].

The mean volumetric expansion of Gutta-percha in Group 3[ZOE 1:3 ]at 30 days was

higher [1782] as compared to 7 days [1746, ZOE 1:3], with the mean difference of

16.36. This Mean difference was statistically significant at [p<0.001].

The mean volumetric expansion of Gutta-percha in Group 4[AH plus] at 30 days was

higher [1768] as compared to 7 days [1735, AH plus], with the mean difference of 30.52.

This Mean difference was statistically significant at [p<0.001].

Paired t test

*Statistically Significant

Table 1: The obturated mean volume of root canals and standard deviation after 7,

and 30 days

Paired Differences T Sig. (2-

tailed)

Mean Std.

Devia

tion

95% Confidence

Interval of the

Difference

7 days 30

days

Lower Upper

Pair 2

ZOE1:1,7

Days

ZOE1:1,30

Days

1664

1684 -

19.38

75

2.023

0

-

21.07

88

-17.6962 -27.106 <0.001

*

Pair 3

ZOE1:2,7

Days

ZOE1:2,30

Days

1728

1757

-

28.81

25

2.138

4

-

30.60

02

-27.0248 -38.110

<0.001*

Pair 4

ZOE1:3,7

Days

ZOE1:3 30

Days

1746

1782

-

31.77

125

5.490

78

-

36.36

165

-

27.18085 -16.366

<0.001*

Pair 5

AH PLUS 7

Days

AH PLUS 30

Days

1735

1768

-

31.78

75

2.945

4

-

34.24

99

-29.3251 -30.525

<0.001*

Table 2 shows Comparison of Expansion of Gutta-percha when using different

sealers after 7 days

Test results showed that the expansion of gutta-percha using different sealer Group 3

[ZOE 1:3] was the highest with mean value 1745.703, followed by Group 4 [AH plus]

with mean value 1734.587and Group 2 [ZOE 1:2] with mean value 1727.562

The test results showed that mean volumetric expansion of Gutta-percha in Group

1[ZOE 1:1] 7 days was lower 1662.662 followed by Group 5 [control group]

1436.913.Results were statistically significant at [p<0.001]

Table 2-Comparison of Expansion of Gutta-percha when using different sealants after 7

days

Groups N Mean Std.

Deviation

95% Confidence Interval for

Mean

F Value P value

Lower

Bound

Upper Bound

Control 8 1436.9125 1.12178 1435.9747 1437.8503

174113.689 <0.001*

ZOE 1:1 8 1662.6625 1.16978 1661.6845 1663.6405

ZOE 1:2 8 1727.5625 .67810 1726.9956 1728.1294

ZOE 1:3 8 1745.7038 .46241 1745.3172 1746.0903

AH Plus 8 1734.5875 .74917 1733.9612 1735.2138

Total 40 1661.4858 117.44335 1623.9255 1699.0460

ANOVA


Table 3- shows Comparison of Expansion of Gutta-percha when using different

sealers after 30 days

Test showed that the expansion of gutta-percha using different sealers Group 3 [ZOE

1:3] was the highest with mean value 1777.475, followed by Group 4 [AH plus] with

mean value 1766.375 and Group 2 [ZOE 1:2] with mean value 1756.375.

The test results showed that mean volumetric expansion of Gutta-percha in Group

1(ZOE 1:1 30 days) was lower 1682.050 followed by Group 5 [control group] 1436.913.

Results were statistically significant at [p<0.001]

Table 3-Comparison of Expansion of Gutta-percha when using different sealants after 30

days

Groups N Mean Std.

Deviation

95% Confidence Interval for

Mean

F Value P value

Lower Bound Upper Bound

Control 8 1436.913 1.1218 1435.975 1437.850

17288.446 <0.001*

ZOE 1:1 8 1682.050 1.6098 1680.704 1683.396

ZOE 1:2 8 1756.375 1.8904 1754.795 1757.955

ZOE 1:3 8 1777.475 5.4437 1772.924 1782.026

AH Plus 8 1766.375 3.2043 1763.696 1769.054

Total 40 1683.838 129.5821 1642.395 1725.280

ANOVA


Table 4: shows multiple pair wise comparison of different sealers used during 7 days

• Multiple comparisons of ZOE 1:1,ZOE 1:2,ZOE 1:3 AH plus and control group were

done using Tukey‘s Post hoc Analysis, which showed there is statistically significant

change in volume of GP in different groups at 7 days and 30 days interval.

There was a statistically significant difference in the volumetric expansion of GP samples

in Groups 2, 3 and 4 compared with Groups 1 and 5 during the 7 days period.

In Group 1[ZOE 1:1], shows a statistically significant less change in volume of GP when

compared with Group 2 ZOE 1:2[64.9 ] ,Group 3 ZOE 1:3 [83.04], Group 4 AH plus

[71.92] .The mean differences in the volumes between groups in 7 days were all

statistically significant.

In Group 2[ZOE 1:2], shows a statistically significant lesser change in volume of GP

when compared with Group 3 ZOE 1:3[18.14] ,Group 4 AH plus [7.02] The mean

differences in the volumes between groups in 7 days were all statistically significant.

In Group 3 [ZOE 1:3], shows a statistically significant higher change in volume of GP

when compared with Group 4 AH plus [11.11] and control group [308.79 ] The mean


In control group, shows a stastically significant no change in volume of GP when

compared to different groups in 7 days.

TABLE -4-Mean Comparison of 7 days

(I) Group (J) Group Mean Difference (I-J) Sig.

Control

ZOE 1:1 -225.75000* .000

ZOE1:2 -290.65000* .000

ZOE1:3 -308.79125* .000

AH Plus -297.67500* .000

ZOE 1:1

Control 225.75000* .000

ZOE1:2 -64.90000* .000

ZOE1:3 -83.04125* .000

AH Plus -71.92500* .000

ZOE1:2

Control 290.65000* .000

ZOE 1:1 64.90000* .000

ZOE1:3 -18.14125* .000

AH Plus -7.02500* .000

ZOE1:3

Control 308.79125* .000

ZOE 1:1 83.04125* .000

ZOE1:2 18.14125* .000

AH Plus 11.11625* .000

AH Plus

Control 297.67500* .000

ZOE 1:1 71.92500* .000

ZOE1:2 7.02500* .000

ZOE1:3 -11.11625* .000

Scheffe’s Test


Table 5: shows multiple pair wise comparison of different sealers used during 30

days

There was a statistically significant difference in the volumetric expansion of GP samples

in Groups 2, 3 and 4 compared with Groups 1 and 5 during the 30 days period.

In Group 1 [ZOE 1:1], shows a statistically significant lesser change in volume of GP

when compared with Group 2 ZOE 1:2 [74.3] ,Group 3 ZOE 1:3 [95.42], Group 4 AH

plus [84.32] The mean differences in the volumes between groups in 30 days were all

statistically significant.

In Group 2 [ZOE 1:2], shows a statistically significant lesser change in volume of GP

when compared with Group 3 ZOE 1:3 [21.1], Group 4 AH plus [10.00] .The mean


In Group 3 [ZOE 1:3], shows a statistically significant higher change in volume of GP

when compared with Group 4 AH plus [11.10] and control group [340.56 ] The mean


In control group, shows a statistically significant no change in volume of GP when

compared to different groups in 30 days.

Multiple Comparisons Table of 30 days

(I) Group (J) Group Mean Difference (I-J) Sig.

Control

ZOE 1:1 -245.1375* .000

ZOE1:2 -319.4625* .000

ZOE1:3 -340.5625* .000

AH Plus -329.4625* .000

ZOE 1:1

Control 245.1375* .000

ZOE1:2 -74.3250* .000

ZOE1:3 -95.4250* .000

AH Plus -84.3250* .000

ZOE1:2

Control 319.4625* .000

ZOE 1:1 74.3250* .000

ZOE1:3 -21.1000* .000

AH Plus -10.0000* .000

ZOE1:3

Control 340.5625* .000

ZOE 1:1 95.4250* .000

ZOE1:2 21.1000* .000

AH Plus 11.1000* .000

AH Plus

Control 329.4625* .000

ZOE 1:1 84.3250* .000

ZOE1:2 10.0000* .000

ZOE1:3 -11.1000* .000

Scheffe’s Test


Graph 1-Mean volumetric expansion of Gutta-percha at 7days interval

Graph 2-Mean volumetric expansion of Gutta-percha for groups at 30 days intervals

1436.9125

1662.66251727.5625 1745.7038 1734.5875

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Control ZOE 1:1 ZOE 1:2 ZOE 1:3 AH Plus

Mean Expansion of gutta percha in different groups after7 days

Graph 3-Comparison of Mean volumetric expansion of Gutta-percha during 7 days and

30 days intervals.

Sealers undergo shrinkage upon setting, there is a potential for gaps or voids creation via

which micro leakage may occur.42

In this present study it was observed that

Overall, canals obturated with gutta-percha with ZOE1:3 showed the lowest voids

and gaps whereas those obturated with AH plus showed the highest voids.

In the coronal third, root canals obturated with gutta-percha with ZOE1:3 showed

the lowest voids and gaps, whereas canals obturated with AH plus showed the

highest voids.

In the middle third,, canals obturated with ZOE 1:3 showed the lowest voids and

gaps , whereas those obturated with ah plus showed the highest voids and gaps

In the apical third. All the groups showed the lowest voids and gaps.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Control zoe1;1 zoe 1;2 zoe 1:3 ah plus

Mean Expansion of Gutta Percha

7 Days 30 Days

DISCUSSION

The final objective of endodontic procedures should be the total obturation of the

root canal space. Biologic necessity requires the elimination of the protein degradation

products, bacteria, and bacterial toxins which emanate from necrotic and gangrenous root

canals. While these irritants may be eliminated by extraction of the tooth, the health of

the dentition is secured more soundly if they are eliminated by the cleaning and shaping,

sterilization, and total obturation of the root canal system. In the final analysis, it is the

sealing off of the complex root canal system from the periodontal ligament and bone

which insures the health of the attachment apparatus against breakdown of endodontic

origin.43After an effective microbial-control phase, an adequately prepared and filled

canal should contribute to a high probability of success.4

GP popularized by Bowman in 1867 is the most widely used root canal-filling

material with different types of sealers.6Gutta-percha seals significantly better when used

in combination with a sealer to provide a fluid-tight seal. 44Unfortunately, it does not

provide chemical bonding to the root canal wall. 4Gutta-percha cone cannot fit perfectly

alone owing to low adhesiveness to the canal walls and the complexity of root canal

systems. This leads to unfavorable microbial leakages in the filled canals. To compensate

for this, various sealer materials are developed and employed to fill the remaining

irregular spaces between the gutta-percha cone and surrounding dentinal wall.7

The sealer is capable of filling imperfections and increases adaptation of the root

filling.44 sealers are essential to optimize the outcome of the root canal treatments and

prevent reinfection.35 Therefore sealer plays an important role in sealing the root canal;

without using sealer, micro leakage may occur.(Marshall &Massler 1961,

Michanowicz&Czonstkowsky 1984, Czonstkowskyet al 1985, ElDeeb 1985, Skinner &

Himel 1987, Hataet al .1992, Wu et al .2000a).20

Micro leakage is a major cause of endodontic failure, which may occur between

the gutta-percha and sealer, between the sealer and dentin, or through voids within the

sealer. Thus, the quality of a root canal filling and the success rate of endodontic

treatment depend greatly on the sealing ability of a root canal sealer.35

Various types of sealers can be used along with GP for obturation of root canal

space. All the sealers which are used for obturation inherently shows shrinkage behavior

during setting, this shrinkage associated with setting might jeopardize the seal of root

canal, leading to root canal failure.11

Among various sealers used, ZOE‑based sealers are commonly used because of

its cost effectiveness, ease of availability and bacteriostatic property. Hammad et al.

performed a study to evaluate the setting shrinkage behavior of recently developed

resin‑based sealer compared to that of ZOE‑based sealer and concluded that ZOE sealer

exhibited statistically lesser shrinkage when compared to that of resin‑based sealers.45

Eugenol has successfully been used in dentistry for more than 125 years and has been

incorporated in many of today’s endodontic sealers. Eugenol has many therapeutic effects

including antimicrobial and anesthetic properties. Eugenol (C10H12O2) is an allyl chain–

substituted guaiacol extracted from certain essential oils, especially from clove oil. It is a

weak acid with a pKa of 10.4 and occurs as hydrogen bonded diamers.2

Eugenol remains in excess in fresh mixes of ZOE where it is not entirely

crystallized as zinc eugenolate. The surface of the set material readily undergoes

hydrolysis, with the release of free eugenol into adjacent fluids.46 Eugenol based sealers

might in fact have a vital role in the expansion of the gutta-percha in the obturated canals

over time; thereby enhancing the sealing capabilities and assisting in the success of the

root canal treatment. Therefore, increasing the amount of eugenol in the mix would not

impair the sealing and physical properties of the sealer and would possibly provide an

increase in free eugenol at the sealer gutta-percha interface. The increase in free eugenol

could possibly contribute to the volumetric expansion of the gutta-percha in the canal

system and might provide a more impermeable seal.2

Chandrasekhar et al. evaluated expansion of GP in contact with various

concentration of ZOE‑based sealers and concluded that as powder/liquid ratio of

ZOE‑based sealer decreases, volumetric expansion of GP cones increases.28

Pulp Canal Sealer EWT was chosen in this study because it is a ZOE based sealer with

extended working time of around 6 hours.28 In this study decreasing order of P/L were

selected in groups ranging from1:1 in Group 1, 1:2 in Group 2 and 1:3 in Group 3.A

study done by Chandrasekhar et al has shown that ZOE 1:4 ratio showed a very minimal

expansion after both 7 and 30 days interval, which could be due to insufficient amount of

contact time of GP with ZOE sealer, which was very thin in consistency.Gerosaet al.

showed that pure eugenol is cytotoxic and represents one of the ingredients responsibility

for its cytotoxicity in ZOE based endodontic cements .ZOE is highly toxic only when

just mixed and its cytotoxicity decreases over time. Hume et al concluded that toxicity of

eugenol depends on its concentration and length of time cells are exposed to. There are

also other toxic components that play a role in cytotoxicity which needs to be verified.12

Hashieh et al reported that amount of eugenol released in periapical space from ZOE-

based sealers are very low. ZOE‑based sealer shows any cytotoxic effect only when it is

extruded beyond the apical foramen and comes in direct contact with cells of periodontal

ligament and alveolar bone; it does not have any cytotoxic effect if confined within the

root canal. 13

Pulp Canal Sealer EWT contains resin to increase the adhesion to dentin, to

improve the mechanical properties of sealer, and to control the setting reaction.

Therefore, this can control the seepage of free eugenol from the canal into the periapical

tissues.28 Maseki et al. demonstrated that no positive correlation was found between

eugenol release and cytotoxicity of the root canal filling material.47

Studies done by Wu et al. and Kontakiotiset al Shown that sealers applied as thin

layers provide a better apical seal than as thick layers .A thin layer of sealer has a smaller

surface area than a thick layer does, and this may favorably reduce the speed of

dissolution; this may explain why thin layers of these materials are associated with less

gross leakage than thick layers.26

In the present study AH plus sealer was chosen to compare with ZOE based

sealer. ZOE-based sealers have been used for many years with clinical success in spite of

their limitations like low viscosity, porosity, lack of chemical adhesion to the dentine and

solubility in tissue fluids.48 AH Plus which is a silver free epoxy based sealer used in

conjunction with gutta-percha in various root-filling techniques 49 frequently used as a

comparison material in endodontic research because of its gold standard properties,

which include long-term dimensional stability, cytocompatibility,

biocompatibility,reduced solubility, apical sealability, microretention to root dentine and

low toxicity (Versiani et al. 2006, Resende et al. 2009, Mar_ın-Bauzaet al. 2012, Silva et

al. 2013)50

Conventional methods to assess quality of root fillings include leakage studies

using dyes or alternative tracers (Wu and Wesselink 93), such as fluid filtration, dye

penetration, radioisotopes, bacterial penetration, and saliva leakage. Previous studies

have indicated that conventional methods have disadvantages, such as being time-

consuming, and cannot be standardized (Siqueira et al., 2000). Moreover, the pressure

used in the fluid filtration method cannot be appropriately standardized (Pommel and

Camps, 2001), dye penetration studies do not simulate the true clinical situation, and dye

studies demonstrate that air entrapped in voids along the root canal filling may hinder

fluid movement (Verssimo and do Vale, 2006). Bacterial micro-leakage studies involve

long periods of observation and do not allow quantification of the number of penetrating

bacteria (Siqueira et al., 2000). Jung et al., 2005.35

High-resolution micro-CT is an emerging technology with several promising

applications in many different fields of dentistry and in endodontics, and its use has

increased dramatically during the past 2 decades. Micro-CT has been used as a research

tool in various applications. In the field of endodontic research, MCT technology has

been used for the evaluation of root canal anatomy and assessment of root canal

morphology after instrumentation.4

Microcomputed tomography (Micro-CT) is a nondestructive 3D imaging

technique used to evaluate the microarchitecture, morphology and density of mineralized

tissues and the internal structure and porosity of biomaterials and scaffolds. It is a

powerful nondestructive 3D analysis tool for visualizing the porous internal

microstructure of dental/endodontic materials at the interface with dentine.32

The micro-CT technique could help to overcome some of the disadvantages of the

methods generally used to assess root canal obturation as it is possible to distinguish

between sealer, gutta-percha cones and voids. With the help of a 3-D reconstruction,

information about the complete filling and about the distribution of the components of a

root canal filling can be obtained.16 Micro-CT offers the possibility of repeated scanning.

Thus, it will be possible to evaluate changes of filling over time. It can show changes

over time with respect to surface area and volume of tissues (Nielsen et al. 1995).16

Mandibular premolars with a single canal were used in this study. They are oval

shape which provide GP to undergo dimensional change. The use of contralateral teeth

provided a more balanced specimen selection, thus excluding sample bias. 34

In the present study, cleaning and shaping was performed using M2 Rotary files [VDW,

Munich, Germany] (35/06).Files of the Mtwo (M2) system (VDW, Munich, Germany)

feature an S-shaped cross-sectional design, a positive rake angle with two cutting edges,

and increasing pitch length from the tip to the shaft. Mtwo has been shown highest cyclic

fatigue resistance, in apical abrupt curvatures, when compared with ProTaper

Universal.51To evaluate the percentage of visible expansion of GP points, a single cone

obturation using a less tapered cone of GP (35/04) [Dentsply Maillefer] was used to

provide space for expansion of GP, if any. The single cone technique was selected in the

study because of its simplicity and because it is less operator- dependent compared to

other root filling techniques, and may be better indicated in round-canal teeth prepared to

the shape of the instruments used. It was suggested that single cone is a frequently used

root canal filling technique. The use of matched-taper gutta-percha points relies on the

original canal shape and the ability to create a tapered circular preparation.7Samples were

Standardized in all groups by applying the sealer of various ratios in their respective

groups by dipping the GP for 5 seconds.

Allan et al. showed different time frames for various sealers to completely set.

Their results verified that Roth’s sealer was the slowest to set, taking 4 – 8 weeks or

longer for a complete set.52

In the present study, mean volumetric expansion of GP was measured in the

presence of various concentrations of ZOE‑based sealers at different time intervals of 7

and 30 days were chosen because it has been suggested that volumetric expansion

increased with time, suggesting that slow-setting eugenol sealers might cause significant

expansion of the obturation mass .2

In present study mean volumetric expansion of Gutta-percha in Group 1, Group

2, Group 3, and Group 4 at 30 days was higher as compared to 7 days. The results of

the present study demonstrated a statistically significant difference in the volumetric

expansion of gutta-percha samples in Group 2 Group 3 & AH plus compared with other

Group 1 and control group during 7 and 30 day period. Results are in accordance with

Michaud et al who concluded that volumetric expansion of gutta-percha occurred in

contact with eugenol. Free eugenol release in 7 days causes expansion. Release of

eugenol continued till 30 days with slow setting sealers which is used in the present

study. An increase in powder/liquid ratio reduced the amount of released eugenol at 1-

month interval for Pulp Canal Sealer EWT. The findings of our study are in accordance

with those of Camps et al, who reported that the higher the powder/ liquid ratio, the lower

the eugenol release, which might be due to the supplementary zinc oxide particles

binding to eugenol as fast as it is released; thus only the outer surface of sealer is prone to

eugenol release. Therefore, a ratio of 1:1 (zinc oxide/eugenol) sealer concentration has

shown less expansion when compared with ZOE 1:2 and Z0E 1:3 groups. The factors

influencing the expansion of gutta-percha could be the amount of free eugenol released

and the contact time of eugenol with gutta-percha, which probably could result in minor

expansion as seen in groups ZOE 1:1 .Therefore, understanding the interactions between

eugenol and gutta-percha might play a significant role in completely sealing the root

canal.10

The increase in the volume of GP with time, in contact with ZOE‑based sealer is

in accordance with study done by Chandrasekhar et al using spiral CT showing

maximum expansion of GP. Camps et al. showed that the influence of the powder/liquid

ratio on the properties of zinc oxide– eugenol– based root canal sealers did not impact on

the sealers’ physical properties. On the basis of their results they concluded that the

practitioner can prepare the zinc oxide eugenol based root canal sealers at their chosen

consistency. Therefore, increasing the amount of eugenol in the mix would not impair the

sealing and physical properties of the sealer and would possibly provide an increase in

free eugenol at the sealer gutta-percha interface.10

Intergroup analysis demonstrated that there is statistically significant change in

volume of GP in different groups at 7 days and 30 days interval. These findings could be

explained by the study by Michaud et al., camp et al., which states that sufficient amount

of time is needed for the expansion in GP to take place.2 10

In the present study AH plus showed expansion in 7 days and 30 days. Expansion

is less compared to group 3 and more compared to group 1 and group 2.AH plus sealer

setting is a two-component paste based on a slow polymerization reaction of epoxy resin

amines, where the conversion of monomers into polymers occurs gradually.53A softening

effect of AH Plus on most brands of gutta-percha that resulted in increased flow has been

observed This was probably because of the liquid of AH-plus bisphenol-A-

diglycidylether, the primary chemical building block for a broad spectrum of epoxy

resins which appears to act as a partial solvent of gutta-percha.9 This is in accordance

with studies done by Resende et al But Ørstaviket al found that resin‑based sealers

showed more shrinkage after setting compared to that of ZOE‑based sealers. In the

present study it has shown that sealers which shrink during setting also shows expansion

of gutta-percha.

AH plus, nowadays is strongly recommended for its excellent physicochemical

and biological properties (Guinesi et al., 2014.35According to Paque et al it may be

speculated that continuous expansion of AH Plus occurred in a liquid environment over

time 54which is contradicting to most of the studies where AH plus is shown to undergo

shrinkage during setting.55In the present study with the use of MCT we could

differentiate between sealer and GP & there was actual expansion of GP was seen in the

presence of AH plus sealer.

In the present study all the specimens were stored in moist environment before

MCT scanning to prevent dehydration. A study done by Michaud et al showed volumetric

increase in gutta-percha when the butt ends were placed in 3-mm- both eugenol and

saline. However the volumetric increase was much greater with free eugenol compared to

saline which continued even after 4.5 years.2But in the present study ,control group did

not show any change in volume of GP with time ,where no sealers were used and no

change in dimensions of GP even though it is kept in moist environment. Thus it rules out

role of moisture in expansion of GP.

MCT also can differentiate between sealer and GP, so can be used to detect voids.

In the present study significant voids were observed in coronal and middle third in group

4.Epoxy resins suffer from traces of moisture, because of the hydrophobic nature. Effect

of moisture is dependent on the type of sealer.56The existence of voids is of clinical

relevance .Shrinkage upto1% of sealers can result in voids and gaps that are large enough

for penetration of bacteria and their noxious products.7

The incidence of voids within root fillings may be affected by many factors such as the

anatomical configuration of the canal system, the quality of canal preparation, the

consistency and volume of sealer, the operator’s expertise, and the technique used.40

AH Plus sets in the presence of moisture and has high tissue compatibility being

considered as the “gold-standard” endodontic sealer If the sealer mixture is dense and

barely flows, only few bubbles will move and open up at the surface. Conversely, if the

mixture is fluid, the bubbles will burst open easier on the surface. It is thus reasonable to

assume that the differences observed among the mixing approaches could be related to

this phenomenon.57

A high amount of gutta-percha and a low amount of sealer are known to be

correlated with a good quality of the root canal filling. However, without the use of

sealer, often the filling fails to adapt to the canal wall and provide high amounts of voids

and gaps.39 On the other hand, a high amount of sealer is discussed to correlate with an

increasing risk for voids and gap. Most sealers shrink during setting, leaving unwanted

voids (Wiener &Schilder 1971; Bandyopadhay 1982) and gradually dissolve (Ørstavik

1983; Peters 1986; Tronstadet al. 1988).Fewer voids have been considered to be a good

measure of long term sealing ability and they properly measure the quality of three-

dimensional filling, which is a sealing prerequisite.9

The presence of voids can be attributed to the fact that resin-based sealers

undergo a polymerization shrinkage, which might lead to gap and void formation

(Hammadet al. 2009, Zogheibet al. 2011, Zogheibet al. 2012, Wolf et al. 2013). 45

AH Plus showed more voids because of the inadequate bonding between the

sealer and the gutta-percha point, allowing fluid to flow at the interface.Another reason

could be the fast setting and subsequent polymerisation shrinkage of this sealer, and low

penetration ability of this sealer within the dentinal tubules, and its hydrophobic property

that prevents good adaptation of to the incompletely dried canal. .More pronounced

shrinkage stresses of AH plus sealer may account for possible earlier debonding of the

sealer from dentine walls and the greater leakage detected after immersion periods.58

The sealing ability of AH Plus may also be affected by other factors; for example, AH

Plus contains silicone oils and other ingredients. As all specimens were kept in 100%

humidity one can speculate that oil based materials such as AH plus could prevent

complete wetting of the root-canal wall and adhere poorly to humid dentine. This may

result in poor adaptation of the material to the root-canal wall, as well as formation of

voids.58

Voids seen at the middle third of root canals in single-cone obturation can be

attributed to the root canal anatomy of mandibular first premolar where the single cone

has failed to fill the canal space completely. A matched taper single-cone obturation

technique may be more effective in narrow round canals, as observed by Gordanet al. and

Daniele et al who stated that the single-cone technique is simple but its application must

be limited to round canals that have assumed a precise shape given by the instrumentation

procedure.6

Voids observed in the apical third were less because apical third of the canal was

filled with a master cone. Main canals usually have a circular or slightly oval apical

section .The enlargement obtained in this study with nickel-titanium rotary instruments

was probably sufficient to provide a uniform apical taper and a good preliminary cone

fitting so that the wedge effect resulted in effective pressing of the gutta-percha against

the canal walls and squeezing the sealer coating, thereby reducing the voids.9

The quality of adhesion between root canal dentin and sealers may also be

affected by the moisture condition of the root canals before filling procedures. Despite

the fact that the perception of moisture may vary widely among clinicians, several

manufacturers recommend that the root canals be maintained in a moist state to benefit

from the hydrophilic properties of their sealers without providing exact clinical

instructions for achieving the degree of residual moisture that is ideal for their products.

Nagas et al found that the degree of residual moisture significantly affects the adhesion of

root canal sealers to radicular dentin. 59

In the present study ZOE showed less voids because moisture may work as a

lubricant for these sealers that allows a better attachment to the root canal wall. 59

LIMITATIONS

Micro-CT technique has limitations with respect to in vivo applications. 16

Micro-CT is confined to the examination of specimens of limited size. 16

Minimal size of voids which could be detected using MCT was directly related to

the voxel size of the Micro-CT images; voids that occupied only a few voxels

could not be distinguished from the background due to the partial volume effect.48

Results obtained by Micro-CT can be underestimated as a consequence of the

dehydration and possible dimensional changes that accompany the prolonged

scanning and reconstruction time .To minimize these adverse effects, we kept the

roots in a water environment except for during scanning.48

FUTURE SCOPE

To assess the effect of dilution of sealer on physicochemical properties like

solubility, setting time, flow, and radiopacity and the surface morphology of

sealers.

To evaluate the effect of different obturation techniques on dimensional changes

of GP.

To evaluate the effect of body temperature and moisture on dimensional changes

of GP.

Thus, null hypothesis in the present study was rejected & it was concluded that there

is difference in volume of GP in contact with various concentrations of ZOE sealer & AH

Plus sealer.

CONCLUSION: Within the limitations of this study it can be concluded that increasing

the ratio of eugenol in sealer resulted in volumetric expansion of GP up till a ratio of 1:3

compared to AH plus in 7 days and 30 days interval .ZOE 1:1 & ZOE 1:2 ,ZOE 1:3 and

AH plus showed more expansion compared to control group. AH plus showed more

expansion compared to ZOE 1:1 & ZOE 1:2 ,and less expansion compared to ZOE 1:3

.However, further studies should be performed to confirm expansion and sealing ability

of GP of the size corresponding to the prepared canal, leading to the achievement of fluid

impervious seal.

Clinical Significance of the present study is that pulp canal sealer shows better expansion

suggesting that it helps us to achieve a fluid tight seal. Even though AH plus shows

expansion main disadvantage is that voids were observed in coronal and middle portion

of the tooth which can be overcome by using proper obturation technique .Further study

is needed to define the potential overtime changes of the voids and their degree of clinical

relevance, and thus improve clinical application and long-term performance of the root

canal sealers.

SUMMARY

One of the keys to a successful root canal therapy is to adequately obturate the

prepared root canal space that aims to provide a complete filling of the root canal in all

dimensions to create a fluid tight seal which cannot be obtained without the use of a

sealer. Gutta-percha (GP) which is commonly used for obturation, does not bond to

dentin walls and has shown a reduction in leakage overtime which indicated an increase

in volume. This expansion of GP compensates for sealer dissolution, resulting in

decreased leakage of the canal system. Zinc oxide-eugenol (ZOE) sealer firmly bonds to

dentin and GP. Eugenol which is a principal component in ZOE based sealers produces a

volumetric expansion of gutta percha creating a better seal overtime. AH plus an epoxy

resin based sealer with superior sealing capacity has also shown continuous expansion in

a liquid environment over time. Micro-CT which is rapid and noninvasive technology,

has been used in endodontics for evaluation of root canal anatomy and details such as

master or accessory gutta percha cones, sealer, recesses or voids etc. Thus, the aim of this

study is to compare the 3D volumetric changes of GP at various powder/liquid ratios of

ZOE-based sealer & AH Plus sealer using Micro CT. The null hypothesis considered in

this study is that there will be no difference in volume of GP at various concentrations of

ZOE sealer & AH Plus sealer.

Method:

Forty freshly extracted single rooted human Mandibular premolars with closed

apices, extracted for orthodontic reasons were used for this study. The sample teeth were

decoronated at cementoenamel junction to obtain standardized length of 17mm in all the

groups. Conventional access to the root canal system was performed using high-speed

Airotor handpiece (NSK PANA Airotor, contra angle handpiece, Japan) and endodontic

access bur no.2 (Dentsply Maillefer, Ballaigues, Switzerland). Patency of each canal was

established by placing a size 10 K-file (Mani Inc, Tochigi, Japan) until it is visible in the

apical foramen. Working length was derived by subtracting 0.5mm from the measured

length. Cleaning and shaping of root canals was performed in all the teeth with M2

ROTARY FILES [DENTSPLY INDIA] as per manufactures instructions up to # 35/06.

Constant irrigation with 5.25% sodium hypochlorite and EDTA (RC Prep Premier Dental

India) as a lubricant, were performed. Ethylene diamine tetra acetic acid (RC-Prep,

Premier Dental, India) were used as the irrigant once complete cleaning and shaping were

done followed by rinsing with saline.

After root canal preparation, teeth were randomly divided into five groups of 08

teeth each. Before obturation, root canals were dried with a #35 paper point. Obturation

was performed with GP points (35/04) and ZOE-based root canal sealer [Pulp canal

sealer EWT, Sybron endo] in different powder-liquid ratios & AH plus sealer [Dentsply].

Samples were divided in following groups: Group 1 - Powder/liquid ratio of ZOE sealer

1:1 and GP

2. Group 2 - Powder/liquid ratio of ZOE sealer 1:2 and GP

3. Group 3 - Powder/liquid ratio of ZOE sealer 1:3 and GP

4. Group 4- AH plus sealer and GP

5. Control Group – Only GP and no sealer was used.

Results:

Increasing the ratio of eugenol in sealer resulted in significant increase in

volumetric expansion of GP in a 7 days and 30days time interval. ZOE 1:1, ZOE 1:2,

ZOE 1:3 and AH plus showed statistically significant more expansion compared to

control group. AH plus showed more expansion compared to ZOE 1:1 & ZOE 1:2 , and

less expansion compared to ZOE 1:3

Conclusion:

Within the limitations of this study it is concluded that increasing concentration of

eugenol causes expansion of GP. AH plus also causes expansion of GP which is lesser

than ZOE 1:3 which might have a role in reducing apical leakage over time. However,

further studies should be performed to confirm expansion and sealing ability of GP of the

size corresponding to the prepared canal, leading to the achievement of fluid impervious

seal.

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KLE SOCIETY’S INSTITUTE OF DENTAL SCIENCES, BENGALURU

DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS

WRITTEN CONSENT

Dear Sir/ Madam,

This is to inform you that your extracted teeth will be stored and used for a research study

titled “A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ANALYSIS OF

GUTTA PERCHA IN CONTACT WITH VARIOUS CONCENTRATIONS OF ZINC

OXIDE EUGENOL SEALER & RESIN BASED SEALER USING MICRO COMPUTED

TOMOGRAPHY-AN INVITRO STUDY” being conducted by Dr. Cynthia P, Post Graduate

student, Department of Conservative Dentistry & Endodontics, KLE Society’s Institute of Dental

Sciences, Bengaluru.

Your participation in the research is voluntary.

Dear Doctor

I have no objection to donate the extracted teeth for research purpose and I hereby give my

voluntary consent.

Date and time:

Place: Signature

(Patient)

Signature

(witness)

Dr.Cynthia p

PG Student

Department of Conservative

Dentistry & Endodontics

KLE Society’s Institute of

Dental Sciences

Bengaluru-22

Dr.Rupali Karale

Professor& HOD

Department of Conservative

Dentistry & Endodontics

KLE Society’s Institute of

Dental Sciences

Bengaluru-22

Name of the patient:

Age:

Sex: Contact number:

PROFORMA

Sn

No

ZOE1:1 ZOE 1:2 ZOE 1:3 AH Plus Control

7 Days 30 Days 7 Days 30 Days 7 Days 30 Days 7 Days 30 Days 7 Days 30 Days

1

2

3

4

5

6

7

8

Figure 1: Armamentarium

Figure 2: 40 premolars

Figure 3: Samples ground with diamond disk

Figure 4: Standardization of specimens

Figure 5: cleaning and shaping using M2 rotary files

Figure 6: Irrigants used in study

Figure 7: Micro CT scanner

Figure 8: Samples subjected to Micro CT Scanning

Figure 9: MCT image showing canals obturated with single cone gutta-percha and ZOE based

sealer at 1:1 & 1:2 at 7-day interval and 30 days interval

Figure 10: MCT image showing canals obturate with single cone gutta-percha and ZOE based

sealer at 1:3 & AH plus at 7-day interval and 30 days interval

Figure 11: MCT image showing canals obturated with only single cone gutta-percha and no

sealer at 7-day interval and 30 days interval

“A THREE DIMENSIONAL COMPARATIVE VOLUMETRIC ...

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