the effect of an additional application of sealer during

The effect of an additional application of sealer

during continuous wave of condensation obturation

Humza Ahmed

A thesis submitted in partial fulfilment for the degree

of Doctor of Clinical Dentistry in Endodontics

University of Otago, Dunedin, New Zealand

2017

ii

Abstract

Background: Root canal fillings with a thin layer of sealer lining the dentine wall, a high

percentage of core material that closely adapts to the dentine and sealer penetration into

dentinal tubules is considered desirable. The continuous wave of condensation (CWC) is a

warm obturation technique. It involves a down-pack of a master apical cone associated with

the partial removal of the core material from the coronal segments of the root canal. Backfilling

with a thermoplasticised core material is then carried out. It is unknown if a second application

of sealer, following the down-pack, would be beneficial.

Aim: To assess the effect of an additional sealer application during the CWC technique by

measuring the distance between gutta-percha (GP) and canal wall, percentage of sealer and

sealer penetration into the dentinal tubules.

Materials and methods: Palatal roots of 105 extracted human maxillary molars were

sectioned and prepared to a master apical file size 40, 0.06 taper with Vortex Blue® files. Roots

were randomly assigned to seven groups (n = 15). Groups A (AH Plus™), B (Roth 801 Root

Canal Cement) and C (Sealapex™) had a single application of sealer dyed with Sudan Black B

before CWC obturation (Elements™ Free). Group D (negative control) was obturated without

sealer. Groups E (AH Plus™), F (Roth 801 Root Canal Cement) and G (Sealapex™) received a

second application of dyed sealer following the down-pack. Roots were sectioned at 2, 3, 4, 6,

7 and 8 mm from the root apex. The obturations were microphotographed (10 and 20x) and

images measured with ImageJ. The distance from GP to canal wall, percentage of sealer and

dentinal tubular penetration depth and direction was calculated at each level. The distance

between the GP and canal wall were analysed using Mood’s median test and the chi-squared

test of independence (p < 0.05).

Results: At each ascending level, sealer percentage decreased for each experimental group

while the number of outer third penetration depths increased when all groups were combined.

Comparisons with Group D revealed all groups had significantly increased distance between

the GP and canal wall at 2 - 4 levels (p = 0.00 – 0.05), increased sealer percentage at 4 – 6

levels (p = 0.00 – 0.03) and increased penetration depths. Comparison between a single and

double application of sealer revealed Group E had increased distance between the GP and canal

wall compared to Group A at the 4 and 6 mm levels (p = 0.01 – 0.05). Group F had increased

iii

distances compared with Group B at 6 mm (p = 0.03) and Group G was increased over Group

C at 8 mm (p = 0.03). A double application of sealer increased the sealer percentage in Group

A at the 2 mm level compared with Group E. No significant difference in sealer percentages

were noted when groups B and F were compared or Groups C and G. Analysis of Groups A

and E revealed that additional sealer increased outer third penetration depths for Group E,

which was also evident for Group G when compared to Group C.

Conclusions: An additional application of sealer slightly increased the distance between the

GP and canal wall. It did not affect Roth’s and Sealapex™ sealers but decreased the sealer

percentage of AH Plus™ to a minor degree. It increased the outer third penetration depths for

AH Plus™ and Sealapex™ but not Roth’s sealer.

iv

Dedication

In dedication to my loving mother (Jameela Ahmed) and father (Mohamed Ahmed).

v

Table of contents

Abstract ...................................................................................................................................... ii

Table of contents ........................................................................................................................ v

List of tables .............................................................................................................................. ix

List of figures ............................................................................................................................. x

List of abbreviations ................................................................................................................ xii

Chapter 1: Introduction .......................................................................................................... 1

Chapter 2: Literature review .................................................................................................. 2

2.1 Root canal treatment.................................................................................................... 2

2.2 A history of root canal obturation ............................................................................... 3

2.3 Obturation materials .................................................................................................... 4

2.3.1 Gutta-percha ......................................................................................................... 5

2.3.2 Sealers .................................................................................................................. 6

2.4 Obturation techniques ............................................................................................... 12

2.4.1 Cold lateral condensation ................................................................................... 14

2.4.2 Warm vertical condensation .............................................................................. 16

2.5 The ideal root filling .................................................................................................. 21

2.6 Research question ...................................................................................................... 21

2.7 Aims .......................................................................................................................... 22

2.8 Hypotheses ................................................................................................................ 22

Chapter 3: Materials and methods ....................................................................................... 23

3.1 Ethical approval......................................................................................................... 23

3.2 Māori consultation..................................................................................................... 23

3.3 Specimens.................................................................................................................. 23

3.4 Preparation of teeth ................................................................................................... 24

3.4.1 Root canal preparation ....................................................................................... 24

vi

3.4.2 Root canal fillings .............................................................................................. 26

3.4.3 Embedding of roots in resin ............................................................................... 27

3.4.4 Sectioning roots ................................................................................................. 28

3.4.5 Evaluation .......................................................................................................... 28

Chapter 4: Results ................................................................................................................ 32

4.1 Gutta-percha adaptation to dentine ........................................................................... 32

4.1.1 AH Plus Jet™ (Dentsply DeTrey) and the negative control (Groups A, D and E)

33

4.1.2 Roth 801 Root Canal Cement (Roth International) and the negative control

(Groups B, D and F)......................................................................................................... 35

4.1.3 Sealapex™ (Kerr) and the negative control (Groups C, D and G) ..................... 37

4.2 Sealer percentage in cross sections ........................................................................... 39


40


(Groups B, D and F)......................................................................................................... 41


4.2.4 The negative control (Group D) ......................................................................... 43

4.3 Depth of sealer penetration ....................................................................................... 44

4.3.1 All groups........................................................................................................... 45


47


(Groups B, D and F)......................................................................................................... 50


Chapter 5: Discussion .......................................................................................................... 56

5.1 Gutta-percha adaptation to dentine ........................................................................... 56

vii


57


(Groups B, D and F)......................................................................................................... 58


5.2 Sealer percentage in cross sections ........................................................................... 61


62


(Groups B, D and F)......................................................................................................... 63


5.2.4 The negative control (Group D) ......................................................................... 64

5.3 Depth of sealer penetration ....................................................................................... 66

5.3.1 All groups........................................................................................................... 66

5.3.2 Direction of sealer penetration ........................................................................... 66

5.3.3 Comparisons with the negative control (Group D) ............................................ 66


67


(Groups B, D and F)......................................................................................................... 67


5.4 Sealer flow................................................................................................................. 68

5.5 Experimental design and study limitations ............................................................... 69

5.5.2 Evaluation .......................................................................................................... 71

5.6 Conclusion ................................................................................................................. 72

References ................................................................................................................................ 73

Appendices ............................................................................................................................... 93

Appendix A: Ethical approval ............................................................................................. 93

viii

Appendix B: Maori consultation .......................................................................................... 95

Appendix C: Sum of 10 intercepts between GP and canal wall .......................................... 97

Appendix D: Mean sealer percentage in cross section ........................................................ 98

Appendix E: Depth of sealer penetration ............................................................................. 99

ix

List of tables

Table 1. Requirements for a root canal filling material (Grossman 1978). ............................... 4

Table 2. Requirements for sealers (Grossman 1976b). .............................................................. 6

Table 3. Advantages and disadvantages of endodontic sealers. ................................................ 9

Table 4. Obturation techniques. ............................................................................................... 13

Table 5 Manufacturer’s recommended torque and speed settings for Vortex Blue® 6% taper

rotary files. ............................................................................................................................... 25

Table 6. Mean distance between the GP and canal wall for all groups (µm). ......................... 33

Table 7. Post-hoc comparisons of distance from GP to canal wall between Groups A, D and E.

.................................................................................................................................................. 35

Table 8. Post-hoc comparisons of distance from GP to canal wall between Groups B, D and F.

.................................................................................................................................................. 37

Table 9. Post-hoc comparisons of distance from GP to canal wall between Groups C, D and G.

.................................................................................................................................................. 39

Table 10. Post-hoc comparisons of sealer percentage between Groups A, D and E. .............. 41

Table 11. Post-hoc comparisons of sealer percentage between Groups B, D and F. ............... 42

Table 12. Post-hoc comparisons of sealer percentage between Groups C, D and G. .............. 43

x

List of figures

Figure 1. (a) Spreader placed, which forces material vertically and laterally. (b) A heated

instrument is used to remove the excess GP. (c) Vertical compaction of GP. ........................ 14

Figure 2. Schilder's obturation technique with (a) master cone to working length. (b) The first

stage of heating and incremental GP removal before (c) vertical condensation of the GP occurs

.................................................................................................................................................. 17

Figure 3. Heating and compacting of the canal whilst removing increments of GP until a dense

apical plug is formed ................................................................................................................ 17

Figure 4. Continuous wave of condensation. (a) Heat initiated vertical condensation. (b)

Separation and withdrawal. (c and d) compaction of apical plug. (e) Dense apical plug of GP.

.................................................................................................................................................. 19

Figure 5. Diagrammatic illustration of filling techniques, emphasising the desirability of

minimum sealer volume. (a) Cold lateral condensation and (b) warm vertical condensation. 20

Figure 6. A mesial view of a maxillary molar with 2B lead pencil markings to indicate the

mesial direction. ....................................................................................................................... 24

Figure 7. A palatal view of a maxillary molar with a 2B lead pencil marking to indicate the

mid-palatal direction. ............................................................................................................... 24

Figure 8. Filled roots placed on their apices in a silicone mould and supported with paper clips.

.................................................................................................................................................. 27

Figure 9. Filled roots submerged in resin that was left undisturbed until it had completely set.

.................................................................................................................................................. 27

Figure 10. Embedded roots after being removed from the silicone mould. ............................ 28

Figure 11. Embedded roots after being trimmed in a bench grinder. ...................................... 28

Figure 12. A 20x magnification image with the superimposed grid system. Gutta-percha

adaptation to dentine was calculated by measuring the distance between the GP and canal wall

at each of the 10 points of intersection. Intercept 1 was oriented towards the mid-palatal surface

and intercept 2 mesially. .......................................................................................................... 29

Figure 13. A 20x magnification image showing the outline of the canal wall (marked yellow)

using Image J. .......................................................................................................................... 30

Figure 14. Four-quadrant pie chart superimposed over the centre of the root canal filling .... 31

Figure 15. Average distance between GP and canal wall for all levels. .................................. 32

xi

Figure 16. Summary of mean distance between GP and canal wall for Groups A, D and E. . 34

Figure 17. Summary of mean distance between GP and canal wall for Groups B, D and F. .. 36

Figure 18. Summary of mean distance between GP and canal wall for Groups C, D and G. . 38

Figure 19. Mean sealer percentage of all groups combined. ................................................... 40

Figure 20. Mean sealer percentage for Group D. ..................................................................... 44

Figure 21. Sample images showing penetration depths of the dyed sealer. Absent (top left),

inner third (top right), middle third (lower left) and outer third (lower right). ........................ 45

Figure 22. Summary of penetration depths and direction of all groups at all levels. .............. 46

Figure 23. Outer penetration depth of all groups combined. ................................................... 47

Figure 24. Summary of Group A penetration depths and direction at all levels. .................... 48

Figure 25. Summary of Group E penetration depths and direction at all levels. ..................... 49

Figure 26. Summary of Group D (negative control) penetration depths and direction at all

levels. ....................................................................................................................................... 50

Figure 27. Summary of Group B penetration depths and direction at all levels. ..................... 52

Figure 28. Summary of Group F penetration depths and direction at all levels. ..................... 53

Figure 29. Summary of Group C penetration depths and direction at all levels. ..................... 54

Figure 30.Summary of Group G penetration depths and direction at all levels. ..................... 55

Figure 31. Cross section of Group D at 7 mm with void (arrow). ........................................... 65

Figure 32. Dentine debris (arrow) evident in a cross section of Group D. .............................. 65

xii

List of abbreviations

AAE American Association of Endodontists

CDJ Cementodentinal junction

CWC Continuous wave of condensation

EDTA Ethylenediaminetetraacetic

GP Gutta-percha

ISO International Standards Organisation

MAC Master apical cone

NiTi Nickel titanium

NaOCl Sodium hypochlorite

μm Micrometres

WL Working length

1

Chapter 1: Introduction

The final stage of root canal treatment involves the filling of the cleaned and shaped root canal

system. This is typically achieved with a flowable sealer cement and a central core material

that pushes the sealer into irregularities of the root canal system which are inaccessible to the

core material. Root canal fillings with a high percentage of core material that closely adapts to

the root dentine, a thin layer of sealer lining the dentine wall, and sealer penetration into

dentinal tubules and lateral canals are considered desirable (Mamootil & Messer 2007). Using

the correct amount of sealer is paramount, as too much or too little has the potential to adversely

affect the quality of the obturation.

The continuous wave of condensation (CWC) technique of root canal obturation (Buchanan

1994) is a currently utilised root filling method based on Schilder’s vertical condensation

technique, creating a 3-dimensional root canal filling (Schilder 1967). Following the down

pack of the master cone, which is associated with the partial removal of the core material from

the coronal segments of the root canal, the technique requires an initial sealer application prior

to backfilling with a thermoplasticised core material. It is currently unknown if a second

application of sealer, prior to backfilling, would be beneficial during the CWC technique.

It is unknown if desirable features of root canal obturation are achieved or improved by

reapplying sealer. This research will analyse the effects of an additional application of sealer

during the CWC technique with regards to sealer thickness, cross-sectional sealer percentage

and sealer penetration into dentinal tubules.

2

Chapter 2: Literature review

2.1 Root canal treatment

Intraradicular bacteria are the primary cause of persistent periradicular inflammation

(Kakehashi et al. 1965, Möller et al. 1981, Nair 2006). In order to eliminate persistent

periradicular inflammation, root canal system infection must be controlled. This involves the

removal of organic debris by adequate cleaning and shaping. As a consequence, resident

microorganisms are either eradicated, significantly reduced in number, or severely disrupted,

which hopefully provides an environment that can no longer promote periradicular disease.

Once this environment has been created, the canal can be obturated. The filling serves three

primary functions (Trope & Debelian 2008):

1. To seal the canal from the ingrowth of bacteria from the oral cavity

2. The entombment of remaining microorganisms

3. To prevent periradicular fluid from tracking into the canal space and providing nutrients

for bacteria

Root canal obturation is defined by the American Association of Endodontists (AAE) as filling

the shaped and debrided canal space with a temporary or permanent filling material (Eleazer et

al. 2012). When root canal treatment is adequately performed, periradicular regeneration with

a hard tissue barrier can usually be observed by the reduction of the radiolucency on a

radiograph (Strindberg 1956, Sjögren et al. 1990, 1997). The quality of obturation is one of

many factors related to the outcome of the treatment. One of the first papers to link obturation

quality with the outcome was authored by Strindberg (1956). The ‘Washington Study’ (Ingle

et al. 1994) together with other research has corroborated Strindberg’s early findings (Sjögren

et al. 1990, Buckley & Spångberg 1995, Chugal et al. 2003, Ricucci & Bergenholtz 2003),

whilst the presence of a lesion, presence of a sinus tract, instrumenting close to the canal

terminus, irrigant choice, as well as the presence of a satisfactory coronal restoration have also

been linked to positive outcomes (Sjögren et al. 1990, Ray & Trope 1995, Ng et al. 2011).

Root canal fillings should be able to maintain an environment that does not promote

periradicular disease long-term and without damaging host tissues. Cleaning, shaping and

3

obturation are vital steps in treatment and if poorly executed, the filling will not adequately

seal the root canal system and failure may ensue (Ricucci & Bergenholtz 2003).

2.2 A history of root canal obturation

Obturation of the pulp space has been documented since 200 BCE (Zias & Numeroff 1987). In

more recent times, B. T. Longbotham and Edward Hudson utilised crude methods of root filling

teeth by plugging gold foil into unprepared root canals, providing an alternative to extraction

as the common treatment modality of the 1800s (Grossman 1976a). In the mid-1800s, root

canal treatment was still being performed primitively with insufficient pulp tissue removal and

feeble attempts to enlarge or shape the pulp space. A myriad of root canal filling materials were

utilised at the time which included gold, tin, lead, amalgam, cotton, wood, spunk, plaster of

Paris, oxyphosphate of zinc cement, oxychloride of zinc cement as well as cotton and iodoform

mixed with phenol or creosote (Grossman 1976a). These materials sealed root canals poorly

(Ørstavik 2005). Some dentists on the other hand, chose not to fill the root canals at all.

Gutta-percha (GP) points for the filling of root canals were first introduced in 1867 by Bowman

and quickly became the mainstay of canal filling materials. In the 1930s, silver points were

introduced by Trebisch and Jasper (Grossman 1976a) as a root canal filling material to maintain

the natural, narrow taper of the root canal without the need for shaping with the stainless steel

instruments of the time (Ørstavik 2005). The inflexible stainless steel instruments of that era

carried a risk of perforation or transportation when used to shape curved canals, making silver

points appear more desirable. Canals filled with silver points required a sectional filling

technique if a retentive post was planned, and removal for orthograde and retrograde re-

treatment also proved to be a challenge. Despite these shortcomings, their use as root fillings

rivalled that of GP. Apical periodontitis associated with silver points, due to minimal canal

cleaning and shaping by some practitioners (Schilder 1967), together with corrosion of the cone

(Seltzer et al. 1972, Brady & del Rio 1975) led to questions about their sealing and in 2011 the

American AAE recommended their use be discontinued. They are rarely used as root canal

fillings in contemporary practice.

4

2.3 Obturation materials

The majority of root fillings are a combination of sealer cement with a central core material

that acts as a piston on the flowable sealer, causing it to be forced into the irregularities of the

root canal system, providing a more three-dimensional fill. GP is the most common core

material in modern endodontics (Johnson & Kulild 2011). GP and other obturation materials

are designed to be contained within the radicular dentine during root canal treatment, however,

they may be inadvertently extruded into the periradicular tissues. In the event of extrusion, it

is essential the materials are non-toxic and biocompatible.

If core materials are to promote the resolution of apical periodontitis, they must fulfil certain

requirements. Grossman (1978) provided a list of 10 requirements for a root canal filling

material (Table 1).

Table 1. Requirements for a root canal filling material (Grossman 1978).

It should be easily introduced into the canal

It should seal the canal laterally as well as apically

It should not shrink after being inserted

It should be impervious to moisture

It should be bacteriostatic or at least not encourage bacterial growth

It should be radiopaque

It should not stain tooth structure

It should not irritate periapical tissue

It should be sterile or quickly and easily sterilised before insertion

It should be easily removed from the root canal if necessary

5

No root canal filling material currently fulfils all of these requirements; the most ideal material

currently available is GP.

2.3.1 Gutta-percha

Gutta-percha is derived from dried juices from trees of the Sapotacaea family (Ørstavik 2005).

Gutta-percha points used in endodontics consist of 20% GP and up to 60-70% zinc oxide and

is harder, more brittle and less elastic than natural rubber (Spångberg 2008). The remaining

constituents vary depending on the manufacturer and comprise metal salts and dyes which are

added for colour and radiographic contrast. Calcium hydroxide (Lohbauer et al. 2005),

chlorhexidine (Lui et al. 2004) or iodoform (Chogle et al.) are sometimes added for their

antimicrobial properties.

2.3.1.1 Thermomechanical properties

Gutta-percha core materials possess no adhesive properties and are used in combination with a

sealer cement to provide a seal with the root canal dentine. Investigations on the

thermomechanical properties of GP show it to be incompressible and with no molecular spring-

back (Schilder et al. 1974b).

Gutta-percha occurs in two crystalline forms, the alpha and beta phases. Alpha-phase GP exists

most commonly in nature whilst the beta-phase is produced by heat applied during the refining

process and is used most frequently in root canal treatment. When heated, GP undergoes two

distinct phase transformations. The first transformation occurs from beta- to alpha-phase when

the material is heated to around 47°C. This then transforms from alpha-phase to amorphous at

around 55°C. When cooled normally, GP returns to beta-phase. Slow cooling results in the

production of alpha-phase GP (Schilder et al. 1974a). Alpha-phase GP is reportedly more fluid

and softens at a lower temperature than beta-phase GP (Zhang et al. 2011).

2.3.1.2 Biocompatibility

The biocompatibility of intraradicular materials is of great importance as they may come into

direct contact with the periradicular tissues. Gutta-percha has been shown to have acceptable

6

biocompatibility with a low degree of toxicity. Sjӧgren et al. (1995) showed by implanting

various sizes of GP, within Teflon cages, subcutaneously into guinea pigs that the size of the

GP particle was related to the intensity of inflammatory response. Larger particles, with a larger

volume to surface area ratio were encapsulated by collagen with little or no inflammatory host

response, whereas small GP particulate fractions with a larger surface area to volume ratio

resulted in a more intense immune reaction.

2.3.2 Sealers

Root canal sealers are necessary to seal the space between the core material and dentinal wall.

Sealers can also fill the space between accessory points during lateral condensation, voids,

lateral canals, accessory canals and canal irregularities and serve as a lubricating material

during obturation. Different sealers exhibit different flow characteristics that are affected by

powder : liquid ratio mixtures (Lacey et al. 2005). In addition to ideal core material properties,

Grossman (1976b) has also listed requirements for sealers. No sealer currently satisfies all

criteria (Table 2).

Table 2. Requirements for sealers (Grossman 1976b).

It should exhibit tackiness when mixed to provide good adhesion between it and the canal

wall when set

It should establish a hermetic seal

It should be radiopaque so it can be visualised radiographically

It should have fine powder particles so that it mixes easily with the liquid

It should not shrink when setting

It should be non-staining to the tooth structure

It should be bacteriostatic or at least not encourage bacterial growth

It should be slow-setting

It should be insoluble in tissue fluids

7

It should be tissue tolerant, that is non-irritating to the periradicular tissues

It should be soluble in a common solvent

Studies have shown that teeth with apical periodontitis often heal even in the presence of

positive bacterial culturing when obturated (Sjögren et al. 1997, Molander et al. 2007),

indicating that the root filling has the ability to overcome some of the limitations of the cleaning

and shaping procedure. Root canal sealers used in combination with core materials strive to

create a root canal filling impervious to moisture by sealing the canal apically and coronally

(Johnson & Kulild 2011). This can also entomb residual bacteria and eliminate space for

irritants that were not eradicated via disinfection (Sjögren et al. 1997). This will allow the

establishment of periradicular health, as microorganisms are deprived of nutrients and space

for growth and proliferation.

During obturation, excess sealer should be forced back into the access cavity. This does not

always occur, particularly with some techniques which tend to force sealer apically and

laterally through the apical foramen and lateral canals (Al-Dewani et al. 2000, Keçeci et al.

2005, Peng et al. 2007). Sealer forced into the periapical tissues through the apical foramen

may result in transitory irritation before the excess material is absorbed by the body. This

phenomenon is sought after by some dentists as a sign of a successfully completed root canal

treatment. Conflicting evidence regarding sealer extrusion through the apical foramen exists.

The cytotoxic nature of sealers (Gutierrez et al. 1999), the ability to induce periradicular

inflammation (Pascon et al. 1991), post-operative discomfort (Schilder 1967) and adverse

effects on periradicular healing (Dahl 2005) have all been advocated as reasons for avoiding

sealer extrusion. Despite these findings, small volumes of sealer extrusion are not considered

a “failure,” whilst excessive extrusion may result in unfavourable complications (Köseogˇlu et

al. 2006, Froes et al. 2009, López‐López et al. 2012).

Sealer cements may have the ability to entomb recalcitrant bacteria residing in dentinal tubules

as well as exhibit tubular penetration. Sealer penetration into tubules is reported as desirable

(Mamootil & Messer 2007). When sealer penetrates the dentinal tubules, the interface between

the dentine and material is increased which may improve the sealing ability (Gee 1998) and

retention of the material through mechanical locking. In addition, sealers may exert an

antimicrobial effect on infected dentinal tubules which is enhanced by a closer approximation

8

to the bacteria (Heling & Chandler 1996) with a range of sealers possessing the potential for

deep tubular penetration (Weis et al. 2004). Resin-based sealers exhibit tubular penetration

most consistently (Mamootil & Messer 2007). The obturation technique may also have an

effect on tubular penetration, however, the evidence is conflicting. Deus and colleagues (2004)

investigated the effect of obturation method on tubular penetration and compared Schilder’s

obturation technique, Thermafil and the cold lateral condensation obturation techniques. The

results indicated warm vertical obturation techniques to be associated with deeper sealer

penetration into tubules. This was in contrast to a study by Weis et al. (2004) who found the

method of obturation did not significantly affect tubular penetration. The study used AH 26

sealer (Dentsply) and compared Simplifil, CWC, Thermafil and cold lateral condensation

obturation techniques. Greater penetration depths were found to occur in a buccal and lingual

direction and deeper and more frequent tubular penetration depths were found at 3 and 5 mm

rather than 1 mm from the working length (WL).

Traditional sealers have shortcomings in that they generally shrink on setting and wash out in

the presence of tissue fluids (Ørstavik et al. 2001, Marín-Bauza et al. 2012, Barros et al. 2014).

In addition, sealers do not form a bond with the GP core material, leaving a gap when the sealer

shrinks upon setting (Mutal & Gani 2005, Marín-Bauza et al. 2012, Barros et al. 2014).

There are a wide range of sealers used in obturation including zinc oxide sealers, resin sealers,

glass ionomer-based sealers, silicone-based sealers, bioceramic and medicated sealers with

chemicals such as calcium hydroxide. This review will focus on resin, zinc oxide and calcium

hydroxide sealers as these are commonly used sealers in endodontic practice which have

different advantages and disadvantages (Table 3). Several methods for placing sealers exist and

these include the use of the master cone, spiral fillers, files, reamers, as well as sonic and

ultrasonic energy. Studies indicate the use of ultrasonics for sealer application to be superior to

manual techniques (Aguirre et al. 1997) and to also improve sealer distribution within the root

canal system (Stamos et al. 1995).

9

Table 3. Advantages and disadvantages of endodontic sealers.

Advantages Disadvantages

AH Plus Low soluability (Resende et

al. 2009).

Minimal shrinkage (Schäfer

& Zandbiglari 2003).

Releases small amounts of

formaldehyde (Leonardo et

al. 1999a).

Roth 801 Long history of use (Curson

& Kirk 1968).

Antimicrobial activity

(Leonardo et al. 2000).

Cytotoxic to periradicular

tissues (Markowitz et al.

1992).

Resorb in periradicular

tissues (Augsburger & Peters

1990).

Shrinkage on setting (Wiener

& Schilder 1971).

May stain tooth structure

(Van der Burgt et al. 1986).

Sealapex Calcium hydroxide release

(Desai & Chandler 2009).

Increased soluability

(Schäfer & Zandbiglari

2003)

2.3.2.1 Resin-based sealers

Resin-based sealers used for root canal obturation include AH 26 (Dentsply DeTrey, Konstanz,

Germany) as well as its successor AH Plus (Dentsply DeTrey, Konstanz, Germany). The AH

series are the most common type of resin-based sealers and are comprised of bis-phenol resin

with methenamine that was first prototyped in 1954 (Schroeder 1954). They have good sealing

and adhesive properties (Lee et al. 2002, Nunes et al. 2008), and antimicrobial activity

(Siqueira Jr et al. 2000). AH 26 releases formaldehyde (Spångberg et al. 1993), a carcinogen

10

(Heck et al. 1990) during its setting reaction which led to the development of AH Plus as a

more biocompatible evolution. AH 26 has largely been superseded by AH Plus, a two paste

system releasing substantially less formaldehyde upon polymerisation (Cohen et al. 1998,

Leonardo et al. 1999b).

2.3.2.1.1 Biocompatibility

It is important that root canal sealers are biocompatible as they line the canal wall and directly

contact the periradicular tissues via the apical foramen. AH 26 exhibits a high toxicity when

freshly prepared but this diminishes after 2 weeks (Pascon et al. 1991). The toxicity is attributed

to the small amounts of formaldehyde release as a result of the setting reaction, which is

thousands of times lower than the long term release from conventional formaldehyde-

containing sealers such as N-2 and Endomethasone (Spångberg et al. 1993).

The cytotoxicity of AH Plus was found to be highest after being freshly prepared and

diminished completely 4 hours after mixing. It was rated as having a lower cytotoxic potential

than AH 26. Sousa et al. (2006) found the inflammatory tissue reaction of AH Plus to be severe

initially which decreased to moderate with regards to bone formation and inflammation. These

results differed to the histopathological findings obtained from a study that placed

subcutaneous implants into rats (Silveira et al. 2011). Their results showed a moderate

inflammatory reaction of AH Plus at 7 days which diminished to a mild inflammatory reaction

at 15 days.

2.3.2.2 Zinc oxide-eugenol sealers

Zinc oxide-eugenol has a long history of use in root canal treatment (Curson & Kirk 1968,

Grossman 1976b). It is composed of zinc oxide power that is mixed with eugenol liquid to form

sealer. Advantages are that it is absorbed if extruded into the periradicular tissues (Augsburger

& Peters 1990), is antimicrobial (Leonardo et al. 2000, Kayaoglu et al. 2005, Sipert et al. 2005,

Pizzo et al. 2006, Tanomaru-Filho et al. 2007) and slow setting (Allan et al. 2001) however, it

exhibits shrinkage on setting (Wiener & Schilder 1971, Ørstavik et al. 2001), solubility

(Kazemi et al. 1993) and may stain the tooth structure (Van der Burgt et al. 1986). The mixture

is chemically set combined with physical embedding of zinc oxide in a matrix of zinc

11

eugenolate. Particle size of zinc oxide, pH and the presence of water regulate the setting

together with other additives. A variety of chemicals are often added such as paraformaldehyde

for mummifying and antimicrobial effects, germicides for antiseptic action, rosin or Canada

balsam for greater dentine adhesion and corticosteroids for immunosuppression.

An early zinc oxide eugenol sealer was introduced by Rickert and Dixon known as Pulp Canal

Sealer (SybronEndo, Orange, CA, USA) and Pulp Canal Sealer EWT (extended working time;

SybronEndo). Procosol (Procosol, Inc., Philadelphia, PA, USA) is a modification of Rickert’s

formula that is non-staining to the tooth structure, with no silver particles. In 1958 Grossman

introduced Roth 801 Sealer (Roth International Ltd, Chicago, IL, USA) that has been

extensively used for root canal obturations.


Zinc oxide-eugenol sealers have been shown to be severely cytotoxic and activate the

complement system, inducing an inflammatory reaction (Serene et al. 1988). These properties

are mainly attributed to the eugenol component of the sealer. Zinc oxide is an effective

antimicrobial agent and in vitro investigations show cytoprotective effects on tissue cells

(Sunzel et al. 1997). Formaldehyde was commonly added to zinc oxide-based sealers for many

years (Endomethasone; Septodont, Saint-Maur, France and N2; Indrag-Agsa, Losone,

Switzerland) however, due to toxicity concerns, conventional formaldehyde sealers are

currently rarely utilised. Rosins are comprised of approximately 70% resin acids, which are

often added to zinc oxide sealers. They are highly cytotoxic, however, provide additional

antimicrobial effects (Sunzel et al. 1997). Kolokouris et al. (1998) performed subcutaneous

injections of Roth 811 sealer into rats. The normal concentrations of zinc, calcium and copper

in various organs were affected, suggesting zinc oxide-eugenol sealers release substantial

amounts of these elements that are deposited into vital organs. Araki et al. (1993) conducted in

vitro cytotoxic examinations with zinc oxide-eugenol and a non-eugenol zinc oxide sealer on

periodontal ligament fibroblast cells (L929). The results revealed the zinc oxide-eugenol sealer

to be significantly more cytotoxic than a non-eugenol containing sealer. Similarly, Klaiber and

colleagues (1981) implicated the eugenol component of the sealer as highly cytotoxic to human

periodontal ligament fibroblasts in their in vitro investigations.

12

2.3.2.3 Calcium hydroxide sealers

Several calcium hydroxide based sealers have been marketed. Examples include Sealapex

(Kerr, Romulus, MI, USA), CRCS (Hygenic, Akron, OH, USA) and Apexit (Vivadent,

Amherst, NY, USA). Calcium hydroxide sealers were developed for therapeutic activity. It was

thought that these sealers would exhibit antimicrobial activity and have osteogenic and

cementogenic activity due to the calcium hydroxide content. Unfortunately, these actions have

yet to be substantiated. Calcium hydroxide must dissociate into calcium ions and hydroxyl ions

to be therapeutically effective. If this is to occur the calcium hydroxide must dissolve and

subsequently lose volume. Thus one of the major concerns with calcium hydroxide-based

sealers is solubility, an undesirable quality of a root canal sealer (Grossman 1976b). In a study

by Tagger et al. (1988) on the calcium and hydroxyl ion release from Sealapex and CRCS,

negligible release was noted from CRCS however Sealapex released more ions but

disintegrated in the process. Further experiments have outlined similar findings with Sealapex

and other zinc oxide eugenol-based sealers (Staehle et al. 1995, Duarte et al. 2000).


Calcium hydroxide sealers are generally characterised as having good cytocompatibility

(Osorio et al. 1998, Ersev et al. 1999, Telli et al. 1999) however some studies dispute this

finding (Boiesen & Brodin 1991, Silva et al. 1997). An in vivo investigation by Soares et al.

(1990) on dog teeth found Sealapex and CRCS disintegrated into the tissue easily, however

both may result in chronic inflammation (Tronstad et al. 1988). Huang et al. (2001) conducted

an in vitro evaluation of the genotoxicity of Sealapex by single-cell gel electrophoresis assay

found Sealapex was not genotoxic.

2.4 Obturation techniques

Modern obturation techniques commonly involve the use of a flowable sealer cement in

combination with a central core material, usually GP (Hommez et al. 2003, Ng et al. 2008,

Kaptan et al. 2012). Obturation of the root canal system can commence after disinfection

through adequate cleaning and shaping. This creates an environment that will promote the

maintenance or reestablishment of periradicular health. There are currently a plethora of

13

obturating techniques available for the placement of GP, of which cold lateral condensation is

the most commonly taught (Benenati 2008). Obturation techniques are shown in Table 4.

Table 4. Obturation techniques.

Cold lateral condensation

Warm lateral condensation techniques

Warmed spreader technique (Luccy et al. 1990,

Liewehr et al. 1993)

Heat softened GP with cold spreader technique

(Himel & Cain 1993)

Reciprocating spreader technique (Gound et al.

2000)

Ultrasonically energised spreader technique

(Deitch et al. 2002, Bailey et al. 2004)

Thermomechanical compaction technique

(Hoskinson et al. 2002)

Warm vertical techniques

Schilder’s technique (1967)

Continuous wave of condensation (Buchanan

1994)

Single cone obturation (Gordon et al. 2005)

Carrier based techniques (Gutmann et al. 1993)

Paste fillings (Johnson & Kulild 2011)

Solvent techniques (Schilder 1967)

14

2.4.1 Cold lateral condensation

Cold lateral condensation is the process of vertically loading a cold, wedge shaped spreader,

adjacent to a master cone, into a prepared root canal (Figure 1). This pressure forces materials

vertically and laterally producing 1-3 kg of load (Harvey et al. 1981). The deformation of the

master cone allows the placement of an accessory GP cone into the vacant space created. The

process is then repeated until the spreader no longer penetrates past the coronal third of the

canal before the excess GP is removed with a heated instrument. The GP is vertically

compacted producing a dense root filling (Whitworth 2005).

Figure 1. (a) Spreader placed, which forces material vertically and laterally. (b) A heated instrument is used to remove the

excess GP. (c) Vertical compaction of GP.

Cold lateral condensation is the most commonly taught and utilised obturation technique

throughout the world (Qualtrough et al. 1999, Jenkins et al. 2001, Hommez et al. 2003, Lynch

& Burke 2006) and the yardstick against which comparisons are made (Gordon et al. 2005,

Peng et al. 2007, Shahriari et al. 2008, Anantula & Ganta 2011, Emmanuel et al. 2013). The

method is non-specific with a wide array of master cone designs and canal adaptations as well

as accessory cone selections, sealer and spreader choices. There is minimal evidence in the

15

literature on how best to achieve cold lateral condensation (Aneet et al. 2001, Huumonen et al.

2003).

Master cone selection for cold lateral condensation is achieved with either a 0.02 International

Standards Organisation (ISO) cone, custom-fit cone such as a 0.04 or 0.06 taper or a non-

standardised cone. Master cones are often customised to closely adapt to the apically prepared

root canal in an attempt to gain an improved apical seal measured by resistance to displacement

or “tug-back” (Johnson & Kulild 2011) which can be achieved in a number of ways (Schilder

1967, Hunter et al. 1991).

Advantages of the cold lateral condensation technique are that it is relatively simple and

provides better length control during condensation when compared to warm vertical techniques

(Gilhooly et al. 2001, Peng et al. 2007). Conversely, the technique may not be suitable to fill

canal irregularities and does not produce a homogeneous mass, as the GP cones are only tightly

connected together and joined by a frictional grip and sealing cement (Schilder 1967). The

technique has also been reported to induce vertical root fractures by virtue of the forces applied

during spreader placement (Holcomb et al. 1987, Lertchirakarn et al. 1999). Textbooks often

advise that the technique is ideally accomplished with a continuously tapering canal

preparation that facilitates the placement of a spreader to within 1-2 mm of the WL (Benenati

2008, Johnson & Kulild 2011), however, this only applies when ISO cones are used and rarely

occurs when non-standardised cones or matched taper GP cones are utilised. As there is no

precisely prescribed method for performing cold lateral condensation, some practitioners

employ hand spreaders whilst others prefer finger spreaders made of either nickel titanium

(NiTi) or stainless steel. Hand spreaders have been shown to provide higher condensation

forces than finger spreaders (Lertchirakarn et al. 1999) and NiTi types have been shown to

penetrate deeper than stainless steel spreaders (Schmidt et al. 2000, Wilson & Baumgartner

2003). Numerous variations of the technique have been reported in an attempt to attain

improved obturation. These include using heated spreaders (Liewehr et al. 1993), heat

softening GP before the placement of a cold spreader (Himel & Cain 1993), finger spreader

activation with a reciprocating handpiece (Gound et al. 2000), ultrasonically activated

spreaders (Deitch et al. 2002, Bailey et al. 2004) and engine-driven thermomechanical

compactors that create frictional heat and force material apically in the canal (Hoskinson et al.

2002).

16

Cold lateral condensation has downfalls that mean it is not ideally suited for obturation of all

canal morphologies. Warm vertical condensation techniques may be better suited for obturation

of root canal system irregularities.

2.4.2 Warm vertical condensation

In the 1960s, Herbert Schilder advocated a thorough cleaning and shaping protocol and a heated

GP obturation technique that provided improved microbial control and a more comprehensive

3-dimensional fill of the root canal system (Lea et al. 2005, Collins et al. 2006). The technique

required a large armamentarium and was time consuming, however, it has evolved with the

advent of new devices that maintained Schilder’s strict obturation principles but in a simplified

and time-efficient manner.

2.4.2.1 Schilder’s technique

Schilder’s (1967) obturation technique requires the canal to be shaped as a continuously

tapering funnel that keeps the apical foramen as small as possible. The procedure involves

placing a sealer cement into a cleaned and shaped canal to line the dentine surface. A pre-

adjusted master GP cone that adapts to the apical canal is then introduced to the terminus of

the canal. A heated instrument is used to sear off the excess coronal GP before a hot spreader

is advanced into the canal 3 – 4 mm which removes a portion of the coronal GP and softens

the remaining apical GP. This is compacted vertically with a cold plugger to increase its density

(Figure 2).

17

Figure 2. Schilder's obturation technique with (a) master cone to working length. (b) The first stage of heating and incremental GP removal before (c) vertical condensation of the GP occurs

Figure 3. Heating and compacting of the canal whilst removing increments of GP until a dense apical plug is formed

18

The procedure is repeated until only an apical plug of GP remains (Figure 3). These steps are

known as the “down-pack” and slowly carry a wave of condensed GP down the root that fills

the canal laterally and vertically. The apical plug at the canal terminus is composed of vertically

compacted GP free of voids. This leaves a space coronally that is progressively filled with

small heat compacted GP segments in a sequential fashion, without an additional sealer

application (Schilder 1967). Schilder’s technique aims to provide a homogeneous, 3-

dimensional root filling that adapts to the anatomic complexities of the root canal system,

including large lateral and accessory canals. This warm vertical condensation technique was

the first to attempt such a 3-dimensional root filling and formed the foundation for modern

warm vertical condensation techniques.

2.4.2.2 Continuous wave of condensation

Schilder’s technique has evolved with the introduction of new technology. Electric heat

devices, such as Touch n’ Heat (SybronEndo, Orange County, CA, USA) and System B

(Analytic Endodontics, Orange, CA, USA) provide efficient GP removal and are used in

combination with hand-held devices such as Obtura III (Obtura Spartan, Earth City, MO, USA)

and Ultrafil 3D (Coltene/Whaledent, Cuyahoga Falls, OH, USA), that inject thermoplasticised

GP into the root canal void. The procedure is initially similar to Schilder’s technique and

requires a cleaned and shaped canal with a continuously tapering funnel-shaped preparation

with the application of sealer before insertion of a master cone to the WL. An electric heating

device is used to initially sever the coronal GP before it is driven apically to initiate

condensation of the GP in a single continuous motion. The heat is deactivated and firm apical

pressure is maintained for 5 – 10 s before a separation application of heat for 1s is performed

to facilitate coronal GP removal with the withdrawal of the instrument. Gutta-percha forced

laterally and apically forms an apical plug which remains in the canal together with a void in

the coronal segments (Figure 4).

19

Figure 4. Continuous wave of condensation. (a) Heat initiated vertical condensation. (b) Separation and withdrawal. (c and

d) compaction of apical plug. (e) Dense apical plug of GP.

Additional sealer is applied to the walls of the canal before it is backfilled with thermoplastic

GP injected into the canal. A homogeneous, 3-dimensional root filling with GP adapting to

complex irregularities of the root canal system is obtained that satisfies Schilder’s obturation

protocol. This technique is known as the “continuous wave of condensation” as the electric

heating device used carries a wave of condensed GP down the canal in a single, continuous

motion, unlike Schilder’s technique that requires multiple waves of heat and condensation. The

latest device for the CWC technique is the Elements Free Obturation Unit (SybronEndo/Kerr

Endodontics, Orange, CA, USA). This instrument incorporates both a System B (Analytic

Endodontics) handpiece and a thermoplastic GP gun to further simplify the technique.

20

Figure 5. Diagrammatic illustration of filling techniques, emphasising the desirability of minimum sealer volume. (a) Cold lateral condensation and (b) warm vertical condensation.

The CWC technique is reportedly faster (Keçeci et al. 2005) and provides a root filling that

better adapts to the complex root canal anatomy than lateral condensation (Lea et al. 2005,

Collins et al. 2006). It has also been shown to have less microbial coronal leakage (Bowman

& Baumgartner 2002) and an improved root canal density compared to lateral condensation

(Lea et al. 2005). The technique, however, requires a more complex armamentarium than cold

lateral condensation and is associated with a higher incidence of canal overfilling (Peng et al.

2007). This may be a reflection of poor cone fit to the apical preparation rather than a downfall

in the obturation technique.

It is always a concern when using heated instruments in root canals that deleterious effects may

occur to the periodontium. A 10° C increase above body temperature on the root surface is

regarded as the threshold at which adverse effects to the periodontium occur (Fors et al. 1985,

Hardie 1986, Gutmann et al. 1987, Saunders 1990). Silver and colleagues (1999) measured the

external root surface temperature of extracted teeth during Schilder’s technique and the CWC

technique and found Schilder’s method increased the temperature above 10° C 4 mm and 9

mm from the anatomic apex, whilst the CWC did not yield a 10° C rise. Schilder’s technique

raised the temperature above the safe threshold, indicating possible adverse effects on the

periodontium. However the technique was modified to use an electric heat device instead of

the flame heated spreader advocated by Schilder, which does not accurately represent the

original method.

21

2.5 The ideal root filling

Root canal fillings are commonly created with a central core and flowable sealer with the aim

of creating a total obturation of the root canal system (Schilder 1967) and eliminating space to

create an environment that is inhospitable to residual intraradicular bacteria (Sjögren et al.

1997, Molander et al. 2007). Gutta-percha does not adhere to the dentine, meaning it must be

used in combination with a sealer cement to create a fluid-tight seal (Ishley & ElDeeb 1986,

Wu et al. 2004). Sealers have been shown to shrink upon setting (Ørstavik et al. 2001, Marín-

Bauza et al. 2012, Barros et al. 2014), thus in order to maximize sealing ability and decrease

the limitations of sealers, it is ideal for sealers to form a thin layer on the dentine surface whilst

also being able to fill spaces inaccessible to GP. This will create a root filling with a minimal

amount of sealer cement, improved GP adaptation to dentine and allow the core GP material

to occupy a high percentage of the available canal space. This has been correlated with an

improved outcome (Ingle et al. 1994, Farzaneh et al. 2004). If excessive sealer cement is used,

it may increase the percentage of sealer occupying the canal space meaning more shrinkage on

setting will occur. This will increase gap formation, decrease GP adaptation to the dentine

surface and allow sealer to mix with thermoplasticised GP, forming a heterogeneous mass. This

may alter the properties of the core material in ways not yet known, potentially resulting in a

suboptimal obturation. Too little sealer may result in sealer not coating the canal wall, not

penetrating into dentinal tubules, lateral canals or canal irregularities and not forming a seal

between the dentine and GP. It is therefore important that the correct amount of sealer is used

with GP core materials if the best possible root filling is to be achieved.

2.6 Research question

In common with Schilder’s warm obturation technique, the CWC method requires an initial

application of sealer to the canal before the introduction of a GP cone. Currently, sealer is

reapplied to the vacant, coronal canal space after heat-facilitated GP removal. There is debate

as to whether additional sealer should be reapplied into the canal during the CWC technique to

improve sealer penetration to produce a higher quality obturation. A second application of

sealer may provide additional benefits during obturation or may affect the GP adaptation to

dentine and increase the percentage of sealer in the obturation as the additional sealer combines

with the thermoplasticised GP. There is no evidence whether an additional sealer application

22

will benefit the quality of obturation. The purpose of this research is to identify the effects of

an additional application of sealer during the CWC technique.

2.7 Aims

1. To assess the effect of additional sealer application on GP adaptation to dentine

2. To assess the effect of additional sealer application on sealer in cross sections

3. To assess the effect of additional sealer application on dentinal tubule penetration

2.8 Hypotheses

1. Gutta-percha adaptation to dentine in the coronal and middle root will decrease with an

additional application of sealer

2. Cross-sectional sealer percentage fill in the coronal and middle root will increase with

an additional application of sealer

3. Dentinal tubule penetration in the coronal and middle root will increase with an

additional application of sealer

23

Chapter 3: Materials and methods

3.1 Ethical approval

The study was approved by the University of Otago Human Ethics Committee (H16/056) and

conformed to the ethical guidelines of Helsinki 2008. Information sheets were distributed to

patients and informed written consent was obtained prior to removal of the tooth/teeth.

3.2 Māori consultation

Prior to the commencement of the study, Māori consultation was obtained and approval was

granted.

3.3 Specimens

Mature permanent maxillary molar teeth were sourced from patients attending the Faculty of

Dentistry, University of Otago. They were stored in 70 mL sterile specimen jars filled with

10% formalin until required. Buccolingual and mesiodistal radiographs were taken of each

tooth to evaluate their morphology.

Inclusion criteria included teeth with a single palatal canal and closed apex. Exclusion criteria

included teeth with more than one palatal root canal, radiographic evidence of palatal root

resorption, an immature apex, radicular fracture of the palatal root, previous root canal

treatment and palatal canals with a curvature greater than 30° assessed radiographically.

A biostatistician calculated a sample size of 105 teeth to be sufficient to detect a statistically

significant difference (alpha level = 0.05, 80% power) with two-sided tests with a standard

deviation of 6%.

24

3.4 Preparation of teeth

3.4.1 Root canal preparation

All specimens were marked with a 2B lead pencil to indicate the mid-palatal and mesial

positions prior to sectioning of the root (Figure 6 and 7).

Figure 6. A mesial view of a maxillary molar with 2B lead

pencil markings to indicate the mesial direction.

Figure 7. A palatal view of a maxillary molar with a 2B lead

pencil marking to indicate the mid-palatal direction.

The crown was then sectioned perpendicular to the long axis of the palatal root with a high-

speed cylindrical diamond bur (Hager & Meisinger GmbH, Neuss, North Rhine-Westphalia,

Germany, ref 806 314 158 524 012) under water coolant to obtain a root length of at least 10

mm from the palatal root apex. Roots that were fused with other roots were sectioned to

separate them. A size 10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) was taken to the

apical foramen until it was visible with 4x magnification prismatic loupes (Zeiss Eyemag Pro;

Carl Zeiss SpA, Arese, Lombardy, Italy) to ensure canal patency. The working length (WL)

was set at 1 mm short of the apical foramen to ensure standardisation. All root canals were

instrumented with a size 15 K-file (Dentsply Maillefer) to WL. Crown down preparation was

accomplished to a master apical file size of 40, 0.06 taper using Vortex Blue® rotary files

(Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) to WL according to the manufacturer’s

torque and speed recommendations (Table 5). Throughout the preparation, each root canal was

irrigated with 5 mL of 3% sodium hypochlorite (NaOCl) solution (Vista Dental Products,

Racine, WI, USA) using a 10 mL syringe (Becton, Dickinson and Company, Aalst, East

Flanders, Belgium) and a 27 gauge endodontic needle (Covidien, Dublin, Leinster, Ireland). A

size 10 K-file (Dentsply Maillefer) was inserted to the apical foramen between each instrument

25

change. At the completion of the mechanical preparation, canals were irrigated with 10 mL of

17% ethylenediaminetetraacetic acid (EDTA) (Vista Dental Products) using a 10 mL syringe

(Becton, Dickinson and Company) and 27 gauge endodontic needle (Covidien) before a final

rinse with 5 mL of 3% NaOCl (Vista Dental Products). Canals were dried with 3 size 40, 0.06

taper absorbent paper points (Dentsply Maillefer) placed to WL.

Table 5 Manufacturer’s recommended torque and speed settings for Vortex Blue® 6% taper rotary files.

File size Speed (rpm) Torque (Ncm)

20/0.06 500 2.0

25/0.06, 30/0.06 500 2.8

35/0.06, 40/0.06 500 3.6

The roots were then randomly assigned to each of the 7 groups (n = 15):

Group A: AH Plus Jet™ (Dentsply DeTrey) and master apical cone (MAC) (size 40,

0.06 taper GP points (Phoenix, Adam Dental Supplies, Mt Waverley, Victoria,

Australia) with no additional sealer after down-pack (experimental group).

Group B: Roth 801 Root Canal Cement (Roth International) and MAC with no

additional sealer after down-pack (experimental group).

Group C: Sealapex™ (Kerr) and MAC with no additional sealer after down-pack

(experimental group).

Group D: No sealer and MAC followed by no additional sealer after down-pack

(negative control).

Group E: AH Plus Jet™ (Dentsply DeTrey) and MAC with additional AH Plus Jet™

(Dentsply DeTrey) after down-pack (experimental group).

Group F: Roth 801 Root Canal Cement (Roth International) and MAC with additional

Roth 801 Root Canal Cement (Roth International) after down-pack (experimental

group).

Group G: Sealapex™ (Kerr) and MAC with additional Sealapex™ (Kerr) after down-

pack (experimental group).

26

3.4.2 Root canal fillings

The AH Plus Jet™ (Dentsply DeTrey), Roth 801 Root Canal Cement (Roth International) and

Sealapex™ (Kerr) were mixed according to the manufacturer’s instructions and each was dyed

with a small amount of Sudan Black B (Poly Scientific R&D, Bat Shore, NY, USA) that was

added until completely dissolved. The dyed AH Plus Jet™ sealer (Dentsply DeTrey) was placed

into the canals of roots in groups A and E, the dyed Roth 801 Root Canal Cement (Roth

International) in groups B and F, and the dyed Sealapex™ (Kerr) in groups C and G. All sealers

were placed using a size 25 Pastinject™ (Micro Mega, Besancon, France) in a slow-speed

handpiece by coating the flutes in sealer and introducing it into the canal, 1 mm from the WL.

The Pastinject™ (Micro Mega) was rotated clockwise for 5 s before withdrawing it from each

canal. The MAC was coated with sealer before it was inserted into the root canal with a

pumping action. Group D had the MAC placed to WL with no application of sealer.

The CWC technique was performed for all groups as follows; a 0.06 taper heated plugger of

an Elements™ Obturation Unit (Sybron Endo) was activated and inserted to 5-7 mm from the

WL. The power was deactivated and the plugger was pushed apically for 10 s. Heat was again

applied for 1 s and after waiting a further second, the plugger was removed. Additional dyed

AH Plus Jet™ sealer (Dentsply DeTrey), Roth 801 Root Canal Cement (Roth International) and

Sealapex™ (Kerr) was applied to groups E, F and G, respectively, by lightly coating the flutes

of a size 25 Pastinject™ (Micro Mega) and placing it to the apical GP before rotating clockwise

in a slow-speed handpiece upon removal. Thermoplastic backfill of the canals by warm GP

injection from the Elements™ Obturation Unit (Sybron Endo) was carried out on all root canals.

The device was set to 200°C and a 23 gauge needle (Elements Gutta Percha Cartridge, Sybron

Endo) was placed into the root canal against the apical GP for 5 s before extruding GP. The

mass of GP was allowed to force the needle coronally to the canal orifice. The device was

deactivated and the needle was removed after 1 s. A 0.8 mm Heat Carrier Plugger (Dentsply

Maillefer) was used to firmly compact the mass of GP at the orifice level. To ensure complete

setting of the sealer, all roots were wrapped in gauze moistened with tap water and stored at

room temperature for at least 2 days in a sealed container.

27

3.4.3 Embedding of roots in resin

Each filled root was soaked in 96% ethanol for at least 24 hours to facilitate the embedding

process. The roots were then placed on their apices in a silicone mould and supported with

paper clips to prevent movement (Figure 8).

Figure 8. Filled roots placed on their apices in a silicone mould and supported with paper clips.

EpoFix™ Cold-Setting Resin (Struers, Birmensdorf, Zürich, Switzerland) was mixed according

to the manufacturer’s instructions and poured into the mould around the supported roots until

they were submerged in the resin. The resin was left undisturbed in the mould until it had

completely set (Figure 9).

Figure 9. Filled roots submerged in resin that was left undisturbed until it had completely set.

28

3.4.4 Sectioning roots

The embedded roots were removed from the silicone mould (Figure 10) and trimmed in a bench

grinder to remove excess resin (Figure 11). The embedded roots were sectioned perpendicular

to the axis of the main canal.

Figure 10. Embedded roots after being removed from the

silicone mould.

Figure 11. Embedded roots after being trimmed in a bench

grinder.

Using a 0.4 mm thick rotary diamond blade (M0D13, Struers, Copenhagen, Hovedstaden,

Denmark) with copious water irrigation, sections were slowly made at 2, 3, 4, 6, 7 and 8 mm

from the root apex. The sections were performed at these increments to allow analysis of the

apical plug and backfill components of the obturation. With the appropriate surface of each

section facing upwards (at 2, 3, 4, 6, 7 and 8 mm from the root apex), polishing was completed

using 1200 followed by 2400 and finally 4000 grit sand paper. This greatly reduced the number

of surface imperfections on the sectioned surface, making microscopic analysis easier.

3.4.5 Evaluation

Each of the sections was viewed under a stereomicroscope (Nikon SMZ 800, Japan) at 10 and

20x magnification and photographed with a digital camera (Nikon DS-Fi2). Images of each

section were imported into computer software (Image J) for analysis.

29

3.4.5.1 Gutta-percha adaptation to dentine

Gutta-percha adaptation to dentine was measured by superimposing a transparent grid system

based on a morphometric method described by Andreasen (1987) for root resorption and

modified for canal cleanliness assessment by Tan and Messer (2002). Using Image J, the grid

system was superimposed over each 20x image and the image zoomed to 200x. It consisted of

10 equally spaced radii projecting from the centre of the canal cavity and intersecting with the

sealer-canal wall interface. Gutta-percha adaptation to dentine was calculated by measuring the

distance between the GP and the canal wall in micrometres (μm) at each of the 10 intercepts

then adding them together. The distance represented the sealer thickness.

To standardise the orientation of the 10 radiating lines between canals and between teeth from

the right and left hand sides of the mouth, intercept 1 was always aimed towards the palatal

and intercept 2 mesially (Figure 12).

Figure 12. A 20x magnification image with the superimposed grid system. Gutta-percha adaptation to dentine was calculated

by measuring the distance between the GP and canal wall at each of the 10 points of intersection. Intercept 1 was oriented towards the mid-palatal surface and intercept 2 mesially.

3.4.5.2 Sealer percentage fill

Sealer percentage of each image was calculated using Image J. Each 20x magnification image

was zoomed to 200x and the outline of the canal wall was marked (Figure 13). The pixel count

30

of each area representing dyed sealer within the root-filled canal was then calculated and

expressed as a percentage of the total canal area.

Figure 13. A 20x magnification image showing the outline of the canal wall (marked yellow) using Image J.

3.4.5.3 Depth of sealer penetration

Analysis of sealer penetration into the dentinal tubules was performed using the 10x

magnification images that showed the whole cross section to the cementodental junction (CDJ).

Sealer penetration was scored using a four-quadrant pie chart superimposed over each image

as described by Weis et al. (2004). The centre of the pie chart was placed over the centre of the

root canal filling. The chart was oriented so that a line drawn from the mid-palatal surface to

the centre of the canal bisects quadrant one. Quadrant 2 was directed towards the mesial (Figure

14).

31

Figure 14. Four-quadrant pie chart superimposed over the centre of the root canal filling

Penetration or absence of sealer into the tubules was scored and recorded for each quadrant as

follows:

A – Absent, with no sealer penetration into the tubules.

I – Inner one-third. Penetration depth extends into the inner third of the distance to the

CDJ.

M – Middle one-third. Depth of penetration extends into the middle third of the distance

to the CDJ.

O – Outer one-third. Depth of penetration extends into the outer third of the distance to

the CDJ.

32

Chapter 4: Results

4.1 Gutta-percha adaptation to dentine

At all levels, GP adaptation to dentine was found to be significantly different. Further post-hoc

analysis was performed to determine the significance between the negative control (Group D)

and each sealer type.

The mean distance between the GP and canal wall for all levels is shown in Figure 15. Group

G was found to have the highest mean distance (35 μm) and Group D the lowest (7 μm).

Figure 15. Average distance between GP and canal wall for all levels.

0

10

20

30

40

50

60

70

80

90

2 mm 3 mm 4 mm 6 mm 7 mm 8 mm Average

Dis

tance

bet

wee

n G

P a

nd

can

al w

all

(μm

)

Group

Mean distance between GP and canal wall for all levels

A B C D E F G

33

4.1.1 AH Plus Jet™ (Dentsply DeTrey) and the negative control (Groups A, D

and E)

The sum of 10 intercepts between the GP and canal wall for Groups A, D and E are shown in

Appendix C. Of the groups obturated with AH Plus Jet™ (Dentsply DeTrey), the largest sum

of the 10 intercepts occurred in Group E at the 2 mm level (511 μm). The mean distance

between the GP and canal wall for Groups A, D and E are shown in Table 6 and Figure 16. The

largest mean distance between the GP and canal wall occurred in Group E at the 2 mm level

(51 μm).

Table 6. Mean distance between the GP and canal wall for all groups (µm).

Group A B C D E F G

2 mm 31.46291 34.86497 69.35299 5.2374 51.10709 38.13257 83.89635

3 mm 29.90427 17.93485 23.51821 7.14892 35.10873 11.87304 53.75399

4 mm 19.00589 15.9317 24.98144 7.68625 28.65702 21.58706 31.57221

6 mm 11.29653 9.05603 9.06871 6.04428 25.90022 15.58953 20.10313

7 mm 6.15579 10.87371 2.819 5.61857 18.28001 8.94359 9.63695

8 mm 7.0412 11.49633 2.45159 7.33027 13.74108 9.10314 9.63695

34

Figure 16. Summary of mean distance between GP and canal wall for Groups A, D and E.

Post-hoc testing was carried out between Groups A, D and E to determine significance (Table

7). Comparison of Groups A and D revealed Group A had significantly increased distance

between the GP and canal wall at the 2 (p = 0.00), 3 (p = 0.01) and 4 (p = 0.05) mm levels.

Comparison of Groups A and E revealed Group E had significantly increased distance between

the GP and canal wall at the 4 (p = 0.05) and 6 (p = 0.01) mm levels.

When compared, Groups D and E revealed Group E had significantly increased distance

between the GP and canal wall at the 2 (p = 0.00), 3 (p = 0.00), 4 (p = 0.00) and 6 (p = 0.00)

mm levels.

0

10

20

30

40

50

60

2 mm 3 mm 4 mm 6 mm 7 mm 8 mm

Dis

tance

bet

wee

n G

P a

nd

can

al w

all

(μm

)

Level

Mean distance between GP and canal wall

A D E

35

Table 7. Post-hoc comparisons of distance from GP to canal wall between Groups A, D and E.

Level A-D A - E D - E

Group with significantly

more sealer


more sealer


more sealer

2 mm A (p = 0.00) Not significant E (p = 0.00)


4 mm A (p = 0.05) E (p = 0.05) E (p = 0.00)

6 mm Not significant E (p = 0.01) E (p = 0.00)

7 mm Not significant Not significant Not significant


4.1.2 Roth 801 Root Canal Cement (Roth International) and the negative

control (Groups B, D and F)

The sum of 10 intercepts between the GP and canal wall for Groups B and F are shown in

Appendix C. Of the groups obturated with Roth 801 (Roth International), the largest sum of 10

intercepts occurred in Group F at the 2 mm level (381 μm). The mean distance between the GP

and canal wall for Groups B, D and F are shown in Table 6 and Figure 17. The largest mean

distance between the GP and canal wall occurred in Group F at the 2 mm level (38 μm).

36

Figure 17. Summary of mean distance between GP and canal wall for Groups B, D and F.

Post-hoc testing was carried out between Groups B, D and F to determine significance (Table

8). Comparison of Groups B and D revealed Group B had significantly increased distance

between the GP and canal wall at the 7 (p = 0.01) and 8 (p = 0.00) mm levels.

Comparison of Groups B and F revealed Group F had significantly increased distance between

the GP and canal wall at the 6 (p = 0.03) mm level only.

When compared, Groups D and F showed Group F had significantly increased distance

between the GP and canal wall at 6 (p = 0.03) and 8 (p = 0.00) mm.

0

5

10

15

20

25

30

35

40

45


Dis

tance

bet

wee

n G

P a

nd

can

al w

all

(μm

)

Level


B D F

37

Table 8. Post-hoc comparisons of distance from GP to canal wall between Groups B, D and F.

Level B-D B - F D - F


more sealer


more sealer


more sealer




6 mm Not significant F (p = 0.03) F (p = 0.03)

7 mm B (p = 0.01) Not significant Not significant

8 mm B (p = 0.00) Not significant F (p = 0.00)

4.1.3 Sealapex™ (Kerr) and the negative control (Groups C, D and G)

The sum of 10 intercepts between the GP and canal wall for Groups C and G are shown in

Appendix C. Of the groups obturated with Sealapex™ (Kerr), the largest sum of 10 intercepts

occurred in Group G at the 2 mm level (838 μm). The mean distance between the GP and canal

wall for Groups C, D and G are shown in Table 6 and Figure 18. The largest mean distance

between the GP and canal wall occurred in Group G at the 2 mm level (83 μm).

38

Figure 18. Summary of mean distance between GP and canal wall for Groups C, D and G.

Post-hoc testing was carried out between Groups C, D and G to determine significance (Table

9). Comparison of Groups C and D revealed Group C had significantly increased distance

between the GP and canal wall at the 2 (p = 0.02) and 4 (p = 0.00) mm levels, whilst Group D

had significantly increased distance at 7 (p = 0.00) and 8 (p = 0.00) mm.

Comparison of Groups C and G revealed Group G had significantly increased distance between

the GP and canal wall at the 8 mm (p = 0.03) level only.

When compared, Groups D and G showed Group G had significantly increased distance

between the GP and canal wall at the 2 (p = 0.00), 4 (p = 0.00), 7 (p = 0.01) and 8 (p = 0.00)

mm levels.

0

10

20

30

40

50

60

70

80

90


Dis

tance

bet

wee

n G

P a

nd

can

al w

all

(μm

)

Level


C D G

39

Table 9. Post-hoc comparisons of distance from GP to canal wall between Groups C, D and G.

Level C-D C - G D - G


more sealer


more sealer


more sealer

2 mm C (p = 0.02) Not significant G (p = 0.00)




7 mm D (p = 0.00) Not significant G (p = 0.01)

8 mm D (p = 0.00) G (p = 0.03) G (p = 0.00)

4.2 Sealer percentage in cross sections

At all levels, sealer percentage was found to be significantly different. Further post-hoc analysis

was performed to determine significance between the negative control (Group D) and each

sealer type.

The average sealer percentage for all groups combined is shown in Figure 19. The largest mean

sealer percentage occurs at the 2 mm level (24%) and the smallest at 8 mm (2%).

40

Figure 19. Mean sealer percentage of all groups combined.


and E)

The mean sealer percentage in cross sections for Groups A and E are shown in Appendix D.

Of the groups obturated with AH Plus Jet™ (Dentsply DeTrey), the largest mean sealer

percentage occurred in Group A at the 2 mm level (52.5%).

Post-hoc testing was carried out between Groups A, D and E to determine significance (Table

10). Comparison of Groups A and D revealed Group A had significantly increased sealer at the

2 (p = 0.00), 3 (p = 0.00), 4 (p = 0.00), 6 (p = 0.00), 7 (p = 0.01) and 8 (p = 0.00) mm levels.

Comparison of Groups A and E revealed Group A had significantly increased sealer at the 2

mm (p = 0.03) level only.

When compared, Groups D and E showed Group E had significantly increased sealer at the 2

(p = 0.00), 3 (p = 0.00), 4 (p = 0.00), 6 (p = 0.00), 7 (p = 0.03), 8 (p = 0.00) mm levels.

0

5

10

15

20

25

30


Sea

ler

per

centa

ge

Level

Mean sealer percentage of all groups

Mean for all groups

41

Table 10. Post-hoc comparisons of sealer percentage between Groups A, D and E.

Level A-D A - E D - E


increased sealer

percentage


increased sealer

percentage


increased sealer

percentage

2 mm A (p = 0.00) A (p = 0.03) E (p = 0.00)








The mean sealer percentage in cross sections for Groups B and F are shown in Appendix D. Of

the groups obturated with Roth 801 (Roth International), the largest mean sealer percentage

occurred in Group F at the 2 mm level (14.0 %).

Post-hoc testing was carried out between Groups B, D and F to determine significance (Table

11). Comparison of Groups B and D revealed Group B had significantly increased sealer at the


Comparison of Groups B and F revealed no significant difference at any level (p > 0.05).

When compared, Groups D and F showed Group F had significantly increased sealer at the 2

(p = 0.03), 6 (p = 0.00), 7 (p = 0.00), 8 (p = 0.01) mm levels.

42

Table 11. Post-hoc comparisons of sealer percentage between Groups B, D and F.

Level B-D B - F D - F


increased sealer

percentage


increased sealer

percentage


increased sealer

percentage








The mean sealer percentage in cross sections for Groups C and G are shown in Appendix D.

Of the groups obturated with Sealapex™ (Kerr), the largest mean sealer percentage occurred in

Group C at the 2 mm level (26.2 %).

Post-hoc testing was carried out between Groups C, D and G to determine significance (Table

12). Comparison of Groups C and D revealed Group C had significantly increased sealer at the


Comparison of Groups C and G revealed no significant difference at any level (p > 0.05).

When compared, Groups D and G revealed Group G had significantly increased sealer at the 2

(p = 0.00), 3 (p = 0.00), 4 (p = 0.00), 6 (p = 0.00), 7 (p = 0.01) and 8 (p = 0.01) mm levels.

43

Table 12. Post-hoc comparisons of sealer percentage between Groups C, D and G.

Level C-D C - G D - G


increased sealer

percentage


increased sealer

percentage


increased sealer

percentage







4.2.4 The negative control (Group D)

The mean sealer percentage for Group D was 0% at the 2, 3, 4 and 6 mm levels. At 7 mm it

increased to 0.1% and at 8 mm 0.2% (Figure 20).

44

Figure 20. Mean sealer percentage for Group D.

4.3 Depth of sealer penetration

Descriptive analysis was performed on the depth of sealer penetration. Figure 21 shows sample

images of each penetration depth.

0

0.05

0.1

0.15

0.2

0.25


Sea

ler

per

centa

ge

Level

Summary of mean sealer percentage in cross section

D

45

Figure 21. Sample images showing penetration depths of the dyed sealer. Absent (top left), inner third (top right), middle

third (lower left) and outer third (lower right).

4.3.1 All groups

At all levels, the total count for each penetration depth was 606 absent, 594 inner third, 298,

middle third and 1016 outer third as shown in Figure 22 and Appendix E: Table E 1. At the 2

mm level, the most frequent penetration depth was inner (166) and the highest count (51)

occurred at the inner third in a buccal direction. At the 3 mm level, the most frequent

penetration depth was inner (161) and the highest count (47) also occurred at the inner third in

a buccal direction. At the 4 mm level, the most frequent penetration depth was absent (120)

and the highest count (37) was absent in a buccal direction. At the 6 mm level, the most frequent

penetration depth was outer (226) and the highest count (63) occurred at the outer third in a

mesial direction. At the 7 mm level, the most frequent penetration depth was outer (260) and

the highest count (68) occurred at the outer third in a mesial direction. At the 8 mm level, the

most frequent penetration depth was outer (286) and the highest count (78) occurred at the

outer third in a palatal direction.

46

Figure 22. Summary of penetration depths and direction of all groups at all levels.

When outer third penetration depth of all groups combined was analysed by level, the outer

penetration depth count was 56 at 2 mm and reached a maximum of 286 at 8 mm (Figure 23).

47

Figure 23. Outer penetration depth of all groups combined.


and E)

For Group A (Figure 24 and Appendix E: Table E 2), the total count for each penetration depth

was 17 absent, 117 inner third, 92 middle third and 134 outer third. The total for Group E

(Figure 25 and Appendix E: Table E 6) was 43 absent, 118 inner, 41 middle and 158 outer.

When comparing the four penetration depths of Group A and E, Group E had more absent

penetrations at all levels, except 8 mm which was equivalent. Group E also had more inner

third penetration depths at 4 mm, 6 mm and 7 mm. The 3 mm and 8 mm levels were equivalent

and Group A had more at 2 mm. Group A had more middle third penetration depths at all levels

and Group E had more outer penetration depths at all levels except 6 mm.

For Group D (negative control) all penetration depths for all levels were scored “absent”

(Figure 26 and Appendix E: Table E 5). When Groups A and E were compared to Group D,

Group D scored more absent penetration depths at all levels. Group D scored fewer inner,

middle and absent penetration depths at all levels.

0

50

100

150

200

250

300

350

2 3 4 6 7 8

Co

un

t

Level

Outer penetration of all groups

48

Figure 24. Summary of Group A penetration depths and direction at all levels.

49

Figure 25. Summary of Group E penetration depths and direction at all levels.

50

Figure 26. Summary of Group D (negative control) penetration depths and direction at all levels.



For Group B (Figure 27 and Appendix E: Table E 3), the total count for each penetration depth

was 39 absent, 100 inner third, 41 middle third and 180 outer third. The total for Group F

(Figure 28 and Appendix E: Table E 7) was 38 absent, 116 inner, 31 middle and 175 outer.

When comparing the four penetration depths of Group B and F, Group F had more absent

penetrations at 3 mm, 4 mm and 8 mm. The 7 mm level was equivalent and Group B had more

51

at 2 mm and 6 mm. Group F also had more inner third penetration depths at 2 mm, 6 mm and

8 mm. The 3 mm level was equivalent and Group B had more at 4 mm and 7 mm. Group B had

more middle third penetration depths at all levels except 6 mm. Group F had more outer

penetration depths at 2 mm, 4 mm and 7 mm whilst Group B had more at 3 mm, 6 mm and 8

mm.

When Groups B and F were compared to Group D (negative control) (Figure 26 and Appendix

E: Table E 5), Group D scored more “absent” penetration depths at all levels. Group D scored

fewer inner, middle and absent penetration depths at all levels.

52

Figure 27. Summary of Group B penetration depths and direction at all levels.

53

Figure 28. Summary of Group F penetration depths and direction at all levels.


For Group C (Figure 29 and Appendix E: Table E 4), the total count for each penetration depth

was 71 absent, 73 inner third, 50 middle third and 166 outer third. The total for Group G (Figure

30 and Appendix E: Table E 6) was 48 absent, 70 inner, 39 middle and 203 outer.

When comparing the four penetration depths of Group C and G, Group C had more absent

penetrations at 2 mm, 4 mm and 6 mm. The 3 mm level was equivalent and Group G had more

at 7 mm and 8 mm. Group C also had more inner third penetration depths at all levels except 2

54

mm and 4 mm. Group C had more middle third penetration depths at 4 mm, 7 mm and 8 mm.

The 3 mm level was equivalent and Group G had more at 2 mm and 6 mm. Group G had more

outer penetration depths at all levels except 2 mm.

When Groups C and G were compared to Group D (negative control) (Figure 26 and Appendix

E: Table E 5), Group D scored more absent penetration depths at all levels. Group D scored

fewer inner, middle and absent penetration depths at all levels.

Figure 29. Summary of Group C penetration depths and direction at all levels.

55

Figure 30.Summary of Group G penetration depths and direction at all levels.

56

Chapter 5: Discussion

5.1 Gutta-percha adaptation to dentine

The distance between the GP and canal wall represents the sealer/film thickness as described

by other investigators. For all groups, the mean distance between the GP and canal wall were

found to be less than in the ex vivo study by de Deus et al. (2003) who recorded an average

sealer thickness of 88 μm. Their study compared obturation techniques with sealer thickness

and found the CWC technique to have a decreased thickness of sealer compared to lateral

condensation. That study, however, used a different tooth model (maxillary central incisors)

and a zinc-oxide eugenol sealer (Endofill). This is the same class of sealer as Roth’s. In

addition, de Deus et al. (2003) found a trend for increased sealer thickness in a coronal to apical

direction, which was a consistent finding for all groups in the current experiment except for the

negative control (Group D).

During root canal preparation, it was noted that some specimens had wider canals and others

narrow and calcified canals. After rotary preparation of specimens with the narrow canals, a

canal shape that closely corresponded to the matching MAC was created (Gordon et al. 2005).

Conversely, the specimens with wide canals were hardly instrumented with the size 40, 0.06

taper master apical file. As a result, when the root fillings were placed in wide canals, the

matching cone (size 40, 0.06 taper) would not correspond well to the shape of the ‘prepared’

but non-instrumented canal. The distance between the GP and root canal wall would therefore

be increased and filled with sealer. Consequently, the results for GP adaptation to dentine

would probably be increased. The CWC obturation technique generally improves GP

adaptation to dentine, however, it has a limited ability to effect the GP adaptation of the most

apical GP (Cusimano et al. 2010, Natera et al. 2011). The distance between the GP and canal

wall was lower in the middle and coronal portions of the canal. The effect of the down-pack

and backfill probably influenced these regions of the root canal, even if the MACs were poorly

adapted to those specimens with wide canals. Therefore, the variability of the canal

morphology and the CWCs inability to greatly affect the adaptation of apical GP accounted for

the trend for increased distance between the GP and canal wall from coronal to apical.

A plastic simulated tooth model has been used to assess GP adaptation to dentine (Gurgel‐Filho

et al. 2006, Karabucak et al. 2008). It would have circumvented the problem of large variations

57

in canal width and its effect on GP adaptation to dentine. A plastic model, however, would

have made the study less relevant to the clinical setting as it would not account for the complex

root canal morphology evident in human teeth (Vertucci 1984, Goldberg et al. 2002) and hence

extracted human teeth were utilised.


and E)

5.1.1.1 Comparisons with the negative control

Compared to Group D (negative control), Group A had significantly increased distance

between the GP and canal wall at 2, 3 and 4 mm. Group E also had increased distances

compared to Group D at the 2, 3, 4 and 6 mm levels. This is to be expected as Group D was

only obturated with GP, while Group A and E were obturated with GP and sealer. It is to be

expected that as Group D had no sealer between the GP and canal wall that the distance between

the GP and canal wall would be decreased compared to Groups A and E.

5.1.1.2 Comparison between a single and an additional sealer application

The effect of a single and additional application of AH Plus or any other sealer during warm

obturation techniques has not been reported in the literature. Comparisons between Group A

and E revealed that Group E had significantly increased distance between the GP and canal

wall at the 4 and 6 mm levels only. This is a small but significant finding. Group A had only

one application of sealer, whilst Group E received the additional application. This suggests the

distance between the GP and canal wall mildly increased with an additional application of

sealer. This confirms the hypothesis for AH Plus and is an expected finding.

The average distance between the GP and canal wall for all levels was 17 μm for Group A and

29 μm for Group E. This was slightly higher than an ex vivo study which involved mandibular

molars (Weis et al. 2004) which reported an average sealer thickness of 12.2 μm after

obturation with the CWC technique. Their study, however, used AH 26, the predecessor of AH

Plus.

58

5.1.1.3 Influence of heat

The effect of warm obturation techniques on root canal sealers has been investigated. AH Plus

has recently been shown to be affected by high temperature (Viapiana et al. 2014b). It contains

dibenzyldiamine, aminoadamantane, and tricyclodecane-diamine in paste 1. These polyamines

act as initiators and react with the resins in paste 2, resulting in polymerization. The heat

disintegrates these phases (Viapiana et al. 2015). The effect of heating AH Plus to 25 and 37

has been shown not to influence viscosity (Lacey et al. 2006). This was in contrast to Camilleri

(2015) who investigated the effects of 100 °C heat for 1 min on AH Plus and found the sealer

properties were modified by heat. In addition, the setting time was reduced and the sealer film

thickness increased. As a consequence, AH Plus was not recommended for warm GP obturation

techniques. This finding is not relevant to the CWC obturation technique used in the current

study as the 0.06 taper heated plugger of the Elements™ Obturation Unit was only applied for

a total of 3 – 5 s in each canal rather than 1 min. In addition, the electronically heated pluggers

set to temperatures above 200 °C (on the display) have been shown to reach a maximum

temperature of only 80 °C (Viapiana et al. 2014b). Hence Camilleri (2015) and other

investigations (Qu et al. 2016) that show heat-related changes to AH Plus at 100 ˚C are not

relevant to the current investigation nor are they relevant to the CWC obturation technique used

in the clinical setting. This view is also shared by Al-Haddad (2017) and is an issue of current

debate in the journals.




Compared to Group D (negative control), Group B had significantly increased distance

between the GP and canal wall at 7 and 8 mm. Group F also had increased distances compared

to Group D at the 6 and 8 mm levels. This is to be expected as Group D was only obturated

with GP.

59

5.1.2.2 Comparison between a single and additional sealer application

The effect of a single and additional application of Roth’s during warm obturation techniques

has not been reported in the literature. Comparisons between Group B and F revealed Group F

had significantly increased distance between the GP and canal wall at the 6 mm level only.

Group B had only one application of sealer, whilst Group F had an additional application. This

suggests the distance between the GP and canal wall increased in the middle third with an

additional application of sealer. This is contrary to the hypothesis for Roth’s, as an increase

was only demonstrated in the middle third of the root and not the coronal third.

The average distance between the GP and canal wall for all levels was 17 μm for Group B and

18 μm for Group F. This was drastically lower than de Deus et al. (2003) who found an average

film thickness of sealer of 88 μm. Analysis by root third revealed the average distance for the

apical, middle and coronal was 26, 12 and 11 μm for Group B and 25, 19 and 9 μm for Group

F. When compared to de Deus et al. (2003) it was found to be up to seven times less, with

average film thicknesses of 187 apically, 47 mid-root and 29 μm coronally. It is important to

note that the other workers used a different tooth model (maxillary central incisors) and sealer

(Endofill). Although the sealer is different, it is the same sealer class as Roth’s and should

therefore be somewhat comparable.


The effect of heat on the physical properties of Roth’s sealer has not been reported in the

literature. Pulp Canal Sealer is a zinc oxide euginol-based sealer. Camilleri (2015) investigated

the effects of 100 °C heat for 1 min on Pulp Canal Sealer and found the setting time and sealer

film thickness were unaffected by heat. As this is the same class of sealer as Roth’s, a similar

outcome would be expected.

60



Compared to Group D (negative control), Group C had a significantly increased distance

between the GP and canal wall at 2 and 4 mm whilst Group D had significantly increased

distance at 7 and 8 mm. The difference was 4 and 3 μm more than Group D between the groups

at the 7 and 8 mm levels, however, it was significant. The decreased distance of Group D is to

be expected as it was only obturated with GP. It is also to be expected that as Group D had no

sealer, the distance between the GP and canal wall would be decreased compared to groups

obturated with sealer. Group G also had increased distances compared to Group D at the 2, 4,

7 and 8 mm levels. Again, it is to be expected that Group D without sealer would have less

distance between GP and the canal wall.


The effect of a single and additional application of Sealapex™ during warm obturation

techniques has not been reported in the literature. Comparisons between Group C and G

revealed Group G had significantly increased distance between the GP and canal wall at the 8

mm level only. Group C had only a single application of sealer, whilst Group G had an

additional application. This suggests the distance between the GP and canal wall increased in

the coronal third with an additional application of sealer. This is contrary to the hypothesis, as

an increase was only demonstrated in the coronal third of the root and not the middle third.

The average distance between the GP and canal wall for all levels was 22 μm for Group C and

35 μm for Group G. There are no studies on Sealapex™ or calcium other hydroxide-based sealer

thickness after warm vertical obturation techniques. However, the distance between the GP and

canal wall was comparable to Weis et al. (2004) who reported an average sealer thickness of

12.2 μm after CWC was performed on mandibular molars. It was also substantially less than

de Deus et al. (2003) who reported an average film thickness of 88 μm with CWC performed

on maxillary central incisors. Both studies, however, used different sealers.

The largest mean distance between the GP and canal wall for all groups at all levels was

measured at 84 μm for Group G. The Sealapex™ sealer groups (Groups C and G) tended to

have larger distances at the 2, 3 and 4 mm levels when compared to the other sealers but this

61

was only significant at 2 and 4 mm when compared with Roth’s. There is little evidence in the

literature to suggest why this may occur, but it may be attributed to the physical properties of

calcium hydroxide-based sealers.


The effect of heat on the physical properties of Sealapex™ have not been reported in the

literature. Apexit Plus is a calcium hydroxide-based sealer. Camilleri (2015) investigated the

effects of 100 °C heat for 1 min on Apexit Plus and found the setting time and sealer film

thickness were unaffected by heat. As this is the same class of sealer as Sealapex™, the outcome

should be somewhat comparable.

5.2 Sealer percentage in cross sections

The mean percentage of sealer for each level is shown in Appendix D. The mean sealer

percentage for all groups at 2 mm was 24% and decreased at 8 mm to 2%. The percentage of

sealer in all groups tended to decrease from apical to coronal. This is a common finding

amongst other investigators, although some report GP percentage rather than sealer percentage

(Smith et al. 2000, Keçeci et al. 2005). This cannot be directly compared between studies

became voids and canal debris may influence the results. It does, however, provide an

indication of sealer percentage and show potential trends.

Silver et al. (1999) and Cathro and Love (2003) have reported low percentages of sealer in

cross sections after the CWC obturation technique with a single application of sealer. Silver’s

group (1999) reported sealer percentage values of 2 – 5% measured at 1, 2, 3, 4, 5, 6 mm from

the root apex. This is markedly lower than the sealer percentages found in the current

investigation which ranged from 0 – 53%. Cathro and Love (2003) reported even lower sealer

percentages, ranging from 0 – 4% measured at 10 levels along the root length. These

investigators used a different sealer (Kerr Pulp Canal Sealer EWT) and plastic simulation

models rather than account for the complex canal irregularities evident in human teeth

(Vertucci 1984).

62

Investigations on extracted human teeth reveal high GP percentages in cross sections after the

CWC with a single application of sealer. Wu et al. (2001) obturated teeth with a multiple wave

technique using AH 26 and reported a percentage of GP of 94% at 2 mm and 100% 4 mm from

the root apex. This is a very high percentage of GP. In the current investigation, sealer

percentage varies significantly from 4 – 53% at the 2 - 4 mm levels across all experimental

groups with an average sealer percentage of 20%. Although direct comparisons between GP

and sealer percentage are not strictly applicable, the sealer percentage is much higher in the

current investigation compared with Wu et al. (2001). Gençoǧlu et al. (2002) obturated teeth

with Kerr Pulp Canal Sealer EWT using a warm vertical technique similar to the CWC method.

They also reported a higher percentage of GP, between 81 – 9%, 1 – 4 mm from the root apex.

The study, however, advanced the electrically heated plugger 3 mm from the WL which is

much further than the current investigation where it was only 5-7 mm from the WL. This is a

significant difference in the methodology as heat application closer to the WL has been shown

to improve GP adaptation and produce higher percentages of GP (Smith et al. 2000, Jung et al.

2003).


and E)

5.2.1.1 Comparisons with the negative control (Group D)

Sealer percentage in cross sections were found to be significantly different at all levels. Post-

hoc comparisons between Groups A, D and E were significant. Compared to Group D (negative

control), Groups A and E had significantly increased sealer at all levels. This is to be expected

as Group D was only obturated with GP, whilst Group A and E were obturated with GP and a

single or double application of sealer. Group D never had sealer applied, therefore, the sealer

percentage would be expected to be decreased compared to Groups A and E.


The effect of a single and additional application of AH Plus during warm obturation techniques

has not been reported in the literature. Comparisons between Groups A and E revealed Group

A had significantly increased sealer percentage at 2 mm only. This is a small but statistically

63

significant finding. Group A had only one application of sealer, whilst Group E had an

additional application. This suggests the sealer percentage at the apical third slightly decreased

with an additional application of sealer. This is contrary to the hypothesis for AH Plus and is

an unexpected finding.




Sealer percentage in cross section was found to be significantly different at all levels. Post-hoc

comparisons between Groups B, D and F were significant. Compared to Group D (negative

control), Groups B and F had significantly increased sealer at all levels. This is to be expected

as Group D was only obturated with GP, whilst Group B and F were obturated with GP and a


percentage would be expected to be decreased compared to Groups B and F.


The effect of a single and additional application of Roth’s during warm obturation techniques

has not been reported in the literature. Comparisons between Groups B and F revealed no

significant differences at any level. Group B had a single application of sealer whilst Group F

had an additional application. This suggests no difference at any level between a single and

additional application of Roth’s on sealer percentage in cross section. This is contrary to the

hypothesis for this sealer.



Sealer percentage in cross section was found to be significantly different at all levels. Post-hoc

comparisons between Groups C, D and G were significant. Compared to Group D (negative

control), Groups C and G had significantly increased sealer at all levels. This is to be expected

64

as Group D was only obturated with GP, whilst Group C and G were obturated with GP and a


percentage would be expected to be lower to that of Group C.


The effect of a single and additional application of Sealapex™ has not been reported in the

literature. Comparisons between Groups C and G revealed no significant differences at any

level. Group C had a single application of sealer whilst Group G had an additional application.

This suggests no difference at any level between a single and additional application of

Sealapex™ on sealer percentage in cross section. This is contrary to the hypothesis for

Sealapex™.

5.2.4 The negative control (Group D)

The sealer percentage in Group D was usually 0%. Zero sealer percentage in cross section is

expected, however, at the 7 and 8 mm levels small sealer amounts were recorded. This is

attributed to an unfortunate shortcoming of the use of the Image J software. In the analysis, the

pixel count of each area represented by dyed sealer within the root-filled canal was then

calculated and expressed as a percentage of the total canal area. The small but “positive” sealer

measured in the 7 and 8 mm levels was probably the result of the program detecting dark pixels

as ‘sealer.’ This was sometimes evident with the presence of a void or discoloured dentine

debris (Figure 31 and Figure 32).

65

Figure 31. Cross section of Group D at 7 mm with void (arrow).

Figure 32. Dentine debris (arrow) evident in a cross section of Group D.

66

5.3 Depth of sealer penetration

5.3.1 All groups

Primary dentine is influenced by ageing (Ketterl 1983) and the amount of dentinal tubular

sclerosis increases with age. It begins at the root apex, adjacent to the cementum and gradually

advances towards the crown. When all groups and levels were combined, the highest

penetration depth count was the outer third (n = 1016). The outer penetration depth count was

lowest at the 2 mm level (n = 56) and increased in a coronal direction, at each level to reach a

maximum of 286 at the 8 mm level. Other investigators also reported increased penetration

depths in an apical to coronal direction (Kara Tuncer 2015, Akcay et al. 2016, Gu et al. 2017,

Turkel et al. 2017). This is an expected finding as the sclerosis of the dentine has been

attributed to tubular penetration inhibition (Paqué et al. 2006).

5.3.2 Direction of sealer penetration

Differences in sealer penetration direction were also observed. For all experimental groups

except for Group E, the highest count of outer third penetration depths was recorded in the

buccal or palatal direction at the 2 and 3 mm levels. This is a significant finding as dentinal

tubular sclerosis begins first apically (Ketterl 1983) and mesially and distally creating a distinct

butterfly shape (Vasiliadis et al. 1983). As a consequence, sealer penetration in the sclerosed

mesial and distal directions will be impeded (Paqué et al. 2006) and increased penetration depth

counts are expected for the buccal and palatal directions. Similar findings were observed by

Weis et al. (2004) who obturated mesial roots of extracted human mandibular molars with four

obturation techniques including CWC. They found the obturation technique did not affect

sealer penetration depths, and that penetration depths were greater and more frequent in a bucco

- lingual direction.

5.3.3 Comparisons with the negative control (Group D)

The total count for each penetration depth for Group D was 660 absent and 0 inner, middle and

outer third. This is an expected finding as Group D was obturated with no sealer, therefore

67

sealer penetration into the dentine is impossible. When all other groups were compared with

Group D, they each showed increased inner, middle and outer third penetration depth counts at

each level. This is an expected finding as Group D never had sealer applied.


and E)


Comparisons between Groups A and E revealed the total count for each penetration depth for

Group A was 17 absent, 117 inner third, 92 middle and 134 outer. This was generally similar

to Group E (43 absent, 118 inner third, 41 middle third and 158 outer third). Group E did,

however, present increased outer third penetration depths.

At each level, Group E had more outer third penetration depths, except 6 mm. This suggests a

trend for increased sealer penetration with an additional application of sealer. This is consistent

with the hypothesis for AH Plus. Group E was expected to have increased sealer penetration

depth counts in the middle and coronal root thirds, however, increased outer third penetration

depths were also observed in the apical root.



5.3.5.1 Comparison between a single and additional sealer application

Comparisons between Groups B and F revealed the total count for each penetration depth for

Group B was 78 absent, 193 inner third, 76 middle and 313 outer. This was generally similar

to Group F (73 absent, 221 inner third, 58 middle third and 308 outer third). Group F did,

however, observe increased inner third penetration depths.

At the 2, 4 and 7 mm levels, Group F had more outer third penetration depth counts whilst

Group B had more at 3, 6 and 8 mm. Each group had more outer third penetration depth counts

at alternating levels. This suggests an additional application of sealer did not affect the depth

of penetration, which is contrary to the hypothesis for Roth’s.

68



Comparisons between Groups C and G revealed the total count for each penetration depth for

Group C was 142 absent, 141 inner third, 93 middle and 284 outer. This was generally similar

to Group G (95 absent, 140 inner third, 73 middle third and 352 outer third). Group F did,

however, observe increased outer third penetration depths.

At each level, Group F had more outer third penetration depths, except at the 2 mm level. This

suggests a trend for increased sealer penetration with the additional application of sealer and is

consistent with the hypothesis for Sealapex™. Group F was expected to have increased sealer

penetration depths in the middle and coronal root thirds, however, increased outer third

penetration depth counts were also observed in the apical root.

5.4 Sealer flow

The ISO6876 (2012) (Institution 2012) specifications dictate the physical properties of root

canal sealers, such as flow. Sealer flow is measured by placing a designated volume of the

mixed sealer between two glass slabs with a weight for compression. The mean diameter of the

compressed disc of sealer is measured to determine the flow.

The physical properties and characteristics of a root canal sealer are fundamental to their

clinical behaviour. Flow allows a sealer to penetrate into the irregularities of the root canal

system (Silva et al. 2013). Root canal sealers with excessive flow run the risk of extrusion

beyond the apex. The ISO6876 (2012) specifications specify the flow of a sealer should be

greater than 17 mm in diameter. AH Plus has been shown to have a flow between 17 – 23 mm

(Viapiana et al. 2014a, Khalil et al. 2016) which is comparable to Roth’s with a flow of 20 mm

(Grossman 1976c) and Sealapex™ 19 mm (Almeida et al. 2007, Viapiana et al. 2014a). The

similar flow of the sealers tested means that flow probably had little impact on the results of

the study.

69

5.5 Experimental design and study limitations

5.5.1.1 Specimens

Palatal roots of maxillary molar teeth were utilised for the study as it was envisaged that the

sufficient numbers of these teeth could be collected within the limited time frame the research

was to be conducted in. Single rooted teeth were deliberately not chosen as other investigators

from the university were already collecting these teeth. In order to collect a sufficient sample

size, the collection time of the specimens would have increased beyond an acceptable range,

thus palatal roots of maxillary molar teeth were chosen. The morphology of palatal roots of

maxillary molar teeth has been shown to vary from that of single rooted teeth (Vertucci 2005),

as a consequence, the results cannot be extrapolated to single rooted teeth. Attempts were made

to standardise the teeth collected by specifying inclusion and exclusion criteria. This was

intended to produce specimens with similar root canal morphology. An age range of

participants at the time of extraction was not included. This resulted in variations in root canal

diameter (Pineda & Kuttler 1972). Some specimens had wider canals whilst others had narrow

and calcified canals. The specimens with narrow canals required more preparation time to take

a size 10 K-file to the apical foramen and more dentine was ultimately removed during

instrumentation procedures. Conversely, the specimens with wide canals were hardly

instrumented with the size 40, 0.06 taper master apical file. This meant that when the root

fillings were placed in wide canals, the matching cone (size 40, 0.06 taper) would not

correspond well to the shape of the ‘prepared’ root canal. The distance between the GP and

root canal wall may be increased and may have been filled with sealer, increasing the sealer

percentage. Consequently, the results for GP adaptation to dentine and the sealer percentage

fill would be influenced based on variations in root canal morphology. In a clinical setting,

instrumentation of root canals is performed with files that are typically larger than the original

anatomy of the main canal. This is performed with instruments of sufficient size and taper. This

would mean that matching cone would correspond well to the root canal, decreasing sealer

percentage and the distance between the GP and canal wall.

70

5.5.1.2 Root canal fillings

Obturation with the CWC method was difficult to completely standardise. During the down-

pack, a 0.06 taper heated plugger of an Elements™ Obturation Unit was activated and inserted

to 5-7 mm from the WL. This left a 2 mm variation of placement of the plugger. The power

was then deactivated and the plugger was pushed apically for 10 s. When pushing apically,

sometimes the plugger was advanced several millimetres and at other times could not be

advanced. Heat was again applied for 1 s and after waiting a further second, the plugger was

removed. The 2 mm variation of the placement of the variation plugger and variation in the

distance the plugger was apically advanced were uncontrolled variables that may have

influenced the results.

Sudan Black B, a histological stain for lipids, is an excellent stain for implanted polymeric

biomaterials such as glycol methacrylate and epoxy resins (Hoeksma et al. 1988). It was used

in a previous ex vivo study that measured sealer thickness and dentine penetration (Weis et al.

2004). They found the dye was completely soluble in sealer and the handling and setting

characteristics of the sealer were not affected. It was also determined that the dye provided

sufficient contrast against dentine and GP and allowed microscopic evaluation of sealer

thickness and penetration. Their study used AH 26, and although the same class of sealer as

AH Plus, this was different to the sealers used in the current study and it may have affected the

sealer handling and setting characteristics. Caution may be advisable extrapolating the results

of the study to the clinical use of sealers not dyed with Sudan Black B.

The dispensing and mixing of the sealers was not standardised. AH Plus was mixed in an auto-

mixing syringe as it was dispensed. A similar type of mixing and dispensing tip would have

been a superior method of dispensing the Sealapex™sealer to improve standardisation.

Difficulties in standardisation were also encountered with the addition of the dye. Each sealer

was mixed according to the manufacturer’s instructions and was coloured with a small amount

of dye added until completely dissolved. The exact amount of dye was not strictly controlled

and this may have influenced the results. The volume of sealer applied to each canal was also

not strictly standardised. All sealers were placed using a size 25 Pastinject™ in a slow-speed

handpiece by coating the flutes in sealer and introducing it into the canal, 1 mm from the WL.

The Pastinject™ was then rotated clockwise for 5 s before withdrawing it from each canal.

There will be variations in the volume of sealer carried by the flutes of the instrument. The

71

MACs were also coated with sealer before insertion with a pumping action. Again, variations

in the volume of sealer are likely.

5.5.2 Evaluation

All data were analysed by a single examiner. To improve reliability and repeatability of the

measurements, multiple examiners should have evaluated the data and kappa scores produced

to show inter-examiner reliability.

5.5.2.1 Sealer percentage

During evaluation of sealer percentage, computer software (Image J) was used to determine

the pixel count of each area representing dyed sealer within the root-filled canal. This was then

calculated and expressed as a percentage of the total canal area. The dye may have also

discoloured and affected the GP and surrounding dentine. This is an inaccuracy that is a

limitation of all dyed sealer investigations (Weis et al. 2004).

5.5.2.2 Depth of penetration

Nine of the teeth exhibited a crack when viewed under high magnification (10x). This may

have been for a number of reasons, such as damage during tooth extraction, rotary nickel

titanium induced stress (Adorno et al. 2011) or the tooth may have suffered a vertical root

fracture prior to extraction. The dyed sealer tended to travel further through cracks which

helped to visualise them (Wright et al. 2004). Higher sealer penetrations through the dentine

were observed in teeth exhibiting cracks.

72

5.6 Conclusion

Within the limitations of this study, the distance between the GP and canal wall as well as

sealer percentage in cross sections decreased from apical to coronal for all experimental groups.

The number of outer third penetration depths, however, increased in an apical to coronal

direction.

Comparisons with the negative control revealed significantly increased distance between the

GP and canal wall, increased sealer percentage in cross sections at most levels and deeper and

more frequent penetration depths for each group.

For each sealer, an additional application of sealer increased the distance between the GP and

canal wall to a minor degree. It had no effect on Roth’s and Sealapex™ but decreased the sealer

percent of AH Plus Jet™ to a minor degree and increased the outer third penetration depths for

AH Plus Jet™ and Sealapex™ but not Roth’s.

73

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Appendices

Appendix A: Ethical approval

95

Appendix B: Maori consultation

97

Appendix C: Sum of 10 intercepts between GP and canal wall

Table C 1. Sum of 10 intercepts between GP and canal wall.

Group A B C D E F G

2 mm 314.6291 348.6497 693.5299 52.374 511.0709 381.3257 838.9635

3 mm 299.0427 179.3485 235.1821 71.4892 351.0873 118.7304 537.5399

4 mm 190.0589 159.317 249.8144 76.8625 286.5702 215.8706 315.7221

6 mm 112.9653 90.5603 90.6871 60.4428 259.0022 155.8953 201.0313

7 mm 61.5579 108.7371 28.19 56.1857 182.8001 89.4359 96.3695

8 mm 70.412 114.9633 24.5159 73.3027 137.4108 91.0314 96.3695

Figure C 1. Sum of 10 intercepts between GP and canal wall (µm).

0

100

200

300

400

500

600

700

800

900


Sum

of

dis

tance

bet

wee

n G

P a

nd

can

al w

all

(μm

)

Level

Sum of 10 intercepts between GP and canal wall

A B C D E F G

98

Appendix D: Mean sealer percentage in cross section

Table D 1. Summary of mean sealer percentage.

Group A B C D E F G

2 mm 52.5789 13.2356 26.1871 0 38.6699 14.0075 25.1309

3 mm 41.5716 10.0794 12.0239 0 23.7215 4.3402 15.3772

4 mm 25.9993 9.7277 11.8597 0 19.4349 5.405 9.7254

6 mm 12.4429 6.0399 3.4255 0 11.6343 6.7972 5.9447

7 mm 3.1377 10.3329 2.7461 0.0997 5.1648 4.1864 6.2866

8 mm 3.0449 3.6457 0.6139 0.2171 2.5047 0.7894 1.1294

Figure D 1. Summary of mean sealer percentage.

0

10

20

30

40

50

60


Sea

ler

per

centa

ge

Level

Summary of mean sealer percentage in cross section

A B C D E F G

99

Appendix E: Depth of sealer penetration

Table E 1. Count of penetration depths and direction for all groups at all levels.

Absent Inner Middle Outer

2 Palatal 44 37 8 16

Mesial 43 34 11 17

Buccal 30 51 12 12

Distal 35 44 15 11

3 Palatal 35 29 15 26

Mesial 28 43 11 23

Buccal 38 47 4 16

Distal 31 42 13 19

4 Palatal 27 32 18 28

Mesial 28 21 29 27

Buccal 37 35 15 18

Distal 28 28 18 31

6 Palatal 17 20 8 60

Mesial 20 9 13 63

Buccal 26 25 10 44

Distal 18 16 12 59

7 Palatal 15 11 13 66

Mesial 15 6 16 68

Buccal 20 21 6 58

100

Distal 17 12 8 68

8 Palatal 15 4 8 78

Mesial 16 6 9 74

Buccal 18 11 14 62

Distal 15 10 8 72

Total 616 594 294 1016

Table E 2. Count of penetration depths and direction for Group A.


2 Palatal 1 10 3 1

Mesial 3 8 4 0

Buccal 1 11 3 0

Distal 1 11 3 0

3 Palatal 2 7 5 1

Mesial 0 10 4 1

Buccal 1 12 2 0

Distal 1 8 6 0

4 Palatal 2 6 4 3

Mesial 1 3 9 2

Buccal 3 6 5 1

Distal 1 5 6 3

6 Palatal 0 1 3 11

101

Mesial 0 1 3 11

Buccal 0 6 4 5

Distal 0 2 4 9

7 Palatal 0 1 4 10

Mesial 0 1 2 12

Buccal 0 3 1 11

Distal 0 1 4 10

8 Palatal 0 0 2 13

Mesial 0 1 2 12

Buccal 0 2 5 8

Distal 0 1 4 10

Total 17 117 92 134

Table E 3. Count of penetration depths and direction for Group B.


2 Palatal 4 5 2 4

Mesial 6 2 5 2

Buccal 4 9 2 0

Distal 4 5 3 3

3 Palatal 2 6 1 6

Mesial 3 6 1 5

Buccal 6 4 0 5

102

Distal 0 11 1 3

4 Palatal 0 6 3 6

Mesial 1 5 3 6

Buccal 4 6 3 2

Distal 1 5 2 7

6 Palatal 0 2 0 13

Mesial 1 1 0 13

Buccal 2 4 1 8

Distal 0 3 2 10

7 Palatal 0 1 2 12

Mesial 0 1 2 12

Buccal 1 7 2 5

Distal 0 4 0 11

8 Palatal 0 0 2 13

Mesial 0 1 1 13

Buccal 0 3 3 9

Distal 0 3 0 12

Total 39 100 41 180

Table E 4. Count of penetration depths and direction for Group C.


2 Palatal 8 3 0 4

103

Mesial 6 4 0 5

Buccal 3 7 0 5

Distal 5 5 2 3

3 Palatal 6 2 2 5

Mesial 4 7 2 2

Buccal 3 10 0 2

Distal 4 4 4 3

4 Palatal 3 2 5 5

Mesial 4 2 7 2

Buccal 7 2 3 3

Distal 5 3 2 5

6 Palatal 1 4 1 9

Mesial 3 2 3 7

Buccal 5 3 0 7

Distal 3 2 2 8

7 Palatal 0 0 3 12

Mesial 0 0 4 11

Buccal 0 4 1 10

Distal 1 2 2 10

8 Palatal 0 1 1 13

Mesial 0 1 2 12

Buccal 0 2 3 10

104

Distal 0 1 1 13

Total 71 73 50 166

Table E 5. Count of penetration depths and direction for Group D.


2 Palatal 15 0 0 0

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

3 Palatal 15 0 0 0

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

4 Palatal 15 0 0 0

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

6 Palatal 15 0 0 0

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

7 Palatal 15 0 0 0

105

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

8 Palatal 15 0 0 0

Mesial 15 0 0 0

Buccal 15 0 0 0

Distal 15 0 0 0

Totals 360 0 0 0

Table E 6. Count of penetration depths and direction for Group E.


2 Palatal 5 8 1 1

Mesial 4 7 2 2

Buccal 3 8 2 2

Distal 2 8 4 1

3 Palatal 3 8 2 2

Mesial 1 11 1 2

Buccal 4 9 1 1

Distal 2 9 1 3

4 Palatal 2 7 2 4

Mesial 3 4 4 4

Buccal 5 7 2 1

106

Distal 3 4 3 5

6 Palatal 1 5 1 8

Mesial 1 1 4 9

Buccal 2 5 2 6

Distal 0 4 1 10

7 Palatal 0 4 1 10

Mesial 0 1 3 11

Buccal 1 2 0 12

Distal 1 2 0 12

8 Palatal 0 0 0 15

Mesial 0 1 1 13

Buccal 0 2 1 12

Distal 0 1 2 12

Totals 43 118 41 158

Table E 7. Count of penetration depths and direction for Group F.


2 Palatal 8 6 0 1

Mesial 4 7 0 4

Buccal 0 7 4 4

Distal 2 9 1 3

3 Palatal 4 4 2 5

107

Mesial 1 9 0 5

Buccal 3 8 0 4

Distal 5 6 0 4

4 Palatal 4 4 2 5

Mesial 1 4 4 6

Buccal 0 7 2 6

Distal 2 6 2 5

6 Palatal 0 5 1 9

Mesial 0 2 1 12

Buccal 0 5 2 8

Distal 0 4 1 10

7 Palatal 0 3 2 10

Mesial 0 3 1 11

Buccal 1 3 0 11

Distal 0 3 2 10

8 Palatal 0 3 2 10

Mesial 1 2 1 11

Buccal 2 2 1 10

Distal 0 4 0 11

Totals 38 116 31 175

108

Table E 8. Count of penetration depths and direction for Group G.


2 Palatal 3 5 2 5

Mesial 5 6 0 4

Buccal 4 9 1 1

Distal 6 6 2 1

3 Palatal 3 2 3 7

Mesial 4 0 3 8

Buccal 6 4 1 4

Distal 4 4 1 6

4 Palatal 1 7 2 5

Mesial 3 3 2 7

Buccal 3 7 0 5

Distal 1 5 3 6

6 Palatal 0 3 2 10

Mesial 0 2 2 11

Buccal 2 2 1 10

Distal 0 1 2 12

7 Palatal 0 2 1 12

Mesial 0 0 4 11

Buccal 2 2 2 9

Distal 0 0 0 15

109

8 Palatal 0 0 1 14

Mesial 0 0 2 13

Buccal 1 0 1 13

Distal 0 0 1 14

Totals 48 70 39 203

the effect of an additional application of sealer during

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