Dr. Mohammed Mustafa

ContentsContents IntroductionIntroduction Definition of access cavity preparationDefinition of access cavity preparation Objectives Objectives Rules Rules Principles of endodontic cavity preparationPrinciples of endodontic cavity preparation Anatomy of pulp-chamber floorAnatomy of pulp-chamber floor Canal configurationsCanal configurations ArmamentariumArmamentarium Access preparation guide linesAccess preparation guide lines Individual tooth access-cavity preparationsIndividual tooth access-cavity preparations Errors in cavity preparationsErrors in cavity preparations Aids in locating canalsAids in locating canals Clues in locating extra-canalsClues in locating extra-canals Conclusion.Conclusion.

INTRODUCTIONINTRODUCTION INTRODUCTIONINTRODUCTION

“It is the efficient uncovering the roof of the

pulp chamber & providing the direct access to

the apical foramina by the way of the pulp

canals”.

According to R.E. Walton, the 3 main objectives

of access cavity preparation are :

1.  Straight line access : Helps in

a.  Improved instrument control.

b.  Improved obturation.

c.  Decreased procedural errors.

2.  Conservation of tooth structure : Helps in

a.  Minimal weakening of tooth.

b.  Prevention of perforation.

3.  Un roofing of chamber and exposure of pulp

horns : Help in

a.  Maximum visibility.

b.  Location of canals.

1.1. The objective of entry is direct access to apical The objective of entry is direct access to apical

foramina, not merely to the canal orifices.foramina, not merely to the canal orifices.

2.2. Access cavity preparations Access cavity preparations operative occlusal operative occlusal

preparations. preparations.

3.3. Interior anatomy of the tooth. Interior anatomy of the tooth.

Rules for proper access preparation Rules for proper access preparation (Franklin S. Weine)(Franklin S. Weine)

4.4. Rubber dam – when canals difficult to find the Rubber dam – when canals difficult to find the

rubber dam should not be placed until correct rubber dam should not be placed until correct

location has been confirmed.location has been confirmed.

5.5. Endodontic entries are prepared through the Endodontic entries are prepared through the

occlusal or lingual surface – never through the occlusal or lingual surface – never through the

proximal or gingival surface. proximal or gingival surface.

6.6. Unsupported cuspsUnsupported cusps

Principles of Endodontic Cavity Principles of Endodontic Cavity Preparation Preparation

Endodontic Endodontic Coronal Coronal Cavity Preparation :Cavity Preparation :

I. I. Outline FormOutline Form

II. II. Convenience FormConvenience Form

III.III. Removal of the remaining carious dentin and Removal of the remaining carious dentin and

defective restorations.defective restorations.

IV.IV. Toilet of the cavityToilet of the cavity

Principle I: Outline FormPrinciple I: Outline Form

The outline form of the endodontic cavity must be The outline form of the endodontic cavity must be

correctly shaped and positioned correctly shaped and positioned

Establish complete access for instrumentation, Establish complete access for instrumentation,

from cavity margin to apical foramenfrom cavity margin to apical foramen

External outline form = internal anatomy of pulpExternal outline form = internal anatomy of pulp

Internal-external relationship.Internal-external relationship.

Three factors ofThree factors ofinternal anatomy must be consideredinternal anatomy must be considered

(1) Size of the pulp (1) Size of the pulp

chamber, chamber,

(2) Shape of the pulp (2) Shape of the pulp

chamber,chamber,

(3) Number of individual (3) Number of individual

root canals, their root canals, their

curvature, and their curvature, and their

position.position.

Principle II: Principle II: Convenience form:Convenience form:

(1) Unobstructed access to (1) Unobstructed access to the canal orifice, the canal orifice,

(2) Direct access to the (2) Direct access to the apical foramen, apical foramen,

(3) Cavity expansion to (3) Cavity expansion to accommodate filling accommodate filling techniques, and techniques, and

(4) Complete authority (4) Complete authority over the enlarging over the enlarging instrument.instrument.

Principle III: Removal of the Remaining CariousPrinciple III: Removal of the Remaining CariousDentin and Defective RestorationsDentin and Defective Restorations

This according to Ingle, must be done for three This according to Ingle, must be done for three reasons:reasons:

(1) To eliminate mechanically as many bacteria as (1) To eliminate mechanically as many bacteria as possible from the interior of toothpossible from the interior of tooth

(2) To eliminate discoloration of tooth structure(2) To eliminate discoloration of tooth structure

(3) To eliminate the possibility of any bacteria- (3) To eliminate the possibility of any bacteria- laden saliva leaking into the prepared cavity.laden saliva leaking into the prepared cavity.

Principle IV: Toilet of the Principle IV: Toilet of the CavityCavity

All of the caries, debris, All of the caries, debris, and necrotic material and necrotic material must be removed. must be removed.

before the radicular before the radicular preparation is begun.preparation is begun.

0bstruction, bacterial 0bstruction, bacterial growth.growth.

Anatomy of the pulp chamber floorAnatomy of the pulp chamber floorJOE, Jan 2004, Vol.30.JOE, Jan 2004, Vol.30.

Two Categories of anatomic patterns were observed:Two Categories of anatomic patterns were observed:

1.1. Relationships of pulp chamber to the clinical crownRelationships of pulp chamber to the clinical crown

2.2. Relationship of the orifices on the pulp chamber Relationship of the orifices on the pulp chamber floor.floor.

Relationships of pulp chamber Relationships of pulp chamber to the clinical crownto the clinical crownThe following observations were noted:The following observations were noted:

Pulp chamber was always in the center of the Pulp chamber was always in the center of the tooth at the level of CEJtooth at the level of CEJ

The walls of the pulp chamber were always The walls of the pulp chamber were always concentric to the external surface of the concentric to the external surface of the crown at the level of the CEJ.crown at the level of the CEJ.

The distance from the external surface of the The distance from the external surface of the clinical crown to the wall of the pulp chamber clinical crown to the wall of the pulp chamber was the same throughout the circumference of was the same throughout the circumference of the tooth at the level of the CEJ.the tooth at the level of the CEJ.

These observations were consistent enough These observations were consistent enough that several that several anatomic lawsanatomic laws could be could be formulated:formulated:

Law of centralityLaw of centrality - the floor of the pulp - the floor of the pulp chamber is always located in the center of chamber is always located in the center of the tooth at the level of CEJ. the tooth at the level of CEJ.

Law of concentricity Law of concentricity – the walls of the pulp – the walls of the pulp chamber are always concentric to the chamber are always concentric to the external surface of the tooth at the level of external surface of the tooth at the level of the CEJ the CEJ

Law of CEJLaw of CEJ – the CEJ is the most consistent, – the CEJ is the most consistent, repeatable landmark for locating the position repeatable landmark for locating the position of the pulp chamber of the pulp chamber

Relationship on the pulp- Relationship on the pulp- chamber floor:chamber floor:The following observations were noted The following observations were noted relative to all teeth.relative to all teeth.

1.1. The floor of the pulp chamber is always a The floor of the pulp chamber is always a darker colordarker color than the surrounding dentinal than the surrounding dentinal walls.walls.

2.2. This This color differencecolor difference creates a distinct creates a distinct junction where the walls and the floor of the junction where the walls and the floor of the pulp chamber meet.pulp chamber meet.

3.3. The orifices of the root canal are always The orifices of the root canal are always located at the located at the junctionjunction of the walls and of the walls and floor.floor.

4.4. The orifices of the root canals are located at The orifices of the root canals are located at the the anglesangles in the floor wall junction. in the floor wall junction.

The orifices lay at the terminals of the The orifices lay at the terminals of the developmental root fusion lines if developmental root fusion lines if present.present.

The developmental root fusion lines The developmental root fusion lines are darker than the floor color.are darker than the floor color.

Reparative dentin or calcifications are Reparative dentin or calcifications are lighter than the pulp chamber floor lighter than the pulp chamber floor and often obscure it and the orifices.and often obscure it and the orifices.

These observations were consistent enough that These observations were consistent enough that several several anatomic lawsanatomic laws regarding the pulp regarding the pulp chamber floor can now be proposed:chamber floor can now be proposed:

Law of symmetry 1Law of symmetry 1: Except for maxillary : Except for maxillary molars, the orifices of the canals are molars, the orifices of the canals are equidistantequidistant from a line drawn in a mesial distal direction from a line drawn in a mesial distal direction through the pulp chamber floor. through the pulp chamber floor.

Law of symmetry 2Law of symmetry 2: Except for the maxillary : Except for the maxillary molars, the orifices of the canals lie molars, the orifices of the canals lie on a lineon a line perpendicular to a line drawn in a mesial-distal perpendicular to a line drawn in a mesial-distal direction across the center of the floor of the pulp direction across the center of the floor of the pulp chamber. chamber.

Law of Color changeLaw of Color change: the color of the pulp : the color of the pulp chamber floor is always darker than the walls. chamber floor is always darker than the walls.

Law of orifice location 1Law of orifice location 1: the orifices of the : the orifices of the

root canals are always located at the junction of root canals are always located at the junction of

the walls and the floor. the walls and the floor.

Law of orifice location 2Law of orifice location 2: the orifices of the : the orifices of the

root canals are located at the angles in the floor root canals are located at the angles in the floor

wall junction. wall junction.

Law of orifice location 3Law of orifice location 3: the orifices of the : the orifices of the

root canals are located at the terminus of the root canals are located at the terminus of the

root development fusion lines. root development fusion lines.

According to Weine

CANAL CONFIGURATIONS

According to Vertucci

Armamentarium for Access Armamentarium for Access PreparationPreparation

1.1. Front surface mirrorFront surface mirror2.2. Endodontic explorer Endodontic explorer 3.3. Endodontic excavatorEndodontic excavator4.4. Plastic instrumentPlastic instrument5.5. Irrigating solutionsIrrigating solutions6.6. SpatulaSpatula

7. Cotton pliers 8. Broaches9. Glass slab10. Files & reamers11. Burs12. Rubber dam kit

Round burRound bur No. 2No. 2

– Mandibular anterior teethMandibular anterior teeth

– Maxillary premolar (narrow chambers & canals)Maxillary premolar (narrow chambers & canals)

– Incisal pulp horn area (Maxillary anterior teeth)Incisal pulp horn area (Maxillary anterior teeth)

No. 4No. 4– Maxillary anterior teethMaxillary anterior teeth

– Mandibular premolar teethMandibular premolar teeth

– Maxillary premolar teethMaxillary premolar teeth

– Maxillary and mandibular molarsMaxillary and mandibular molars

No. 6No. 6– Only in large pulp chamber of molars i.e., Only in large pulp chamber of molars i.e.,

TaurodontismTaurodontism

No. 1No. 1– Used in the floor of pulp chamber to seek additional Used in the floor of pulp chamber to seek additional

canal orifice.canal orifice.

Long shank, No. 701 or 558:Long shank, No. 701 or 558:– Round or safe tipped tapered fissure burRound or safe tipped tapered fissure bur

– 702U: Access cavity through restoration, full crown 702U: Access cavity through restoration, full crown and inlayand inlay

Access Preparation GuidelinesAccess Preparation GuidelinesI) I) First step - Diagnostic radiographFirst step - Diagnostic radiograph

visualization of the location of the pulp space. visualization of the location of the pulp space.

Buccolingual angulations and coronal anatomy are judged Buccolingual angulations and coronal anatomy are judged visually. visually.

In difficult situation - initial access be prepared without a In difficult situation - initial access be prepared without a rubber dam in place.rubber dam in place.

II)II) Restorative material impinging on the Restorative material impinging on the

straight-line access should be removed straight-line access should be removed before pulp chamber is accessed to prevent before pulp chamber is accessed to prevent lodging of debris in the canals.lodging of debris in the canals.

Caries is removed to prevent irrigating Caries is removed to prevent irrigating

solutions from leaking past the rubber dam solutions from leaking past the rubber dam into the mouth and to prevent bacterial into the mouth and to prevent bacterial contamination of the canal system with contamination of the canal system with saliva.saliva.

Place an interim restoration. Place an interim restoration.

A 1mm to 2mm of occlusal adjustment of A 1mm to 2mm of occlusal adjustment of teeth may be done.teeth may be done.

III)III) The roof of the pulp chamber is best perforated The roof of the pulp chamber is best perforated

with a round bur. with a round bur. A no.2 bur ( anterior and premolar teeth)A no.2 bur ( anterior and premolar teeth) A no. 4 bur should be used in molar teeth.A no. 4 bur should be used in molar teeth.

For teeth with porcelain crowns. For teeth with porcelain crowns.

The bur is best directed toward largest part of pulp The bur is best directed toward largest part of pulp chamber.chamber.

In calcified, multi-rooted teeth, it is better to direct In calcified, multi-rooted teeth, it is better to direct

the access toward the largest canal.. the access toward the largest canal..

IV)IV)

Once the pulp chamber is located (with light upward pressure), the Once the pulp chamber is located (with light upward pressure), the

round bur is used to remove the roof of the pulp chamber from round bur is used to remove the roof of the pulp chamber from

underneath; the “belly” of the bur should be used to cut on the underneath; the “belly” of the bur should be used to cut on the

outstroke. outstroke.

This should establish an initial outline form. This should establish an initial outline form.

The pulp chamber should be frequently flushed with sodium The pulp chamber should be frequently flushed with sodium

hypochlorite solution to remove debris and bacteria. hypochlorite solution to remove debris and bacteria.

V)V) A sharp DG 16 double ended explorer is used to locate canal orifices. A sharp DG 16 double ended explorer is used to locate canal orifices.

In heavily calcified teeth - transillumination, and the careful In heavily calcified teeth - transillumination, and the careful examination of internal dentin color. examination of internal dentin color.

Once the canals are located, a no.10 or no. 15 type of file is introduced Once the canals are located, a no.10 or no. 15 type of file is introduced into the canal to determine patency. into the canal to determine patency.

Tooth length may be determined at this point. Tooth length may be determined at this point.

VI)VI) Final outline form is established with a round tip, Final outline form is established with a round tip,

tapered, diamond bur after the canals have been tapered, diamond bur after the canals have been located and the initial opening has been completed. located and the initial opening has been completed.

This important outline form is dictated by the internal This important outline form is dictated by the internal anatomy and modified to improve visibility, establish anatomy and modified to improve visibility, establish convenience form and conserve critical tooth convenience form and conserve critical tooth structure. structure.

Pulp Canal Anatomy and Access Cavity Preparations

Endodontic Cavity Preparation Maxillary Anterior Teeth

Maxillary Central IncisorMaxillary Central Incisor

Pulp chamber: Pulp chamber: – Centrally located.Centrally located.– Broad mesio-Broad mesio-

distally.distally.– Broadest incisallyBroadest incisally– 3 pulp horns3 pulp horns

Root & Root canalRoot & Root canal Access opening:Access opening:

– Triangle in shape.Triangle in shape.

Maxillary Lateral incisorMaxillary Lateral incisor

Pulp chamberPulp chamber– Similar to central.Similar to central.– 2 pulp horns2 pulp horns

Root & root canalRoot & root canal Access openingAccess opening

– Triangular / ovoid Triangular / ovoid

Maxillary CanineMaxillary Canine Pulp chamberPulp chamber

– Largest among single Largest among single rooted teethrooted teeth

– Triangular Triangular (labiolingually) (labiolingually)

– Flame shaped Flame shaped (mesiodistally) (mesiodistally)

– 1 pulp horn1 pulp horn Root & root canalRoot & root canal Access openingAccess opening

– Ovoid Ovoid AnomaliesAnomalies

– Rarely 2 roots may be Rarely 2 roots may be present.present.

Endodontic Cavity Preparation in Mandibular Anterior Teeth

Mandibular Central and Lateral Incisors

Pulp chamberPulp chamber– Smallest in the arch.Smallest in the arch.– Flat (mesiodistally)Flat (mesiodistally)– Ovoid Ovoid

(labiolingually)(labiolingually)– 3 pulp horns3 pulp horns

Root & root canalRoot & root canal Access openingAccess opening

– Long oval Long oval (incisogingivally)(incisogingivally)

Mandibular Canine

Pulp chamberPulp chamber– More wide More wide

(labiolingually)(labiolingually) Root & root canalRoot & root canal Access openingAccess opening

– Ovoid Ovoid AnomaliesAnomalies

– Rarely more than 1 Rarely more than 1 canal and 1 root.canal and 1 root.

Endodontic Preparation of Maxillary Premolar Teeth

Maxillary First Premolar

Pulp chamberPulp chamber– Narrow (mesiodistally).Narrow (mesiodistally).– Wide (buccolingually)Wide (buccolingually)– 2 pulp horns (Buccal & 2 pulp horns (Buccal &

Palatal)Palatal)– Roof: Roof: – Floor:Floor:

Root & root canalRoot & root canal– 2 roots (i.e. Buccal & Palatal)2 roots (i.e. Buccal & Palatal)

Access openingAccess opening– Ovoid (buccolingually).Ovoid (buccolingually).– Slight occlusal divergenceSlight occlusal divergence– Border.Border.– Differ from (Class I)Differ from (Class I)

AnomaliesAnomalies– Rarely 3 root canalsRarely 3 root canals

Maxillary Second Premolar Pulp chamberPulp chamber

– Similar to 1Similar to 1stst premolar premolar

– 2 pulp horn.2 pulp horn.

– Single canal orifice.Single canal orifice.

Root & root canalRoot & root canal– Single rooted (90%)Single rooted (90%)

Access openingAccess opening– Ovoid (buccolingually)Ovoid (buccolingually)

AnomaliesAnomalies– Very rarely 3 root canals Very rarely 3 root canals

may be presentmay be present

Endodontic Preparation of Mandibular Premolar Teeth

Mandibular First Premolar Pulp chamberPulp chamber

– Transitional tooth.Transitional tooth.– Prominent buccal pulp Prominent buccal pulp

horn.horn.– 30° lingual tilt of crown.30° lingual tilt of crown.

Root & root canalRoot & root canal– Narrow (mesiodistally)Narrow (mesiodistally)– Broad (buccolingually)Broad (buccolingually)

Access openingAccess opening– Ovoid Ovoid – Upper 1/3Upper 1/3rdrd lingual lingual

incline of buccal cusp.incline of buccal cusp.

Mandibular Second Premolar Pulp chamberPulp chamber

– Prominent lingual pulp Prominent lingual pulp horn.horn.

Root & root canalRoot & root canal– Wider (mesiodistally)Wider (mesiodistally)

– Broad (buccolingually)Broad (buccolingually)

Access openingAccess opening– Ovoid Ovoid

– Widen (mesiodistally) to Widen (mesiodistally) to the wider pulp chamberthe wider pulp chamber

Endodontic Preparation of Maxillary Molar Teeth

Maxillary First Molar

Pulp chamberPulp chamber– Largest in dental Largest in dental

arch.arch.– 4 pulp horns.4 pulp horns.– Roof: rhomboidalRoof: rhomboidal

Root & root canalRoot & root canal– 3 roots and 3 canals3 roots and 3 canals

Access openingAccess opening– Rhomboidal Rhomboidal

Maxillary Second Molar

Pulp chamberPulp chamber– Similar to 1Similar to 1stst molar. molar.– Narrow Narrow

(mesiodistally)(mesiodistally) Root & root canalRoot & root canal

– 3 roots & 3 canals3 roots & 3 canals Access openingAccess opening

– Similar to 1Similar to 1stst molar molar with variations as with variations as anatomy dictates.anatomy dictates.

Endodontic Preparation of Mandibular Molar Teeth

Mandibular First Molar

Pulp chamberPulp chamber– 4 pulp horns.4 pulp horns.– Roof: rectangularRoof: rectangular– Floor: rhomboidalFloor: rhomboidal

Root & root canalsRoot & root canals– Usually 2 roots & 3 Usually 2 roots & 3

canalscanals Access openingAccess opening

– Trapezoidal or Trapezoidal or rectangular (if 2rectangular (if 2ndnd distal canal present).distal canal present).

Mandibular Second Molar

Pulp chamberPulp chamber– Same as 1Same as 1stst molar. molar.

Root & root canalsRoot & root canals– Usually 2 roots & 3 Usually 2 roots & 3

canalscanals Access openingAccess opening

Trapezoidal or Trapezoidal or rectangular (if 2rectangular (if 2ndnd distal canal present).distal canal present).

ERRORS IN CAVITY PREPARATIONERRORS IN CAVITY PREPARATION : :

1. Perforations : caused due to failure to recognize

inclinations; depth of pulp chamber; assuming canal is

straight.

2. Gouging , overextension : caused due to failure to

recognize inclinations; unsuccessful search for canals or

receded pulp.

3. Under extension : Entire roof of pulp chamber not

removed, lingual shoulder not removed leading to curved

access.

4. Ledge : caused due to loss of instrument control.

5. Discoloration : incomplete removal of pulp debris.

6. Missed canals : due to small access cavity.

7. Broken Instruments : occurs in curved canals due to

failure in extending outline/internal prep.

Aids in locating canalsAids in locating canals

Presence of dark lines on the floor of the pulp Presence of dark lines on the floor of the pulp chamber(dentinal map).chamber(dentinal map).

A drop of iodine on the floor of the pulp chamber.A drop of iodine on the floor of the pulp chamber.

Use of fiber optic on buccal or lingual surface, Use of fiber optic on buccal or lingual surface, either directly or indirectly.either directly or indirectly.

Magnification and illuminationMagnification and illumination

Clues in locating extra canals Clues in locating extra canals RADIOGRAPHICALLY:RADIOGRAPHICALLY:

1.1. Short bulky roots.Short bulky roots.

2.2. Sharp change in Sharp change in

radiographic density of radiographic density of

root canal space.root canal space.

3.3. Unclear outline or Unclear outline or

unusual contour of any unusual contour of any

root.root.

4.4. Dark shadow running Dark shadow running

nearly parallel to a file in nearly parallel to a file in

a root canal space.a root canal space.

Clues in locating extra root canals – ClinicallyClues in locating extra root canals – Clinically

conclusionconclusion

An Access An Access A foundation to success.A foundation to success.

THANK YOUTHANK YOU

Methods of locating calcified canalsMethods of locating calcified canals Preoperative radiographPreoperative radiograph

Chronic inflammatory processesChronic inflammatory processes

All canals must be cleaned and shaped. All canals must be cleaned and shaped.

Serious errors with inappropriate attempts (root wall and Serious errors with inappropriate attempts (root wall and canal perforations) can occur canal perforations) can occur

No rapid techniqueNo rapid technique Safety approachSafety approach

Access Through Full Veneer CrownsAccess Through Full Veneer Crowns

Properly made crowns are constructed with the Properly made crowns are constructed with the occlusal relationship of the opposing tooth as a occlusal relationship of the opposing tooth as a primary consideration primary consideration

Preoperative radiographPreoperative radiograph

Achieving access through crowns should be done with Achieving access through crowns should be done with coolants because frictional heatcoolants because frictional heat

Once penetration of metal accomplished Once penetration of metal accomplished can change to a sharp, round bur and can change to a sharp, round bur and move toward the central pulp chamber.move toward the central pulp chamber.

Metal filings and debris from the access Metal filings and debris from the access

cavity should be removed.cavity should be removed.