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ROOT CANAL SEALERS

Seminar by

Dr. M.SHANMUGARAJ Postgraduate Student

DEPARTMENT OF CONSERVATIVE DENTISTRY & ENDODONTICS SRI RAMACHANDRA DENTAL COLLEGE AND HOSPITALS CHENNAI


2

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


3

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, KetacEndo 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. 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.


4 ♦

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. 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.


5 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. 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.


6 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.

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.


7 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. 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.


8 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. 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,

suppression of inflammatory reaction.

and

corticosteroids

for


9 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. 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.


10 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

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.


11 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

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

developing a sealer that afforded more working time.

purpose

of


12 PROCOSOL RADIOPAQUE SILVER CEMENT Composition Powder contains Zinc oxide USP

-

45.0%

Silver (precipitated)

-

17.0%

Hydrogenated resin

-

36.0%

Magnesium oxide

-

2.0%

Eugenol

-

90.0%

Canada Balsam

-

10.0%

Liquid contains

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%

Eugenol

-

80.0%

Sweet oil of Almond

-

20.0%

Liquid contains

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.


13 GROSSMAN’S SEALER (Grossman, 1974) Power contains Zinc Oxide

-

42%

Stabelite resin

-

27%

Bismuth sub carbonate

-

15%

Barium sulfate

-

15%

Sodium borate (anhydrous)

-

1%

-

100%

Liquid contains Engenol 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.


14 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 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.


15 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. 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.


16 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%

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.


17 It is a good germicidal Relatively low tissue irritant . The sealer is biocompatible to the periapical tissue. It has a good setting time. DISADVANTAGES 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.


18 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%

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.


19 DISADVANTAGES Since the Tubliseal sealer has a very low viscosity it makes extrusion through the apical foramen more likely and recommends a 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.


20 CONTRAINDICATIONS Tubliseal sealer is contraindicated if overfill is probable with normal periapical issue. 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


21 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. 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-φ contain filler particles (eg zinc oxide) to reduce the shrinkage. Zinc oxide also increases radio opacity. COMPOSITION KLOROPERCHA N – φ (NYGARD – OSTBY 1939) Powder contains Canada Balsam

-

19.6 %

Rosin

-

11.8 %

Gutta percha

-

19.6 %

Zinc oxide

-

49.0 %


22 Liquid contains Chloroform

-

100 %

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.


23 COMPOSITION 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 sealer


24 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.


25 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 Calcium hydroxide

6.5 % 25.0 %

Butyl benzene Sulfonamide Zinc stearate Catalyst contains Barium sulfate Titanium dioxide Proprietary resin Isobutyl salicylate Aerocil R 972.

18.6 % 51 %


26 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 %

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 %


27 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, AHPlus. 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, β di-ketone. A very tacky material, it contracts slightly while setting, which is subsequently negated by uptake of water. Its setting efficacy is good.


28

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 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.


29 This amount of brief release formaldehyde however is thousands of

times lower

than the

long-term release from

conventional

formaldehyde containing sealers, such as N2. 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 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


30 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 glassionomer 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 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.


31 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. 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.


32 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 KetacEndo 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. 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 N 2. Although not much different in content as far as toxicity is concerned, N 2 has been the material most commonly focused on when discussing the phenomenon. This material is also known as RC-2B or the “Sargenti


33 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 N 2 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. 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.


34 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. 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.


35 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. 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


36 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: 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:


37 “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; 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.


38 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-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 N 2. 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.


39 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. 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 inflammation.

and

AH-26,

Diaket,

when

became

overfilled

encapsulated

showed

only

mild

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 10¾m. 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 N 2 look alike, RC2B 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 over the world.


46 Pittford found for example, that N 2 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 µm 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.

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