for students of dentistry

1. Waleed K.O. Jaber
Root canal filling
materials.
Root filling
techniques.

2. Purpose of root canal filling
 To prevent bacteria and bacterial elements
from spreading from (or through) the canal
system to the periapical area,
 the fully instrumented root canal has to be
provided with a tight and long-lasting
obturation.
 A root canal filling material should, therefore,
prevent infection/reinfection of treated root
canals. Together with an acceptable level of
biocompatibility (inert material) this will
provide the basis for promoting healing of
the periodontal tissues and for maintaining
healthy periapical conditions.

3. Instruments for root canal filling
 Lentulo spiral filler/rotary paste filler
 Function and features
 • Small flexible instrument used to place
materials into the canal
 • Fits into the conventional handpiece
 • Use with caution as it can be easily
broken
 • Different sizes available

4. Finger spreader
Function, features and precaution
• Used to condense gutta percha into the
canal during obturation
• Finger instrument with a smooth, pointed,
tapered working end
• Disposed of in the sharps’ container
Varieties
Can be of the hand instrument type (lateral
condenser)

5. Endodontic plugger
Function
Working end is flat to facilitate plugging or
condensing the gutta percha after the excess
has been removed by melting off with a heated
instrument
Varieties
• Different sizes of working ends are available
•Available as hand or finger instruments

6.  Gutta percha points
Function and features
 •Non-soluble, non-irritant points that are
condensed into the pulp chamber during
obturation
 • Standardised type: follows same ISO
classification as endodontic files
 • Non-standardised: have a greater taper than
the standard ISO type
Varieties
 • Can be packaged in single dose or bulk
packages
 • Different sizes with different tapers available

7. OBTURATING MATERIALS
Sealers
 Regardless of the obturation technique
employed, sealers are an essential
component of the process. Sealers fill the
space between the canal wall and core
obturation material and may fill lateral
and accessory canals, isthmuses, and
irregularities in the root canal system.

8. The ideal properties of endodontic sealer
are as follows:
 1. It should be tacky when mixed to provide good adhesion
between it and the canal wall when set.
 2. It should produce a watertight seal
 3. It should be radiopaque so that it can be visualized o on X-ray.
 4. The particles of powder should be very fine so they can mix easily
with the liquid.
 5. It should not shrink on setting.
 6. It should not stain tooth structure.
 7. It should be bacteriostatic or at least not encourage bacterial
growth.
 8. It should set slowly.
 9. It should be insoluble in tissue fluids.
 10. It should be tissue-tolerant, that is nonirritating to periradicular
tissue.
 11. It should be soluble in a common solvent in case removal of
the root canal filling becomes necessary.

9. The most popular sealers are grouped by
type:
 Zinc oxide-eugenol formulations,
 Calcium hydroxide sealers,
 Glass- ionomers, and
 Resins.
Regardless of the sealer selected, all are
toxic until they set. For this reason,
extrusion of sealers into the periradicular
tissues should be avoided.

10.  Zinc oxide-eugenol and resin sealers have a
history of successful use over an extended
period. Zinc oxide-eugenol sealers have the
advantage of being resorbed if extruded into
the periradicular tissues .
 Calcium hydroxide sealers were recently
introduced for their potential therapeutic
benefits. In theory these sealers exhibit an
antimicrobial effect and have osteogenic
potential. Unfortunately these actions have not
been demonstrated, and the solubility required
for release of calcium hydroxide and sustained
activity is a distinct disadvantage.
 Glass ionomers have been advocated for use
in sealing the radicular space because of their
dentin bonding properties. A disadvantage is
their difficult removal if retreatment is required.

11.  Sealerscontaining paraformaldehyde are
contraindicated in endodontic treatment.
Although the lead and mercury
components have been removed from
the formulations over time, the
paraformaldehyde content has remained
constant and toxic. These sealers are not
approved by the U. S. Food and Drug
Administration.

12.  Controversy surrounds removal of the smear
layer before obturation. The smear layer is
created on the canal walls by manipulation
of the files during cleaning and shaping
procedures. It is composed of inorganic and
organic components that may contain
bacteria and their by-products. In theory
remnants left on the canal wall may serve as
irritants or substrates for bacterial growth or
interfere with the development of a seal
during obturation. Although fluid movement
may occur in obturated canals, bacterial
movement does not appear to take place.
Recent evidence suggests that removal of
the smear layer can enhance penetration of
the sealer into the dentinal tubules.

13.  Removal of the smear layer can be
accomplished after cleaning and shaping
by irrigation with 17%
ethylenediaminetetraacetic acid (EDTA)
for 1 minute. Irrigation should be followed
with a final rinse of sodium hypochlorite.

14. Acceptable methods of placing the sealer in
the canal include the following:
• Placing the sealer on the master cone
and pumping the cone up and down in
the canal
 • Placing the sealer on a file and spinning
it counter clockwise
 • Placing the sealer with a lentulo spiral
 • Using a syringe
 • Activating an ultrasonic instrument
The clinician should use care when placing
sealer in a canal with an open apex to
avoid extrusion.

15. Core Obturation Materials
 Historically,a variety of materials have
been employed to obturate the root
canal, falling into three broad categories:
 solids,
 semisolids, and
 Pastes(sealers)

16. Sealers
 A wide variety are available. The calcium
hydroxide materials (e.g. Sealapex) or the
eugenol-based sealers (e.g. Tubliseal) are perhaps
the safest choice. Some would advocate the
routine use of non-setting calcium hydroxide paste
(Hypocal) as an inter-appointment medicament.
 Calcium hydroxide This is considered separately,
because it has a wide range of applications in
endodontics due to its antibacterial properties
and an ability to promote the formation of a
calcific barrier. The former is thought to be due to
a high pH and also to the absorption of carbon
dioxide, upon which the metabolic activities of
many root-canal pathogens depend. It is also
proteolytic.

17. Indications for the use of calcium
hydroxide include:
• To promote apical closure in immature
teeth.
 • In the management of perforations.
 • In the treatment of resorption.
 • As a temporary dressing for canals
where filling has to be delayed. In the
management of recurrent infections
during RCT.

18. Solid materials
 Silver cones met many of the criteria for
filling materials but suffered from several
deficiencies. The rigidity that made them
easy to introduce into the canal also
made them impossible to adapt to the
inevitably irregular canal preparation,
encouraging leakage. When leakage
occurred and the points contacted tissue
fluids, they corroded, further increasing
leakage.

19. Semisolid material
 Gutta-percha, a semisolid material, is the most
widely used and accepted obturating material.
Gutta-percha is a natural product that consists
of the purified coagulated exudate of mazer
wood trees (Isonandra percha) from the Malay
archipelago or from South America.
 Typical composition of gutta-percha cones.

20.  Gutta-percha does not adhere to the canal
walls, regardless of the filling technique
applied, resulting in the potential for
marked leakage. Therefore, it is generally
recommended that gutta-percha (used
cold or heated) is used together with a
sealer. For an optimal seal the sealer layer
should generally be as thin as possible.

22. Root canal filling technique.
Solid core technique
 Single cone
The single-cone technique consists of matching
a cone to the prepared canal. For this
technique a type of canal preparation is
advocated so that the size of the cone and
the shape of the preparation are closely
matched. When a gutta-percha cone fits the
apical portion of the canal snugly, it is
cemented in place with a root canal sealer.
Although the technique is simple, it has
several disadvantages and cannot be
considered as one that seals canals
completely. After preparation, root canals are
seldom round throughout their length, except
possibly for the apical 2 or 3 mm. Therefore,
the single-cone technique, at best, only seals
this portion.

23.  Cold lateral condensation This is a commonly
taught method of obturation and is the gold
standard by which others are judged.
The technique involves placement
of a master point chosen to fit
the apical section of the canal.
Obturation of the remainder is
achieved by condensation of
smaller accessory points. The
steps involved are:

24.  1. Select a GP master point to correspond with the master
apical file instrument. This should fit the apical region snugly at
the working length so that on removal a degree of resistance or
'tug-back' is felt. If there is no tug-back select a larger point or
cut 1 mm at a time off the tip of the point until a good fit is
obtained. The point should be notched at the correct working
length to guide its placement to the apical constriction.
 2 . Take a radiograph to confirm that the point is in correct
position if you are in any doubt.
 3. Coat walls of canal with sealer using a small file.
 4. Insert the master point, covered in cement.
 5 . Condense the GP laterally with a finger spreader to provide
space into which accessory points can be inserted until the
canal is full.
 6. Excess GP is cut off with a hot instrument and the remainder
packed vertically into the canal with a cold plugger.

25. Sketch showing a cross-sectional cut through
a root canal filled with a master cone and
multiple accessory cones

26.  Warm lateral condensation As above, but
uses a warm spreader after the initial cold
lateral condensation. Finger spreaders
can be heated in a flame or a special
electronically heated device (Touch of
heat) can be used.

27. Vertical condensation
 Inthis technique the GP is warmed using a
heated instrument and then packed
vertically. A good apical stop is necessary
to prevent apical extrusion of the filling,
but with practice a very dense root filling
can result. Time consuming.

28.  Diagram of the warm vertical condensation technique.
 A, After a heated spreader
is used to remove the coronal
segment of the master cone,
a cold plugger is used to apply
vertical pressure to the softened
master cone.
 B, Obturation of the coronal
portion of the canal is
accomplished by adding a gutta
-percha segment.
 C, A heated spreader is used to
soften the material.
 D, A cold plugger is then used
to apply pressure to the
softened gutta-percha.

29.  Thermomechanical compaction This involves a
reverse turning (e.g. McSpadden compactor or GP
condenser) instrument which, like a reverse
Hedstroem file, softens the GP, forcing it ahead of,
and lateral to the compactor shaft. This is a very
effective technique, particularly if used in
conjunction with lateral condensation in the apical
region, but requires much practice to perfect.
 Thermoplasticized injectable GP (e.g. Obtura, Ultrafil)
These commercial machines extrude heated GP
(70-160°C) into the canal. It is difficult to control the
apical extent of the root filling, and some
contraction of the GP occurs on cooling. Useful for
irregular canal defects, e.g. following internal root
resorption.

31.  Coated carriers (e.g. Thermafil) These are
cores of metal or plastic coated with GP. They
are heated in an oven and then simply
pushed into the root canal to the correct
length. The core is then severed with a bur. A
dense filling results, but again apical control is
poor and extrusions common. They are
expensive and difficult to remove.
 Once the filling is in place the tooth will need
to be permanently restored, provided the
follow-up radiograph is satisfactory. Fillings
that appear inadequate radiographically
may be reviewed regularly, or replaced,
depending upon the clinical circumstances.

32. THE CORONAL SEAL
 Regardless of the technique used to obturate the canals,
coronal microleakage can occur through seemingly well-
obturated canals within a short time, potentially causing
infection of the periapical area. A method to protect
the canals in case of failure of the coronal restoration is to cover
the floor of the pulp chamber with a lining of glass ionomer
cement after the excess gutta-percha and sealer have been
cleaned from the canal. Glass ionomers have the intrinsic
ability to bond to the dentin, so they do not require a
pretreatment step. The resin-modified glass ionomer cement is
simply flowed approximately 1 mm thick over the floor of the
pulp chamber and polymerized with a curing light for 30
seconds. Investigators found that this procedure resulted in
none of the experimental canals showing leakage