endodntic access

7/28/2019 Endodntic Access

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ENDODONTICCAVITY PREPARATION

By

Dr.Mohamed khalefa

Prof. Of endodontics

Al-Azhar University.


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ENDODONTIC

CAVITY PREPARATION

Divided into:

* Intra-Coronal preparation.

* Intra-Radicular preparation.


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Endodontic cavity preparation

Objectives:

1) Obtaining direct line access

to both RC orifices & Apical

foramen.

2) Conservation of tooth

structure.

3) Reroofing of the Pulp

chamber.


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1) Intra-Coronal Cavity Preparation.


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Principles of Intra-Coronal Cavity

Preparation:

(I): Out line Form.

(II): Convenience Form.

(III): Removal of Remaining

Carious Dentin &

Defective Restorations.

(IV): Toilet of the Cavity.


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Principle I: Outline Form:

Endodontic cavity is correctlyshaped & positioned to establish

complete access for instrumenta-

tion from cavity margin to theapical foramen.


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N.B.

External outline form is established

by mechanically projecting the internal

anatomy of the pulp into

the external surface of the tooth.


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Factors affecting Outline Form

1) Size of the pulp chamber.

2) Shape of the pulp chamber.

3) Number, Position &

Curvature or Direction

of each individual root canal

4) Age of the patient.


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Principle II: Convenience Form:

I .e. Modification of theCavity Outline Form to

establish greater conven-

-ience in preparation aswell as obturation of the

root canals.


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Benefits of Convenience Form:

1) Unobstructed access to thecanal orifice & searching for

extra canal.

2) Direct access to the apicalforamen.

3) Complete authority over the

enlarging instruments.

4) Cavity expansion to accommodate

filling techniques


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Principles III: Removal of the Remaining

Carious Dentin & Defective Restorations:

I .e.All carious & loosed or fracturedrestorations must be removed &

the cavity is sealed with hardrestoration before Endodontic

cavity preparation is established.


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Benefits of Removal of Carious Dentin

& Defective Restorations:1) To eliminate mechanically as many micro-organismsas possible from the interior of the tooth.

2) To eliminate the discolored tooth structure.

3) To eliminate the possibility of micro-organisms coming

with saliva leakage through defective restoration.

4) To avoid detached tooth or restoration particles from

entering & closing the root canal.


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Principle IV: Toilet of the cavity:

(Irrigation of the Cavity)

All the detached carious dentin, debris & necrotic

material must be removed from the pulp chamber

before the Radicular preparation is begun because

they may:

1) Obstruction of the canal during enlargement.

2) Increase bacterial possibilities in the canal(RCs infection).

3) Discoloration of the crown.


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Access Cavity

Preparation

for Anterior

Teeth

(Step by Step)


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Maxillary Incisors


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Mandibular Incisors


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Maxillary Cuspid (Canine)


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Mandibular Cuspid (Canine)


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-Maxillary & Mandibular premolar : the outlineform prepared in the center of the occlusal surface

as OVAL shape .


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Maxillary molars The access preparation on the occlusal surface as a triangular

shape , with the base toward the buccal surface and the apex

toward the palatal surface .

The first penetration of enamel is made using round bur at the

central groove midway between the mesial marginal ridge & the

oblique ridge and the roof of the pulp chamber is removed

completely . The access preparation is to be enlarged to accommodate the

fourth canal in the MB root .


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Mandibular molars :The access preparation on the occlusal surface as a

triangular shape in case of 3 canals ,or rectangular shape

in case of 4 canals . The base of the triangle is towared themesial surface and the apex toward the distal .


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AccessPreparation

AccessOpening

ENDO ACCESS BUR(Dr Howard Martin)

Grain : Coarse

Shank : FG


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AccessPreparation

Access Opening

Orifice Location

Pathfinder orendodontic

explorer is used forReaching, Feeling,and Digging atcanal opening.

Orifice Loction :


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Errors in coronal cavity preparation of

maxillary & mandibular anterior teeth :

1-discoloration of the crown which caused by

failure to remove pulp debris .

2- failure to explore the second canal which

caused by inadequate inciso-cervical extension of

coronal cavity .

3-perforation at the labio-cervical caused byfailure to complete extension towered incisally .

4- gouging of labial & distal wall caused by failureto correct angulations of bur during access cavity.

5- ledge formation at apico-distal curvecausedbyusing incurved instruments .


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Errors in cavity preparation of maxillary &

Mandibular premolars

1- Under or over extended preparation .

2- perforation at mesio-cervical indentation .

3-failure to explore second or third canal .

Molar teeth1- Perforation into furcating region .

2- failure to detect fourth canal .

3-perforation at mesio-cervical caused by failure

to orient bur with long axis of molar severelytipped to mesial .


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