Ass.Prof.Dr.Mohamed ALsakkafAss.Prof.Dr.Mohamed ALsakkaf 11

Obturation Of Root Canal System

.It is essential, that endodontic therapy must include sealing of the root canal system to prevent tissue fluids from percolating in the root canal and prevent toxic by – products from both necrotic tissue and microorganisms regressing into the periradicular tissue.

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.The current accepted method of obturation of prepared canals employs a solid or a semisolid core such as gutta – percha and root canal sealer.

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The Objectives Of Obturation

1.To prevent percolation of periradicular exudate into the pulp space via the apical foramina and / or lateral and furcation canals.

2 .To prevent percolation of gingival exudate and microorganisms into the pulp space via lateral canals opening into the gingival sulcus.

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3 .To prevent microorganisms left in the canal after preparation from proliferating and escaping into the periradicular tissue via the apical foramina or / and lateral canals.

4 .To seal the pulp chamber and canal system from leakage via the crown in order to prevent passage of microorganism and / or toxins along the root canal filling and into the periradicular tissue via the apical foramina and / or lateral canals.

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.So the quality of canal obturation depends on :

-The complexity of the canal system.

-The quality of canal preparation.

The materials to be used.

-The skills of the operator.

-The restoration of the clinical crown to prevent leakage into the pulp chamber (Is obturation the final step in R.C.T?).

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Timing Of Obturation

.The canal obturation may be delayed for one or more visits after preparation to give time for medicaments sealed into the canals to reduce or eliminate the microbial population and for the patients signs specially in complex cases.

.Teeth with little or no problems can be prepared and filled in one appointment.

Prerequisites for Filling the Root CanalPrerequisites for Filling the Root CanalA root canal can be obturated when:

There is no pain, swelling, tenderness to percussion, or fistulation associated with the tooth.

The instrumented canal is dry and free of odor (no exudates or purulent discharges into the canal)

If the pulp is necrotic or a periapical lesion is present, the root canal cannot be filled before the second appointment.

Teeth associated with procedural accident, perforation must not be filled until another treatment are made.

EXTENSION OF THE ROOT CANAL FILLINGEXTENSION OF THE ROOT CANAL FILLING

•Canals filled to the apical dentinocemental Canals filled to the apical dentinocemental junctionjunction

are filled to the anatomic limit of the canalare filled to the anatomic limit of the canal..

•Filling to the radiographic end of the Filling to the radiographic end of the root is actually root is actually overfillingoverfilling

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Complicated Cases:

1 .Teeth with signs of apical periodontitis (tenderness due percussion).

2 .Radiographic signs of apical periodontitis.

3 .Teeth with excessive exudate.

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4 .Teeth with purulent discharge.

5 .Teeth associated with a procedural accident, like perforation.

Note: Some teeth with these problems can be treated in one visit.

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Materials Used For Obturation

.A large number of materials have been used to obturate R.C.S ranging from orange wood sticks through precious metals to dental cements, but most materials that showed a wild world usage are the Gutta – Percha and sealers.

Root Canal Filling MaterialsRoot Canal Filling Materials

Core materialCore material::

.a.aSolid materials : Silver pointSolid materials : Silver point

.b.bSemisolid materials: Semisolid materials: GuttaperchaGuttapercha..

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Sealers: A root canal sealer is used in combination with root filling materials (gutta – percha). Now the sealer has a primary role in sealing the canal by obliterating the irregularities between the canal wall and the core material.

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Why We Use Sealers?

Root canal sealers are used with core filling materials for the following:

1 .Cementing (luting) the core material into the canal.

2 .Filling the discrepancies between the canal walls and the core material.

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3 .It acts as a lubricant to help in positioning of core material.

4 .Bactericidal agent.

5 .Acting as a marker for accessory canals, resorptive defects, and other spaces into which the main core material may not penetrate.

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Requirement Of An Ideal Sealer

a. Non – irritating to periapical tissue.

b. Insoluble in tissue fluids.

c. Dimensionally stable.

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d. Hermetic sealing ability.

e. Radiopaque.

f. Bacteriostatic.

g. Sticky and good adhesion to canal walls when set.

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h. Easily mixed.

i. Non – staining to dentin.

j. Good working time.

k. Readily removable if necessary.

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Note:

1 .There is no single material that satisfy all requirements.

2 .Sealers are toxic and cause periapical irritation when freshly prepared but this reduced after setting.

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3 .Most sealers are absorbable, so the volume must be minimum.

4 .Less viscous sealer should be forced by core material into canal anastomoses.

5 .Excess sealer should ideally flow backwords out of the canal orifice.

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Types of Sealer

Sealers in use today can be divided into four groups based on their constituents.

1 .Zinc Oxide – eugenol sealers: Commercial products include: Tubliseal, Pulp canal sealer, Roth sealer.

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Properties:

.Once set ZOE sealers form relatively weak materials, which are susceptible to decomposition.

.Potential for sensitization.

.Mutagenic in extremely high doses.

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-These problems are not apparent clinically.

-They are probably used more often than all the other sealer combined and give good results.

-The products have a range of setting time and flow properties to satisfy filling difficult canals (slow set).

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2. Calcium hydroxide sealers:

The commercial products involve: Sealapex, a calcium hydroxide – containing polymeric resin, and Apexit.

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Properties:

.They preserve the vitality of the pulp stump and stimulate healing of hard tissue formation at the foramen.

.Sealing ability is similar to ZOE.

.Soluble and may leach out and weaken the remaining cement when expose to tissue fluid.

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3. Resin Sealers:

Like AH26 which consists of an epoxy resin, which set slowly when mixed with an

activator .

Properties:

.Less popular than ZOE and Ca(OH)2.

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.Good sealing and adhesive properties.

.It has antibacterial activity.

.Give an initial severe irritation, which subsides after some weeks.

.Strong mutagenic potential, which causes allergy and paraesthesia.

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4. Glass Ionomer Sealers:

The products include: Ketac, Endo, Espe, Seefeid.

Properties:

.Ability to adhere to dentine.

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.Less effective or no difference in the apical sealing properties when comparing with others.

.Less coronal leakage, than ZOE.

.Shear bond strength to Gutta – Percha is similar to ZOE sealers.

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Gutta – Percha:

.It is the most widely used and acceptable obturating material.

.G.P is a form of rubber obtained from a number of tropical trees. It is transpolyisoprene, which in its pure form is hard, brittle and less elastic than natural

rubber .

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.It is mixed with variety of other materials to produce a blend G.P (19 – 22%), zinc oxide (59 – 75%) and various waxes, coloring agents, antioxidants and metal salts to provide radiopacity.

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Advantages Of G.P:

1 .Inert.

2 .Dimensionally stable.

3 .Non – allergic.

4 .Antibacterial.

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5 .Non – staining to dentine.

6 .Radiopaque.

7 .Softened by heat.

8 .Softened by organic solvents.

9 .Removable from the R.S.C when necessary.

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Disadvantages Of G.P:

1 .Lack of rigidity.

2 .Do not adhere to dentine.

3 .Can be stretched.

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Obturation Techniques

.There are two main techniques:

1 .Lateral Condensation (Cold).

2 .Vertical Condensation (Hot).

Methods for Guttapercha Methods for Guttapercha ApplicationApplication

•Lateral CondensationLateral Condensation..

•Vertical CondensationVertical Condensation..

•Thermomechanical CondensationThermomechanical Condensation..

•Injection TechniquesInjection Techniques

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1 .Lateral Condensation:

.This technique is the most popular one.

.The core of this technique is placing tapered Gutta – Percha cones in the canal and then compacting them against the canal walls under pressure by using spreader.

IT IS THE MOST POPULAR TECHNIQUE OF IT IS THE MOST POPULAR TECHNIQUE OF OBTURATIONOBTURATION..

•INDICATIONS:INDICATIONS: Lateral Condensation of Lateral Condensation of gutta-percha may be used in most cases, gutta-percha may be used in most cases, exception: severely curved or abnormally exception: severely curved or abnormally

shaped canals or those with gross shaped canals or those with gross irregularities such as internal resorptionirregularities such as internal resorption..

Three dimensional filling of the canal is Three dimensional filling of the canal is obtained and bacterial tight seal obtained and bacterial tight seal . .

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Steps:1 .After the R.C preparation finished, select

master Gutta – Percha. Cone whose size is the same with the largest file used up to the working length. One should feel the tugback with master gutta – percha point. It should be notched at working distance analogous to the level of incisal or occlusal edge reference .

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2 .Radiographically make sure that the cone is fit. Remove the cone if it fit and insert it in NaOCL .

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If the cone is going beyond the foramen, so select the larger number cone or cut it to the WL.

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3 .Select the size of spreader to be used for L.C. It should reach 1 – 2mm of true WL.

The cement (sealer) is mixed and given The cement (sealer) is mixed and given the spatula test to determine the desired the spatula test to determine the desired consistency (must be soft)consistency (must be soft)..

The apical half of the master point (except The apical half of the master point (except the tip) is coated with sealer and inserted the tip) is coated with sealer and inserted into the canal to the predetermined depthinto the canal to the predetermined depth..

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4 .Dry the canal using paper point and apply sealer into the prepared R.C.

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5 .The nominated and premeasured cone is coated with sealer and place into the R.C. After placement of cone, a selected spreader is placed into the canal alongside the cone .

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Spreader acts as a wedge to squeeze the G.P laterally under vertical pressure not by pushing it sideways.

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6 .Spreader then removed from the canal by rotating it back and forth. This compacts the G.P and provide space lateral to the master cone.

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7 .Place in the created space beside the master cone an accessory one, and repeat the same procedure until the spreader longer cannot penetrate beyond the cervical line.

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8 .Protruding G.P points at canal orifice should be removed by using hot instrument.

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Advantages Of L.C Technique

a. It can by used widely in most cases.

b. It prevent overfilling by length control during condensation.

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Disadvantages

a. May not fill the canal irregularities efficiently.

b. Does not provide homogenous mass.

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C. Space may exist between master and accessory cones.

Warm Lateral CondensationWarm Lateral Condensation It is a variant of traditional lateral condensation It is a variant of traditional lateral condensation

and and is especially indicated is especially indicated for teeth with internal for teeth with internal resorptive defectsresorptive defects

•A heated instrument is introduced into a tooth already A heated instrument is introduced into a tooth already obturated by lateral condensation to soften the gutta-obturated by lateral condensation to soften the gutta-percha mass and enhance adaptation to the internal percha mass and enhance adaptation to the internal anatomy of the canalanatomy of the canal..

•The Endotec instrument is then activated for 4 to 5 The Endotec instrument is then activated for 4 to 5 seconds and moved in short, continuous motions in and seconds and moved in short, continuous motions in and out of the gutta-percha massout of the gutta-percha mass..

•A cold spreader is introduced and rotated to condense A cold spreader is introduced and rotated to condense the thermoplasticized gutta-percha into the the thermoplasticized gutta-percha into the canal canal anatomyanatomy

•Accessory points coated with sealer are then added until Accessory points coated with sealer are then added until the canal is completely obturatedthe canal is completely obturated..

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2. Vertical Condensation

.Vertical Condensation by using warm G.P cones to fill the R.C is known as Schilders technique.

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.Because in the R.C.S may present many lateral and accessory canals, which make the R.C complex, the use of the heated G.P cones, will be helpful in the filling of these accessory canals, by maximum amount of G.P and minimum amount of sealer.

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This technique requires the following:

a) Continuous tapering funnel shape from orifice to apex.

b) Apical opening kept as small as possible.

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c) Decreasing the cross sectional diameter at every point apically and increasing at each point coronally.

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Steps: 1 .After selection the master cone

according to shape and size of the prepared canal, be sure that the cone fit in 1 – 2mm of apical stop, to avoid moving the heated cone apically.

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2 .Radiographically confirm the fit of the cone, if fit, remove it and insert in NaOCL.

3 .Irrigate and dry the canal.

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4 .Select the instrument for heating (Plugger) according to the shape of canal.

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5 .Apply little amount of sealer into the canal.

6 .Cut the coronal end

of selected G.P at canal orifice. '

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7 .Heat the plugger and force the G.P by it into the canal. The blunted end of plugger provides a depression in the center of master cone. The outer walls of G.P then folded inward to fill the central void, at the same time mass of softened G.P is moved apically, and laterally. This procedure also removes 2 – 3mm of coronal part of G.P.

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8 .After completing apical filling, complete obturation by backfilling. Obturate the remaining canal by heating small segments of G.P and condense them by heated plugger.

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9 .Do not apply sealer on the softened G.P, this will prevents their adherence to G.P present in the canal.

10 .Finally clean the pulp chamber with alcohol to remove the remnants.

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Advantages Of Vertical Condensation:

Good sealing of canal apically, laterally and obturation of accessory canals.

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Disadvantages

a) Risk of vertical root fracture.

b) Overfilling.

c) Time consuming.

Thermoplastic Injection Thermoplastic Injection TechniqueTechnique

•Gutta-percha heated toGutta-percha heated to70 °C (158 °F) is injected 70 °C (158 °F) is injected into the root canal by means of a Peripress into the root canal by means of a Peripress syringe, and is supposed to fill all ramificationssyringe, and is supposed to fill all ramifications..

•Ampules containing gutta-percha are heated for Ampules containing gutta-percha are heated for 15 minutes in the apparatus to plasticize the 15 minutes in the apparatus to plasticize the guttaperchaguttapercha..

•A short A short cannula with a diameter of 0.7 mm is cannula with a diameter of 0.7 mm is attached to each ampuleattached to each ampule..