Methods of filling root canals: principles and practices

Endodontic Topics 2005, 12, 2–24
All rights reserved
Copyright r Blackwell Munksgaard
ENDODONTIC TOPICS 2005
1601-1538
Methods of filling root canals:
principles and practices
JOHN WHITWORTH
Contemporary research points to infection control as the key determinant of endodontic success. While
epidemiological surveys indicate that success is most likely in teeth which have been densely root-filled to within
2 mm of root-end, it is unclear whether the root canal filling itself is a key determinant of outcome. It is also unclear
how different materials and methods employed in achieving a ‘satisfactory’ root filling may impact on outcome.
This article provides an overview of current principles and practices in root canal filling and strives to untangle the
limited and often contradictory research of relevance to clinical practice and performance.
Introduction
Successful root canal treatment depends critically on
controlling pulp-space infection. In evaluating root
canal-treated teeth, it is unusual for external assessors
to have full information on the methods used and the
detail of infection-controlling steps. Attention therefore tends to focus on aspects of treatment which can
be readily identified and measured, such as the radiographic nature, length and density of root fillings, with
the assumption that these are good proxy markers of
the overall package of infection-managing care. It is not
surprising that the majority of epidemiological surveys
in endodontics have focused on radiographic appearances alone (1), despite our recognized limitations in
radiographic interpretation (2, 3), and acceptance that
the radiographic ‘white lines’ reveal only limited
information.
The classic ‘Washington study’ (4), although never
published in a peer-reviewed journal, set the tone by
observing that 58.66% of endodontic failures were
caused by incomplete obturation. Other well-established undergraduate textbooks have emphasized that
‘lack of adequate seal is the principal cause of
endodontic failure’ (5), positions based on the best
clinical scientific evidence at the time.
Contemporary research points to cleaning and
shaping of the root canal as the single most important
factor in preventing and treating endodontic diseases
(6), and it is difficult to endow root canal filling with
2
the same primary importance. But to take such views
too rigidly, and to use reports of periapical healing
without definitive root filling as evidence that root
canal filling is unnecessary (7–10) is to miss the
important role it may play in securing short- and
long-term health (11, 12).
In technical terms, we anticipate that ‘success’ will be
associated with root canals (prepared and) densely filled
to within 2 mm of radiographic root end (1, 13).
However, the body of high-quality clinical research on
which such conclusions are founded is limited (14).
Even less clear is whether a technically ‘satisfactory’
root canal treatment will deliver health regardless of the
materials and methods, or whether some are inherently
‘better’ than others in terms of predictability, safety,
consistency, healing, and tooth longevity.
Commercial pressures and glossy advertising have
never been more prominent, but the debates are not
new. As early as 1973, Brayton et al. (15) noted that
‘Many techniques have been advocated for filling root
canals. Controversies and disputes have arisen, dividing
practitioners into different schools of thought. To date,
there is still very little evidence other than clinical
impression to support or deny any particular technique.’
As no single approach can unequivocally boast superior
evidence of healing success (13), decisions may be based
on such factors as speed, simplicity, economics, or ‘how it
feels in my hands.’ For some, there may be other issues at
stake, such as the desire to keep ‘up to date,’ to
demonstrate ‘mastery,’ to keep ahead of referring
Methods of filling root canals: principles and practices
colleagues, or to enliven the working day by ‘the thrill of
the fill’ (16) as unexpected canal ramifications are
demonstrated more consistently. For others, issues such
as root strengthening, or a fundamental lack of confidence
in established materials may be critical (17–19).
The role of root canal fillings in
endodontic success
The shaped and cleaned canal space represents an
environment in which microbial communities have
been eliminated or seriously disrupted and can no
longer promote periradicular disease (6, 20).
But how is this condition preserved? Undue reliance
on a coronal seal is probably unacceptable without first
filling the canal system (21–23) with materials that
control infection:
1.Directly: by actively killing microorganisms (24)
which remain (25) or which gain later entry to the
pulp space, and
2.Ecologically: by denying nutrition, space to multiply,
and correct Redox conditions for the establishment
of significant biomass of individual microbes, or the
development of harmful climax communities.
They should do so long-term and without damaging
host tissues.
Basic approaches
Textbook accounts describe a spectrum of filling
methods (Fig. 1) ranging from paste-only fills, through
pastes with single cones of rigid or semi-rigid material,
to cold compaction of core material and finally, warm
compaction of core material with sealer paste. It is likely
that most accounts have assumed the materials involved
to be traditional sealer cements (such as zinc oxideeugenol pastes) in combination with metallic or gutta
percha cones. Sealer cements are usually regarded as the
critical, seal-forming ‘gasket’ of the root canal filling
(26), but paradoxically, as the weak link of the system
whose volume should be minimized by core compaction (27, 28).
Paste-only root fillings
Paste-only root fillings have a poor reputation in clinical
endodontics. Notable approaches have included highly
toxic resin cements such as ‘Traitement SPAD’ and the
Fig. 1 Classic
spectrum
of
filling
techniques,
emphasizing the desirability of minimum sealer volume,
from (A) paste only (least desirable), through (B) single
cones with paste, and (C) cold lateral condensation, to
(D) thermoplastic compaction.
original, formaldehyde-containing Endomethasone
(Septodont, St Maur des Fosses, France), which were
advocated for rapid results in minimally prepared
canals. Although success was reported, in some cases
after deliberate apical extrusion with a spiral paste-filler
(29), such ‘quick and dirty’ approaches appeared to
deny the biological perspective that what came out of
the canal was more important to success than what
went in. Inadvertent accidents of over extension into
vital structures such as the inferior alveolar canal left a
distressing legacy for affected patients. Concerns were
compounded by the all too frequent insolubility and
hardness of such materials, making removal for retreatment a challenge to the most skilled of operators
(30, 31).
Even with fluid materials which are regarded as bland
and biocompatible, risks of erratic length control
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during application are recognized. Fannibunda et al.
(32) reported a case of inferior alveolar nerve paraesthesia, which followed the inadvertent extrusion of
molten gutta percha. Porosities in large volumes of
fluid paste, setting contraction with loss of wall contact,
and dissolution with time have all reinforced the
negative views of such approaches. Even 1% shrinkage
of a material after setting has been recognized as a
potentially significant problem in terms of seal and
success (33).
Single-cone obturations
For similar reasons, the sealer-heavy root fillings
associated with single-cone root fillings have not been
regarded well. Single-cone obturations came to the fore
in the 1960s with the development of ISO standardization for endodontic instruments and filling points (34).
After reaming a circular, stop preparation in the apical
2 mm of the canal, a single gutta percha, silver, sectional
silver or titanium point was selected to fit with ‘tugback’ to demonstrate inlay-like snugness of fit. The
cone was then cemented in place with a (theoretically)
thin and uniform layer of traditional sealer, at least in
the apical part of the canal. Hommez et al. (35) have
recently reported that single-cone obturation was still
the method of choice for 16% of Flemmish dentists.
Data from the UK has indicated that 49% of dentists
qualified more than 20 years and 13.2% of those
qualified 3 years regularly used single-cone techniques
(36). All experienced dentists have witnessed success
following the use of such techniques in skilled hands,
and within the context of infection control. In a
retrospective clinical study, Smith et al. (37) demonstrated 84% success following cementation of an apical
silver cone with sealer, and 81% with a full-length silver
cone and sealer. Equally, all those who accept endodontic referrals are very familiar with single-cone
removal from canals in which a large volume of
surrounding sealer has leached away or dissolved under
the action of tissue or oral fluids. Concerns were
compounded by the realization that canal transportation is common and that damaged roots are difficult to
seal (38).
The advent of nickel titanium makes predictably
centred preparations more realistic than ever in curved
canals (39), and may make accurate apical cone
fit a possibility in many cases (40). Contemporary
advertising on ergonomic, matched file and cone
4
Fig. 2. Matched, ergonomic shaping files and filling
cones may inadvertently promote single cone filling
techniques.
Fig. 3. Some commercial
Trioxide Aggregate
presentations
of
Mineral
systems may serve to promote single-cone cementation
techniques (Fig. 2). Laboratory evidence in fact
suggests comparable cross-sectional area of canal
occupied by gutta percha using single-matched taper
cones compared with lateral condensation, and in
significantly less time (41), but clinical trial data is
hitherto unavailable.
Are our views on paste-heavy fills still valid?
Mineral Trioxide Aggregate (MTA) (Fig. 3) has
challenged the view that paste-only root canal fillings
are difficult to control, unacceptably porous, dimen-
Methods of filling root canals: principles and practices
Fig. 4. Gathering Mineral Trioxide Aggregate ( on the
end of a plugger from a ‘Lee’ block.
sionally unstable and unacceptably soluble (42).
Unpublished data (43) indicates that endodontists
worldwide have adopted this material as first choice in a
range of applications from pulp capping, to the nonsurgical management of wide open apices.
A medical-grade Portland building cement (44),
MTA is mixed into a stiff paste with sterile water. The
consistency and behavior may be adjusted by varying
the powder:liquid ratio (45), and premature desiccation is prevented by covering the mixed material with
moist gauze (Dentsply/Maillefer instruction guide
REF A 0405). Although the composition of the grey
and white forms is broadly comparable (44), the white
version appears to be less ‘gritty’ and more cohesive.
Material may be carried to the canal:
1. In a narrow, MTA carrier (or ‘apicectomy’ amalgam
gun),
2. On the end of a plugger after wiping material into
the grooves of a dedicated teflon ‘Lee’ block (46), or
after expressing a pellet of material from a gun (47)
(Fig. 4).
Material is then compacted with pluggers set to extend
2–3 mm short of working length, often supplemented
by ultrasonic (48) or sonic vibration with the intention
of improving settlement and adaptation, although the
merits of vibration remain contentious (49). Further
consolidation can be achieved by tamping the material
with the broad end of paper points to wick out excess
water which could retard the curing process (Dentsply/Maillefer). ProRoot MTA (Dentsply) is then
usually overlaid with moist cotton wool or sponge to
Fig. 5. Wide canal with a blown-out root end filled with
Mineral Trioxide Aggregate
ensure a humid environment for the hydration setting
reaction (Dentsply/Maillefer). The need for this action
has not been established. Setting is checked by re-entry
at least 4 h after placement, and ongoing treatment may
then proceed. Another commercial version, MTA
Angelus (Angelus, Londrina, Brazil) (Fig. 3) is claimed
to set within 15 min and may therefore require no
overlay or re-entry.
MTA is firmly established as the material of choice for
open apices (precisely those where length control is
likely to be an issue, Fig. 5) (50), and perforation
repairs (51), where there is no risk of wash-out during
the lengthy setting period. It is possible that MTA may
supersede calcium hydroxide ‘apexification’ procedures
in the management of traumatized immature teeth
(52). Volumetric change and leakage (53) have not
been identified as significant issues.
MTA has not yet found widespread acceptance in
curved and relatively narrow canals, probably due to
difficult manipulation and concerns about re-treatment. But its adoption in a range of challenging
applications suggests that concerns about root canal
filling cements are not universal. A question that
research must answer is whether other classes of cement
can be used safely and effectively in thick section during
root canal filling.
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Fig. 6. GuttaFlow expressed from the end of a cannula
after trituration.
matching the apical preparation size are seated to
length in the sealer-filled canal, encouraging flow to the
apical region and into lateral ramifications.
Laboratory investigations indicate 0.2% setting expansion (33), biocompatibility (59), and acceptable wall
coverage (60). A clinical trial comparing silicone sealer
with zinc-oxide eugenol in lateral condensation revealed
comparable healing outcomes (61), but outcome studies
on the single-cone method are not yet available.
The optimal canal preparation and shape of cone to
ensure adaptation and carriage to length without extrusion has not been established. Silicone rubbers provide
long-term seal in a range of wet environments and sealing
root canals may be a valid new application (62).
Can all cements be viewed like traditional
endodontic sealers?
Limited evidence exists that other classes of material
may also be suitable for ‘sealer heavy’ or minimal
compaction techniques.
Glass ionomer cements
Ketac Endo (3M ESPE, St Paul, MN, USA) was
developed as an adhesive, root-reinforcing root canal
sealer to be applied in thick section with a single gutta
percha cone. Evidence on root reinforcement was
equivocal (17, 54, 55) and concerns have been
expressed about long-term solubility (56, 57), but
one clinical trial which included both single cone and
cold laterally condensed root canal fillings provided
outcomes comparable to those of other materials and
techniques (58).
Urethane methacrylates
EndoRez (Ultradent, South Jordan, UT, USA) is a
hydrophilic urethane methacrylate resin capable of
good canal wetting and flow into dentinal tubules.
The mixed material is deposited into the canal by
passive injection through a narrow, 30 gauge ‘Navitip’
needle (Fig. 7) which is claimed to minimize pressure
buildup and over-extension. A single cone is again
floated to length to encourage material flow and
provide a pathway into the canal for re-entry. The
material is reported to have acceptable biocompatibility
(59, 63, 64) and to seal as well as other established
materials in vitro (65). No clinical data are available on
paste-only or single-cone EndoRez root canal fillings,
although in combination with cold lateral condensation, it was associated with 91.3% healing at 14–24
Silicone rubbers
Addition polyvinylsiloxanes are well established in
dentistry as inert, dimensionally stable materials.
Formulations with reduced hydrophobicity are now
widely available, including two developed specifically
for endodontics. RoekoSeal (Roeko, Langenau, Germany) is a white, fluid paste, whereas GuttaFlow
(Roeko) appears to be based on RoekoSeal, with the
addition of powdered gutta percha.
Materials are mixed with automix tips similar to
impression materials (RoekoSeal) or by trituration
(GuttaFlow) before carriage to the canal on a gutta
percha cone, or by passive injection through dedicated
plastic cannulae (Fig. 6). Single gutta percha cones
6
Fig. 7. EndoRez expressed from a narrow Navitip
applicator needle.
Methods of filling root canals: principles and practices
Fig. 10. EZ-fill/single cone root canal filling. (A)
Immediate postoperative radiograph, (B) 6-months
follow-up (courtesy Barry Musikant).
Fig. 8. (A) SimpliFill device seated fully to length with
sealer before unscrewing the handle; (B) preparing to
backfill by injecting sealer.
Fig. 9. Innovative bi-directional spiral for controlled
sealer placement.
months (66), results comparable to other materials.
Tay et al. (67) have recently described the use of resin
coated gutta percha cones in combination with a dualcuring EndoRez in an effort to enhance bond and seal.
Resin tags were demonstrated impregnating canal
walls, but interfacial leakage was not prevented.
Epoxy resins
Epoxy resins are well established as effective root canal
sealers, displaying acceptable biocompatibility (68, 69),
insolubility and dimensional stability (70).
AH 26 and AHPlus (Dentsply) are classic examples
with proven track records over many years of clinical use
(71, 72). In vitro tests have demonstrated comparable
seal in thin and thick section (65, 73).
AHPlus is specifically advocated with the single-cone
Lightspeed SimpliFill technique (Lightspeed Technologies, San Antonio, TX, USA). Following the preparation of an apical stop and parallel, cylindrical
preparation in the apical 5 mm of the canal with
Lightspeed instruments, a size matched gutta percha
(or Resilon) apical tip is selected which fits snugly just
short of working length in a moistened canal. After
conventional drying of the canal, a light coating of
sealer is applied, the apical tip is seated firmly to length,
and the handle removed by unscrewing anti-clockwise
(Fig. 8A). Carpules with 27 gauge needles which form
part of a dedicated injection system are then filled with
sealer, and the canal backfilled with cement (Fig. 8B).
One or more gutta percha points may be added if
desired. A recent in vitro leakage study has suggested
that backfill with AHPlus alone provided a better seal
against coronal leakage than AHPlus compacted with
injection-molded gutta percha (74).
EZ-fill (Essential Dental Systems, South Hackensack,
NJ, USA) is a similar material, presented like AH26 as a
powder and liquid for control of material viscosity.
Mixing with a warm spatula decreases the material’s
viscosity. Controlled delivery is achieved with an
innovative ‘bi-directoral spiral’ paste filler (Fig. 9).
The bi-directional spiral controls apical flow of sealer
cement by virtue of its blades which drive material
apically in the coronal region, and coronally in the
apical 2–3 mm. Canals are rapidly filled with sealer
before floating a pre-fitted 8% gutta percha cone to
length without the need for further vertical or lateral
compaction (Fig. 10).
EZ-fill is a rapid method, which appears to demonstrate canal complexities well and in vitro studies have
shown it to seal as well as other established techniques
(75). Review of clinical cases managed in a multi-
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surgery practice have indicated favorable clinical outcomes estimated at 94.1% (76, 77), although once
again, independent clinical trial data are not yet
available.
has indicated that compaction may reduce canal wall
contact and seal of materials with insufficiently low
minimum film thickness (26).
Cold lateral condensation
Non-Instrumentation Technology
The previous section has described the delivery of sealer
cements by rotary instruments, injection, or carriage on
points of core material. A highly innovative approach is
found in non-instrumentation technology (NIT),
where the controlled development of a vacuum within
the tooth allows fluid sealer to be drawn into the
complexities of the canal system (78). This technology
has been subjected to one clinical trial in which the
radiographic quality of root fillings with AH 26 was
comparable to that of conventional techniques (79).
Gutta percha compaction methods
Despite the possibilities described, compaction methods continue to dominate clinical endodontics as
practitioners strive to optimize density of the core
material and minimize sealer volume. It is not
established beyond question whether compaction
methods benefit patients or dentists by preserving
health better, healing more disease or demonstrating
more canal complexities. Conversely, they could offer
no improvement and risk adverse events such as root
fracture or more frequent overfill. One in vitro study
Cold lateral condensation is probably the most
commonly taught and practiced filling technique
worldwide (35, 36, 80–82) and is regarded as the
benchmark against which others must be evaluated.
The method is generic, encompassing a range of
approaches in terms of master cone design and
adaptation, spreader and accessory cone selection,
choice of sealer and spreader application. There is little
clear evidence on how it is ‘best’ done (61, 83, 84).
Prerequisites
Canal preparation
Cold lateral condensation demands a canal which is
continuously flared from apex to coronal opening (85).
The superiority of apical stop or tapering control zone
preparations for lateral condensation has not been
investigated clinically.
Spreader selection
Condensing tools must be selected and tried into the
canals before compaction begins. For optimal deformation of material through the length of the canal, a
spreader must be pre-fitted which extends deeply into
Fig. 11. Accessory cones must occupy the space left by the spreader (A & B), otherwise an air or sealer-filled space will
result (C).
8
Methods of filling root canals: principles and practices
the empty canal (86, 87). Hand spreaders encourage
higher compaction forces than finger spreaders (88),
with the theoretical risk of root flexion or fracture (89).
Nickel titanium spreaders may penetrate more deeply
(90, 91), generate less internal stress (92) and
distribute forces more evenly (93), especially in curved
canals.
Lateral condensation works by vertical loading of the
wedge-shaped spreader to move materials vertically and
laterally. The greater the taper of the spreader, the
greater the lateral component of force. Vertical loads in
the range of 1–3 kg have been reported as typical (94),
and adequate to deform gutta percha without undue
risks to the tooth (88, 95). Forces associated with
lateral condensation should not be a direct cause of
vertical root fracture (88).
Fig. 12. Chloroform customized master cone.
Accessory cone selection
In order to secure a dense filling, accessory cones must
be able to fully occupy the space left by the compacting
spreader (Fig. 11). They should therefore be the same
size or slightly smaller than the selected spreader (84).
Incompatibility will result in the accessory cone
‘hanging up’ before full insertion, resulting in a cement
pool at best or a void at worst. In vitro evidence
suggests that tapered gutta percha accessory cones may
slide to length more predictably and be more forgiving
in the hands of non-specialists than ISO accessory
cones (84).
Master cone selection
There is no clear evidence whether ISO or unstandardized cones are preferred. Laboratory investigations
(83, 87) suggest that ISO master cones allowed deeper
spreader penetration and a larger number of accessory
cones to be inserted, although this did not result in a
superior seal against microbial leakage. Unstandardized
cones may be trimmed to provide accurate apical sizing,
and are usually tried in an irrigant-lubricated canal.
Solvent dipping has been shown to improve apical
adaptation and seal of master cones in vitro (96). This is
typically achieved by immersing the apical 2–3 mm of
the master cone in chloroform or halothane for 2 s
before seating it to length in an irrigant-moistened
canal (Fig. 12).
Sealer selection
It is not known which sealer works most effectively with
cold lateral condensation, but clinical evidence suggests
that sealer choice may not have a decisive impact on
Fig. 13. Cold lateral condensation. (A) Condensation and addition of gutta percha cones continues until the spreader
will reach no more than 2–3 mm into the canal. Forces generated by vertical loading of the spreader are vertical and
lateral. (B) Heat severs the gutta percha points and allows consolidation deep into the canal.
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outcome (61, 97). A slow setting sealer cement is
generally preferred, which will allow adequate lubrication for accessory point insertion, and accommodate
revision and consolidation of the fill if voids are
detected on intermediate radiographs.
Leaving accessory cones with their tips immersed in
sealer may soften them and compromise their ability to
slide fully to length.
Cold lateral condensation: the process (Fig. 13)
Cold lateral condensation commences by liberally
coating canal walls with sealer cement. In vitro evidence
suggests that application with a spiral paste filler, fine
injection needle, or an ultrasonically energized file
ensures the most complete wall coverage (98–100),
although application on the master cone, a paper point
or a small file are popular alternatives. The master cone
is slid to working length and the measured spreader
applied under vertical loading for 10–60 s to
deform material apically and laterally (101, 102).
Optimal time of spreader insertion has not been
scientifically validated in the clinical setting. Withdrawal is with watch-winding motion to ensure that the
master cone is not pulled free, and the first accessory
cone is slid promptly to length with a light coating of
sealer. Compaction and accessory cone insertion
continues, as the filling develops, each spreader
insertion being slightly less deep than the previous
one mirrored by shorter and shorter accessory cone
insertion. Condensation usually continues until the
spreader will reach no further than 2–3 mm into the
canal (Fig. 13A). How closely general practitioners
comply with such guidelines has not been scientifically
evaluated.
Although the technique is described as cold lateral
condensation, heat is always applied to sever the root
filling at or below canal orifice level, and compact it
apically with a cold plugger (Fig. 13B). This may soften
and consolidate material several mm into the canal and
improve seal (103).
Variants on cold lateral condensation
A number of measures have been reported to enhance
gutta percha adaptation and density in lateral condensation. Examples include:
Warming spreaders before each use in a hot bead
sterilizer
10
Fig. 14. Lateral condensation supplemented with ultrasound in a complex upper molar (courtesy Dr Graham
Bailey, London).
Fig. 15. An unsuitable case for predictable filling by cold
lateral condensation.
Softening gutta percha with heat before insertion of
the cold spreader (104)
Mechanical activation of finger spreaders in an
endodontic reciprocating handpiece (105)
Application of an ultrasonically energized spreader
(106, 107), and
Application of an engine-driven thermomechanical
compactor which creates frictional heat and advances the material apically within the canal (108,
109).
Figure 14 shows a complex canal system filled by
lateral condensation, supplemented with ultrasound.
Appraisal
Lateral condensation is regarded as safe, cost-effective
and user-friendly, and case reports continue to be
Methods of filling root canals: principles and practices
Warm vertical condensation
Fig. 16. Scalpel-trimming an unstandardised gutta
percha cone to conform to the ISO-gauged canal
terminus diameter.
published showing successful healing after its use in a
variety of clinical scenarios (61, 110–114). A key
limitation is when the root canal system has an abrupt
change of diameter, as seen in internal resorption (Fig.
15). Such cases demand the application of heat to adapt
gutta percha more thoroughly, or a reliance on large
volumes of sealer in some areas of the canal. Adaptation
may be equally limited in ribbon-shaped canals, where
Kersten et al. (3) showed that clinical radiographs may
not reveal poor filling density.
However, recent clinical reports have confirmed the
ability of high-quality laterally condensed root canal
fillings to exclude the oral flora after long-term
exposure (115, 116) and it should also be noted that
the majority of epidemiological studies on which we
base our views on the predictability of root canal
treatment have included canal filling by cold lateral
condensation (117–123). Numerous other clinical
trials from around the world involving cold (39, 124–
133) and warm lateral condensation (134) have
validated this approach in clinical practice. But how
much of the observed success was directly attributable
to the filling technique is not known.
A common criticism leveled at lateral condensation is
that it is a time-consuming method, and this was borne
out in a recent clinical study, where Thermafil obturation was found to be on average 20 min per tooth
quicker (133).
Philosophical battles have long been waged between
advocates of cold lateral and warm vertical condensation, presenting compelling cases on the benefits and
shortcomings of each (135).
Warm vertical condensation was perfected and
promoted by Herbert Schilder (136). His approach
to filling was described as ‘3-dimensional,’ indicating
an intention to fill all ramifications of the pulp space,
rather than just the primary root canal, and the package
of care to achieve this included clear guidelines on canal
preparation, cone fit and condensation.
Contemporary advocates of this approach (137) list
the criteria for satisfactory canal shaping as:
1. Continuously tapered preparation.
2. Original anatomy maintained.
3. Position of the apical foramen maintained.
4. Foramen diameter as small as practicable.
The tapered canal preparations thus created allow
softened materials to enter anatomical complexities as
heat and pressure are applied in a canal of rapidly
diminishing diameter. Resistance to over-filling is
achieved by the creation of an apical control zone as
opposed to a traditional ISO ‘stop.’ Shaping is
considered to be sufficient when a Fine-Medium or
Medium cone (137) or other taper-matched cone (e.g.,
F2 for a ProTaper F2 prepared canal) can fit to length in
the canal.
Fig. 17. Markings on the master gutta percha cone
produced by insertion of a file into an adjacent orifice
indicates confluence.
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Such preparations are now created rapidly and
predictably with a range of hand and engine driven
NiTi instrumentation techniques (138) and tapered,
rather than ISO master cones are scalpel trimmed to fit
snugly 1.0–0.5 mm short of an electronically confirmed
canal terminus (Fig. 16), or constant drying point
(139, 140). Snugness of fit is usually confirmed by
slight resistance to withdrawal from the canal (short
tug-back), indicating that the cone tip is binding at the
preparation terminus (141). Resistance to withdrawal
which continues beyond 1 mm may indicate that the
cone is binding along a greater length of canal wall and
not apically.
Canal confluence may be confirmed by the insertion
of a cone to working length before inserting a file or
spreader into the adjacent canal. Failure of the
instrument to advance to length, or evidence of
instrument markings on the side of the master cone
indicates confluence (Fig. 17). The master cone for the
second canal is trimmed to the point of confluence with
a scalpel.
Sealer selection
Classic descriptions of warm vertical condensation have
specifically advocated zinc oxide-eugenol sealers (Pulp
Canal Sealer, Kerr, Romulus, MI, USA) which are
believed to set rapidly in the event of extrusion and
hopefully become inert in the periradicular tissues (16).
There is, however, little clinical evidence that other
classes of material, such as slow-setting epoxy resins
may not perform equally well in warm vertical
condensation.
Multiple wave warm vertical condensation
Plugger and heater-tip selection
In common with other filling techniques, condensing
tools must be selected before treatment, and it is usual
to select three or more pluggers which will extend
progressively deeper into the canal, the narrowest
extending within 4–5 mm of root-end (142). Nickeltitanium instruments such as the double-ended Buchanan or Dovgan pluggers may be better suited to curved
Fig. 18. Warm vertical condensation – multiple wave. Heating and compaction occurs in three or more stages (A–C),
taking an increment of gutta percha from the canal each time and continuing until the apical 4–5 mm are ‘corked’ with
gutta percha and sealer.
12
Methods of filling root canals: principles and practices
canals than stainless steel Machtou or Schilder pluggers.
Heat may be applied to the canal either with
traditional ‘heat carriers’ which are warmed in a Bunsen
burner flame, or more safely and neatly with an
electronic touch-and-heat instrument. The instrument
for delivering heat must have a narrow enough tip to
reach within 5 mm of root-end.
Sealer application
Warm vertical condensation generates significant hydraulic forces and there is an increased risk that excess
sealer may be extruded into the periradicular tissues
(109). In contrast with cold lateral condensation, sealer
application is therefore sparing, and often applied on
the master cone, coating its length before insertion and
seating to length initially before withdrawing to inspect
that its entire surface (and therefore presumably the
entire surface of the canal) has a light coating of sealer
16, 141).
The compaction process (Fig. 18)
Fig. 19. Ultrafil
percha.
low-temperature
injectable
gutta
Downpack
Compaction of the root canal filing occurs in multiple
waves as the material is softened with heat and driven
apically with cold pluggers. The first wave severs the
gutta percha cone at canal orifice level, taking care not
to withdraw the master cone from the canal. The largest
cold plugger is then applied, gently condensing
material around the walls of the canal entrance before
positioning in the centre of the mass of gutta percha
and compacting apically with firm finger pressure. Care
should be taken to avoid contact of the plugger with
canal walls, which is believed to carry an unacceptable
risk of damaging force transmission to the root.
The second wave of heating follows, plunging the
heat carrier or touch-and-heat tip 3–4 mm into the
Fig. 20. Calamus: engine-driven thermoplastic gutta percha in pre-dispensed cannulae (Courtesy Dentsply).
13
Whitworth
Fig. 21. Elements – combined System B and gun system
in a single unit (Courtesy Sybron).
mass of compacted gutta percha and removing an
increment of material from the canal. Condensation
proceeds in the same manner as previously, using the
next plugger. Third and fourth waves of heating,
material removal and compaction proceed in a similar
manner until the apical 4–5 mm of the canal is ‘corked’
with thermally compacted gutta percha and sealer.
Progressive heating and compaction is expected to
drive gutta percha and sealer into all accessible canal
ramifications during the downpack (143, 144).
Backfill
Empty canal space is most quickly and efficiently filled
with injection-molded gutta percha, delivered from a
gun in increments of 3–4 mm and compacted by hand
to counteract cooling contraction. A variety of systems
are available, including:
Pre-heated carpule systems offering gutta percha in
a range of viscosities (e.g., Ultrafil, Hygenic) (145)
(Fig. 19). Such systems are relatively inexpensive,
but offer limited working time before the carpule
must be re-heated.
Manual gun systems which work on the same
principle as a glue gun, heating gutta percha pellets
and maintaining heat to the point of expression
from the gun (e.g., Obtura II), which offer the
14
advantage of unlimited working time. Radiographically seamless union with the downpack is more
likely to be achieved if the needle of the gun system
touches the cut gutta percha surface in the canal and
is held in place for 5–10 s before commencing
backfill injection.
New-generation engine-driven gun systems, in
which temperature and flow rate can be regulated
(Fig. 20).
Systems incorporating downpacking and backfilling
devices (Fig. 21).
Injectable gutta percha is commonly deposited in 3–
5 mm increments, with further compaction, although
one laboratory study supported the deposition of
increments up to 10 mm (146).
Alternative backfill methods include the incremental
addition of ‘backfill’ lengths of pre-trimmed gutta
percha which are heated and compacted as in the
downpack (147), and sealer-only backfills, which
recent laboratory reports have suggested are superior
to gutta percha compaction methods in terms of seal
(74, 148).
Single-wave vertical condensation (Fig. 22)
System B was the first of a new generation of electronic
heat carriers which allowed rapid heating and cooling of
tips to facilitate their use as both heat carrier and
plugger (Fig. 23).
Tip selection
System B is supplied with a variety of tips in 4%, 6%, 8%,
10%, and 12% taper, each marked at 5 mm intervals
along their length (16) (Fig. 23).
A single tip is selected which will extend to within 4–
5 mm of canal terminus before binding on canal walls.
Following cone fit, sparing sealer application and
cone insertion, the System B is set for maximal rate of
heat increase and to a working temperature setting of
2001C.
The cold tip is presented to canal entrance before
activating the heater. Within 1 s, the tip has reached
working temperature and is swept in one fluid movement over the course of 2–3 s until it sits 2 mm short of
the binding point. At this point, the unit is deactivated, allowing the tip to cool rapidly, and pressure
is maintained for 5–10 s on the cooling mass of gutta
percha in order to counteract cooling contraction. The
plugger now being locked into the canal by a solidifying
Methods of filling root canals: principles and practices
Fig. 22. Warm vertical condensation – single wave. (A) Single wave downpack. (B) Separation and withdrawal. (C)
Apical 4–5 mm ‘corked’ with gutta percha and sealer.
Fig. 23. Original System B heat source with a range of tips.
mass of gutta percha, further heating is necessary to
release the tip for withdrawal from the canal. The heater
is therefore re-activated, classically by a 1 s ‘separation
burst’ before smooth withdrawal. The apical gutta
percha mass is then condensed further by hand before
backfilling by any of the methods described previously
(16).
Evaluation of warm vertical condensation
Compaction techniques of any sort require dentine
removal to accommodate condensing instruments and
the application of potentially damaging forces in nonphysiological directions.
In warm vertical condensation, opponents have
historically argued that the cost in terms of dentine
15
Whitworth
removal to accommodate appropriate pluggers was
excessive compared with that required for lateral condensation. This seems to be less of an issue in current
practice with controlled canal flaring by contemporary
instruments, and a welcome range of sufficiently
narrow and efficient heat carriers, pluggers (including
nickel titanium pluggers) and backfill needles.
Additional concerns have been raised with regard to
thermal damage to the periodontal ligament during
thermal compaction techniques, particularly if temperature guidelines are exceeded (149–152). Evidence
on this appears to be equivocal (153, 154), with most
of the modeling taking place in the laboratory setting
where the heat-buffering effects of a richly perfused
periodontium cannot properly be taken into account.
There is little clinical evidence of adverse periodontal
responses following thermoplastic obturation in clinical practice.
Perhaps as important are the questions of efficacy and
control.
Many laboratory studies have addressed how well
warm vertically compacted gutta percha adapts to canal
walls and reduces sealer-pools following heating and
compaction to different depths. The consensus of
recent laboratory reports is that heating and compaction within the apical 2–3 mm of the canal is required
for optimal gutta percha adaptation to the canal
terminus (155–159), with significant (30%) differences
in area of canal occupied by gutta percha following heat
application to 2 or 4 mm from canal terminus (157). It
is difficult to imagine that the majority of practitioners
working in curved canals are able to consistently deliver
heat and pressure to such depths, and in reality, many
warm vertically compacted root canal fillings may
comprise of a single, minimally distorted cone in the
apical few millimeters.
Warm vertical condensation techniques are designed
to drive materials into anatomical complexities (16),
but a higher prevalence of sealer extrusion is recognized
(109) with potential for further tissue injury and
delayed healing. However, a recent clinical report (160)
found no association between sealer extrusion and
postoperative pain, whereas small extrusions of zinc
oxide-eugenol sealers have been shown to resorb
(161). A recent 20–27 year review on teeth with
extruded of filling materials showed progressive periapical improvement with time (162).
Clinical studies (39, 109, 125, 132) and case reports
(163, 164) have convincingly reinforced the view that
warm vertical condensation techniques can enjoy
comparable success to lateral condensation methods.
The impact on clinical outcome is central to our choice of
techniques, and until recently, there has been little to
separate established methods. However, data from a recent
longitudinal study suggests that root canal treatments
involving minimal apical enlargement and warm vertical
condensation may be associated with higher successes than
large apical preparations and cold condensation (165).
Whether the filling technique or the overall approach to
treatment was critical is hitherto unclear.
Carrier systems
Carrier systems represent another convenient means of
delivering thermally softened gutta percha to canal
Fig. 24. Carrier obturation. (A) Verification of the canal with a blank carrier. (B) Smooth insertion into a lightly sealercoated canal. (C) Cut-back of the carrier.
16
Methods of filling root canals: principles and practices
Fig. 25. A Thermafil device prepared for use. Upper device unaltered; lower device trimmed to remove excess gutta
percha apically and coronally.
Clinical application (Fig. 24)
Verifying the preparation
In common with other techniques, the compacting
tool (in this case, a plastic blank, which in the filling
devices is covered with gutta percha) must first be tried
in the canal to ensure that it will be able to carry and
compact material to full length. This takes special
importance in the case of carrier systems, where
insertion occurs in one action, with little opportunity
to revise the result if the carrier does not go to length
first time.
Products from different manufacturers have differing
degrees of taper, which may make some systems more
suitable with certain canal shapes than others.
Whole systems are available with matched shaping
instruments, absorbent points, and carrier devices (40,
169).
Such systems introduce an element of ergonomics to
root canal treatment and may be welcomed by many.
The relative success of such systems in different
configurations is largely unknown.
Fig. 26. (A) Resilon, a biodegradable polycaprolactone
with (B) matching sealer.
systems with some degree of control. This approach is
typified by Thermafil, which has developed from a
method involving the coverage of a conventional file
with regular gutta percha (166) to contemporary
plastic carriers coated with flowable, reduced molecular
weight gutta percha (167). Carrier methods and may
be considered low temperature techniques with little
risk of overheating tissues (168).
Preparing the device
The majority of practitioners probably use Thermafil
and other devices as supplied.
As there is usually an excess of gutta percha on the
carrier, and as the excess apical to the tip of the plastic
carrier is not accurately known, some choose to
trim back the apical extent of gutta percha until
1.5 mm of the tip of the carrier is visible, with the
reported intention of allowing more accurate
carrier control during insertion and limiting excess
gutta percha extrusion beyond the root apex (16)
(Fig. 25)
Remove the most coronal 2–3 mm of gutta percha
from the carrier, with the intention of limiting
17
Whitworth
excessive gutta percha in the pulp chamber (16)
(Fig. 25).
It is critical for the development of adequate flow and
to facilitate insertion that the device is heated to the
correct temperature, and for the required time in the
manufacturer’s recommended oven.
Sealer application
The insertion of a well-fitting Thermafil device is akin
to inserting the plunger of a syringe to the root canal.
As a consequence, and in contrast to cold lateral
condensation, where excess sealer will slowly migrate
coronally, excessive sealer application should be
avoided to reduce the risk of large-scale apical extrusion.
Sealer is generally applied sparingly on a paper point,
with the subsequent insertion of further dry paper
points to ensure that excess has been removed and that
there is even, light wall contact (16).
Carrier insertion
When the carrier is adequately heated, it is removed
from the heater without delay or distraction and
smoothly seated to full working length in one smooth,
fluid movement.
In the hands of skilled and experienced operators,
the extent of gutta percha and sealer movement
can be controlled by the rate of carrier insertion
(G. Cantatore, personal communication, 2005), and
laboratory evidence (170) has suggested that more
rapid insertion captures apical detail better than slow
insertion.
Condensation pressure may be applied with a small
plugger to compensate for some of the shrinkage which
inevitably accompanies cooling. The shank may then be
severed with a bur or heated instrument.
Evaluation
Laboratory evidence suggests that Thermafil obturation is a low-pressure technique (171, 172), capable of
rapid, and dense filling of root canal systems and their
ramifications (11, 173–175).
Periapical extrusion has again been identified as a
potential drawback of Thermafil (175) and Da Silva et
al. (176) have therefore described a modified carrier
obturation technique in which a sealer-coated master
gutta percha cone is first inserted to length before the
heat-softened carrier. This method has been shown in
vitro to create dense root canal fillings while controlling
apical extrusion of materials, and presumably, after
pain.
18
Two clinical trials have been reported recently.
Gagliani et al. (177) have shown 94.9% periapical
health in teeth with apical periodontitis, and 48.2%
healing in teeth without apical periodontitis, 24
months after treatment with Profile and Thermafil,
whereas Chu et al. (133) showed comparable, 80%
success at 3 yr review in teeth filled with Thermafil or
lateral condensation. Lateral condensation was, however, found to take 20 min longer on average per tooth
than Thermafil.
Carrier devices are firmly established in clinical
practice, and are reported to be especially effective in
long, curved canals, where the insertion of conventional spreaders and pluggers may be compromised
(167).
Resilon (Fig. 26)
Despite apparently satisfactory performance over many
decades, and in a variety of guises, gutta percha and
sealer filling techniques do not represent the universal
ideal. Although few materials, with the exception of
MTA, have seriously challenged gutta percha and sealer
in the majority of filling situations, research continues
to find alternatives which may seal better, mechanically
reinforce compromised roots, and avoid any potential
for adverse responses in latex-allergic patients.
Resilon, a polycaprolactone core and sealer filling
system has recently entered the market as Real Seal
(Dentsply, Tulsa, OH, USA), Epiphany (Pentron,
Wallingfort, CT, USA) and Resilon Simplifill (Lightspeed Technologies). Cones of ISO and increased
taper, and pellets for injection-molding are available,
with the recommendation that the material can be used
in any conventional technique. Melting temperatures
are, however, reduced to 1501C for System B, and to
1401C for Obtura (178). Anecdotal reports suggest
that the material is user-friendly but does not retain its
softness after heating as well as gutta percha. Components were developed to bond with each other and with
canal walls to produce an hermetically sealing (19) and
root-reinforcing (18) monobloc of material. Claims on
the in vitro sealability of Resilon were recently
challenged by independent researchers (178), but
recent clinical research in dogs has confirmed that
Resilon provides a better coronal seal against microbial
ingress than laterally or vertically compacted gutta
percha with AH26 (179). Clinical studies in humans
are awaited.
Methods of filling root canals: principles and practices
Conclusions
Although the importance of root canal filling should
not be diminished within a package of infectioncontrolling care, clinical trials have failed to identify
filling methods as significant in endodontic outcome
(39, 109, 129, 132, 133). Meta analysis has also
provided little evidence that endodontic outcomes have
improved with time (180), indicating that the explosion of technology in endodontics may have met needs
other than those of simply healing more disease. Recent
case reports demonstrate the extraordinary skills of
contemporary endodontists, but the message of the
radiographic white lines may be weakened without
follow-up images to demonstrate biological success
(181, 182).
Most critical may be the elements of care which are
not seen; the integrity of the operator in securing
infection control at every step, rather than the details of
materials and methods. Within that framework, the
choices of practitioners may justifiably be based on
individual preference and particular practice circumstances.
The clinical science of root canal filling is weak, and
weighted toward laboratory studies, often of questionable clinical relevance and with little standardization of
method. There is a need to translate daily practice into
research data to provide stronger evidence to support
our care of patients.
References
1.
2.
3.
4.
5.
6.
7.
Friedman S. Prognosis of initial therapy. Endod Topics
2002: 2: 59–88.
Eckerbom M, Magnusson T. Evaluation of technical
quality of endodontic treatment – reliability of
intraoral radiographs. Endod Dent Traumatol 1997:
13: 259–264.
Kersten HW, Wesselink PR, van Thoden SK. The
diagnostic reliability of the buccal radiograph after
root canal filling. Int Endod J 1987: 20: 20–24.
Ingle JI, Beveridge EE, Glick DH, Weichman JA
Chapter 1: Modern Endodontic Therapy. Endodontics,
4th edn. Malvern: Ingle and Bakland, 1984: 1–52.
Harty FJ. Chapter 7: Conventional Root Canal Therapy
– II. Endodontics in Clinical Practice, 1st edn. Bristol:
Harty FJ, Wright, 1982: 137–172.
Haapasalo M, Endal U, Zandi H, Coil JM. Eradication
of endodontic infection by instrumentation and
irrigation solutions. Endod Topics 2005: 10: 77–102.
Klevant FJH, Eggink CO. Effect of canal preparation
on periapical disease. Int Endod J 1983: 16: 68–75.
8. Walker RT. A practical guide to pulp canal therapy. 5.
Canal obturation. Dent Update 1984: 11: 9–16.
9. Donnoley JC. Resolution of a periapical radiolucency
without root canal filling. J Endod 1990: 16: 394–395.
10. De Rossi A, Silva LA, Leonardo MR, Rocha LB, Rossi
MA. Effect of rotary or manual instrumentation, with
or without a calcium hydroxide/1% chlorhexidine
intracanal dressing, on the healing of experimentally
induced chronic periapical lesions. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 2005: 99: 628–636.
11. Weis MV, Parashos P, Messer HH. Effect of obturation
technique on sealer cement thickness and dentinal
tubule penetration. Int Endod J 2004: 37:
653–663.
12. Katebzadeh N, Hupp J, Trope M. Histological
periapical repair after obturation of infected root
canals in dogs. J Endod 1999: 25: 364–368.
13. Kirkevang L-L, Hrsted-Bindslev P. Technical aspects
of treatment in relation to treatment outcome. Endod
Topics 2002: 2: 89–102.
14. Schaeffer MA, White RR, Walton RE. Determining
the optimal obturation length: a meta-analysis of the
literature. J Endod 2005: 31: 271–274.
15. Brayton SM, Davis SR, Goldman M. Gutta-percha
root canal fillings. An in vitro analysis. Oral Surg Oral
Med Oral Pathol 1973: 35: 226–231.
16. Buchanan LS. Filling root canal systems with centered
condensation: concepts, instruments and techniques.
Endod Prac 2005: 8: 9–15.
17. Johnson ME, Stewart GP, Nielsen CJ, Hatton JF.
Evaluation of root reinforcement of endodontically
treated teeth. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2000: 90: 360–364.
18. Teixeira FB, Teixeira EC, Thompson JY, Trope M.
Fracture resistance of roots endodontically treated
with a new resin filling material. J Am Dent Assoc 2004:
135: 646–652.
19. Shipper G, Orstavik D, Teixeira FB, Trope M. An
evaluation of microbial leakage in roots filled with a
thermoplastic synthetic polymer-based root canal
filling material (Resilon). J Endod 2004: 30:
342–347.
20. Trope M, Bergenholtz G. Microbiological basis for
endodontic treatment: can a maximal outcome be
achieved in one visit? Endod Topics 2002: 1: 40–53.
21. Dugas NN, Lawrence HP, Teplitsky PE, Pharoah MJ,
Friedman S. Periapical health and treatment quality
assessment of root-filled teeth in two Canadian
populations. Int Endod J 2003: 36: 181–192.
22. Hommez GM, Coppens CR, De Moor R. Periapical
health related to the quality of coronal restorations and
root fillings. Int Endod J 2002: 35: 680–689.
23. Tronstad L, Asbjornsen K, Doving L, Pedersen I,
Eriksen HM. Influence of coronal restorations on the
periapical health of endodontically treated teeth.
Endod Dent Traumatol 2000: 16: 218–221.
24. Saleh IM, Ruyter IE, Haapasalo M, Ørstavik D.
Survival of Enterococcus faecalis in infected dentinal
tubules after root canal filling with different root
19
Whitworth
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
20
canal sealers in vitro. Int Endod J 2004: 37:
193–198.
Nair PN, Henry S, Cano V, Vera J. Microbial status of
apical root canal system of human mandibular first
molars with primary apical periodontitis after ‘‘one
visit’’ endodontic treatment. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 2005: 99: 231–252.
Wu M-K, Özok AR, Wesselink PR. Sealer distribution
in root canals obturated by three techniques. Int
Endod J 2000: 33: 340–345.
Eguchi DS, Peters DD, Hollinger JO, Lorton L. A
comparison of the area of the canal space occupied by
gutta-percha following four gutta-percha obturation
techniques using Procosol sealer. J Endod 1985: 11:
166–175.
Wu M-K, Wesselink PR, Boersma J. A 1-year follow-up
study on leakage of four root canal sealers at different
thicknesses. Int Endod J 1995: 28: 185–189.
Boggia R. A single-visit treatment of septic root canals
using periapically extruded endomethasone. Br Dent J
1983: 155: 300–305.
Vranas RN, Hartwell GR, Moon PC. The effect of
endodontic solutions on resourcinol-formaldehyde
paste. J Endod 2003: 29: 69–72.
Schwandt NW, Gound TG. Resourcinol-formaldehyde resin ‘Russian Red’ endodontic therapy. J Endod
2003: 29: 435–437.
Fanibunda K, Whitworth J, Steele J. The management
of thermomechanically compacted gutta percha extrusion in the inferior dental canal. Br Dent J 1998:
184: 330–332.
Ørstavik D, Nordahl I, Tibballs JE. Dimensional
change following setting of root canal sealer materials.
Dent Mater 2001: 17: 512–519.
Ingle JI. A standardised endodontic technique using
newly designed instruments and filling materials. Oral
Surg 1961: 14: 83–91.
Hommez GMG, De Moor RJG, Braem M. Endodontic treatment preformed by Flemish dentists. Part 2.
Canal Filing and decision making for referrals and
treatment of apical periodontitis. Int Endod J 2003: 36:
344–351.
Seccombe GV.. What dentists do and why they do it: a
survey of endodontics in the General Dental Services.
PhD Thesis, University of Newcastle, UK, 2000.
Smith CS, Setchell DJ, Harty FJ. Factors influencing
the success of conventional root canal therapy – a five
year retrospective study. Int Endod J 1993: 26:
321–333.
Wu MK, Fan B, Wesselink PR. Leakage along apical
root fillings in curved root canals. Part I: effects of
apical transportation on seal of root fillings. J Endod
2000: 26: 210–216.
Peters OA, Barbakow F, Peters CI. An analysis of
endodontic treatment with three nickel-titanium
rotary root canal preparation techniques. Int Endod J
2004: 37: 849–859.
Buchanan LS. The predefined preparation comes of
age. Endod Prac 2001: 4: 6–18.
41. Gordon MPJ, Love RM, Chandler NP. An evaluation
of .06 tapered gutta percha cones for filling of .06 taper
prepared curved root canals. Int Endod J 2005: 38: 87–
96.
42. Torabinejad M, Hong CU, McDonald F, Pitt Ford
TR. Physical and chemical properties of a new rootend filling material. J Endod 1995: 21: 349–353.
43. Whitworth JM, Endal U, Padachey N, Haapasalo M.
2005 Survey of material selection amongst endodontic
opinion leaders. Unpublished data.
44. Camilleri J, Montesin FE, Brady K, Sweeney R, Curtis
RV, Ford TR. The constitution of mineral trioxide
aggregate. Dent Mater 2005: 21: 297–303.
45. Fridland M, Rosado R. Mineral trioxide aggregate
(MTA) solubility and porosity with different water-topowder ratios. J Endod 2003: 29: 814–817.
46. Lee ES. A new mineral trioxide aggregate root-end
filling technique. J Endod 2000: 26: 764–765.
47. Whitworth JM, Hunt K. Hunt out your micro
amalgam gun – an alternative mould for MTA
placement. Endod Pract 2005: 8: 17–18.
48. Lawley GR, Schindler WG, Walker WA III, Kolodrubetz D. Evaluation of ultrasonically placed MTA and
fracture resistance with intracanal composite resin in a
model of apexification. J Endod 2004: 30:
167–172.
49. Aminoshariae A, Hartwell GR, Moon PC. Placement
of mineral trioxide aggregate using two different
techniques. J Endod 2003: 29: 679–682.
50. Kratchman SI. Perforation repair and one-step apexification procedures. Dent Clin North Am 2004: 48:
291–307.
51. Menezes R, da Silva Neto UX, Carneiro E, Letra A,
Bramante CM, Bernadinelli N. MTA repair of a
supracrestal perforation: a case report. J Endod 2005:
31: 212–214.
52. Steinig TH, Regan JD, Gutmann JL. The use and
predictable placement of mineral trioxide aggregate in
one-visit apexification cases. Endod Pract 2004: 7:
15–24.
53. Al-Hezaimi K, Naghshbandi J, Oglesby S, Simon JH.,
Rotstein I. Human saliva penetration of root canals
obturated with two types of mineral trioxide aggregate
cements. J Endod 2005: 31: 453–456.
54. Lertchirakarn V, Timyam A, Messer HH. Effects of
root canal sealers on vertical root fracture resistance of
endodontically treated teeth. J Endod 2002: 28:
217–219.
55. De Bruyne MAA, De Moor RJG. Review: the use of
glass ionomer cements in both conventional and
surgical endodontics. Int Endod J 2004: 37: 91–104.
56. Schäfer E, Zandbiglari T. Solubility of root-canal
sealers in water and artificial saliva. Int Endod J 2003:
36: 660–669.
57. Carvalho-Junior JR, Guimaraes LF, Correr-Sobrinho
L, Pecora JD, Sousa-Neto MD. Evaluation of solubility, disintegration, and dimensional alterations of a
glass ionomer root canal sealer. Braz Dent J 2003: 14:
114–118.
Methods of filling root canals: principles and practices
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
Friedman S, Lost C, Zarrabian M, Trope M. Evaluation of success and failure after endodontic therapy
using a glass ionomer cement sealer. J Endod 1995: 21:
384–390.
Bouillaguet S, Wataha JC, Lockwood PE, Galgano C,
Golay A, Krejci I. Cytotoxicity and sealing properties
of four classes of endodontic sealers evaluated by
succinic dehydrogenase activity and confocal laser
scanning microscopy. Eur J Oral Sci 2004: 112:
182–187.
Ardila CN, Wu MK, Wesselink PR. Percentage of filled
canal area in mandibular molars after conventional
root-canal instrumentation and after a noninstrumentation technique (NIT). Int Endod J 2003: 36: 591–
598.
Huumonen S, Lenander-Lumikari M, Sigurdsson A,
Ørstavik D. Healing of apical periodontitis after
endodontic treatment: a comparison between a
silicone-based and a zinc oxide-eugenol-based sealer.
Int Endod J 2003: 36: 296–301.
Wu MK, Tigos E, Wesselink PR. An 18-month
longitudinal study on a new silicon-based sealer, RSA
RoekoSeal: a leakage study in vitro. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 2002: 94: 499–
502.
Zmener O. Tissue response to a new methacrylatebased root canal sealer: preliminary observations in the
subcutaneous connective tissue of rats. J Endod 2004:
30: 348–351.
Zmener O, Banegas G, Pameijer CH. Bone tissue
response to a methacrylate-based endodontic sealer: a
histological and histometric study. J Endod 2005: 31:
457–459.
Kardon BP, Kuttler S, Hardigan P, Dorn SO. An in
vitro evaluation of the sealing ability of a new rootcanal-obturation system. J Endod 2003: 29: 658–661.
Zmener O, Pameijer CH. Clinical and radiographic
evaluation of a resin-based root canal sealer. Am J Dent
2004: 17: 19–22.
Tay FR, Loushine RJ, Monticelli F, Weller RN, Breschi
L. Effectiveness of resin-coated gutta-percha cones
and dual-cured, hydrophilic methacrylate resin-based
sealer in obturating root canals. J Endod 2005: 31:
659–664.
Kaplan AE, Ormaechea MF, Picca M, Canzobre MC,
Ubios AM. Rheological properties and biocompatibility of endodontic sealers. Int Endod J 2003: 36:
527–532.
Miletić I, Jukić S, Anić I, eljezić D, Garaj-Vrhovac V,
Osmak M. Examination of cytotoxicity and mutagenicity of AH26 and AH Plus sealers. Int Endod J 2003:
36: 330–335.
McMichen FR, Pearson G, Rahbaran S, Gulabivala K.
A comparative study of selected physical properties of
five root-canal sealers. Int Endod J 2003: 36:
629–635.
Ørstavik D, Horsted-Bindslev P. A comparison of
endodontic treatment results at two dental schools.
Int Endod J 1993: 26: 348–354.
72. Leonardo MR, Salgado AA, da Silva LA, Tanomaru
Filho M. Apical and periapical repair of dogs’ teeth
with periapical lesions after endodontic treatment with
different root canal sealers. Braz Oral Res 2003: 17:
69–74.
73. Kontakiotis EG, Wu MK, Wesselink PR. Effect
of sealer thickness on long-term sealing ability:
a 2-year follow-up study. Int Endod J 1997: 30:
307–312.
74. Whitworth JM, Baco L. Coronal leakage of sealer-only
backfill: an in vitro evaluation. J Endod 2005: 31: 280–
282.
75. Cohen BI, Pagnillo MK, Musikant BL, Deutsch AS.
The evaluation of apical leakage for three endodontic
fill systems. Gen Dent 1998: 46: 618–623.
76. Musikant BL., Cohen BI, Deutsch AS. A two-and-ahalf year perspective on simplified endodontic
techniques. Compend Contin Educ Dent 2003: 24:
46–52.
77. Deutsch AS, Musikant BL, Cohen BI, Kase D. A study
of one visit treatment usinf EZ-fill root canal sealer.
Endod Pract 2001: 4: 29–36.
78. Lussi A, Imwinkelreid A, Stich H. Obturation of root
canals with different sealers using non-instrumentation technology. Int Endod J 1999: 32: 17–23.
79. Lussi A, Suter B, Fritzsche A, Gygax M, Portmann P.
In vivo performance of the new non-instrumentation
technology (NIT) for root canal obturation. Int Endod
J 2002: 35: 352–358.
80. Qualtrough AJ., Whitworth JM, Dummer PM. Preclinical endodontology: an international comparison.
Int Endod J, 32: 406–414.
81. Jenkins SM, Hayes SJ, Dummer PMH. A study of
endodontic treatment carried out in dental practice
within the UK. Int Endod J 2001: 34: 16–22.
82. Bjrndahl L, Reit C. The adoption of new endodontic
technology amongst Danish general dental practitioners. Int Endod J 2005: 38: 52–58.
83. Bal AS, Hicks ML, Barnett F. Comparison of laterally
condensed .06 and .02 tapered gutta-percha and sealer
in vitro. J Endod 2001: 27: 786–788.
84. Van Gheluwe J, Wilcox LR. Lateral condensation
of small, curved root canals: comparison of
two types of accessory cones. J Endod 1996: 22:
540–542.
85. Allison DA, Weber CR, Walton RE. The influence of
the method of canal preparation on the quality of
apical and coronal obturation. J Endod 1979: 5:
298–304.
86. Allison DA, Michelich RJ, Walton RE. The influence
of master cone adaptation on the quality of the apical
seal. J Endod 1981: 7: 61–65.
87. Wilson BL, Baumgartner JC. Comparison of spreader
penetration during lateral compaction of .04
and .02 tapered gutta percha. J Endod 2003: 29:
828–831.
88. Lertchirakarn V, Palamara JEA, Messer HH. Load and
strain during lateral condensation and vertical root
fracture. J Endod 1999: 25: 99–104.
21
Whitworth
89.
90.
91.
92.
93.
94.
95.
96.
97.
98.
99.
100.
101.
102.
103.
104.
105.
22
Tamse A. Iatrogenic vertical root fractures in endodontically treated teeth. Endod Dent Traumatol 1988:
4: 190–196.
Berry KA, Loushine RJ, Primack PD, Runyan DA.
Nickel-titanium versus stainless-steel finger spreaders
in curved canals. J Endod 1998: 24: 752–754.
Sobhi MB, Khan I. Penetration depth of nickel
titanium and stainless steel finger spreaders in curved
root canals. J Coll Phys & Surg – Pakistan 2003: 13:
70–72.
Gharai SR, Thorpe JR, Strother JM, McClanahan SB.
Comparison of generated forces and apical microleakage using nickel-titanium and stainless steel finger
spreaders in curved canals. J Endod 2005: 31: 198–
200.
Joyce AP, Loushine RJ, West LA, Runyan DA,
Cameron SM. Photoelastic comparison of stress
induced by using stainless-steel versus nickel titanium
spreaders in vitro. J Endod 1998: 24: 714–715.
Harvey TE, White JT, Leeb IJ. Lateral condensation stress in root canals. J Endod 1991: 7:
151–155.
Dulaimi SF, Wali Al-Hashimi MK. A comparison of
spreader penetration depth and load required during
lateral condensation in teeth prepared using various
root canal preparation techniques. Int Endod J 2005:
38: 510–515.
van Zyl SP, Gulabivala K, Ng YL. Effect of customization of master gutta-percha cone on apical control of
root filling using different techniques: an ex vivo
study. Int Endod J 2005: 38: 658–666.
Waltimo TM, Boiesen J, Eriksen HM, Ørstavik D.
Clinical performance of 3 endodontic sealers. Oral
Surg Oral Med Oral Pathol Oral Radiol Endod 2001:
92: 89–92.
Kahn FH, Rosenberg PA, Schertzer L, Korthals G,
Nguyen PNT. An in vitro evaluation of sealer
placement methods. Int Endod J 1997: 30: 181–186.
Hall MC, Clement DJ, Dove SB, Walker WA. III A
comparison of sealer placement techniques in curved
canals. J Endod 1996: 22: 638–642.
Hoen MM, LaBounty GL, Keller DL. Ultrasonic
endodontic sealer placement. J Endod 1988: 14: 169–
174.
Dang DA, Walton RE. Vertical root fracture and root
distortion: effect of spreader design. J Endod 1989: 15:
294–301.
Sakkal S, Weine FS, Lemian L. Lateral condensation:
inside view. Compend Contin Educ Dent 1991: 12:
796–802.
Taylor JK, Jeansonne BG, Lemon RR. Coronal
leakage: effects of smear layer, obturation technique
and sealer. J Endod 1997: 23: 508–512.
Himel VT, Cain CW. An evaluation of the number of
condenser insertions needed with warm lateral condensation of gutta percha. J Endod 1993: 19: 79–82.
Gound TG, Riehm RJ, Makkawy HA, Odgaard EC. A
description of an alternatve method of lateral condensation and a comparison of the ability to obdurate
106.
107.
108.
109.
110.
111.
112.
113.
114.
115.
116.
117.
118.
119.
canals using mechanical or traditional lateral condensation. J Endod 2000: 26: 756–759.
Zmener O, Banegas G. Clinical experience ofcanal
filling by ultrasonic condensation of gutta percha.
Endod Dent Traumatol 1999: 15: 57–59.
Bailey GC, Ng YL, Cunnington SA, Barber P,
Gulabivala K, Setchell DJ. Root canal obturation by
ultrasonic condensation of gutta-percha. Part II: an in
vitro investigation of the quality of obturation. Int
Endod J 2004: 37: 694–698.
Tagger M, Tamse A, Katz A, Korzen BH. Evaluation
of the apical seal produced by a hybrid root canal
filling method, combining lateral condensation
and thermatic compaction. J Endod 1984: 10:
299–303.
Hoskinson SE, Ng Y-L, Hoskinson AE, Moles DR,
Gulabivala K. A retrospective comparison of outcome
of root canal treatment using two different protocols.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2002: 93: 705–715.
Ebihara A, Yoshioka T, Suda H. Garrès osteomyelitis
managed by root canal treatment of a mandibular
second molar: incorporation of computerised tomography with 3D reconstruction in the diagnosis and
monitoring of the disease. Int Endod J 2005: 38: 255–
261.
Tsurumachi T. Endodontic treatment of an invaginated maxillary lateral incisor with a periradicular
lesion and a healthy pulp. Int Endod J 2004: 37: 717–
723.
ÇaliSkan MK. Prognosis of large cyst-like periapical
lesions following nonsurgical root canal treatment: a
clinical review. Int Endod J 2004: 37: 408–416.
Jung M. Endodontic treatment of dens invaginatus
type III with three root canals and open apical
foramen. Int Endod J 2004: 37: 205–213.
Sedgley CM, Wagner R. Orthograde retreatment an
apexification after unsuccessful endodontic treatment,
retreatment and apicectomy. Int Endod J 2003: 36:
780–786.
Ricucci D, Gröndahl K, Bergenholtz G. Periapical
status in root-filled teeth exposed to the oral environment by loss of restoration or caries. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 2000: 90: 354–
359.
Ricucci D, Bergenholtz G. Bacterial status in rootfilled teeth exposed to the oral environment by loss of
restoration and fracture or caries – a histobacteriolgical
study of treated cases. Int Endod J 2003: 36:
787–802.
Strindberg LZ. The dependence of the results of pulp
therapy on certain factors – an analytic study based on
radiographic and clinical follow-up examination. Acta
Odont Scand 1956: 14: 1–175.
Kerekes K, Tronstad L. Long-term results of endodontic treatment performed with a standardised
technique. J Endod 1979: 5: 83–90.
Byström A, Happonen RP, Sjögren U, Sundqvist G.
Healing of periapical lesions of pulpless teeth after
Methods of filling root canals: principles and practices
120.
121.
122.
123.
124.
125.
126.
127.
128.
129.
130.
131.
132.
133.
134.
135.
136.
endodontic treatment with controlled asepsis. Endod
Dent Traumatol 1987: 3: 58–63.
Ørstavik D, Kerekes K, Eriksen HM. Clinical performance of three endodontic sealers. Endod Dent
Traumatol 1987: 3: 178–186.
Sjögren U, Hägglund B, Sundqvist G, Wing K.
Factors affecting the long-term results of endodontic
treatment. J Endod 1990: 16: 498–504.
Ørstavik D. Time-course and risk analyses of
the development and healing of chronic apical
periodontitis in man. Int Endod J 1996: 29:
150–155.
Sjögren U, Figdor D, Persson S, Sundqvist G.
Influence of infection at the time of root filling on
the outcome of endodontic treatment in teeth with
apical periodontitis. Int Endod J 1997: 30: 297–306.
Oliet S. Single-visit endodontics: a clinical study. J
Endod 1983: 9: 147–152.
Pekruhn RB. The incidence of failure following singlevisit endodontic therapy. J Endod 1986: 12: 68–72.
Shah N. Nonsurgical management of periapical
lesions: a prospective study. Oral Surg Oral Med Oral
Pathol 1988: 66: 365–371.
Cali1kan MK, Sen BH. Endodontic treatment of teeth
with apical periodontitis using calcium hydroxide: a
long-term study. Endod Dent Traumatol 1996: 12:
215–221.
Trope M, Delano EO, Ørstavik D. Endodontic
treatment of teeth with apical periodontitis: single vs
multiple visit treatment. J Endod 1999: 25: 345–350.
Reid RJ, Abbott PV, McNamara JR, Heithersay GS. A
five year study of Hydron root canal fillings. Int Endod
J 1992: 25: 213–220.
Weiger R, Rosendahl R, Löst C. Influence of calcium
hydroxide intracanal dressings on the prognosis of
teeth with endodontically induced periapical lesions.
Int Endod J 2000: 33: 219–226.
Dammascke T, Steven D, Kamp M, Reiner KH. Longterm survival of root-canal-treated teeth: a retrospective study over 10 years. J Endod 2003: 29: 638–
643.
Friedman S, Abitbol S, Lawrence HP. Treatment
outcome in endodontics. The Toronto Study. Phase I:
initial treatment. J Endod 2003: 29: 787–793.
Chu CH, Lo ECM, Cheung GSP. Outcome of root
canal treatment using Thermafil and cold lateral
condensation filling techniques. Int Endod J 2005:
38: 179–185.
Peters LB, Wesselink PR. Periapical healing of
endodontically treated teeth in one and two visits
obturated in the presence or absence of microorganisms. Int Endod J 2002: 35: 660–667.
Weine FS, Buchanan LS. Controversies in clinical
endodontics: part 1. The significance and filling of
lateral canals. Compend Contin Educ Dent 1996: 17:
1028–1038.
Schilder H. Filling root canals in three dimensions.
Dent Clin North Am 1967: 11: 723–744.
137. Ruddle CJ. Chapter 8: Cleaning and Shaping the Root
Canal System. Pathways of the Pulp, 7th edn. St Louis:
Cohen and Burns, 2002: 231–291.
138. Hülsmann M, Peters OE, Dummer PMH. Mechanical
preparation of root canals: shaping goals, techniques
and means. Endod Topics 2004: 10: 30–76.
139. Rosenberg DB. The paper point technique: part one.
Endod Pract 2004a: 7: 6–12.
140. Rosenberg DB. The paper point technique: part two.
Endod Prac 2004b: 7: 7–11.
141. Gutmann J, Witherspoon D. Chapter 9: Obturation of
the Cleaned and Shaped Root Canal System. Pathways
of the Pulp, 7th edn. St Louis: Cohen and Burns, 2002:
293–364.
142. Guess GM, Edwards KR, Yang ML, Iqbal MK, Kim S.
Analysis of continuous-wave obturation using a singlecone and hybrid technique. J Endod 1993: 29: 509–
512.
143. DuLac KA, Nielsen CJ, Tomazic TJ, Ferrillo PJ Jr,
Hatton JF. Comparison of the obturation of lateral
canals by six techniques. J Endod 1999: 25: 376–380.
144. Reader CM, Himel VT, Germain LP, Hoen MM.
Effect of three obturation techniques on the filling of
lateral canals and the main canal. J Endod 1993: 19:
404–408.
145. Olson AK, Hartwell GR, Weller RN. Evaluation of the
controlled placement of injected thermoplasticized
gutta-percha. J Endod 1989: 15: 306–309.
146. Johnson BT, Bond MS. Leakage associated with single
or multiple increment backfill with the Obtura II
gutta-percha system. J Endod 1999: 25: 613–614.
147. Buchanan LS. Continuous wave of condensation
technique. Endod Pract 1998: 1: 7–23.
148. Wu MK, Van Der Sluis LW, Wesselink PR. Fluid
transport along gutta-percha backfills with and without sealer. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2004: 97: 257–262.
149. Silver GK, Love RM, Purton DG. Comparison of two
vertical condensation obturation techniques: touch ‘n
heat modified and system B. Int Endod J 1999: 32:
287–295.
150. Floren JW, Weller RN, Pashley DH, Kimbrough WF.
Changes in root surface temperatures with in vitro use
of the System B heat source. J Endod 1999: 25: 593–
595.
151. Villegas JC, Yoshioka T, Kobayashi Ch, Suda H.
Intracanal temperature rise evaluation during the
useage of the System B: replication of intracanal
anatomy. Int Endod J 2005: 38: 218–222.
152. Lipski M. Root surface temperature rises during root
canal obturation in vitro by the continuous wave of
condensation technique using System b heat source.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2005: 99: 505–510.
153. Romero AD, Green DB, Wucherpfennig AL. Heat
transfer to the periodontal ligament during root
obturation procedures using an in vitro model. J
Endod 2000: 26: 85–87.
23
Whitworth
154. Sweatman TL, Baumgartner JC, Sakaguchi RL.
Radicular temperatures associated with thermoplasticized gutta-percha. J Endod 2001: 27: 512–515.
155. Wu MK, van der Sluis LW, Wesselink PR. A
preliminary study of the percentage of gutta-perchafilled area in the apical canal filled with vertically
compacted warm gutta-percha. Int Endod J 2002: 35:
527–535.
156. Bowman CJ, Baumgartner JC. Gutta-percha obturation of lateral grooves and depressions. J Endod 2002:
28: 220–223.
157. Jung IY, Lee SB, Kim ES, Lee CY, Lee SJ. Effect of
different temperatures and penetration depths of a
System B plugger in the filling of artificially created
oval canals. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2003: 96: 453–457.
158. Villegas JC, Yoshioka T, Kobayashi C, Suda H. Threestep versus single-step use of system B: evaluation of
gutta-percha root canal fillings and their adaptation to
the canal walls. J Endod 2004: 30: 719–721.
159. Kececi AD, Unal GC, Sen BH. Comparison of cold
lateral compaction and continuous wave of obturation
techniques following manual or rotary instrumentation. Int Endod J 2005: 38: 381–388.
160. Ng Y-L, Glennon JP, Setchell DJ, Gulabivala K.
Prevalence and factors affecting post-obturation pain
in patients undergoing root canal treatment. Int
Endod J 2004: 37: 381–391.
161. Ausburger RA, Peters DD. Radiographic evaluation of
extruded obturation materials. J Endod 1990: 10:
492–497.
162. Fristad I, Molven O, Halse A. Nonsurgically retreated
root filled teeth – radiographic findings after 20–27
years. Int Endod J 2004: 37: 12–18.
163. Stefen H, Splieth C. Conventional treatment of dens
invaginatus in maxillary lateral incisor with sinus tract:
one year follow-up. J Endod 2005: 31: 130–133.
164. Nallapati S. Three canal mandibular first and second
premolars: a treatment approach. A case report. J
Endod 2005: 31: 474–476.
165. Farazaneh M, Abitbol S, Lawrence HP, Friedman S.
Treatment outcome in endodontics – the Toronto
study. Phase II: initial treatment. J Endod 2004: 30:
302–309.
166. Johnson WB. A new gutta-percha technique. J Endod
1978: 4: 184–188.
167. Cantatore G. Thermafil versus System B. Endod Pract
2001: 5: 30–39.
168. Behnia A, McDonald NJ. In vitro infrared thermographic assessment of root surface temperatures
generated by the thermafil plus system. J Endod
2001: 27: 203–205.
169. Buchanan LS. ProSystem GT: design, technique, and
advantages. Endod Topics 2005: 10: 168–175.
24
170. Levitan ME, Himel VT, Luckey JB. The effect of
insertion rates on fill length and adaptation of a
thermoplasticised gutta percha technique. J Endod
2003: 29: 505–508.
171. Blum JY, Machtou P, Micallef JP. Analysis of forces
developed during obturations. Wedging effect: part II.
J Endod 1998: 24: 223–228.
172. Saw LH., Messer HH. Root strains associated with
different obturation techniques. J Endod 1995: 21:
314–320.
173. Jarrett IS, Marx D, Covey D, Karmazin M, Lavin M,
Gound T. Percentage of canals filled in apical cross
sections – an in vitro study of seven obturation
techniques. Int Endod J 2004: 37: 392–398.
174. Gencoglu N. Comparison of 6 different gutta-percha
techniques (part II): Thermafil, JS Quick-Fill, Soft
Core, Microseal, System B, and lateral condensation.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2003: 96: 91–95.
175. Clinton K, Van Himel T. Comparison of a warm guttapercha obturation technique and lateral condensation.
J Endod 2001: 27: 692–695.
176. Da Silva D, Endal U, Reynaud A, Portenier I, Orstavik
D, Haapasalo M. A comparative study of lateral
condensation, heat-softened gutta-percha, and a
modified master cone heat-softened backfilling technique. Int Endod J 2002: 35: 1005–1011.
177. Gagliani MA, Cerutti A, Bondesan A, Colombo M,
Godio E, Giacomelli G. A 24-month survey on root
canal treatment performed by NiTi engine driven files
and warm gutta-percha filling associated system.
Minerva Stomatol 2004: 53: 543–554.
178. Tay FR, Loushine RJ, Weller RN, Kimbrough WF,
Pashley DH, Mak Y-F, Lai C-NS, Raina R, Williams
MC. Ultratructural evaluation of the apical
seal in roots filled with a polycaprolactone-based
root canal filling material. J Endod 2005: 31:
514–519.
179. Shipper G, Teixeira FB, Arnold RR, Trope M.
Periapical inflammation after coronal microbial inoculation of dog roots filled with gutta-percha or resilon. J
Endod 2005: 31: 91–96.
180. Lewsey JD, Gilthorpe MS, Gulabivala K. An introduction to meta-analysis within the framework of multilevel modelling using the probability of success of root
canal treatment as an illustration. Commun Dent
Health 2001: 18: 131–137.
181. Ferguson DB, Kjar KS, Hartwell GR. Three canals in
the mesiobuccal root of a maxillary first molar: a case
report. J Endod 2005: 31: 400–402.
182. De Moor RJG, Calberson FLG. Root canal treatment
in a mandibular second premolar with three canals. J
Endod 2005: 31: 310–313.