Upload
kowmudimaddineni
View
171
Download
20
Tags:
Embed Size (px)
Citation preview
NARAYANA DENTAL COLLEGE AND HOSPITALDEPARTMENT OF CONSERVATIVE DENTISTRY
AND ENDODONTICS
Seminar On
Root canal sealers
Presented by : -
Dr.T.Lenin Babu
CONTENTS
INTRODUCTION
REQUIREMENTS OF ROOT CANAL SEALER
SELECTION OF ROOT CANAL SEALER
CLASSIFICATION
Eugenol Based Root Canal Sealer
Kerr’s Sealer (Rickett’s Formula)
Grossman’s Sealer
Wach’s paste Sealer
Tubliseal
Non-eugenol Root Canal Sealer
Chloropercha
Nogenol
Calcium Hydroxide
Calcibiotic root canal sealer
Seal Apex
Life
Apexit
Vitapex
Powders and Resins
Diaket
AH-26
AH-plus
Endofill
Glass Ionomer (Ketac-Endo)
Formaldehyde containing root canal sealer
Experimental root canal sealer
EFFICACY OF ROOT CANAL SEALER
TISSUE TOLERANCE OF ROOT CANAL SEALER
STUDIES RELATED TO ROOT CANAL SEALER
1
INTRODUCTION
The sealer plays an important role in the obturation of root
canal. The Sealer fills all the space the gutta percha is unable to fill
because of gutta-percha’s physical limitations. The sealer acts as a
binding agent, to the dentin and to the core material, which usually
is gutta percha. The sealers are usually a mixture that hardens by
chemical reaction, such reaction normally includes the release of
toxic material, making the sealer less biocompatible.
Several sealer and cements, such as AH-26, AH-Plus, Ketac-
Endo and Diaket may be used as the sole filling material because
they have sufficient volume stability to maintain a seal. Under such
preventing excess is often difficult because the sealer is applied
with a lentulo spiral.
There are a variety of sealers from among which to choose
and the clinician must be careful to evaluate all characteristics of a
sealer before selecting.
Sealer helps to fill in irregularities and minor discrepancies
between the filling and canal walls, accessory canals and multiple
foramina. Sealer discloses the presence of ancillary canals,
resorptive areas, root fractures, shape of the apical foramen and
other structures due to its radio-opacity. A sealer is a good lubricant
and helps in the seating of primary cone into the canal. It is a good
germicidal or antibacterial.
2
REQUIREMENTS FOR AN IDEAL ROOT CANAL SEALER:
It should be tacky when mixed to provide good adhesion
between it and the canal wall when set.
It should make a hermetic seal.
Sealers should have ample setting time, giving the clinician
sufficient time to make necessary adjustments to the filling
material.
The particles of powder should be very fine so they can mix
easily with the liquid.
It should not shrink upon setting
All the Sealers shrink slightly upon setting and gutta percha
also shrinks when returning from a warmed of plasticized
state.
It was found that zinc oxide eugenol sealers begin shrinking
within hours after mixing, but that AH-26 and Endo-fill first
expanded and showed no shrinkage for 30 days. The least
dimensional change at any time was observed for Endo-fill.
Significant dimensional change and continued volume loss can
occur in some endodontic sealers.
Sealers should not stain tooth structure.
The admonition that sealers and filling materials “should not
stain tooth structure”, Grossman’s requirement is evidently
being violated by a number of sealers.
Vander Burgt from Holland and her associates reported,
“Grossman’s cement, zinc-oxide eugenol, Endomethasone,
and N2 induced a moderate orange red stain to the crowns of
upper premolar teeth.
3
She further found that “Diaket and Tubliseal caused a mild
pink discoloration whereas AH-26 gave a distinct color shift
towards gray.
On the other hand ‘Rieblers paste caused a severe dark red
stain. Diaket caused the least discoloration.
As far as the staining ability of other materials is concerned,
Vander Burgt found that Cavit produced “a light to moderate
yellowish /green stain that gutta percha caused a milk pinkish
tooth discoloration,” that AH-26 Silver free and Duo Percha
induced a distinct color shift towards gray” and that crowns
filled with IRM and Dycal became somewhat darker.
No discolorations were recorded for teeth filled with Durelon,
Fuji glass ionomer, Fletchers cement, or zinc phosphate
cement.
Sealers that contain silver as radio opacifier, such as Kerr’s
Root Canal sealers (Rickett’s Formula) or the original AH-26
are notorious as tooth strainers.
It should be bacteriostatic, or at least not encourage
bacterial growth.
Grossman tested 11 root canal cements and concluded that
they all exerted antimicrobial activity to a varying degree,”
those containing para-formaldehyde to a greater degree
initially. With time however, this latter activity diminished so
that after 7 to 10 days the formaldehyde cements were no
more bactericidal than other cements.
4
More recently a British group studying the antibacterial
activity of four restorative materials reached much the same
conclusion regarding zinc oxide eugenol and glass ionomer
cement.
Another study founded that 10 sealers inhibited growth of
streptococcus sanguis and streptococcus mutans.
A Temple university study found that Grossman’s sealer had
the greatest overall antibacterial activity, but that AH-26 was
the most active against bacteroides endodontalis, an
anaerobe.
Sealers should be insoluble in tissue fluids.
Smith and McComb found a wide variance in sealer solubility
after 7 days in distilled water, ranging from 4% for Kerr’s pulp
canal sealer to much less than 1% for Diaket.
Peters found after two years that virtually all the sealer was
dissolved out of test teeth filled by lateral or vertical
compaction. Therefore most sealers are soluble to some
extent.
It should set slowly.
It should be tissue tolerant that is non-irritating to
periradicular tissue.
Para formaldehyde containing sealers appear to be the most
toxic and irritation to tissue. A case in point is reported from
Israel necrosis of the soft tissue and sequestration of crestal
alveolar bone from the leakage of para formaldehyde paste
from a gingival level perforation.
5
It should be soluble in a common solvent if it is necessary to
remove the root canal filling.
It should not provoke an immune response in periradicular
tissue.
It should be neither mutagenic nor carcinogenic.
SELECTION OF SEALER
For use with gutta-percha, appropriate sealers should be
selected to aid in the filling of the canal. The operator should
determine the amount of lubrication needed, the length of working
time estimated, and the filling material to be used before deciding
which sealer or sealers would best perform the necessary function.
In lateral condensation methods use of sealer should be
minimal, since the compressible filling material will be able to fill
most irregularities. All the sealers have resorbable properties when
expressed into periapical tissue, although rarely has resorption of
the sealer within the canal been noted. Still, it is preferable to seal a
canal with the packed solid-core material, which is largely un-
resorbable, as compared to the sealer.
A good sealer should be biologically compatible and well
tolerated by the periapical tissues. All sealers are highly toxic when
freshly prepared; however their toxicity is greatly reduced after
setting takes place. A few days after cementation practically all root
canal sealers produce varying degrees of periapical inflammation
(usually temporary); this usually does not appear to prevent tissue
healing and repair.
6
Although most cement sealers were highly irritating to
periapical tissues, the most severe alveolar and bone destruction
was caused by poor debridement and poor filling of the root canal
system. Minimal tissue reaction was found when the canal was not
over-filled. Over instrumentation and overfilling caused immediate
periapical inflammation, which tended to persist and to cause
epithelial proliferation and cyst formation. In teeth filled short of the
foramen, the reaction was temporary and complete repair
eventually took place.
ROOT CANAL SEALER CEMENTS
In most clinical situation, core materials are used with root
canal sealer cement. The bond between the sealer and the core
material is non-adhesive. The core and sealer root canal filling
techniques involve 2 inter phases – one between the core and the
sealer and the other between the sealer and dentin.
Root canal sealer cements are divided into:
1) Eugenol based cement
2) Non-Eugenol based cement
EUGENOL BASED SEALER CEMENTS
Many root canal cements are based on zinc oxide eugenol,
which is known to provide a good seal.
Many endodontic sealers are simply zinc oxide eugenol
cements that have been modified for endodontic use.
7
The mixing vehicle for these materials is mostly eugenol. The
powder contains zinc oxide that is finely sifted to enhance the flow
of the cement.
Setting time is adjusted to allow for adequate working time.
One millimeter of zinc-oxide eugenol cement has a radio-
opacity corresponding to 4-5 mm of aluminum, which is slightly
lower than gutta-percha. These cements easily lend themselves to
the addition of chemicals and para-formaldehyde is often added for
antimicrobial and mummifying effects, germicides for antiseptic
action, rosin or Canada balsam for greater dentin adhesion, and
corticosteroids for suppression of inflammatory reaction.
Zinc oxide eugenol sets because of the combination of
chemical and physical reaction, yielding a hardened mass of zinc
oxide embedded in a matrix of a long sheath like crystals of zinc
eugenolate [C10 H11 O2]2 Zn. Excess eugenol is invariably present and
is absorbed by both zinc oxide and eugenolate. The presence of
water, particle size of the zinc oxide, the pH and the additives are all
important factors in the setting reaction.
Hardening of the mixture is due to zinc eugenolate formation;
unreacted eugenol remains trapped and tends to week and the
mass.
All zinc oxide eugenol cements have an extended time but set
faster in the tooth than the glass slab, due to increased body
temperature and humidity. If the eugenol used in Grossman’s
cement becomes oxidized and brown, the cement sets too rapidly
for ease of handling. If two much sodium borate has been added,
the setting time is overextended.
8
The original zinc oxide-eugenol cement, developed by
Rickert’s, was the standard for the profession for years. It admirably
met the requirement set by Grossman for severe staining. The
silver, added for radiopacity, causes discoloration of the teeth, thus
creating an undesirable public image for endodontics. Removing all
cement from the crowns of teeth would prevent these unfortunate
incidents.
In 1958, Grossman recommended non-staining zinc oxide
eugenol cement as a substitute for Rickert’s formula. It has become
the standard by which other cements are measured because it
reasonably meets most of Grossman’s requirements for cement.
The most common zinc oxide eugenol cements are Rickert’s
sealer, Grossman’s sealer, Wach’s paste, Tubliseal.
KERR’S SEALER (Rickert’s formula)
Rickert’s formula was developed in 1931 as an alternative to
the chloropercha, eupercha sealers of the period. Gutta-percha
based sealers mentioned above lacked dimensional stability after
setting. Rickert’s formula was developed to eliminate this problem.
Powder contains
Zinc Oxide 41.2 parts
Precipitated silver 30.0 parts
White resin 16.0 parts
Thymol iodide 12.8 parts
Liquid
Oil of clove 78 parts
Canada balsam 22 parts
9
Setting time
Half an hour
Advantages:
The powder in Kerr’s sealer acts as a good germicidal.
It has excellent lubricating and adhesive qualities.
It has the ability to increases the body of Kerr’s sealer.
Disadvantages:
Staining due to presence of silver. Any Surplus of the
cement in the crown of an anterior tooth should be removed
immediately after root fillings.
Prolonged spatulation during mixing is needed to break up
particles and reduce viscosity due to large particle size.
INDICATIONS
Warm vertical condensation of gutta percha when lateral
canals are anticipated. Since the silver present in the
powder is radio opaque, the lateral canal with the sealer is
the silver rather than the mass of sealer mix or any
softened gutta percha.
Weine has observed that lateral canals demonstrated with
Kerr’s sealer remained observable radiographically for
longer than do such canals with Wach’s paste.
Obturation with silver points
10
CONTRAINDICATIONS
Sealer not advised in anterior. If used, the pulp chamber
should be washed out with xylol after condensation of gutta percha
to ensure removal of sealer.
MANIPULATION
Supplied as pellets or bulk (powder) and the liquid in a
dropper bottle. One drop of liquid to one pellet of powder (1:1 ratio)
is taken and mixed with a heavy spatulation until relative
homogeneity is obtained. Because of the precipitated silver, some
granular appearance remains even when the spatula is completed.
GROSSMAN’S SEALER
Due to the relatively rapid setting time of Rickert’s sealer,
Grossman’s formula appeared an 1936, with the purpose of
developing a sealer that afforded more working time.
PROCOSOL RADIOPAQUE SILVER CEMENT
Composition
Powder contains
Zinc oxide USP - 45.0%
Silver (precipitated) - 17.0%
Hydrogenated resin - 36.0%
Magnesium oxide - 2.0%
Liquid contains
Eugenol - 90.0%
Canada Balsam - 10.0%
11
However, the use of precipitated silver for radiopacity was
criticized. So a revised version of Grossman’s formula was marketed
for many years as
PROCOSOL NON STAINING ROOT CANAL CEMENT (Grossman
1958)
Powder contains
Zinc oxide (reagent) - 40.0%
Stabelite resin - 27.0%
Bismuth sub-carbonate - 15.0%
Barium sulfate - 15.0%
Liquid contains
Eugenol - 80.0%
Sweet oil of Almond - 20.0%
Grossman’s formula was again revised by the addition of
sodium borate to the powder component and by the elimination of
all in Ingredient except eugenol from the liquid component.
GROSSMAN’S SEALER (Grossman, 1974)
Power contains
Zinc Oxide - 42%
Stabelite resin - 27%
Bismuth sub carbonate - 15%
Barium sulfate - 15%
Sodium borate (anhydrous) - 1%
Liquid contains
Engenol - 100%
12
Setting time:
2hrs at 37 C
In the root canal, setting time 10-30 minutes due to the
presence of moisture in the dents.
Factors influencing the setting time:
1) Quality of zinc oxide
2) pH of resin
3) Technique of mixing to its proper consistency.
4) Amount of humidity
5) Temperature and dryness of mixing slab and spatula
MANIPULATION
Sterile glass slab and spatula are taken. Not more than 3
drops of liquid should be used at a time, because excessive time
and effort would be required to spatulate a large amount. Small
increments of powder is added to liquid and mixed to a creamy
consistency.
Spatulation time – 1 minute/drop
The cement will not harden for 6-8 hrs if left on the glass slab.
The mixed batch of cement can therefore be used for several
hours. If it thickens, spatulation will break up any crystals formed
and will restore the mix to proper consistency. In the canal, because
of moisture in the dentinal tubules, it begins to set in half an hour.
TEST FOR PROPER CONSISTENCY
DROP TEST
13
The mass of cement is gathered onto the spatula, held
edgewise, the cement should not drop off the spatula’s edge for 10-
12 sec. A root canal instrument can be used for this test. After a
no:25 file is rotated in the gathered mass of cement, it is withdrawn
and held in a vertical position. A correctly mixed cement should
remain with very little movement in the blade of the instrument (5-
10 sec). If a tear drop forms, the mix is too thin and more powder
should be added.
SPRING TEST
After touching the mass of cement with its flat surface, the
spatula is raised slowly from the glass slab. The cement should
string out atleast one inch without breaking.
ADVANTAGES
The use of Grossman’s sealer reduced leakage nearly 50%
when they compared lateral condensation and compaction methods
with or without the use of sealer. Plasticity and slow setting time
due to the presence of sodium anhydrate. Grossman’s sealer has a
good sealing potential. There is small volumetric change upon
setting. The sealer has the ability to be absorbed in case of apical
extrusion of the sealer during canal obturation.
Grossman’s sealer is soluble in chloroform, carbon
tetrachloride, xylol and ether. The sealer is easily removed from the
glass slab and spatula with alcohol or solvent.
It present a minimal level of irritation and high level of
antimicrobial activity.
14
DISADVANTAGES
Zinc eugenolate can be decomposed by water through a
continuous loss of eugenol making zinc oxide eugenol a weak,
unstable material.
Toxicity studies have shown that a small amount when
extruded may first cause an inflammatory reaction, nevertheless it
is well tolerated by the periapical tissues. When a periapical lesion is
present, a transient toxic effect of the medicament is permissible
because healing continuous longer than toxicity. Often the excess
is removed from the periapical tissues by phagocytosis.
WACH’S PASTE
Wach’s paste, a variant of zinc oxide eugenol formula was
originally formulated in 1925, but did not receive widespread
adoption until its publication and reintroduction in 1955. It first
became popular in Chicago Beachwood creosate is added as a
medical component. It is highly desirable sealer for use with gutta-
percha.
COMPOSITION
It is dispensable as powder and liquid.
The powder contains
Zinc Oxide - 61.0 – 61.4%
Calcium phosphate tribasic - 12.0 – 12.2%
Bismuth sub-nitrate - 21.0 – 21.4%
Bismuth sub-iodide - 1.9 – 2%
Magnesium oxide - 3.1 – 4.0%
15
Liquid contains:
Canada balsam - 74 .0 – 76.9%
Oil of cloves - 22.0 – 23.1%
Eucalyptol - 2.0%
Beechwood creosate - 2.0%
INDICATIONS
Wach’s paste is indicated in all lateral condensation methods
especially when chance of overfilling is present
CONTRAINDICATIONS
Wach’s paste is contraindicated when heavy lubrication is
needed as with short master cone.
ADVANTAGES
Wach’s paste has a smooth consistency without a heavy body,
it is useful in small curved canals of minimal calibre as this light
body does not deflect the small gutta percha used to fill these
canals.
The sealer is very sticky due to the presence of Canada
balsam. Hence the paste will remain on the reamer during
placement until it is spun off in the apical portion of the preparation
and does not completely rub off on the canal walls during insertion.
Hence sealer loaded on the tip stays in position.
It is a good germicidal Relatively low tissue irritant .
The sealer is biocompatible to the periapical tissue. It has a
good setting time.
DISADVANTAGES
16
Wach’s paste has medium working time and has less
lubricating quality.
MANIPULATION
The sealer is supplied as powder and liquid separately. One
drop of liquid is used with an appropriate amount of powder. No
measuring device is included with the powder, so sample batches
should be mixed to enable the mixer to tell what amount gives
desirable results.
Mixed to a creamy smooth consistency and should string out
atleast one inch when spatula is raised from the glass slab.
Larger canals generally require a slightly thicker mix and also
if there is any chance of overfilling.
TUBLISEAL
This sealer was introduced by Kerr manufacturing company in
1961, as an alternative to Rickert’s formula. Tubliseal is a two paste
system as opposed to the powder liquid system of other zinc oxide
types.
Base paste contains
Zinc Oxide - 57.4 - 59.0%
Oleo resins - 18.5 - 21.25%
Bismuth Inoxide - 7.5%
Thymol Iodine - 3.5% - 5%
Oils and Waxes - 10.0 - 10.1%
17
The catalyst contains
Eugenol
Polymerised resin
Annidalin
Some base paste also contains barium sulfate as radio
opacifier, mineral oil cornstarch and lecithin.
The catalyst paste may contain polypale resin, eugenol and
thymol iodide.
MANIPULATION
Tubliseal sealer is contained in two collapsible tubes
containing a base and accelerator which when mixed together to
about half an inch (which is sufficient in most cases) forms a creamy
mix.
ADVANTAGES
The sealer does not stain the tooth structures. It is extremely
lubricating has a high rate of flow giving a thinner film.
It allows maximal condensation in packing.
Since the sealer is white in colour it provides a good contrast
to the flapped tissue during surgical procedures.
DISADVANTAGES
Since the Tubliseal sealer has a very low viscosity it makes
extrusion through the apical foramen more likely and recommends a
18
short spatulation time and leaving the cement for a short period
before use.
The Tubliseal sealer is very irritating to the periapical tissue,
causing considerable periapical sensitivity when used in teeth where
the pulp was vital and the periapical tissue normal before
treatment. But this can also be turned into an advantage, when it is
used in teeth where a large radiolucency is present, since the sealer
may act as a stimulant to the periapical area.
The working time of the sealer is less than 30 minutes and
even shorter in the presence of moisture.
In multi-rooted teeth for which a longer working time is
necessary plans should be made to use more than one mix.
Additionally great care should be exercised to ensure that all
canals are as dry as possible prior to sealer insertion and extra
wiping with paper points provide additional insurance against
moisture.
INDICATIONS
Tubliseal sealer is used in instance when shorter setting time
is required (eg) where a root filling is to be followed immediately by
apicectomy.
This sealer is used in cases where master cone becomes
difficult to reach last millimeter of the preparation, due to its
lubricating property.
CONTRAINDICATIONS
Tubliseal sealer is contraindicated if overfill is probable with
normal periapical issue.
19
This sealer should not be used in multi-rooted tooth where
longer working time is necessary.
NON-EUGENOL SEALER CEMENTS
The Two sealer cements that do not contain eugenol are
1) Chlorepercha
2) Nogenol
CHLOROPERCHA
This is a type of sealer that has been in use for many years. It
was introduced in 1939 in Norway. Chloropercha (Myco) is a direct
descendent, relatively unaltered, of material in use for nearly a
century.
Chlorepercha is obtained by mixing gutta percha with
chloroform. This will allow a gutta percha root filling to fit better in
the canal. It is important to recognize however, that chlorepercha
has no adhesive property.
Various forms of chloropercha have a radio-density (1 mm
thick) corresponding to only 1.2 to 2.7 mm of aluminum, which is
much less than 1mm of gutta percha at 6.4mm of aluminium. These
sealers appear vague on radiograph.
One variant of chloropercha technique is to use a mixture of
5% to 8% of resins in chloroform. A rosin chloroform wash of the
root canal leaves a very adhesive residue. This residue in
combination with dipping of the gutta-percha cone in resin
chloroform provides the sealer in this technique. This is a difficult
technique because there is no sealer to fill areas where there are
voids between the gutta percha cones.
20
Chloroform technique for obturation requires that the operator
has good basic skills with various obturation technique, because the
technique is very sensitive to proper manipulation.
When the chloroform technique is correctly used the
shrinkage is not greater than when the gutta percha is plasticized
by heat.
The use of chloroform has been sharply curtailed in recent
years because of its projected toxicity. Thus when used for softening
of gutta percha during revision of old root fillings, the chloroform
should be dispensed through a syringe and hypodermic needle. For
other uses the exposure time, amount used and chloroform surface
exposed should all be kept to a minimum.
The general problem with most chloropercha products is their
shrinkage during the evaporation or disappearance of the
chloroform. Some brands such as chloropercha N- contain filler
particles (eg zinc oxide) to reduce the shrinkage. Zinc oxide also
increases radio opacity.
COMPOSITION
KLOROPERCHA N – (NYGARD – OSTBY 1939)
Powder contains
Canada Balsam - 19.6 %
Rosin - 11.8 %
Gutta percha - 19.6 %
Zinc oxide - 49.0 %
Liquid contains
Chloroform - 100 %
21
DISADVANTAGES OF CHLOROPERCHA
Chloro percha is carcinogenic
Chloro percha products undergo shrinkage of during the
evaporation of chloroform.
It acts as an irritant to the periapical tissues.
Chloro percha has been shown to be associated with a
greater degree of leakage than other materials.
INDICATIONS OF CHLOROPERCHA
Chloro percha produces excellent result in the filling of
unusual curvatures or where the apical part of root canal is
inaccessible and also in cases of perforation and ledge formation.
It is used in case of canals, which divide in the apical part of
the root into two major branches, these can be forced beyond the
level of division into the unfilled canal if filling of one severely
restricts the access to the other.
CHLOROPERCHA (MYCO)
Gutta percha - 9 %
Chloroform - 91.0 %
NOGENOL
This was developed to overcome the irritating quality of
eugenol. The product is an outgrowth of a non-eugenol periodontal
pack.
COMPOSITION
22
Base
Zinc oxide with barium sulfate as a raiopacifer along with
vegetable oil.
Catalyst
The setting of the sealer is accelerated by hydrogenated rosin,
methyl abeitate, lauric acid, chlorothymol and salicylic acid
ADVANTAGES
Nogenol is a less irritating sealer
The sealer expands on setting and may improve its sealing
efficacy with time.
CALCIUM HYDROXIDE SEALERS
Calcium hydroxide has can advantage over zinc oxide eugenol
because of its ability to preserve the vitality of pulp stump. Several
calcium hydroxide based sealers have been brought to the market.
Examples of such sealers are sealapex (Kerr) Calciobiotic Root canal
Sealer (CRCS) and Apexit (Vivadent).
These sealers are promoted as having therapeutic effect
because of the calcium hydroxide content. However no such
convincing results from scientific trials have been shown. To be
therapeutically effective calcium hydroxide must be dissociated into
Ca++ and OH. Therefore to be effective, an endodontic sealer
based on calcium hydroxide must dissolve and the solid
consequently lose content, Thus one major concern is that the
calcium hydroxide content may dissolve, leaving obturation voids.
This would ruin the function of the sealer, because it would
disintegrate in the tissue. These sealers also have poor cohesive
strength. There is no objective Proof that the calcium hydroxide
23
sealer provides only advantage for root canal obturations or has any
of the desirable biologic effects of calcium hydroxide paste.
In a study of diffusion of hydroxyl ions into surrounding dentin
after root filling with seal apex and Apexit no traces were found in
teeth with Apexit Some hydroxyl ions could be detected in the
dentin close to the root filling with sealapex.
In a similar study of calcium and hydroxyl ions release from
Sealapex and CRCS, negligible release was noted from CRCS.
Sealapex released more ions but disintegrated in the process.
Studies in vivo of sealapex and CRCS have demonstrated that
Sealapex and CRCS easily disintegrate in the tissue. They both
cause chronic inflammations considering the alternatives, calcium
containing sealers are not a practical choice of materials.
CALCIBIOTIC ROOT CANAL SEALERS (CRCS)
It is essentially a zinc oxide eugenol/eucalyptol sealer to which
calcium hydroxide has been added for its so-called osteogenic
effect.
It represents the first of the calcium hydroxide based sealers.
Contains 14% by weight of calcium hydroxide. It takes 3 days to set
fully either in dry or humid environment This means that it is quiet
stable and improves its sealant qualities but brings into question its
ability to actually stimulate cementum or bone formation. It calcium
hydroxide is not released from the cement, it cannot exert an
osteogenic effect and thus its intended role is negated.
24
CRCS is supplied as powder and liquid component
Powder contains
Calcium Hydroxide
Zinc Oxide
Bismuth dioxide
Balsom Sulfate
Liquid contains
Eugenol
Eucalyptol
SEAL APEX
It is also a calcium hydroxide containing sealer delivered as
paste to paste in collapsible tubes
COMPOSITION
Base Contains
Zinc Oxide 6.5 %
Calcium hydroxide 25.0 %
Butyl benzene
Sulfonamide
Zinc stearate
Catalyst contains
Barium sulfate 18.6 %
Titanium dioxide 51 %
Proprietary resin
25
Isobutyl salicylate
Aerocil R 972.
In 100% humidity, seal apex takes 3 weeks to set. In a dry
atmosphere it never sets. It expands on setting. A negligible amount
of dissolution occurred when extruded from the periapex. The
dissolution was probably due to water sorption Thus eventually
breaking the apical seal. The fluid sorption characteristics may be
due to its porosity that allows marked ingress of water. It is
biologically active sealer intended to promote periapical healing.
Holland reported the ability of sealapex, to induce apical
closure by cementum in histological studies.
LIFE
It is a calcium hydroxide liner and pulp capping material
similar in formulation to Sealapex, has also been suggested as a
sealer.
APEXIT
From Liechtenstein comes an experimental calcium hydroxide
sealer called Apexit. Australians found that it sealed better than
Imbiseal.
COMPOSITION
Base
Calcium hydroxide 31.9 %
Zinc oxide 5.5 %
26
Calcium Oxide 5.6 %
Silicon dioxide 8.1 %
Zinc stearate 2.3 %
Hydrogenised colophony 31.5 %
Tricalcium phosphate 4.1 %
Poly dimethyl siloxane 2.5 %
ACTIVATOR
Trimethyl hexanedioldisalicylate 25.0 %
Bismuth carbonate basic 18.2 %
Bismuth oxide 18.2 %
Silicon dioxide 15.0 %
1,3 Butanediol di Salicylates 11.4 %
Hydrogenised colophony 5.4 %
Tricalcium phosphate 5.0 %
Zinc stearate 1.4 %
VITAPEX
This sealer is introduced by Japanese. Its components appear
to be iodoform and silicone oil. One week following deposits in rats,
Vitapex containing calcium ions labeled calcium hydroxide, was
found throughout the skeletal system. This attests to the dissolution
and uptake of this material. No evidence is given about the sealing
or osteogenic capabilities of Vitapex.
POWDERS AND RESINS
Other sealers that enjoy favour worldwide are based more on
resin chemistry than essential oil catalysts. Now sealers are mostly
polymers. The more common brands are Diaket, Endofill, AH-26, AH-
Plus.
27
DIAKET
Diaket, an early one, first reported in 1951, is a resin
reinforced chelate formed between zinc oxide and a small amount
of plastic dissolved in the liquid, di-ketone. A very tacky material,
it contracts slightly while setting, which is subsequently negated by
uptake of water. Its setting efficacy is good.
Powder:
Zinc oxide 98.0%
Bismuth phosphate 2.0%
Liquid:
2,2-Dihydroxy 5.5’
dichlorodiphenylmethane
Proplonylacetaphenone
Triethanolamine
Caproic acid
Copolymer of vinyl acetate,
Vinyl chloride, and vinyl
Isobutyl ether
AH-26 ROOT CANAL SEALER
AH-26 is an epoxy resin that initially was developed to serve
as a single filler material. Because of its good handling
characteristics it has been exclusively used as a sealer. It is glue,
and its base is bisphenol A-epoxy. The catalyst is hexamethylene
tetra mine. It also contains 60% bismuth oxide for radiographic
contrast. One millimeter of AH-26 has a radiopacity corresponding
to 6.66 mm of aluminum, thus it is very similar to gutta percha.
It has a good flow, seals well to dentin walls and allows for
sufficient working time. As AH-26 sets, traces of formaldehyde are
28
temporarily released which initially makes it antibacterial AH-26 is
temporarily toxic while the setting takes place, but the toxicity is
one of the lowest of all endodontic sealers after 24 hrs. This is due
to the release of very small amount of formaldehyde, as a result of
chemical setting process.
This amount of brief release formaldehyde however is
thousands of times lower than the long-term release from
conventional formaldehyde containing sealers, such as N.
AH-26 is not sensitive to moisture, and will even set under
water. It will not set, however if hydrogen peroxide is present. It sets
slowly in 24 to 36 hours. The Swiss manufacturer of AH-26
recommend that mixed AH-26, be warmed on a glass slab over an
alcohol flame, which renders it less viscous. AH-26 is also sold world
wide as thermaseal.
COMPOSITION
Powder
Silver Powder 10%
Bismuth oxide 60%
Hexamethylenetatramine 25%
Titanium oxide 5%
Liquid
Bisphenoldiglycidyl ether 100%
AH-PLUS ROOT CANAL SEALER
A new formulation of AH-26 is now available called AH plus.
This is a paste and paste mixing system that assures a better
29
mixture. It has an increasing radiopacity, shorter setting time, lower
stability and a better flow compared with AH-26.
The material sets quickly in the root canal at body
temperature but remains soft longer at room temperature. It is
highly toxic in vitro and causes extensive tissue necrosis. This
irritation is long lasting
COMPOSITION
Epoxy paste (A)
Epoxy resin
Calcium tungstate
Zirconium oxide
Aerosil
Iron oxide
Amine paste (B)
Adamantane amine
N,N – Di benzyl –5- oxanonanediamine
Calcium tungstate
Zirconium oxide
Aerosil
Silicon oil
Two additional root canal sealers have been marketed: one a
silicone rubber like material called Lee Endofill and the other glass-
ionomer cement called ketac-Endo.
ENDOFILL
Endofill, when set has a rubbery consistency. Initially the
manufacturer recommended that it be injected into the canal as the
30
sole sealer. Overzealous dentists, not following the instructions,
ejected the material out through the apex and court cases ensued.
This is remarkable in that Endofill is virtually nontoxic the least
irritating sealer on the market. When used properly as a sealer with
gutta percha it is quite similar to other sealers.
COMPOSITION
The base of Endo-Fill is heavily loaded with bismuth sub
nitrate as radio opacifier. Hence it is densely radiopaque. The active
ingredients are hydroxyl terminated dimethyl poly-siloxane,
undecylenic acid, benzyl alcohol and hydrophobic amorphous silica
(10 to 30 milli microns particle size).
The catalysts are ethyl ortho silicate, poly dimethyl siloxane
and catalyst intermediate.
ADVANTAGES
It is easy to prepare,
It has a adjustable working time, low viscosity and rubbery
in consistency. It is easy to remove as Gutta Percha.
DISADVANTAGES
The endofill cannot be used in the presence of hydrogen
peroxide and the canal must be absolutely dry.
It also shrinks upon setting, but has an affinity for flowing into
tubuli.
31
GLASS IONOMER CEMENT (Ketac-Endo)
Recently glass ionomer cements have been introduced as
endodontic sealers (Ketac-Endo). Glass ionomer cements are known
to cause less tissue irritation. It has a low toxicity in vitro. Little
biological data are available relative to its use as an endodontic
sealer, so safety and efficacy of glass ionomer cements have not
been established. There are questions about the quality of the seal
with Ketac Endo because of observed dentin and sealer adhesive
failures.
Saito suggested using Fiji Type I luting cement to fill the entire
canal.
Pittford in England recommended endodontic glassionomer as
early as 1976. However he found that setting time was too rapid.
Stewart was combining Ketac-Bond and Ketac-Fill before these glass
ionomers were specifically formulated for endodontics.
At Temple University, eight different formulation of Ketac
cement was researched for ease of manipulation, radiopacity,
adoption of dentin sealer interphase and flow. They chose the sealer
with best physical properties. A method of triturating and injecting
the cement into the canal was also developed.
In a follow-up Study, Temple group evaluated efficacy of
Ketac- Endo as a sealer, and at the end of 6 months reported that
success and failure rates were comparable.
Their greatest concern was the problem of removal in the
event of retreatment since there is no known solvent for glass
ionomers.
32
A Toronto/Israel group reported that Ketac- Endo sealer can be
effectively removed by hand instruments and chloroform solvent
followed by one minute with an ultrasonic No. 25 file.
FORMALDEHYDE CONTAINING SEALERS
A large group of endodontic sealers and cements have
substantial additives of Para formaldehyde. Some of the more
common are Endomethasone, Kri paste, Reblers paste and N2.
Although not much different in content as far as toxicity is
concerned, N2 has been the material most commonly focused on
when discussing the phenomenon. This material is also known as
RC-2B or the “Sargenti technique”. Throughout the years it has
been heavily commercialized. It is difficult to understand the anyone
can subscribe to the idea that treating the apical pulp wound with a
strong tissue coagulating toxic material may enhance healing.
N2 is basically a zinc oxide eugenol sealer. Its composition has
been varied extensively through out the years. The significant
content of lead oxide and smaller amount of organic mercury, that
formerly were major toxic components of N2 are often missing in
recent formulas. However this material still contains large amount of
formaldehyde. It seals well in combination with a core. Because it
contains 6% to 8% Para formaldehyde, it loses substantial volume
when exposed to fluid. It also absorbs more than 2% of fluid during
the 1st week.
N2 is very toxic in experiments in vitro and in animal
experiments. The tissue reaction normally observed is a coagulation
necrosis within a very short time, reaching its maximum in less than
3 days. The coagulated tissue is altered to such an extent that it
cannot undergo any repair for months because it is formaldehyde
impregnated.
33
With time the formaldehyde is washed out of the necrotic
tissue, allowing either bacteria to be established in the necrosis or,
if blood supply is adequate, repair to take place. In clinical
applications this untoward tissue reactions can be seen as localized
inflammatory reactions in the periapical tissues.
EXPERIMENTAL SEALERS
1) BISGMA UNFILLED RESIN
At Tufts University, experiments are underway to employ a
BISGMA unfilled resin as a sealer. At present, precipitated silver is
being used as a radiopacifier. However tantalum is planned for the
future. The material might be marketed as Seal Dent – Endo or
Micro seal.
An unpublished leakage study should show over 75% of the
specimen with zero leakage. The new material was found to be
biocompatible but is impossible to remove.
34
2) PIT AND FISSURE SEALANTS
Low viscosity resins such as pit and fissure sealants have
been tried as sealers but would not seem suitable as root canal
filling materials.
Close adaptation depends upon smear layer removal, which
was difficult to achieve in the apical third of canal.
3) ISOPROPYL CYANOACRYLATE
At Loma Linda University, isopropyl cyanoacrylate was found
to be more adequate in sealing canals than other commercial
sealers. However further research was discontinued due to lack of
acceptance by U.S. FDA.
4) BARRIER:
A polyamide varnish – Barrier has also been tried as a sealer
but was not found as effective as zinc oxide eugenol.
5) DENTIN BONDING AGENTS:
At the university of Minnesota, the efficacy of 4 different
dentin bonding agents used as root canal sealers was tested.
No leakage was measurable in 75% of the canals sealed with
Scotch bond, 70% sealed with Restodont, 50% sealed with Dental
Adhesive and 30% sealed with GLUMA.
One might even visualize rebirth of the silver point combined
with one of the adhesives as Amalgam bond that adheres to dentin
as well as metals.
35
Obstacles faced by bonding agents before they become
endodontic sealers
Preparation of dentin to remove the smear layer is difficult in
the apical third even with NaOcl or citric acid is used with
ultrasonic debridement.
Radiopacity – Radiopaquing metal salts must be added to the
adhesive which will upset the delicate chemical balance that
leads to polymerization.
All bonding agents are very technique sensitive and many do
not polymerize in the presence of moisture of
Hydrogenperoxide.
Placement – The question of a delivery system that will best
ensure a total porosity free placement is a problem.
Removal in the event of failure – These resins polymerize very
hard.
RESINIFYING THERAPY
This was suggested by Chinese has a method of Canal
obturation. They do not carefully debride the canal but rather
remove the pulp or gross necrotic debris with a broach and then
insert a resinfying agent, which is made up of formaldehyde,
aerosol, alcohol, resorcin and NaoH. It sets 5-15 mts in vitro. The
Chinese Claim that the residual pulpal tissues and infected
substances in the canal will become resinified and harmless after
polymerization. They claim a success rate of 84.9% and show rather
healing inspite of the formidable phenolaldehyde antibacterial
formula.
6) CALCIUM PHOSPHATE SEALERS:
36
Two dry powders one acidic and one basic are mixed with
water, and injected into the root canal. It sets as hard as enamel
within five minutes.
Tetra calcium phosphate is the basic constituent and the
acidic component is either dicalcium phosphate di-hydrate or
anhydrous dicalcium phosphate. Water is merely a vehicle for
dissolution of the reactants. Setting time may be extended by
adding glycerin to the mixture. Usually mild phosphoric acid solution
speeds up the dissolution of the reactants. Even aliquots of blood
from a surgical site may be substituted for water.
The final set cement consists of nearly all crystalline material
and porosity is a direct ratio to the amount of solvent used. It is as
radiopaque as bone. It is nearly insoluble in water and is insoluble in
saliva and blood. It is readily soluble in strong acids, which may be
considered in the event it must be removed.
SEALER EFFICACY
Hovland and Dumsha probably summarized it best:
“Although all root canal sealers leak to some extent—there is
probably a critical level of leakage that is unacceptable for healing
and therefore results in endodontic failure;
37
This leakage may occur at the interface of the denture and
sealer, at the interface of the solid core and sealer and through the
sealer itself or by dissolution of the sealer.
Hence in choosing a sealer, factors other than adhesion must
be considered – setting time, case of manipulation, antimicrobial
effect, particle size, radiopacity, proclivity to staining dissolvability,
chemical contaminant (H2O2, NaOcl) cytotoxicity, cementogenesis
and osteogenesis.
RESUME OF ADHESION:
All presently available sealers leak; they are not impermeable.
But some leak more than others mostly through dissolution. The
greater the sealer/peri radicular interface (i.e.) apical perforations
blunderbuss open apices, the faster dissolution takes place.
Zinc Oxide, Ca (OH2) Type sealers:
In a 2-year solubility study, Peters found that zinc oxide
eugenol sealer was completely dissolved away.
One might think that first lining the canal with varnishes such
as Barrier or Copalite might improve the seal, but neither does.
More recent studies relating to zinc oxide base sealers and
others have found essentially the same: zinc oxide eugenol and Ca
(OH2) solubility.
In spite of their deficiencies, zinc oxide eugenol cements and
their variations continue to be most popular root canal sealers
worldwide. But they are just that, sealers and any attempt to
depend on them wholly or in great part, materially reduces long-
38
term success. That is the principal reason why silver points failed
too little solid core and too much cement in an avoid canal.
If the apical orifice can be blocked principally by solid core
material, success is immeasurably improved over long term, if not
for lifetime.
On the other hand in every study in which obturation without
sealers is attempted, the leakage results are enormously greater
sealers and necessary.
PLASTICS AND RESIN TYPE SEALERS
It seems reasonable to assume that plastics, resins and glues
should be more adhesive to dentin and less resorbable than the
mineral oxide cements. But they have not proved dramatically so: In
one study AH-26 was found comparable to zinc oxide eugenol
sealer.
In another study AH-26 and Diaket were found satisfactory as
sealers along with all the zinc oxide eugenol products. Another
study found Diaket less effective than Tubliseal but better than N2.
Lee Endofill was a efficacious as Grossman’s Sealer.
In a very recent Australian study, however AH-26 was found to
have better sealing capabilities than three other cements, (i.e.)
Apexit, Sealapex and Tubliseal.
As far as the new glass ionomer cement Ketac-Endo is
concerned Ray and Seltzer found it superior to Grossman’s Sealer,
but others found it difficult to remove in retreatment.
39
The early leakage reports on the adhesives used
experimentally as root canal sealers are most encouraging. A 1987
report when adhesives were in their infancy, placed Scotch bond
first, with “no leakage measurable in 75% of the canals” and
GILUMA last with 30% showing no leakage.
Adhesives today are in their third and fourth generation far
superior to the initial resins. Also, there are adhesives such as C&B
Metabond or All Bond that actually polymerize best in most
environments.
EXPERIMENTAL CALCIUM PHOSPHATE SEALERS (CPS):
Studies emanating from the ADA Paffenberger center find
calcium phosphate cements very praise worthy, for their sealing
properties, as well as tissue compatibility. In one study they proved
better sealants than a zinc oxide eugenol gutta percha filling.
In another study they found the apatite injectable material
“demonstrated a uniform and tight adaptation to the dentinal
surfaces of the chambers and root canal walls”.
TISSUE TOLERANCE OF ROOT CANAL SEALERS, CEMENTS
AND PASTES.
All the materials used to seal root canals – gutta percha,
silver, the sealers, cements, pastes; plastics irritate periradicular
tissue if followed to escape from root canal. And if placed against a
pulp stump as in partial pulpectomy, they irritate the pulp tissue as
well.
40
At present four approaches are being used to evaluate
scientifically the toxic effects of endodontic materials.
1) Cytotoxic evaluation
2) Subcutaneous implants
3) Intraosseous implants
4) Invivo peri radicular reactions.
CYTOTOXIC EVALUATION
Cytotoxic studies are done by measuring leucocytes migration
in a Boyden Chamber by measuring the effect suspect materials or
their extracts have on fibroblasts in culture, or using radioactively
labeled tissue culture calls or tissue- culture agar overlay or a
fibroblast mono layer on a Millipore filter disk. The results are quiet
similar.
According to the studies, almost all of today’s sealers are toxic
to when first mixed, while they are setting over hours, days or
weeks and some continue to age noxious elements for years. This is
of course caused by dissolution of the cement thus releasing the
irritants. For eg. Eugenol is not only cytotoxic but also neurotoxic.
More recently, it has been reported that, the cyto- toxicity of zinc
oxide eugenol may be based on the possible toxic effect of zinc ions.
In testing the toxicity of gutta percha only the pure raw gutta
percha was nontoxic while the gutta percha with zinc oxide showed
toxicity due to release of zinc ions.
As far as cytotoxicity studies are concerned one would have to
rank the pure zinc oxide eugenol sealer as worst- Grossman’s and
Rickert’s followed by Wach’s and Tubuliseal, Sealapex CRS and
finally Nogenol.
41
The least toxic of the resins, in fact the least toxic of all the
sealers is Lee EndoFill, followed by AH-26, Diaket.
SUBCUTANEOUS IMPLANTS
Subcutaneous implants of root canal sealers, to test their toxic
effects are done either by needle injection under the skin of animals
or by incision and actual insertion of the product, either alone or in
Teflon tubes or cups. Freshly mixed material may be implanted
allowing it to set in situ or completely set material may be inserted
to judge long term effects.
Tissue implantation ranking of endodontic sealers would again
have to list Lee EndoFill as the least toxic followed by Nogenol, AH-
26, Sealapex, and Tubliseal, CRCS along with Zinc Oxide Eugenol
sealers, would rank higher in Toxicity and formaldehyde cements
rank as unacceptable.
OSSEOUS IMPLANTS
The sealers implanted directly into bone evoke less
inflammatory response than the same cements evoke in soft tissue.
From Marseille comes a report of two zinc oxide eugenol
sealers implanted into rabbit’s mandible. At four weeks both sealer
implants showed “slight to moderate reactions –no bone formation,
or bone resorption.
At 12 weeks there was slight to very slight reactions – bone
formation in direct contact with sealers and bone ingrowth into the
implant tubes.
42
Part of the implanted sealer was absorbed; macrophages were
loaded with the sealer.
In Argentina, Zmener tested glass ionomer cements in dog
tibias and stated that at 90 days “the inflammatory picture had
resolved with progressive new bone formation.
Again, the Para formaldehyde containing cements came off
second best.
There is not enough evidence to rank cements implanted into
bone. However, one must be impressed with the mild to stimulating
reactions that are reported in bone.
IN-VIVO TISSUE TOLERANCE EVALUATION
Most ideal method of testing drug, a substance or a technique
is in vivo in a human subject. But this is often dangerous, costly,
unethical, and so animals are substituted. The closer ones to
Humans are the monkeys.
Erausquin and Muruzabal, working in Buenous Aires performed
the seminal in-vivo research on tissue tolerance to sealers, and
concluded that all commercial root canal sealers are toxic causing
extensive to moderate tissue damage as soon as they escape
through the foramen.
In comparing the various sealers, Erausquin and Muruzabal
found that straight zinc oxide eugenol cement was highly irritating
to the periradicular tissues and caused necrosis of the bone and
cementum. Inflammation persists, for 2 weeks or more. Finally, the
zinc oxide eugenol becomes encapsulated. U.S. National Bureau of
Standards also agreed to this.
43
Erausquin and Muruzabal studied all zinc oxide eugenol based
cements, and concluded that, “All the cements, if the canal was
overfilled showed a tendency to be resorbed by phagocytes.
Grossman’s sealers and N2 both provoked severe
inflammatory reactions and Rickert’s sealer caused moderate
infiltration. Poor debridement and poor filling of the canals however
caused the most severe destruction of the alveolar bone. The least
reaction was found when the canal was not overfilled.
Seltzer and colleagues, after their studies concluded that,
when root canals were filled short of foramen, the reacts tended to
subside within 3 months and complete repair eventually took place.
In contrast, the teeth with overfilled root canals exhibited persistent
chronic inflammatory responses. There was also a greater tendency
towards epithelial proliferation and cyst formation in the overfilled
canals.
Diaket and AH-26, when overfilled showed only mild
inflammation. Diaket, became encapsulated while AH-26 was
resorted.
More recently, Norwegians tested AH-26 against
Endomethasone, Kloropercha and zinc oxide eugenol. At 6 months
they concluded that the periradicular reaction to the endodontic
procedures and to the materials was limited.
On the other hand, the connecticut group found a long term
(2 to 3 yrs) differences ranking AH-26 as mild irritant, ZOE as
moderate and Kloropercha as severe.
44
One must conclude that periradicular tissue reaction to all the
cements will first be inflammatory, but as the cements reach their
final set, cellular repair takes place unless the cement continues to
break down, releasing one or more of its toxic components.
To brief, the reactions shown by various cements in- vivo.
ZINC OXIDE EUGENOL
Inflammation was intensified when the material was extruded
into the periapical tissues. X-ray microanalysis of the dentin
indicated that the zinc from zinc oxide eugenol cement
diffuses into the dentin depending on time and distance.
These kinds of dentin become more resistant to acid
dissolution.
For many years precipitated silver powder was added to zinc
oxide eugenol because of its bacteriostatic properly. Silver
particles penetrate the dentin all the way to the border of and
sometimes into the cementum. The tubules become intensely
stained. Hazard inherent to the use of eugenol is the potential
for sensitization.
The rate of release of eugenol declined with time due to
progressive hydrolysis of the cement surface. The original
release correlated with an initial depression of macrophage
activity.
AH-26
It is well tolerated by periapical tissues. Excess material in the
periapex tunnel to become encapsulated. A few cases
reported paresthesia and neurotoxcity by partially inhibiting
nerve conduction. The inhibition is partially reversible.
45
Normal cell growth and cell manipulation were observed.
Other studies showed moderate to toxicity. It was found to
inhibit leukocyte migration.
DIAKET
Well tolerated by apical and periapical tissues, overfilling
caused no inflammatory reactions and were encapsulated by
fibrous connective tissue.
GIC
Freshly prepared material was found to be toxic to fibroblasts,
macrophages, monocytes and lymphocytes. But the toxicity
tends to decrease after setting.
POLYCARBOXYLATE
Materials produced an inflammatory response when it is
extruded into periapical tissues.
CALCIUM PHOSPHATE
The sealer penetrated and occluded the radicular dentinal
tubules and enhanced hydroxy apatite formation. This
penetrated the dentinal tubules upto 10m.
PARAFORMALDEHYDE TOXICITY
As initially compounded, N2 was a zinc-oxide eugenol cement
congaing 6.5% para formaldehyde as well as some lead and
mercury salts. Concern over lead and mercury transport via the
blood stream to vital organs forced the American producers of the
N2 look alike, RC-2B to drop the heavy metals. But in no way would
they reduce the toxic para formaldehyde from the formula. A myriad
of damaging research paper-in vitro, in vivo, clinical – denouncing
these products, have been published in the last 20 years from all
46
over the world. Pittford found for example, that N2 and
Endomethasone caused a universal ankylosis and root resorption of
dog’s teeth filled, but not overfilled with these toxic products.
A study was conducted but Indiana University using para
formaldehyde and it was concluded that the treated pulps were in
no better shape than the untreated inflammed controls.
NERVE DAMAGE FROM PARA FORMALDEHYDE
If N2 or RC-2B is forced into maxillary sinus or the mandibular
canal, it results in persisting paresthesia. In 1988, Brodin reported
that sealers containing formaldehyde were irreversible unless
surgical treatment was performed.
The tragedy of overfilling into the mandibular canal, especially
with such toxic materials, related to a misconception of the size of
the pulp. Dentists spin more and more material into the canal, far
more than it to takes to fill the space. Fanibunda points out that the
average pulp space of a maxillary central incisor is the size of drop
of water. This entire pulp space, crown and root. The root canal is
only a small portion of this volume.
N2 is now seldom used – probably because of the numerous
reports of its adverse effects and the fact that is not recommended
by dental schools.
47
STUDIES RELATED TO ROOT CANAL SEALERS
1) R. Gerosa, MD. DDS, M. Puttini MD, DDS and G. Caralleri MD,
DDS, Phd, conducted a study to assess the cytotoxicity of pure
eugenol, by diluting it to various concentrations in alcohol. They
concluded that pure eugenol is toxic for human gingival
fibroblasts, and eugenol in an alcohol, solution at concentrations
of < 1.9 m is non-cytotoxic.
2) According to Brett I. Cohen PhD., Mark K. Pgnillo who conducted
an invitro study to determine the cytotoxicity of two root canal
sealers. (AH 26 & AH Plus), both were considered cytotoxic.
3) An invitro study to evaluate the relative cyto compatibility of
three endodontic materials: calcium hydroxide, a calcium oxide
based compound and zinc oxide eugenol based compound was
concluded by Martine Guigand, DDS, Pascal Pellen – Mussi, DDS.
The results showed that, after 168hrs all of the fibroblasts in
contact with zinc oxide based compounds were dead. Fibroblasts
in contact with calcium oxide based sealers, showed cell
proliferation of 115% and those in contact with calcium
hydroxide had a cell proliferation of 108%.
4) The effect of newly developed root canal sealers on rat dental
pulp cells was assessed by Kokichi Matsumoto and others. It was
concluded that the new sealers were the least toxic in vitro,
compared with five conventional, sealers – AH26, Diaket, Canals,
Tubli Seal and Sealapox.
5) A Comparative study of tissue toxicity of 4 endodontic sealers –
zinc oxide eugenol, Tubliseal, Seal apex and Endoflas F.S. by
Meenu Mittal et al and concluded that no inflammatory response
was seen after 3 months, after injecting the sealers
subcutaneously into rats.
48