root canal filling materials

7/30/2019 Root Canal Filling Materials

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Root canal fillingmaterials.

Root filling

techniques.

Lecturer: Levkiv MarianaDepartment ofTherapeutic Dentistry

TSMU


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Purpose of root canal filling

To prevent bacteria and bacterial elementsfrom spreading from (or through) the canalsystem to the periapical area,

the fully instrumented root canal has to beprovided with a tight and long-lasting

obturation. A root canal filling material should, therefore,

prevent infection/reinfection of treated rootcanals. Together with an acceptable level ofbiocompatibility (inert material) this will

provide the basis for promoting healing ofthe periodontal tissues and for maintaininghealthy periapical conditions.


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Instruments for root canal filling

Lentulo spiral filler/rotary paste filler Function and features

Small flexible instrument used to placematerials into the canal

Fits into the conventional handpiece Use with caution as it can be easily

broken

Different sizes available


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Finger spreader

Function, features and precaution Used to condense gutta percha into the

canal during obturation

Finger instrument with a smooth, pointed,

tapered working end Disposed of in the sharps container

Varieties

Can be of the hand instrument type (lateral

condenser)


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Endodontic plugger

Function Working end is flat to facilitate plugging or

condensing the gutta percha after the excess

has been removed by melting off with a heatedinstrument

Varieties Different sizes of working ends are available

Available as hand or finger instruments


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Gutta percha points

Function and features

Non-soluble, non-irritant points that arecondensed into the pulp chamber duringobturation

Standardised type: follows same ISOclassification as endodontic files

Non-standardised: have a greater taper thanthe standard ISO type

Varieties

Can be packaged in single dose or bulkpackages

Different sizes with different tapers available


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OBTURATING MATERIALS

Sealers

Regardless of the obturation techniqueemployed, sealers are an essential

component of the process. Sealers fill thespace between the canal wall and coreobturation material and may fill lateraland accessory canals, isthmuses, andirregularities in the root canal system.


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The ideal properties of endodontic sealer

are as follows: 1. It should be tacky when mixed to provide good adhesion

between it and the canal wall when set.

2. It should produce a watertight seal

3. It should be radiopaque so that it can be visualized o on X-ray.

4. The particles of powder should be very fine so they can mixeasily with the liquid.

5. It should not shrink on setting.

6. It should not stain tooth structure.

7. It should be bacteriostatic or at least not encourage bacterialgrowth.

8. It should set slowly.

9. It should be insoluble in tissue fluids.

10. It should be tissue-tolerant, that is nonirritating to periradiculartissue.

11. It should be soluble in a common solvent in case removal ofthe root canal filling becomes necessary.


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The most popular sealers are grouped by

type:

Zinc oxide-eugenol formulations,

Calcium hydroxide sealers,

Glass- ionomers, and

Resins.Regardless of the sealer selected, all aretoxic until they set. For this reason, extrusionof sealers into the periradicular tissuesshould be avoided.


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Zinc oxide-eugenol and resin sealers have ahistory of successful use over an extendedperiod. Zinc oxide-eugenol sealers have the

advantage of being resorbed if extruded intothe periradicular tissues .

Calcium hydroxide sealers were recentlyintroduced for their potential therapeuticbenefits. In theory these sealers exhibit an

antimicrobial effect and have osteogenicpotential. Unfortunately these actions have notbeen demonstrated, and the solubility requiredfor release of calcium hydroxide and sustainedactivity is a distinct disadvantage.

Glass ionomers have been advocated for usein sealing the radicular space because of theirdentin bonding properties. A disadvantage istheir difficult removal if retreatment is required.


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Sealers containing paraformaldehyde arecontraindicated in endodontic treatment.

Although the lead and mercurycomponents have been removed fromthe formulations over time, theparaformaldehyde content has remained

constant and toxic. These sealers are notapproved by the U. S. Food and DrugAdministration.


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Controversy surrounds removal of the smear

layer before obturation. The smear layer is

created on the canal walls by manipulationof the files during cleaning and shaping

procedures. It is composed of inorganic and

organic components that may contain

bacteria and their by-products. In theory

remnants left on the canal wall may serve asirritants or substrates for bacterial growth or

interfere with the development of a seal

during obturation. Although fluid movement

may occur in obturated canals, bacterial

movement does not appear to take place.Recent evidence suggests that removal of

the smear layer can enhance penetration of

the sealer into the dentinal tubules.


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Removal of the smear layer can beaccomplished after cleaning and shaping

by irrigation with 17%ethylenediaminetetraacetic acid (EDTA)for 1 minute. Irrigation should be followedwith a final rinse of sodium hypochlorite.


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Acceptable methods of placing the sealer inthe canal include the following:

Placing the sealer on the master coneand pumping the cone up and down inthe canal

Placing the sealer on a file and spinning

it counter clockwise Placing the sealer with a lentulo spiral

Using a syringe

Activating an ultrasonic instrument

The clinician should use care when placingsealer in a canal with an open apex toavoid extrusion.


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Core Obturation Materials

Historically, a variety of materials havebeen employed to obturate the rootcanal, falling into three broad categories:

solids,

semisolids, and

Pastes(sealers)


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Sealers

A wide variety are available. The calciumhydroxide materials (e.g. Sealapex) or theeugenol-based sealers (e.g. Tubliseal) are perhapsthe safest choice. Some would advocate theroutine use of non-setting calcium hydroxide paste(Hypocal) as an inter-appointment medicament.

Calcium hydroxide This is considered separately,because it has a wide range of applications inendodontics due to its antibacterial propertiesand an ability to promote the formation of acalcific barrier. The former is thought to be due toa high pH and also to the absorption of carbon

dioxide, upon which the metabolic activities ofmany root-canal pathogens depend. It is alsoproteolytic.


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Indications for the use of calcium

hydroxide include:

To promote apical closure in immatureteeth.

In the management of perforations.

In the treatment of resorption.

As a temporary dressing for canalswhere filling has to be delayed. In themanagement of recurrent infectionsduring RCT.


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Solid materials

Silver cones met many of the criteria forfilling materials but suffered from severaldeficiencies. The rigidity that made themeasy to introduce into the canal alsomade them impossible to adapt to the

inevitably irregular canal preparation,encouraging leakage. When leakageoccurred and the points contacted tissuefluids, they corroded, further increasing

leakage.


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Semisolid material

Gutta-percha, a semisolid material, is the mostwidely used and accepted obturating material.Gutta-percha is a natural product that consistsof the purified coagulated exudate of mazerwood trees (Isonandra percha) from the Malay

archipelago or from South America. Typical composition of gutta-percha cones.


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Gutta-percha does not adhere to the canalwalls, regardless of the filling techniqueapplied, resulting in the potential formarked leakage. Therefore, it is generallyrecommended that gutta-percha (usedcold or heated) is used together with a

sealer. For an optimal seal the sealer layershould generally be as thin as possible.


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Root filling techniques

Solid core techniques

Single coneSimpleQuick Good length control Round standard preparation required

Lateral compaction Good length control

Not one compact mass of gutta-perchaTime-consuming technique Supposed risk of root fracture

Softened core techniques Warm lateral compaction Moderate length control

Time-consuming t chnique Heat may damage periodontium Warm vertical compaction Poor length controlSealer extrusion Heat may damage periodontium

Injection-molded gutta-perchaQuick technique Poor length control

Heat may damage periodontium Thermomechanical compactionQuick technique Poor length control Heat may damage periodontium Instrument fracture risk Core carrier

Quick techniqueSealer extrusion Gutta-percha may be stripped offcarrier in curvature Difficult to remove for retreatment In combination with posts, inconvenienttechnique Chloroformresin

Quick technique Potential health hazard effects ondental personnel with long-termuse


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Root canal filling technique.

Solid core technique

Single cone

The single-cone technique consists of matchinga cone to the prepared canal. For thistechnique a type of canal preparation isadvocated so that the size of the cone and the

shape of the preparation are closely matched.When a gutta-percha cone fits the apicalportion of the canal snugly, it is cemented inplace with a root canal sealer. Although thetechnique is simple, it has severaldisadvantages and cannot be considered as

one that seals canals completely. Afterpreparation, root canals are seldom roundthroughout their length, except possibly for theapical 2 or 3 mm. Therefore, the single-conetechnique, at best, only seals this portion.


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Cold lateral condensation This is a commonly

taught method of obturation and is the goldstandard by which others are judged.

The technique involves placement

of a master point chosen to fit

the apical section of the canal.

Obturation of the remainder is

achieved by condensation of

smaller accessory points. Thesteps involved are:


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1. Select a GP master point to correspond with the masterapical file instrument. This should fit the apical region snugly atthe working length so that on removal a degree of resistance or

'tug-back' is felt. If there is no tug-back select a larger point orcut 1 mm at a time off the tip of the point until a good fit isobtained. The point should be notched at the correct workinglength to guide its placement to the apical constriction.

2 . Take a radiograph to confirm that the point is in correct

position if you are in any doubt. 3. Coat walls of canal with sealer using a small file.

4. Insert the master point, covered in cement.

5 . Condense the GP laterally with a finger spreader to providespace into which accessory points can be inserted until thecanal is full.

6. Excess GP is cut off with a hot instrument and the remainderpacked vertically into the canal with a cold plugger.


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Sketch showing a cross-sectional cut through

a root canal filled with a master cone andmultiple accessory cones


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Warm lateral condensation As above, butuses a warm spreader after the initial cold

lateral condensation. Finger spreaderscan be heated in a flame or a specialelectronically heated device (Touch ofheat) can be used.


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Vertical condensation

In this technique the GP is warmed using aheated instrument and then packedvertically. A good apical stop is necessaryto prevent apical extrusion of the filling,but with practice a very dense root fillingcan result. Time consuming.


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Diagram of the warm vertical condensation technique.

A, After a heated spreader

is used to remove the coronal

segment of the master cone,

a cold plugger is used to apply

vertical pressure to the softened

master cone.

B, Obturation of the coronal

portion of the canal is

accomplished by adding a gutta

-percha segment.

C, A heated spreader is used to

soften the material.

D, A cold plugger is then used

to apply pressure to the

softened gutta-percha.


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Thermomechanical compaction This involves areverse turning (e.g. McSpadden compactor or GP

condenser) instrument which, like a reverseHedstroem file, softens the GP, forcing it ahead of,and lateral to the compactor shaft. This is a veryeffective technique, particularly if used inconjunction with lateral condensation in the apical

region, but requires much practice to perfect. Thermoplasticized injectable GP (e.g. Obtura, Ultrafil)

These commercial machines extrude heated GP (70-160C) into the canal. It is difficult to control theapical extent of the root filling, and somecontraction of the GP occurs on cooling. Useful forirregular canal defects, e.g. following internal rootresorption.


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Coated carriers (e.g. Thermafil) These arecores of metal or plastic coated with GP. They

are heated in an oven and then simplypushed into the root canal to the correctlength. The core is then severed with a bur. Adense filling results, but again apical control ispoor and extrusions common. They are

expensive and difficult to remove. Once the filling is in place the tooth will need

to be permanently restored, provided thefollow-up radiograph is satisfactory. Fillingsthat appear inadequate radiographically

may be reviewed regularly, or replaced,depending upon the clinical circumstances.


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THE CORONAL SEAL

Regardless of the technique used to obturate the canals,coronal microleakage can occur through seemingly well-

obturated canals within a short time, potentially causing

infection of the periapical area. A method to protect

the canals in case of failure of the coronal restoration is to cover

the floor of the pulp chamber with a lining of glass ionomercement after the excess gutta-percha and sealer have beencleaned from the canal. Glass ionomers have the intrinsic abilityto bond to the dentin, so they do not require a pretreatmentstep. The resin-modified glass ionomer cement is simply flowedapproximately 1 mm thick over the floor of the pulp chamber

and polymerized with a curing light for 30 seconds. Investigatorsfound that this procedure resulted in none of the experimentalcanals showing leakage


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Thank you for your attention

root canal filling materials

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