ROOT END FILLING MATERIALS

Introduction:

The purpose of root end filling is to establish a tight and biocompatible apical seal

between the radicular space and the periapical tissues.

Ideal Properties:

Ideal properties for root end filing materials as proposed by Dr. L.I. Grossman

are,

1. Should be well tolerated by periapical tissues

2. Should adhere to the tooth structure

3. Should be dimensionally stable

4. Should be resistant to dissolution

5. Should promote cementogenesis

6. Should be bactericidal or bacteriostatic

7. Should be non-corrosive

8. Should be electrochemically inactive

9. Should not stain tooth or periradicuar tissue

10. Should be readily available and easy to handle

11. Should allow adequate working time, then set quickly

12. Should be radiopaque

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Recommended Materials:

The suggested root-end filling materials till date include,

1. Gutta percha

2. Silver cones

3. Amalgam

4. Zinc oxide eugenol

5. Cavit

6. Polycarboxylate

7. Composite

8. Zinc phosphate

9. Gold foil

10. Glass ionomer cement

11. Lead points

12. Gold scres

13. Ward’s wonderpack cement

14. Poly hema

15. Tin foil

16. Ivory and plastics

17. Powdered dentin mixed with sulfathiazoles

18. Rickert’s root canal sealer

19. Titanium posts and screws

20. Silver post

21. Tin post

22. Aluminium oxide ceramic posts

23. Resorcine-formalin resin

24. Diaket

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25. Biobond and EDH adhesive

26. Metallic retentive pins

27. Bone cements

28. MTA

29. Calcium hydroxide

30. Compomer

31. Hydroxyapatite cements

1. Gutta Percha:

Either cold or warm gutta-percha can be used as a root end filling material. The

cold gutta-percha can be condensed apically or pulled through the apical foramen or can

be manipulated at its apical marginal interface with the root dentin walls to enhance its

adaptation and seal. This can be accomplished with the use of solvents, excavtors,

scalpels, burs and burnishers – both hot and cold. The adaptation of gutta percha is

dependent on a multitude of variables such as.

a) Nature of Gutta-Percha Used:

Gutta-percha should have high rigidity, flexibility and yield strength. In addition,

it should also have high percentage elongation and low resilience. But for these properties

it requires chemical proportions opposite to those found in gutta percha endodontic filling

materials. Gutta percha has both elastic and viscous properties and therefore referred to as

viscoelastic. The property manifests itself during use in the root canal. Gutta percha

requires a large, sustained force of condensation over an adequate period of time to

deform plastically. The more it deforms, the more it flows and adapt to the dentin wall,

decreasing gaps in the gutta-percha dentin interface.

b) Thoroughness of Condensation:

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For years many practitioners are achieving a respectable degree of success even

without the placement of a root end filling material but with proper obturation and

resecting the root ends. However, the effects of the resection on the seal had never been

evaluated. Most of the canals were filled with single cone techniques as the concept of

coronal flaring was non-existent. The sealers used would produce a very poor seal against

fluids, which would also produce voids in the sealer gutta-percha interface which can be

easily exposed during the resection technique.

Cunningham in 1975 demonstrated that single cone gutta percha fills exhibited

tearing and puling away from the dentin margin during resection.

Harrison and Todd showed that root end resection with a high speed rotary

instrument did not adversely affect the sealing property of well condensed gutta-percha

sealer obturation.

c) Placement and Condensation of Gutta-percha:

Earlier the pulling of gutta-percha through the resected root end had also been

advocated to ensure maximum adaptation to the dentinal walls. But this has been shown

to result in voids in the gutta-percha dentin interface as the gutta-percha tends to retract

from the walls creating significant gaps at the interface. Most authors have recommended

coronal condensation of the gutta-percha into the apical third of the canal and through the

foramen, prior to removal of the excess material. This approach would tend to ensure a

better gutta percha sealer adaptation to the dentin walls.

d) Use of Solvents:

Use of various solvents such as euclyptol, chloroform or rosin have been

recommended to enhance adaptation of the gutta-percha at the apex with or without

resection. But it has been shown that the material loses its dimensional stability as the

solvent is lost from the mixture.

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e) Type of instrument used for adaptation of gutta-percha:

Various instruments such as burs, scalpels, spoon, excavators, plastic filling

instruments and burnishers have been recommended to remove, contour or adapt the over

extended gutta-percha filling material to perfect the marginal interface. However, the

quality of adaptation appears to be operator dependent.

Blum in 1930 claimed that the resecting bur burnished the gutta-percha at the

orifice.

Ross in 1973 indicated gutta-percha drags due to bur rotation during root end

resection.

f) Temperature of instrument used to remove gutta-perha:

For years the use of a warm to hot instrument was advocated to smooth or burnish

the gutta-percha at the normal apex or at the resected root end.

Tanzilli et al. compared the use of warm plastic instrument in a cutting or searing

motion and a cold ball burnishes to adapt the gutta-percha at the resected root end. In

their study 3 discrepancies in adaptation were identified under SEM evaluation. The were

defined as defect – constant spacing between the material and dentin.

Blister-circular hole which was found after heat application and Pullaway – void

probably caused by the instrument pulling the gutta-percha away from the dentin.

Average size of the discrepancy

Pullaway – 104

Blister – 62 (width) and 109 (length)

Cold burnishing – Largest 5.6

Cold gutta-percha appeared to have superior adaptation to both amalgam and

gutta-percha fills subsequent to root-end resection only.

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Kaplan and associates demonstrated that cold gutta-percha yielded least dye

penetration.

Kos and coworkers found that the gutta-percha whether heat sealed or cold

burnished did not prevent leakage, as 95% of the samples in their study demonstrated

penetration of the bacterial products.

McDonald et al. found that hot burnished gutta-percha yielded a significantly

greater leakage pattern to a silver nitrate dye than did cold burnished gutta-percha.

King and co-workers demonstrated that cold-burnished gutta-percha with sealer

had significantly less leakage over time than amalgam with varnish and GIC with silver.

Leakage studies have demonstrated that high temperature thermoplasticized gutta-

percha seals well and if not better than high copper amalgam. Periradicular healing

adjacent to root end fills with thermoplaticized gutta-percha was not significantly

different than that adjacent to amalgam, although initial osseous regeneration was slightly

slow.

g) Root canal sealers:

The root canal sealers used in conjunction with solid core obturating materials are

intended to enhance the fluid-tight or hermetic seal throughout the root canal system. It

will have a direct bearing on the seal of the root canal system subsequent to root end

resection and on the periradicular healing at the resected root surface with or without a

root end filling.

Commercial sealers are generally grouped as a) eugenol based, b)non-eugenol

based, c) therapeutic based.

The residual eugenol in the eugenol based sealers that remains after the sealer set

can affect the sealer’s properties or the periradicular tissue response.

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Non-eugenol based sealers use solvents such as chloroform or eucalyptol which

have demonstrated toxicity in the initial stages of sealer set.

Therapeutic sealers contain materials such as iodoform, paraformaldehyde or

trioxymethylene which are claimed to have therapeutic properties.

Initially, all sealers can cause tissue inflammation and cellular damage.

Subsequent to resection in root filled teeth with these sealers, there is significant contact

of these sealers with the periradicular tissues which may result in extensive tissue

destruction with or without root end filling. The severity of damage appears to be related

to the nature of the material, its physical properties, its setting time and quantity or

surface area of the material in contact with the tissues.

2. Silver Cones:

Silver cones have been used to obturate root canals since the early 1930’s. The

ability of the silver cones to seal the root canal system three-dimensionally has been

justifiably challenged, as the circular, tapered nature of the cone provides only a central

core material which is surrounded by a sea of root canal sealer. This problem is

accentuated subsequent to angled root-end resection as large areas of sealer is visible

between the cone and dentin wall.

There are various recommendations for the use of silver cones as the apical filling

material at the time of periradicular surgery. Sommer’s in 1946 presented a technique for

a root-end fill with a silver cone subsequent to reverse canal instrumentation. The cone

was inserted into the canal at the resected root end, tapped to place with a chisel and cut

off and smoothened or burnished to confirm to the resected root surface.

Elkof recommended a similar approach, especially when a post-core crown was

present. A special instrument was designed to exert pressure along the long axis of the

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“Silverstift” during placement from the resected root end to the apical extent of the canal,

post.

Maxmen, Pryor and Summers have recommended the pulling or tapping of a

silver cone through the resected root end, followed by grinding or planning of the cone

flush with the resected surface.

Trice recommended a fissure bur to cut through previously placed silver cones,

followed by a smoothing of the surface with a round bur. However, these techniques have

not specifically recommended the placement of a root end fill subsequent to resection of a

silver cone.

Harrison and Todd demonstrated that resection of root ends of single rooted teeth

obturated with single silver cones and sealer adversely affected the seal, necessitating a

root-end fill.

In addition to the strong potential for voids and leakage to exist between a

resected silver cone and dentin wall, corrosion of a metal-worked con looms a a major

factor for continued periradicular tissue irritation and ultimate failure of resected silver

cone cases.

Ideally, teeth containing silver cones and requiring surgery should be non-

surgically retreated, if possible prior to surgery, removing any silver corrosion products

from the root canal system and replacing the silver cone with a well condensed gutta-

percha and root canal sealer fill.

3. Amalgam:

One of the first reports of placing a root-end amalgam filing subsequent to

resection is attributed to Farrar. Although there are a number of studies suggesting the

use of amalgam as a root end filling material, there are many controversies for the same.

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The factors to be considered when amalgam is used as a root end filling material

are.

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a) Type of amalgam:

The chemical reaction in conventional alloys between mercury and other

components is as follows.

Ag3Sn + Hg Ag3Sn + Ag2Hg3 + Sn8Hg 1 2

where – phase is the strongest phase

1- reasonably corrosion resistant and

v2 – comparatively weak, corrosion prone phase and may be a site of

crack initiation and marginal failure

High copper alloys:

Ag3Sn + Cu + Hg Ag3Sn + Ag2Hg3 + Cu6Sn5

1 n

The copper that replaces some of the silver in these alloys reacts to form copper-

tin compound, the eta phase which eliminates or diminishes the weak, corrosion prone

2-phase.

The presence of high levels of copper has increased resistance to marginal

breakdown, higher compressive strength and reduced dimensional changes. Studies have

shown that the use of a dentin adhesive prior to placing a high copper spherical alloy has

shown promise in the elimination of marginal leakage.

Another aspect of amalgam is the potential for release of mercury from the set

amalgam over time. The release of Hg may have an effect on the periradicular tissues and

ultimate healing. The greatest potential for Hg release occurs from unreacted Hg in

freshly triturated alloy. However, all unreacted Hg is consumed within 2 hrs of set.

Therefore, once solid amalgam phases form, the potential for Hg release is significantly

reduced.

Further studies have suggested a reduction in Hg vapour release when a sealer is

placed over the alloy, although sealant durability is limited.

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Then is the role f zinc in amalgam as a root end filling materials. The presence of

zinc in amalgam might cause hygroscopic expansion of the material in the presence of

moisture, which might further lead to amalgam or root fracture and leakage.

In 1959, Omnell resented a case which involved a female patient who had

undergone root end resection of a maxillary lateral incisor. He has used silver amalgam

as a root end filling material in a tooth which contained a metallic post used to support a

metallic crown. He found periradicular bone destruction and deposition of a radiopaque

substance reappeared after a second resection procedure. Microradiographic and

radiographic diffraction investigations revealed the substance to be a zinc carbonate

precipitate, which could have deposited as a result of an electrolytic process because of

the presence of the metallic post. Subsequent to this case report, and with little

substantiative scientific basis, recommendations appeared advocating the useof non-zinc

amalgam alloys for root-end filligns.

On the other hand, zinc alloy minimizes the amount of porosity, reduces corrosive

tendencies, enhances marginal integrity and reduces marginal fracture. Sarkar and Eyer

have described this phenomenon of reduced marginal fracture as a function of the high

electroactivity of the zinc component of the amalgam. They have also shown in vitro the

formation of a zinc stannate passive film over the alloy, which minimizes the major

chemical reactions in the corrosion process.

In 1982 Kimura used dogs to determine the dissolution of metallic elements and

the incidence of a zinc carbonate precipitate from zinc and non-zinc root-end silver

amalgam fillings and bone implants. Of the 16 specimens analysed, zinc was detected in

the surrounding bone in two zinc amalgam root-end fills and in one non-zinc amalgam

root-end fill. No precipitate, suggestive of zinc carbonate was detected after 22 months of

in vivo amalgam implantation. However, chemical analysis of non-zinc amalgams in a

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1% NaCl solution demonstrated the presence of a tin hydroxide film, which is more

susceptible to corrosive action without the presence of zinc.

b) Marginal Adaptation:

Multiple technique have been advocated to determine the apical leakage or

marginal adaptation of root end amalgam fillings. The conclusions that can be drawn

from these studies are that roote-end amalgam fillings may be minimally adequate at first,

but shrinkage on setting wil occur. The key factors which interact with the marginal

discrepancies include the –

a) Mean leakage observed and its alteration with time

b) Standard leakage from the mean leakage observed

c) Depth of the amalgam

d) Amount of amalgam corrosion and expansion anticipated

e) Manipulation of the alloy during preparation and placement

f) Place of the alloy in the canal prior to resection versus its us as a root-end fill

only.

g) Cleanliness and seal of the root canal system coronal to the root-end fill

h) Use of cavity varnish

Studies have shown that the use of two coats of varnish to seal not only the walls

of the root-end preparation but also the cut dentinal tubules at the root surface reduces

microleakage to a certain extent. However, evaluations using hydroxyl ions to detect

leakage have shown that varnishes do not inhibit microleakage in conjunction with

amalgam restoration over a 6 month period. Their study indicated that varnish dissolution

occurred around the 7 month and that the corrosion process in a complex dynamic

interplay, may compensate for further leakage.

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Negm, in an in vitro study used varnish and a light cured fissure sealant to

enhance the sealing capacity. He found that varnish did not significantly enhance the

sealing capacity of the root-end filling materials where the use of a light cured fissure

sealant (Helioseal) showed promise as an adjunct to foraminal and root face sealing.

c) Tissue compatibility:

Compatibility studies have demonstrated that freshly mixed conventional silver

amalgam is very cytotoxic due to the unreacted mercury with cytotoxicity decreasing

rapidly as the material hardens.

Studies have shown that zinc amalgams have more lasting cytotoxicity compared

to the non-zinc amalgam which have very little cytotoxicity at 24 hrs after mixing.

In 1975 Flanders and coworkers placed implants of non-zinc amalgam and cavit

in the subcutaneous tissue and adjacent to bone in rats. They found tht cavit produced

more severe reactions than did amalgam.

Martin and associates implanted both zinc and non-zinc amalgam in the

subdermal and supramuscular regions of a rat. They could not find any significant

differences in tissue response with the zinc and non-zing amalgam at 30 days.

Ligett and coworkers implanted freshly mixed, unset zinc and non-zinc amalgam

in the tibias of rats. They found that the surface of all the implants were covered with an

organic film at the 3 week evaluation period and with bone at later intervals. X-ray

microprobe analysis showed that bone adjacent to the amalgam implants contained tin

and surface irrespective of the presence of zinc, indicating an outward migration of

specific components of the amalgam. This may be reflective of ongoing corrosion and

alteration in the amalgam in contact with tissue fluids.

d) Material preparation and manipulation:

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The preparation and manipulation of the amalgam alloy at the time of placement

is crucial in determining amalgam strength, marginal adaptation, degree of porosity,

surface smoothness and the nature of surface constituents.

Some key points to consider relative to alloys placed intraorally are as follows:-

1. Alloy:- Hg ratio-to be followed Eames technique or Jorgensen and Saito.

Amalgams squeezed of their excess Hg have a decrease in their final strength.

2. Manufactures instructions to be followed during trituration. In an attempt to

minimize variations, mixes of amalgam heavier than two spills should be avoided.

3. Amalgams are more closely adapted to the confines of the cavity during

mechanical rather than hand condensation. However, the use of mechanical

condensers may be limited.

4. Alloys consisting of spherical or mostly spherical particles are more fluid under

condensation pressures; and the use of large condenser in a lateral fashion may be

desirable because a small head condenser tends to force amalgam mass away from

the areas of condensation. Also, less pressure is required to properly condense

these alloys.

5. The optimal structure for the amalgam margins can be obtained by overfilling and

burnishing of the margins and removal of the excess by carving.

6. Burnishing improves the marginal adaptation and seal.

7. Burnishing as a one-step procedure may be optimally accomplished at 4 to 6 min

after trituration. Carving will still be necessary after burnishing, followed by

burnishing to render the surface smother, thereby discouraging formulation of

small corrosion cells on the surface.

In 1919, Lucas recommended root canal fillings with amalgam before root-end

resection. Hill, Herbert, Messing and Cook recommended the use of root canal fillings

with amalgam prior to resection. Specific instruments such as Messing gun, Hill

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endodontic amalgam carrier and Endogun have been developed to introduce the amalgam

to the apical third of the roots or to conveniently place a root-end filling. Once the apical

portion is filed with 3 to 7 mm of amalgam, the remainder of the canal can be obturated

with gutta-percha or left vacant for post space. Later, root end resection is performed,

exposing the apical amalgam, which can be polished or burnished to enhance the

marginal seal and surface finish. If not smoothly polished, the abraded amalgam due to

bur marks from resection may be more prone to corrosion.

e) Galvanic Currents:

The placement of a root-end amalgam in a tooth which has a metallic post or

crown restoration could create a galvanic couple, which has the potential to generate

significant amounts of electrical currents. Metallic changes due to the generation of

electric currents have been identified as increases in tarnishing, corrosion, porosities and

marginal breakdown with leaching in metallic ion (Cu, Zn, Sn, Hg and Ag) into the

surrounding media.

f) Tissue staining or argyria:

The possibility of tissue staining subsequent to root-end resection and/or root-end

amalgam fillings may be due to –

1. Amalgam scattered in the surgical site during placement of the root-end filling.

2. Amalgam scattered in the surgical site due to removal of a failing root-end

amalgam.

3. Fractured or loosened amalgam root-end fillings.

4. Chemical corrosion of the root-end amalgam or silver cones at the resected root

surface.

5. Galvonism

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6. Silver scattered in the surgical site during resection of roots containing silver

cones.

7. Deterioration of silver containing root canal sealer (Rickert’s sealer).

Based on this discussion certain guidelines for amalgam as a root-end fillign material, if

used are,

1. Control of moisture in the surgical site is essential.

2. High copper alloys are preferred to the others.

3. Varnish or dentin bonding agents must be used prior to alloy placement.

4. Zinc alloys are the material of choice when moisture is controlled.

5. Carefully condense, burnish, carve and burnish the alloy using a minimal number

of firm strokes directed to the alloy dentin interface.

6. Create a smooth surface on the finish alloy.

7. Prevent dispersion of alloy particles in the surgical site.

8. The diameter of the fill should be as small as possible, although the bulk of the

alloy must be thick enough to resist fracture and to obdurate the entire canal

system at the resected root surface.

4. Zinc-oxide Eugenol:

In 1962, Nicholls showed preference for zinc-oxide eugenol cement over

amalgam. The original ZnO eugenol cements were weak and had a long setting time.

When used as a retrograde filling, the cement tended to be absorbed over time because of

its high water solubility. Because of the hydrolysis, Zn hydroxide and Eugenol are

formed. The eugenol will continue to be removed by leaching until all the Zn eugenolate

is converted to Zn (OH). Further, the free eugenol may have several undesirable effects.

In order to overcome some of these problems to original ZnO eugenol cements

were modified as IRM whch is reinforced by the addition of 20% polymethacrylate by

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weight to the powder and super EBA which was modified by the addition of

ethoxybenzoic acid to alter the setting time and increase the strength of the mixture. In

this, partial substitution of eugenol (liquid) was done with ortho-ethoxybenzoic acid and

fused quartz or alumina are added to the powder.

Ex: Stailine super EBA – Powder – ZnO - 60%

SiO2 - 34%

Natural resin - 6%

Liquid – EBA - 62.5%

Eugenol- 37.5%

IRM:

IRM was found to have a milder reaction than unmodified ZnO eugenol. In a

tissue tolerance study it was found that IRM elicited a mild to no inflammatory effect

after 80 days.

In a retrospective study done by Dorn and Gartner, IRM was found to have a

statistically significant higher success rate compared to amalgam. In a retrospective study

done by Schwartz et al. amalgam and IRM had the same clinical effectiveness when used

as a root end filling material.

To further improve IRM as a retrograde filing material, 10% to 20%

hydroxyapatite was added because of its biocompatibility with bone. This had produced a

better seal than amalgam, but was not statistically different from plain IRM. The only

disadvantage with this was increased disintegration which may allow leakage of potential

irritants after a certain time period.

Owadally and associates reported on an in-vitro antibacterial activity and

ctotoxicity study comparing amalgam and IRM. They found than IRM was significantly

more antibacterial than amalgam and also that amalgam was more cytotoxic than IRM.

Chong and associates compared the cytotoxicity of a GIC, Kalzinol, IRM, Super

EBA and amalgam. Their results indicated that fresh IRM cement exhibit the most

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pronounced cytotoxicity of all materials. Aged Kalzinol was the second most cytotoxic

material with no significant difference being reported between Vitrebond, EBA and

amalgam.

Super Ethoxybenzoic Acid:

Because of the addition of the above mentioned modifiers the solubility of the

cement was increased. To overcome this Tamazawa et al. added a soluble fluoride –

Potassium hexafluoroziroconate which reduced the solubility of EBA cement to half of

that of ZnPO4 in the in vitro evaluation.

Stailine super EBA has a neutral pH, low solubility and radiopaque. EBA is the

strongest and least soluble of all ZnO eugenol formulations. It yields a high compressive

and tensional strength.

Leakage studies demonstrated that Super EBA allowed significantly less leakage

than amalgam and produces a tight seal compared with amalgam, GIC and hot burnished

gutta-percha.

However, Super EBA is a difficult material to manipulate because the setting is

short and is greatly affected by humidity. Compared to IRM, Super EBA is difficult to

mix and handle. The liquid powder ratio is 1 : 4. The powder is mixed into the liquid

slowly in small increments. When the mixture is thick but still shiny, additional powder

has to be added. When the rolled super EBA mixture loses its shine and the tip does not

droop when picked up by a carrier, the mixture has the right consistency. After placing

the mix in the cavity it has to be either burnished or polished.

Studies have shown that burnishing super EBA without polishing provides a

better seal. Tissue tolerance studies show that super EBA and eugenol cements produce

similarly mild reactions.

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Brower and coworkers showed good apical marginal adaptation and less leakage

of Super EBA compared to amalgam, heat-sealed and cold-burnished gutta-percha and

apical root-end resection only, using 45Ca leakage.

Beltes and associates examined the seal of super EBA and compared it with

amalgam and varnish, GIC and hot burnished gutta-percha. They found that Super EBA

exhibited the least amount of leakage of all the materials tested.

5. Cavit:

It is a temporary filing material which contains zinc oxide, calcium sulphate, zinc

sulfate, glycol acetate, triethanolamine and polyvinyl acetate, polyvinyl chloride acetate

and a red pigment. It is also available in forms without the red pigment such as cavit-G

and cavit-W.

It is soft when placed in the tooth and subsequently undergoes a hygroscopic set

after permeation with water, giving it a high linear expansion. This property has been

cited as a rational for its use as a root-end filling material.

The ability of cavit to seal cavities is controversial. Initial studies by Parris and

coworkers showed that during temperature cycling, cavit sealed against dye and bacterial

penetration as well as amalgam. On the other hand, cavit-G has been shown to exhibit

greater leakage than IRM or ZOE.

Delivanis and Tabibi, when evaluating apical leakage patterns demonstrated that

the cavit seal deteriorated and leaked more than amalgam over a 6 month period.

Biocompatibility studies with cavit are in conflict, showing it to be both toxic and

non-toxic. Tissue toxicity studies have shown that cavit is toxic to subcutaneous tissue

and bone.

6. Zinc Polycarboxylate:

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It is available as a powder-liquid system. Powder consists of modified zinc oxide

with fillers such as Magnesium oxide and Stannous floride. And the liquid is an aqueous

solution of polyacrylic acid. When the powder and liquid are mixed, a reaction occurs

between the zinc ions and the carboxyl groups on the polyacrylic acid, with the free

carboxyl groups having the capacity to chelate calcium. Therefore, adhesion to tooth

structure is a significant property of these cements.

The pH of the cement is approximately 1.7. However, the liquid is rapidly

neutralized by the powder during material set.

When placed in osseous tissue, they are well tolerated with no evidence of

osteocyte destruction. However, the osseous tissue adjacent to the polycrboxylate

implants showed decalcification, which is probably due to the chelating property of the

cement. When placed in subcutaneous tissue, severe irritation has been reported with the

polycarboxylates.

Apical leakage studies have indicated that polycarboxylates when used as root-

end fillings, leak at levels significantly greater than amalgam or gutta-percha. Therefore,

based on their poor sealing ability and uncertain periradicular tissue response, the use of

polycarboxylates as root-end filling materials is highly questionable.

7. Zinc phosphate cements:

Rhein in 1897 used zinc phosphate cement along with gutta-percha to seal the

root canal system prior to root end resection. In 1941, Herbert recommended zinc

phosphate mixed with thymol for immediate root canal fills in conjunction with root-end

resection.

The available literature on the use of zinc phosphate as a root end filling material:

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1) it is soluble, especially in dilute organic acids. This would be a significant

problem in root-end fills, particularly with the presence of chronic

inflammation in the periradicular tissues.

2) It is irritating to the tissues, especially in the presence of bacteria.

3) These cements are prone to leakage and are affected by moisture during

placement.

Studies have shown radiographically field root end resections which had canals

filled with gutta-percha and zinc oxyphosphate cement. The surface of the resection was

highly porous, especially at the gutta-percha sealer-dentin interface. Dissolution of he

zinc phosphate was obvious serving as a continuous periradicular irritant. As zinc

phosphate does not fulfill most of the properties of an ideal root-end filling material, it is

not indicated as a root-end filling material.

8. Gold foil:

Some of the first reports on gold foil as a root-end filling material is attributed to

Schuster in 1913 and Lyons in 1920. the use of gold foil was recommended because of

the ease of direct manipulation, marginal adaptation, surface smoothness and tissue

biocompatibility.

Cytotoxicity studies have indicated variations in the inhibition of cell growth

based on the formulation of the gold. Fine pellet gold did not inhibit cell growth, whereas

newer formulations (New Biofil and Karat) inhibited up to 80% of the cellular growth.

Tissue biocompatibility studies have indicated a mild response to

undercondensed, irregular pieces of gold foil. Marginal adaptation and leakage studies

have indicated minimal or no leakage.

Wilstermann developed a ring-type instrument which could be fit around the

resected root end to isolate it from moisture contamination during placement of Goldent.

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Key to the claimed success in the use of gold foil was the close adaptation to the dentinal

walls and the ability to highly polish the metal filling.

Although it possesses favorable material properties, the routine use of gold foil as

a root-end filling material does not appear practical because of the need to establish a

moisture free environment, the need for careful placement and finishing, the possibility

of root fracture under excessive condensation pressures and the need for surgeons

expertise in material management.

9. Glass Ionomer:

They are a hybrid of silicate and polycarboxylate cements which bond

physicochemically to dentin and enamel an possess anticariogenic activity. It is available

as a powder-liquid system. Powder consists of calcium-alumino siliate glass particles and

the liquid consists of polyacrylic acid. When the powder is mixed with liquid the acid

extracts calcium and aluminium ions from the glass particles, initiating a prolonged two-

phase setting reaction. Calcium ions bind to the polyacrylic acid producing a firm gel that

provides initial adhesion to the tooth structure. From 30 min to 24 hrs after mixing,

aluminium polycarboxylates are formed. During first 60 min of setting, while calcium

salts predominate glass ionomers extremely sensitive to moisture contamination and

dehydration. Therefore, it is recommended to use a water resistant varnish for initial

protection during the formation and maturation of aluminium polycarboxylate at the

material’s surface.

Biocompatibility studies have shown evidence of initial cytotoxicity with freshly

prepared samples, with decreasing toxicity as setting occurs. Glass ionomers have also

shown to have antibacterial properties, due to their acidity and fluoride release.

Marginal adaptation and adhesion of glass ionomer cements to dentin have been

shown to be improved with the use of acid conditioners and varnishes.

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Studies have shown resin modified glass ionomer cements to be better than

conventional glass ionomer cements and both of them to be better than cements. The long

term success of GIC as a root end filling material has been confirmed in several studies

compared to amalgam, where GIC appeared to perform as well. The moist environment

does not seem to be detrimental to the surface and GIC seen to be less susceptible to

moisture than expected.

Rosier’s et al. in 2005 studied the microleakage of IRM, Fuji IX and MTA as root

end filling materials and found that at 24 hrs Fuji IX leaked less than Pro root MTA,

which leaked less than IRM. At 1 month the leakage decreased with significant difference

between IRM and Fuji IX and no significant difference between other materials. At 6

month the leakage increased with significant difference between IRM and Fuji IX and no

significant difference between other materials. At 6 month the leakage increased with

significant difference between IRM and Fuji IX and between MTA and Fuji IX and no

significant difference between IRM and MTA was observed.

Economides et al. in 2004 compared the sealing ability of 2 root end filling

materials (Fuji II LC and Admira) with and without the use of dentin boding agents (Fuji

bond and Admira bond). They found that Fuji II LC showed less leakage than

(composite) Admira and Admira with boding showed less leakage than Admira alone.

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10. Compomers:

They are the combination of composites and glass ionomers. These materials are

essentially polymer-based composites that have been slightly modified to take advantage

of the potential fluoride-releasing behaviour of glass ionomers. The mechanical

properties of polyacid modified resin composites are superior to those of traditional glass

ionomers and resin-modified glass ionomers and in some cases are equivalent to those of

contemporary polymer-based composites.

Charles et al. in 2001 studied the effect of an acid environment on leakage of

Amalgam, Geristore, Super EAA, MTA, calcium phosphate cement or MTA with

calcium phosphate cement. They concluded that the acid environment did not hinder the

sealing ability of the materials tested but in turn enhanced the sealing ability of Geristore

and MTA with calcium phosphate cement.

Pashley et al. studied the sealing ability of Dyract, Geristore, Super EBA and

IRM. After 1 day they found greater leakage for super EBA than other materials. No

significant difference between IRM and Geristore, whereas Dyract demonstrated

statistically less leakage than the other 3 materials. The final results after 180 days

showed significantly greater leakage for IRM than Geristore but not for the other

materials. They conclude that compomers are equal or superior to IRM and equivalent to

super EBA in their sealing ability when used as root end filling materials.

Wonnfors in 2004 studied the effectiveness of Dyract AP as a root end filling

material, with Prime & Bond NT. The control group was fille with Ketac Silver. They

cocluded that when used as a root-end filling material in a shallow concave preparation, a

light cured compomer and a dental adhesive improves healing regardless of the quality of

the remaining root-filling.

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Ozbas et al. in 2003 studied the reactions of connective tissue compomers (F-

2000 & Dyract), composite (Valux plus) and Amalgam (Oralloy) and found

biocompatibility with all the materials tested.

11. Biobond and EDH Adhesive:

They are originally used for the prevention of intracranial aneurysm and

reinforcement of vessel walls has been evaluated by Nordenram for use as a root-end

filling material. Clinical and radiographic evaluation over 24 months showed results

comparable to root-end resection only and slightly better than teeth with root-end gutta-

percha fills.

12. Metallic Retention Pins:

Available as a thin metal cap with a vertical loop (similar to an umbrella) is

cemented into the prepared apex. Chloropercha NO is applied between the cap and the

cut surface. The perimeter of the cap would encompass the entire resected root face and

be flush with the cemental wall. Not only would the root canal system be sealed with this

technique but also the cut dentin tubules.

13. Cyanoacrylate:

Because of bonding properties and soft tissue compatibility, cyanoacrylate was

evaluated as a root-end filling material.

Leakage studies have shown that cyanoacrylate leaked less than amalgam with or

without varnish and hot or cold gutta-percha root-end fills. Kinoshita demonstrated

adverse tissue response to cyanoacrylate as compared to amalgam and composites with

bonding agents.

However, controversies over the ultimate biocompatibility of cyanoacrylates have

minimized its extensive and aggressive use in dental procedures.

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14. Bone Cements:

They are polymethacrylate basedand contain an antibiotic (Gentamicin Sulphate),

they are radiopaque and have been recommended for root-end filling.

In vitro studies have shown the cements to have distinct bacteriocidal properties

and to exhibit favorable compatibility in tissues culture, compared to amalgam. However,

when placed in the root end, the sealability of these cements was less than that of

amalgam.

15. Root Canal Sealers:

a) Diaket:

It is a polyvinyl resin, used as a root canal sealer and has been recommended by

few clinicians as a root-end filling material. Studies have shown that Diaket produced

long term chronic inflammation in osseous and subcutaneous tissue and to be cytotoxic in

cell culture, inhibiting DNA synthesis in rat dental pulp cells.

On the other hand, Stewart showed that it was tolerated by tissues, was

impervious to methylene blue penetration and did not dissolve or absorb in the presence

of periradiclar tissues and fluids.

Tetsch has advocated the use of Diaket to enhance a minimally adequate apical

seal. Diaket is mixed to a thicker consistency than when normally used as a sealer and is

condensed into small voids identified in the root canal fill at the resected root surface.

Leakage studies comparing Diaket with non-zinc alloy and two glass ionomers

(Ketac fil and Ketac Silver) have shown Diaket to display superior sealing qualities.

Gutmann et al. in 2002 compared Diaket and MTA when use as a root end filing

material to support regeneration of the periradicular tissues and found that both Diaket

and MTA can support almost complete regeneration of periradicular periodontiim when

used as root-end filling materials in periradicular surgery on non-infected teeth.

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b) Sealer-26:

It is a resinous root canal sealer similar to AH-26 but it contains Ca(OH)2 and not

silver. Siqueire et al. in 2001 studied the ability of sealer 26, IRM and GIC to prevent

bacterial leakage. After 60 days leakage was observed in all samples with GIC (Fuji IX),

95% samples with IRM and only 65% samples with Sealer 26. They concluded that

sealer 26 was more effective in preventing bacterial leakage when compared to other

materials tested.

16. Composite resins:

Since 1990, certain composite resins have been advocated as the root-end filing

material of choice. Creation of a leak-resistant apical seal is possible with this material,

although such use is technique sensitive. A dry field is necessary for the dentin bonding

agent and composite resin root-end fill.

Safavi & associates evaluated cellular attachment to resected root-ends and root-

end filling materials (amalgam and composite) in cell culture. Good marginal adaptation

was found with composite, while amalgam whether carved or burnished consistently

exhibited marginal gaps. Cell attachment to the surface of the composite was remarkably

less than that of amalgam. In addition, cell attachment to the root dentin was highly

variable. Overall, composites exhibited a poorer biocompatibility than amalgam.

Rud et al have demonstrated excellent long-term clinical success with the use of

Retroplast composite resin and Gluma dentin bonding agent. The biocompatibility of

selected dentin boding agents and composite resins appear favorable and reattachment of

periodontal ligament fibres has been reported.

Gluma has been shown to have distinct in vivo antibacterial properties that seen to

prevent bacterial growth at the tooth-restoration interface.

Use of dentin bonding agent and composite resin also permits a conservative root

end preparation. Some authors have suggested a slightly concave preparation rather than

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a conventional deep cavity followed by subsequent resin bonding to the entire resected

root end. This has the advantage of sealing exposed dentinal tubules as well as the main

well.

All polymerizing resins leave an uncured oxygen-inhibited surface layer that may

interfere with initial healing and should therefore be removed with a cotton swab before

wound closure.

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17. MTA:

It is a powder consisting of fine hydrophilic particles.

Composition:-

Tricalcium silicate

Tricalcim aluminate

Tricalcium oxide

Silicate oxide

Bismuth oxide

Tetracalcium aluminoferrrite

It is 75% Portland cement to which certain modifiers are added. Its pH when set is

12.5 and its setting time is 2 hrs and 45 min. Because of its high pH similar to that of

calcium hydroxide it has a property of induction of hard-tissue formation.

The sealing ability of MTA has been shown to be superior to that of amalgam or

even super EBA, it is not adversely affected by blood contamination.

MTA in contact with periradicular tissue forms fibrous connective tissue and

cementum, causing only low levels of inflammation. The regeneration of new cementum

over MTA is a unique phenomenon that has not been reported with other root-end

fillings.

Jacob Saidon et al. conducted a study to compare the cyttoxic effect in vitro and

in vivo and tissue reaction of MTA and Portland cement. They found that MTA and

Portland cement show comparative biocompatibility and results suggest that Portland has

the potential to be used as a less expensive material but further research and long term

follow up has to be carried out.

Martel et al. studied the electrical and leakage of IRM, Super EBA and MTA.

They found less leakage with MTA almost similar to the negative controls. Therefore,

they suggest MTA as the root end filling material which provides superior seal.

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Caroline et al. studied the influence of the thickness of MTA on the sealing ability

as root-end filling material. They compared 1, 2, 3 & 4 mm thickness of MTA and found

that 1mm MTA was the least effective in preventing apical leakage. No significant

difference was found between 2 & 3mm. 4mm MTA was significantly more effective

than the other thicknesses tested. Therefore, they suggest that the thickness of 4mm is the

most adequate for the use of MTA as a root-end filling material.

Saad and Aziza in 2003 studied the anti-fungal activity of MTA. They found that

the freshly mixed MTA was effective in killing the tested fungi after 1 day of contact,

whereas the 24 hr set MTA was effective after 3 days of incubation.

The use of MTA has many advantages:-

1. Least toxic of all the root end filling materials.

2. Excellent biocompatibility.

3. Hydrophilic, sets in the presence of moisture and is not adversely affected by

blood contamination.

4. Good marginal adaptation.

5. Good sealing ability.

6. Antibacterial.

7. Induces hard tissue formation.

Disadvantages:

1. Long setting time

2. Difficult to manipulate

3. Expensive

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