root canal morphology & access preparation

Dr. Nithin Mathew

Root Canal Morphology &

Access Cavity Preparation

CONTENTS

• Introduction

• Root canal system

• Classification

• Guidelines for cavity preparation

• Principles of Endodontic cavity preparation

• Anomalies to Pulp Cavity

• Root Morphology and Access Cavity preparation of Each tooth

• Conclusion

• References

3 Dr. Nithin Mathew - Root Canal Morphology & Access Preparation

INTRODUCTION

• Major factors for development of pulpal and periradicular diseases:• Loss of integrity of coronal tooth substance• Entry of microorganisms into the dentin and pulpal space

• Aim of Root canal treatment:• Chemomechanical removal of microorganisms, their substrate and products

from the dentin and pulp space.• 3D obliteration and sealing of the pulp space to prevent bacterial

contamination.


• One must have a thorough understanding of the tooth anatomy, an essentialprerequisite to achieve the objectives of access preparation through cleaning,disinfection and obturation of the pulp space.

• Problems encountered during the treatment occur because of inadequateunderstanding of the pulp space anatomy.

• Clinician must familiarize himself with the irregularities, complexities andaberrations which are likely to occur within the pulp space.


OBJECTIVES OF RCT

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Mechanical Objectives Biologic Objectives

• Prepare a sound anatomical matrix• Create a continuously tapering funnel

shaped preparation• Avoid overzealous instrumentation

• Precurve files when necessary

• Remove all residues from the canal• Maintain patency through the apical

foramen

• Establish an exact working length

• Confine instrumentation to canal

• Remove all irritants from the canal• Avoid pushing debris past the apical

constriction• Create a significant width in the

coronal half of the canal to allow for copious irrigation

Dr. Nithin Mathew - Root Canal Morphology & Access Preparation

ROOT CANAL SYSTEM

• The entire space in the dentin where the pulp is housed - Cohen


PULP CHAMBER

• Roof of pulp chamber• Dentin covering the pulp chamber occlusally or incisally.

• Pulp horn• Accentuation of the roof of the pulp chamber directly

under a cusp or developmental lobe.

• Floor of pulp chamber• Runs parallel to the roof and consists of dentin

bounding the pulp chamber near the cervical area of thetooth.

• Canal orifices• Openings in the floor of pulp chamber leading in to root

canals8 Dr. Nithin Mathew - Root Canal Morphology & Access Preparation

ANATOMY OF THE APICAL ROOT (Kuttlers)

1. The Apical constriction

2. The Cementodentinal junction

3. The Apical Foramen


• Part of the root canal with the smallest diameter

• Reference point for apical termination

• Distance ranges from 0.5mm -1.5mm inside theapical foramen

Apical Constriction (Minor Apical Diameter)


Cementodentinal Junction

• Point in the canal where cementum meets dentin

• Approximately 1mm from the apical foramen


Apical Foramen (Major Apical Diameter)

• Differentiate the terminal of cemental canal from the exterior surface of the tooth.

• Rounded edge like a funnel / crater

• Not necessarily always at the centre of root apex

• Average 0.4 – 0.7 mm away from the anatomic apex


• Space between major and minor apical diameter - FUNNEL SHAPED, HYPERBOLICor having the shape of a MORNING GLORY

• Mean distance between major and minor diameter:• 0.5mm in young individual• 0.67mm in older individual


• Apical third : highest percentage of ramifications and accesory canals.

• These ramifications and accesory canals were increasingly eliminated by• 1mm root end resection - 52%• 2mm root end resection - 78%• 3mm root end resection - 98%

• Reason for removing the apical 3mm during apicoectomy.- Cohen

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• Apical Delta :• Describes the primary or secondary canal that

terminates short of the apex with lateral canals fanningout from this point to the end of root surface.


Complexity of Apical Root

• After the tooth erupts the HERS is still active in the formation of the root.

• Occlusal loading at this stage can cause a discontinuity of this sheath which results inthe formation of accessory foramen and lateral canals.

• Mesial migration of the tooth due to loading is the reason for the curvatures at theapex - dilacerations

• After the formation of the roots are complete the location of the apical foramen andthe apical anatomy keeps changing constantly because of continuous cementumapposition.


Accessory Canals

• Minute canals that extend in a horizontal, vertical, or lateral direction from the pulp tothe periodontium.

• 73.5% - apical third• 11.4% - middle third• 15.1% - cervical third. - Cohen

• Contain connective tissue and vessels but do not supply the pulp with collateralcirculation.

• Formed by the entrapment of periodontal vessels in Hertwig's epithelial root sheathduring calcification. - Grossman


Lateral Canals

• An accessory canal that branches to the lateral surface ofthe root.

• Opening of accessory and lateral canals in the root surface.

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Accessory Foramena


• There are always two apices recognized for any tooth:• Radiographic Apex• Anatomic Apex

• Radiographic Apex:• It is the external border of the root tip which is seen

radiographically.

• Anatomic Apex:• Natural apical constriction formed by the cemento-

enamel junction


Course of Root Canals

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Curved root canals with apical foramen

distant from the apex

Curved root canals with apical foramen

near the apex

Constricted root canal as the apical foramen is

approached

Double curvature of root canal with the

foramen at a distance from the root apex


Shape of the Canals - Torabineajad

• Six different shapes have been noted

• Round

• Oval

• Deep oval

• Bowling pin

• Kidney bean

• Hour glass


Classification of Endodontic Treatment based on the degree of difficulty - Ingle

• Type IInsignificant curvature of root canal

• Type IIAnatomic problems like severe dilaceration, complex apical region withdivergence of canal, with numerous foramina

• Type IIIOpen foramen, incomplete root formation

• Type IVDecidous teeth, resorption of root tip


Canal Isthmus

• Narrow, ribbon-shaped communication between two rootcanals that contains pulp or pulpally derived tissue.

• It was found that the percentage of occurrence of isthmusincreases continuously for every 1mm from the apex for thefirst 4mm.


Types

• Type IIncomplete isthmus; faint communication betweentwo canals.

• Type IICharacterized by two canals with definite connectionbetween them.

• Type IIIVery short complete isthmus between two canals.


• Type IVComplete or incomplete isthmus between two ormore canals.

• Type VMarked by two or three canal openings withoutvisible connections


According to Melton et al (1991)

Category 1 : Continuous C-shaped canal from pulpchamber to apex

Category 2 : One canal was separated by dentin from theC-shaped canal(semi colon)

Category 3 : C-shaped orifice with 2 or more distinct andseparate canals


According to Hsu & Kim

• Type ITwo or three canals with no notable communicationbetween them

• Type IITwo canals with definite communication

• Type IIIDiffers from Type II due to presence of three canalsinstead of two.Incomplete C shaped canals with 3 canals included


• Type IVCanals extending to isthmus area

• Type VTrue connection or corridor throughout section


CLASSIFICATION OF ROOT CANAL SYSTEM

Dr. Nithin Mathew - Root Canal Morphology & Access Preparation 28

According to Weine

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Type I Type II Type III Type IV


According to Vertucci


According to Gulabiwala


Root Canal Curvatures

SCHNEIDER‘s classification on the basis of degree of curvature

Straight• : 5 ̊ or less

Moderate• : 10° - 20°

Severe• : 25° - 70 ̊


Guidelines for Cavity Preparation

• CEJ is the most important anatomical landmark for determining the location of pulpchamber and root canal orifices – Krasner & Rankow

• Laws of Pulp Chamber Anatomy:• First law of symmetry• Second law of symmetry• Law of color change• First law of orifice location• Second law of orifice location• Third law of orifice location


Laws of Pulp Chamber Anatomy – Krasner & Rankow

First• law of symmetryExcept• for maxillary molars, orifices of the canalsare equidistant from a line drawn in a mesio-distaldirection through the floor of the pulp chamber.

Second• law of symmetryExcept• for maxillary molars, orifices of the canalslie on a line perpendicular to to a line drawn in amesiodistal direction across the center of the floorof the pulp chamber


Laws of Pulp Chamber Anatomy

• Law of color change• Color of the pulp chamber floor is always darker

than the walls

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• First law of orifice location• Orifices are always located at the

junction of the walls and the floor.



• Second law of orifice location• Orifices are located at the angles of the wall-floor

junction.

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• Third law of orifice location• Orifices are located at the terminus of the root

developmental fusion lines.



• Law of CEJ• Distance from external surface of clinical crown to the

wall of pulp chamber is same throughout thecircumference of the tooth at the level of CEJ.

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Law• of ConcentricityExternal• root surface anatomy reflects the internalpulp chamber anatomy

Law• of Centralityfloor• of pulp chamber always located in the centre oftooth at the level of CEJ.


• Champagne Bubble Test• Use of sodium hypochlorite in the pulp chamber to

check for bubbles


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Tests• For Locating Canals

Vital• cases bleed - blood can be visualized as a small droplet above anorifice or a "RED LINE" within a groove that emanates off an orifice /system.

Additionally,• a spot of blood on the side of a paper point that is placedwithin a shaped canal may suggest a LATERAL CANAL or the entrance to adeeply branching system.

In• necrotic cases, a "WHITE LINE" can be visualized as the clinician troughsalong a groove.

Eg• : Following a white line off the MB1 system towards the palataloften times leads to the MB2 orifice / canal system.


Objectives of Access Cavity Preparation

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I. To remove all cariesII. To conserve sound tooth structureIII. To completely deroof the pulp chamberIV. To remove all coronal pulp tissue (vital or necrotic)V. To locate all root canal orificesVI. To achieve straight- or direct-line access to the apical foramen or to the

initial curvature of the canalVII. To establish restorative margins to minimize marginal leakage of the

restored tooth


Principals of Endodontic Cavity Preparation

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Coronal Cavity Preparation Radicular Cavity Preparation

I. Outline Form

II. Convenience Form

III. Removal of remaining carious dentin

IV. Toilet of cavity

I. Outline & Convenience Form

II. Toilet of Cavity

III. Retention Form

IV. Resistance Form


PRINCIPLE I – Outline Form

• Must be correctly shaped and positioned to establish complete access forinstrumentation from the cavity margin to apical foramen.

• To achieve the optimal preparation, the following factors of internal anatomy must beconsidered

i. Size of the pulp chamberii. Shape of the pulp chamberiii. Number of individual root canals, their curvature and position.


Size of the pulp chamber

Young• patients – more extensive than older patients

Quite• apparent while preparing anterior tooth in youngsters, whose large root canalsrequire larger instruments.


Shape of the pulp chamber

• Finished outline form should accurately reflect the shape of the pulp chamber.

• Eg: floor of pulp chamber in maxillary molar is triangular in shape

• This shape is extended outwards occlusally to the surface, hence final occlusalcavity outline form is generally triangular


Number, Position and Curvature of root canals

To• prepare each canal efficiently without interference, cavity walls must be extendedto allow an unstrained instrument approach.

Often• cavity walls have to be extended to improve instrumentation.Hence,• outline form in materially affected.

This• change is for convenience in preparation hence, convenience form partlyregulates the ultimate outline form.


PRINCIPLE II – Convenience Form

• Convenience form in endodontics makes more convenient and accurate preparationand filling of the root canal.

• 4 important benefits gained through convenience form modification are

i. Unobstructed access to the canal orificeii. Direct access to apical forameniii. Cavity expansion to accommodate filling techniqueiv. Complete authority over the enlarging instrument.


i. Unobstructed access to the canal orifice

Enough• tooth structure must be removed to allow instrument to be placed easily intothe orifice of each canal without interference from the overhanging walls.

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• Failure to observe this principle not only endangers the successfuloutcome of the case, but also adds materially to the duration of thetreatment.

• But precautions must be followed in case of certain tooth likemandibular incisors.


• Leubke said that an entire wall need not be extended in case of a severely curvedcanal to prevent instrument impringment or to access an extra canal.

• Here only that area of the wall need to be prepared to free the instrument.

• Finally a cloverleaf appearance of the outline form.

• Hence, Leubke has termed it as “SHAMROCK PREPARATION”.


ii. Direct access to Apical Foramen

Enough• tooth structure must be removed to allow the instruments freedom withinthe coronal cavity.

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• So that they extend down into the canal in an unstrainedpositioned.

• This is true when the canal is severely curved or when the canalleaves the chamber at an obtuse angle


iii. Extension to accommodate filling techniques

• Often necessary to expand outline form to make certain filling techniques moreconvenient or practical.

• Eg: Thermoplastic obturation techniques requires use of heavy instruments, henceoutline form must be widely extended to accommodate them.


iv. Complete Authority over enlarging instrument

• Failure to properly modify the access cavity outline by extending the convenienceform will ultimately lead to failure by either

• Root perforation• Ledge or shelf formation within the canal• Instrument breakage• Incorrect shape of completed canal preparation• Apical transporation


PRINCIPLE III – Removal of remaining carious dentin & defective restorations

I. To eliminate mechanically as many bacteria as possible from the interior of thetooth.

II. To eliminate discoloured tooth structure that may ultimately lead to staining ofthe crown.

III. To eliminate the possibly of any bacteria laden saliva leaking into the preparedcavity.

• After the caries is removed, if carious perforation of the wall is allowing salivaryleakage, the area must be repaired with cement, preferably from inside the cavity.


If• caries is soo extensive, that the lateral walls are destroyed, or if a defectiverestoration is in place, then entire wall is removed and later restored.

Restoration• is postponed until the radicular preparation is completed since it is mucheasier to complete radicular preparation through an open cavity than through arestored crown.


PRINCIPLE IV – Toilet of Cavity

• All caries, debris & necrotic material must be removed from the chamber before theradicular preparations begins.

• If calcified / metallic debris is left in the chamber & carried to the canal, it may act asobstruction.

• Soft debris carried to the canal might increase the bacterial population in the canal.

• Coronal debris may also stain the crown (anteriors)

• Toilet of the cavity makes a significant portion of the radicular preparation


Instruments used in Access Preparation

BURS•

No• . 2, 4 & 6 round burs

Fissure• / carbide burs for axial wall extension

EndoAccess• bursCombination• of round and tapered fissured burFor• preparation of pulp chamber & flaring of walls


• BURS

• Endo Z bur• Long tapered• Create funnel shape for easier access to chamber• Round non cutting safe ended tip

• Gates Glidden Drills


• Endodontic Explorer

• DG-16• To identify canal orifices• To determine canal angulation

• CK-17• To identify calcified canals

• Endodontic spoon excavator


• # 17 Operative Explorer

• Detecting any remaining pulp chamber roof,particularly in the area of pulp horn

• Ultrasonic Unit & Tips

• Used to trough & deepen developmental grooves toremove tissues & explore for canals

• BUC tips (1-3)


Anomalies of Pulp Cavity

• Dentinogeneis Imperfecta• Pulp cavities may be small or even obliterated

• Hyperparathyroidism• Cause pulp calcification and loss of lamina dura

• Hypofunction of Pituitary Gland• Lead to retarded eruption of teeth and to open apices


Dentinal• dysplasiaObliteration of pulp chamber and defective rootformation

Taurodontism•Short root and larger than normal pulp chamber

Dens• Invaginatus

Malformation due to an invagination of enamelepitelium resulting in a chanel or lumen surroundedby hard tissues within the tooth.

Frequently occurs in the palatal surface of max. lateralincisor


• Dens Evaginatus

Is an extra cusp, usually in the central groove orridge of a posterior teeth and in the cingulum of thecentral or lateral incisor

• Fusion

Union in dentin and/or enamel between two ormore normal teeth

• Gemination

Incomplete division of a tooth germ or a unionbetween normal and a supernumerary tooth


• Rhizomicry

Length of the root is shorter than the height of thecrown

Associated with osteoporosis

Predominantly affecting maxillary incisors andpremolars


Maxillary Central Incisor

• Single rooted, straight root trunk

• Triangular / ovoid in cross section, tapers towards lingual

• Single root canal system

• Mid root and apical lateral canals are common

• Root apex & apical foramen are located distolabially.

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Av. Tooth Length 23.5 mmAv. Crown Length 10.5 mmAv. Root Length 13 mm

Maxillary Central IncisorDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Located in the centre of crown equidistant from

dentinal walls• Broad mesiodistally – broadest part incisally• Follows contours of crown & has 3 pulp horns which

correspond to mammelons

Cross-Section• Cervical Large in young• Middle Ovoid to round shaped• Apical Round shaped


• Roots• Majority are straight - 75%• Distally curved - 8%• Mesially curved - 4%• Palatally curved - 4%• Labially curved - 9%

• Lateral Canals - 23%• Apical Ramifications - 9%

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Anomalies• Talon’s Cusp• Dens invaginvatus• Fusion• Gemination• Palatogingival Groove


Maxillary Lateral Incisor

• Single rooted

• Root trunk smaller than central incisor

• Circular / ovoid in cross section, tapers towards lingual

• Single root canal system

• Root apex & apical foramen are displaced distolingually.

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Av. Tooth Length 22.5 mmAv. Crown Length 9 mmAv. Root Length 13 mm

Maxillary Lateral IncisorDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Similar to maxillary central incisor (smaller)• 2 pulp horns corresponding to developmental mammelons

Cross-Section• Cervical Slightly ovoid becomes progressively

round• Middle Slightly ovoid to round• Apical Round


• Roots• Distally curved - 53%• Others are straight - 30%

• Lateral Canals (frequently) - 26%• Apical Ramifications - 12%

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Anomalies• Dens invaginvatus• Peg laterals (Gardner’s syndrome)• Fusion (with Central Incisor)• Gemination• Palatogingival Groove


Maxillary Canine

• Single rooted, largest tooth in dentition

• Root is wider labiolingually

• Developmental depressions present in mesial & distalsurfaces

• Ovoid in cross section

• Usually single root canal system

• Root apex & apical foramen are displaced distolabially.

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Av. Tooth Length 26 mmAv. Crown Length 10 mmAv. Root Length 17 mm

Maxillary CanineDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Triangular in shape with apex towards single cusp &

broad base in cervical third of crown• Mesiodistally : narrow resembling a flame

Cross-Section• Cervical Slightly ovoid• Middle Canal is smaller and remains ovoid• Apical Round


• Roots• Straight - 39%• Distally curved - 32%• Mesially curved - 0%• Palatally curved - 7%• Labially curved - 13%

• Lateral Canals - 24%• Apical Ramifications - 8%

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Anomalies• Dilaceration• Dens evaginvatus• Dens invaginvatus• Supernumery Canine• 2 canals / 2 roots


Access Cavity Preparation In MAXILLARY ANTERIOR TEETH

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Initial penetration is made at the exact center

of lingual surface

Round pointed tapering fissure bur in an

accentuated speed handpiece at right angle to the long axis of the tooth

Rotate the handpiece to the incisal so that the bur is parallel to the long axis

of toothPreliminary cavity outline

funnelled and fanned incisally with a fissure bur


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No: 2 or 4 round bur in a slow speed handpiece is

used to penetrate the pulp chamber

Working from inside to outside, a round bur is used

to remove the lingual & labial walls of the pulp

chamber

Working from inside the chamber to outside, long

tapering diamond point is used to remove the

lingual shoulder No: 1 or 2 round bur used laterally and incisally to

eliminate pulp horn debris

Cavity Preparation In MAXILLARY ANTERIOR TEETH


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Final preparation: triangular internal anatomy in young

teeth

Cavity preparation in adult- ovoid

Cavity Preparation In MAXILLARY ANTERIOR TEETH


ERRORS In Cavity Preparation In MAXILLARY ANTERIOR TEETH

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Perforation at the labiocervical

Gauging of Labial wall

Pear shaped preparation of apical canal

Gauging of Distal wall

Discoloration of crown


ERRORS In Cavity Preparation In MAXILLARY ANTERIOR TEETH

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Ledge formation at apical distal curve

Perforation at apical distal curve

Ledge formation at apical labial curve


Mandibular Central Incisor

• Single rooted

• Broader labiolingually than mesiodistally

• Developmental depressions present in mesial & distal rootsurfaces

• Ovoid to hourglass in cross section

• Usually single root canal system, ovoid/ribbon

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Av. Tooth Length 20.8 mmAv. Crown Length 9 mmAv. Root Length 12.5 mm

Mandibular Central IncisorDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Small & flat – mesiodistally• Wide labiolingually• Tapers incisally

Cross-Section• Cervical Slightly ovoid• Middle Round• Apical Round


• Roots• Straight - 60%• Distally curved - 23%• Mesially curved - 0%• Labially curved - 13%• Lingually curved - 0%

• Lateral Canals - 5.2%

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Anomalies• Fusion• Gemination• Dens invaginvatus• Talon’s Cusp

CanalsOne canal, one foramen 70.1%2 canals, 1 foramen 23.4%2 canals, 2 formina 6.5%


Additional Canal Configurations – Mandibular IncisorsBy Kartal et al

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Type I

• Two separate canals extended from the pulpchamber to midroot

• Lingual canal divided into two• All three canals joined in the apical third of

the root and exited as one canal

Type II

• One canal left the pulp chamber• Divided into two in the middle third of the

root, then rejoined to form one canal,• Which again split and exited as three separate

canals with separate foramina


Mandibular Lateral Incisor

• Similar to Central Incisor

• Major difference is incisal edge anatomy

• Slight angulation to mesiolabial & distolingual of crown

• Usually single root canal system, round/ribbon shaped

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Mandibular Lateral IncisorDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Similar to central incisor but slightly larger dimension• Small & flat – mesiodistally• Wide labiolingually• Tapers incisally

Cross-Section• Cervical Slightly ovoid• Middle Round• Apical Round


• Roots• Straight - 60%• Distally curved - 23%• Mesially curved - 0%• Labially curved - 13%• Lingually curved - 0%

• Lateral Canals - 13.9%

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Anomalies• Fusion• Gemination• Dens invaginvatus• Talon’s Cusp

CanalsOne canal, one foramen 56.9%2 canals, 1 foramen 14.7%2 canals, 2 formena 29.4%


Mandibular Canine

Single• rooted

Broader• labiolingually

Developmental• depressions are present in mesial and distal rootsurface.

Usually• single canal system

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Av. Tooth Length 25 mmAv. Crown Length 11 mmAv. Root Length 16 mm

Mandibular CanineDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Resembles maxillary canine but smaller• Narrow mesiodistally• One pulp horn

Cross-Section• Cervical Ovoid• Middle Ovoid (smaller)• Apical Round


• Roots• Straight - 68%• Distally curved - 20%• Mesially curved - 1%• Labially curved - 7%• Lingually curved - 0%• Bayonet curve - 2%

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Anomalies• Dilaceration• 2 canals, 2 roots• 2 canals in single root• 2 canals in single apical foramen• Dens evaginvatus

CanalsOne canal, one foramen 94%2 canals, 2 formena 6%Variation – Vertucci Type II & III


Cavity Preparation In MANDIBULAR ANTERIOR TEETH

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Initial penetration is made at the exact center

of lingual surface

Round pointed tapering fissure bur in an

accentuated speed handpiece at right angle to the long axis of the tooth

Rotate the handpiece to the incisal so that the bur is parallel to the long axis

of toothPreliminary cavity outline

funnelled and fanned incisally with a fissure bur


89

No: 2 round bur in a slowspeed handpiece is usedto penetrate the pulpchamber

Working from inside tooutside, a round bur is usedto remove the lingual &labial walls of the pulpchamber

Working from inside thechamber to outside, longtapering diamond point isused to remove thelingual shoulder No: 1 round bur used

laterally and incisally toeliminate pulp horndebris



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Final preparation: triangular internal anatomy in young

teeth

Cavity preparation in adult- ovoid



ERRORS In Cavity Preparation In MANDIBULAR ANTERIOR TEETH

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Gouging at the labiocervical

Gauging of Labial wall

Failure to explore the second canal

Gauging of Distal wall


ERRORS In Cavity Preparation In MANDIBULAR ANTERIOR TEETH

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Ledge formation at apical labial curve

Discoloration of crown


Maxillary 1st Premolar

• Prominent developmental depressions on mesial and distal rootsurfaces (mesial root concavity more prominent)

• Broader buccopalatally & narrow mesiodistally

• Kidney shaped cross section at CEJ

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Maxillary 1st PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Narrow mesiodistally, wider buccopalatally• Pulp horn under each cusp, buccal pulp horn more

prominent• Floor is convex• 2 canal orifices (lies deep in coronal third of root below

cervical line)

Cross-Section• Cervical Ovoid• Middle Round • Apical Round


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Anomalies• Dens evaginvatus• Gemination (rare)• Taurodontism (rare)

Canal System• 2 roots

• When fused roots, a groove running in occlusso-apical direction divides the root into buccal &palatal portions each containing a single rootcanal


Maxillary 2nd Premolar

Single• rooted form – most common

Broader• buccopalatally & narrow mesiodistally

Prominent• developmental depressions on mesial and distal rootsurfaces

Single• canal system – 50.3%

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Maxillary 2nd PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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PULP CHAMBER• Narrow mesiodistally• Wider buccopalatally than Maxillary 1st premolar• Pulp horn under each cusp, buccal pulp horn more

prominent

Cross-Section• Cervical Ovoid• Middle Round • Apical Round


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Anomalies• Dens invaginvatus• Taurodontism• Deep distal root concavity• 2 roots, 3 canals

Canal System• Single root – 90.3%

• 2 well developed roots – 2%

• 2 roots partially fused – 77%

• When 2 canals are present, they’ll be distinct &separated along the entire length of root


Access Cavity Preparation In MAXILLARY PREMOLARS

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Access starting location point is on central groove between cusp tip


http://www.pathwaysofthepulp.com/content/bookcontent.cfm?ID=HC007024



100

Initial penetration made with bur parallel long axis

of tooth

No. 2/4 round bur, drop is felt when pulp chamber is

reached

Canal orifices located using endodontic

explorer

Removal of roof of pulp chamber



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Buccolingual extension and finish of cavity walls

using fissure bur

Final preparation should provide unobstructed access to canal orifice

Outline form of final cavity preparation –

ovoid


ERRORS In Cavity Preparation In MAXILLARY PREMOLARS

102

Under extended preparation

Overextentedpreparation

Faulty alignment of access cavity

Perforation at mesiocervical

indentation


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Failiure to explore 3rd canal/ 2nd canalBroken instrument

ERRORS In Cavity Preparation In MAXILLARY PREMOLARS


Mandibular 1st Premolar

• Single rooted

• Broader buccolingually

• Developmental depressions on distal root surface is deeper thanmesial surface

• Ovoid / hourglass shape in cross section

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Mandibular 1st PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

105

PULP CHAMBER• Narrow mesiodistally• Wider buccolingually with prominent buccal pulp horn• Prominent buccal cusp & small lingual cusp

Cross-Section• Cervical Very narrow and ovoid• Middle 2 branches of canals are Round• Apical Round


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Anomalies• Dens invaginvatus/ evaginatus• Gemination• H-shaped canal

single canal can split into 2 of which the buccal is straight& the lingual canal splits at a right angle, this gives theappearance of the letter ‘h’

Canal System• Single root• Usually 1 canal – 70%• 1 canal bifurcates into 2 and ends in 2 foramina – 24%• 2 canals exit in 2 foramina – 1.5%• 1 canal may bifurcate into 2, uniting into 1 canal in the

apical third and exiting in one foramen – 4%• 3 canals exit in 3 foramina – 0.5%


Mandibular 2nd Premolar

• Single rooted

• Mesial surface of root is flat / convex

• Developmental depressions on distal root surface

• Ovoid in cross section

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Mandibular 2nd PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

108

PULP CHAMBER• Narrow mesiodistally• Wider buccolingually• Prominent Lingual pulp horn

Cross-Section• Cervical Very narrow and ovoid• Middle Less ovoid • Apical Round


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Anomalies• Dens evaginatus• 2 roots

Canal System• Single canal – 97.5%• Some roots bifurcates exiting in 2 foraminas – 2.5%


Access Cavity Preparation In MANDIBULAR PREMOLARS

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2ND PREMOLAR1/3rd way up the lingual incline of buccal cusp on a line connecting buccal cusp tip and lingual groove between the lingual

cusps

Ist PREMOLARHalfway up the lingual incline on a line

connecting cusp tips

Mandibular premolar-tilted lingually to root and must be adjusted to this tilt






111

Initial penetration made through occlusal surface

No. 4 round bur, drop is felt when pulp chamber is

reached

Canal orifices located using endodontic

explorer

Removal of roof of pulp chamber


112

Buccolingual extension and finish of cavity walls

using fissure burFinal preparation should

provide unobstructed access to canal orifice

Outline form of final cavity preparation – ovoid



ERRORS In Cavity Preparation In MANDIBULAR PREMOLARS

113

Perforation at the mesiogingival

Incomplete preparation & instrument breakage

Bifurcation of a canal missed


114

Perforation of apical curvature

Apical perforation

ERRORS In Cavity Preparation In MANDIBULAR PREMOLARS


Maxillary 1st Molar

• Mesiobuccal Root :• Broad buccolingually• Developmental depressions in both mesial &

distal root surfaces

• Distobuccal Root :• Round / ovoid in cross section

• Palatal Root :• Broad mesiodistally• Ovoid in cross section• Buccal curvature at the apical third

115


Maxillary 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

116

PULP CHAMBER• Largest in the arch• 4 pulp horns : MB, MP, DB, DP• Roof – Rhomboidal in shape• Roof converges, lingual wall disappears and forms a triangular

form• Anatomic dark lines in the floor connect the orifices• Orifices are located in the 3 angles of the floor• Mesiobuccal orifice under mesio-buccal cusp• May have a depression in the palatal end of the mesiobuccal

orifice where a 4th canal may be present• MB2 canal is located mesial to or directly on a line between the

MB and palatal orifice



Canal SystemMesiobuccal Root• Have distal curvature – 78%• Straight – 21%• Bayonet – 1%• Narrowest of 3 canals• Apical foramen centrally locatedDistobuccal Root• Small• Straight – 54%• Distal curve – 17%• Mesial curve – 19%• Bayonet – 10%• Apical foramen centrally locatedPalatal Root• Largest root & diameter, ovoid mesiodistally, tapers apically• May curve buccally in the apical third

117 Maxillary 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

• Locating MB2 orifice –• Difficult as its buried under

• dentine bridge formed as a result of aging• reparative dentin formation as result of caries

/restoration

• Canal located mesial to or directly on a line between the MB1and palatal orifices ,within 3.5mm palatally and 2mm mesiallyof MB1 orifice.

118 Maxillary 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation



119

Anomalies• Taurodontism• Root fusion• 2 palatal canals• Single root and single canal• 2 distal canals• 2 palatal roots• C-shaped canals

Maxillary 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

Maxillary 2nd Molar

• Similar to maxillary 1st molar

• Roots have a distal inclination

• Normally has 3 roots

• Roots tends to close together, higher tendency towards fusion of2/3 roots

120

Av. Tooth Length 17.1 mmAv. Crown Length 7 mmAv. Root Length 12 mm

Maxillary 2nd MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

121

PULP CHAMBER• Similar to maxillary 1st molar, except narrower mesiodistally• Roof – Rhomboidal in shape• Floor – obtuse triangle• Mesiobuccal and distobuccal canals closer together

Maxillary 2nd Molar

Canal SystemMesiobuccal Root• Broad buccolingually• Prominent depression in mesial and distal surfaces• 1 or 2 canalsDistobuccal Root• Rounded / ovoid, single canal• Orifice appears on same line joining mesiobuccal & palatal canalsPalatal Root• Broad mesiodistally• Ovoid, Single canal




122

Anomalies• Taurodontism• Root fusion• Single root, single canal• 2 palatal canals in double palatal root• Incidence of pulp stones

Maxillary 2nd MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

Access Cavity Preparation In MAXILLARY MOLARS

123

• Mesial and Distal boundary should be established

• Mesial boundary for maxillary molars is the line connecting mesial cusp tips

• Distal boundary for maxillary-oblique ridge




124

Initial penetration made at the center of occlusal

pit with bur directed palatally No. 4 round bur directed to

the palatal canal orifice or mesiobuccal orifice

Endodontic explorer used to locate canal orifices

Round bur is used to remove roof of the pulp

chamber


125

Final finish & funnelling of cavity walls with

tapered diamond pointFinal preparation provide

ease of access improved by leaning the preparation to

the buccal

Outline form of final cavity preparation – Triangular



ERRORS In Cavity Preparation In MAXILLARY MOLARS

126

Underextended / Over extended preparation Perforation into furcation


127

Disoriented occlusal outline form

Inadequate vertical preparation - severe

buccal inclination

ERRORS In Cavity Preparation In MAXILLARY MOLARS

Ledge formation Perforation of palatal root


Mandibular 1st Molar

• Typically 2 rooted

• Roots are broader buccolingually which are widely separated

• Mesial & distal roots separated with a furcation level• Buccally – 3mm• Lingually – 4mm

• Mesial root concavities on both mesial and distal surfaces

• Distal root – ovoid in cross section

128


Mandibular 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

129

PULP CHAMBER

• 4 pulp horns : MB, ML, DB, DL

• 3 distinct orifices : MB, ML & distal

• Roof – Rectangular in shape

• Walls converge to form a rhomboidal floor

• Pulp horns recede with age and so decrease in chamber size

• Roof is located on the cervical 3rd of the crown just above the cervix of tooth, floor is located on cervical third of root


Canal SystemNormally 2 mesial and 1 distal canalMesial Root• 2 canals exit in 2 foramina – 41%• 2 canals exit in 1 foramina – 28%• 2 canals form 1 canal & bifurcate & exit in 2 foramina – 13%• 1 canal in 1 foramina – 12%• 1 canal bifurcates & exits in 2 foramina – 8%• Rare cases – 3 canals exit in 3 foramina ( 3rd canal is the middle

mesial canal)Distal Root• 1 canal exiting in 1 foramen – 70%• 2 canals exiting in 1 foramen – 15%• 1 canal bifurcating & exiting in 2 foramina – 8%• 2 canals in 2 foramina – 5%

130 Mandibular 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

131

Anomalies• Taurodontism (most common)• Supernumery Roots – Radix Entomolaris• C-shaped canals


Mandibular 2nd Molar

• 2 rooted

• Mesial & distal roots close together

• Roots are broader buccolingually

• More frequently roots are fused

132


Mandibular 2nd MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

133

PULP CHAMBER• Similar to 1st molar but smaller in size

Canal System• Mesial root – higher incidence of 1 canal – 14%• Higher incidence of root fusion• C-shaped canals are frequent

Mandibular 2nd Molar

• In a mandibular second molar with two canals,both orifices are in the mesiodistal midline.

If• two orifices are not directly in themesiodistal midline, a search should be madefor another canal on the opposite side usingKrasner and Rankow's laws of anatomy


134 Mandibular 2nd Molar

Anomalies• C-shaped canals• Taurodontism• Fused or single canal• Supernumery roots – Radix Entomolaris


Access Cavity Preparation In MANDIBULAR MOLARS

135

• Mesial and Distal boundary should be established

• Mesial boundary for mandibular molars are line connecting mesial cusp tips

• Distal boundary is the line connecting buccal and lingual grooves



136

Initial penetration made at the center of mesial pit with bur directed towards

distal No. 4/No.6 round bur is used, directed towards the orifice of mesiobuccal or

distal canal

Endodontic explorer used to locate canal orifices

Round bur is used to remove roof of the pulp

chamber


137

Final finish & funnelling of cavity walls with

tapered diamond point

Final preparation provide ease of access improved by leaning the preparation to

the buccal



ERRORS In Cavity Preparation In MANDIBULAR MOLARS

138

Over-extended preparation

Perforation into furcation

Disoriented occlusal outline form

Perforation at mesiocervical – tilted to

mesial


ERRORS In Cavity Preparation In MANDIBULAR MOLARS

139

Failure of finding 2nd

distal canalPerforation of distal rootLedge formation


Access Cavity Preparation In Teeth with Calcified Canals

140

Mandibular first molar with a Class I restoration,

calcified canals, and periradicular

radiolucenciesExcavation of a restoration

and base material

Long-shank #2 or #4 round bur to remove

dentin

Endodontic explorer is used to probe the pulp

floor


141

The smallest instrument (i.e., a #.06 or #.08 file)

should be introduced into the canal

A small hand K-file negotiates the canal to its

terminus



• Color is also a critical indicator when chasing a receded or calcified canal.

• Typically, a small dark brown dot is visualized and represents the position where thecanal used to be.

• Chasing apically along this colored route typically leads to a more open canal that canbe negotiated.

142



Apical Diameter - Cohen

143

Teeth Mean Value (µm)Maxillary incisors 289.4Mandibular incisors 262.5Maxillary premolars 210Mandibular premolars 268.25Maxillary molars

Palatal 298Mesiobuccal 235.05Distobuccal 232.2

Mandibular molarsMesial 257.5Distal 392


Suggested Preparation Sizes - Ingle


CONCLUSION

Thorough• Knowledge of root canal anatomy & cavity preparation will enable theclinician to produce endodontic treatments of high quality and considerable longevity.

• A successful treatment outcome depends on the complete debridement anddisinfection of all canals.


REFERENCES

• Text book of Endodontics-Ingles( 5th edition)

• Text book of Endodontics—Mahmood Torabinajad, Richael E.Walton (4th edition)

• Grossman’s Endodontic Practice (12th Edition)

• Endodontic Therapy – Franklin S. Weine (6th Edition)

• Pathways of pulp –Cohen


root canal morphology & access preparation

Education