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 essential
prerequisite to achieve the objectives of access preparation through cleaning,
disinfection and obturation of the pulp space.
• Problems encountered during the treatment occur because of inadequate
understanding of the pulp space anatomy.
• Clinician must familiarize himself with the irregularities, complexities and
aberrations which are likely to occur within the pulp space.

OBJECTIVES OF RCT
6
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 the
tooth.
• Canal orifices
• Openings in the floor of pulp chamber leading in to root
canals

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 the
apical 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, HYPERBOLIC
or 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%
• Reason for removing the apical 3mm during apicoectomy.
- Cohen
14
• Apical Delta :
• Describes the primary or secondary canal that
terminates short of the apex with lateral canals fanning
out 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 in
the formation of accessory foramen and lateral canals.
• Mesial migration of the tooth due to loading is the reason for the curvatures at the
apex - dilacerations
• After the formation of the roots are complete the location of the apical foramen and
the apical anatomy keeps changing constantly because of continuous cementum
apposition.

Accessory Canals
• Minute canals that extend in a horizontal, vertical, or lateral direction from the pulp to
the 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 collateral
circulation.
• Formed by the entrapment of periodontal vessels in Hertwig's epithelial root sheath
during calcification. - Grossman

Lateral Canals
• An accessory canal that branches to the lateral surface of
the root.
• Opening of accessory and lateral canals in the root surface.
17
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
19
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 I
Insignificant curvature of root canal
• Type II
Anatomic problems like severe dilaceration, complex apical region with
divergence of canal, with numerous foramina
• Type III
Open foramen, incomplete root formation
• Type IV
Decidous teeth, resorption of root tip

Canal Isthmus
• Narrow, ribbon-shaped communication between two root
canals that contains pulp or pulpally derived tissue.
• It was found that the percentage of occurrence of isthmus
increases continuously for every 1mm from the apex for the
first 4mm.

Types
• Type I
Incomplete isthmus; faint communication between
two canals.
• Type II
Characterized by two canals with definite connection
between them.
• Type III
Very short complete isthmus between two canals.

• Type IV
Complete or incomplete isthmus between two or
more canals.
• Type V
Marked by two or three canal openings without
visible connections

According to Melton et al (1991)
Category 1 : Continuous C-shaped canal from pulp
chamber to apex
Category 2 : One canal was separated by dentin from the
C-shaped canal(semi colon)
Category 3 : C-shaped orifice with 2 or more distinct and
separate canals

According to Hsu & Kim
• Type I
Two or three canals with no notable communication
between them
• Type II
Two canals with definite communication
• Type III
Differs from Type II due to presence of three canals
instead of two.
Incomplete C shaped canals with 3 canals included

• Type IV
Canals extending to isthmus area
• Type V
True connection or corridor throughout section

CLASSIFICATION OF ROOT CANAL SYSTEM
28

According to Weine
29
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 pulp
chamber 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 symmetry
Except• for maxillary molars, orifices of the canals
are equidistant from a line drawn in a mesio-distal
direction through the floor of the pulp chamber.
Second• law of symmetry
Except• for maxillary molars, orifices of the canals
lie on a line perpendicular to to a line drawn in a
mesiodistal direction across the center of the floor
of the pulp chamber

Laws of Pulp Chamber Anatomy
• Law of color change
• Color of the pulp chamber floor is always darker
than the walls
35
• 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.
36
• 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 the
circumference of the tooth at the level of CEJ.
37
Law• of Concentricity
External• root surface anatomy reflects the internal
pulp chamber anatomy
Law• of Centrality
floor• of pulp chamber always located in the centre of
tooth at the level of CEJ.

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

39
Tests• For Locating Canals
Vital• cases bleed - blood can be visualized as a small droplet above an
orifice 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 placed
within a shaped canal may suggest a LATERAL CANAL or the entrance to a
deeply branching system.
In• necrotic cases, a "WHITE LINE" can be visualized as the clinician troughs
along a groove.
Eg• : Following a white line off the MB1 system towards the palatal
often times leads to the MB2 orifice / canal system.

Objectives of Access Cavity Preparation
40
I. To remove all caries
II. To conserve sound tooth structure
III. To completely deroof the pulp chamber
IV. To remove all coronal pulp tissue (vital or necrotic)
V. To locate all root canal orifices
VI. To achieve straight- or direct-line access to the apical foramen or to the
initial curvature of the canal
VII. To establish restorative margins to minimize marginal leakage of the
restored tooth

Principals of Endodontic Cavity Preparation
41
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 for
instrumentation from the cavity margin to apical foramen.
• To achieve the optimal preparation, the following factors of internal anatomy must be
considered
i. Size of the pulp chamber
ii. Shape of the pulp chamber
iii. 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 canals
require 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 occlusal
cavity outline form is generally triangular

Number, Position and Curvature of root canals
To• prepare each canal efficiently without interference, cavity walls must be extended
to 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 partly
regulates the ultimate outline form.

PRINCIPLE II – Convenience Form
• Convenience form in endodontics makes more convenient and accurate preparation
and filling of the root canal.
• 4 important benefits gained through convenience form modification are
i. Unobstructed access to the canal orifice
ii. Direct access to apical foramen
iii. Cavity expansion to accommodate filling technique
iv. 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 into
the orifice of each canal without interference from the overhanging walls.
48
• Failure to observe this principle not only endangers the successful
outcome of the case, but also adds materially to the duration of the
treatment.
• But precautions must be followed in case of certain tooth like
mandibular incisors.

• Leubke said that an entire wall need not be extended in case of a severely curved
canal 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 within
the coronal cavity.
50
• So that they extend down into the canal in an unstrained
positioned.
• This is true when the canal is severely curved or when the canal
leaves the chamber at an obtuse angle

iii. Extension to accommodate filling techniques
• Often necessary to expand outline form to make certain filling techniques more
convenient or practical.
• Eg: Thermoplastic obturation techniques requires use of heavy instruments, hence
outline 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 convenience
form 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 the
tooth.
II. To eliminate discoloured tooth structure that may ultimately lead to staining of
the crown.
III. To eliminate the possibly of any bacteria laden saliva leaking into the prepared
cavity.
• After the caries is removed, if carious perforation of the wall is allowing salivary
leakage, 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 defective
restoration is in place, then entire wall is removed and later restored.
Restoration• is postponed until the radicular preparation is completed since it is much
easier to complete radicular preparation through an open cavity than through a
restored crown.

PRINCIPLE IV – Toilet of Cavity
• All caries, debris & necrotic material must be removed from the chamber before the
radicular preparations begins.
• If calcified / metallic debris is left in the chamber & carried to the canal, it may act as
obstruction.
• 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• burs
Combination• of round and tapered fissured bur
For• 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 to
remove 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• dysplasia
Obliteration of pulp chamber and defective root
formation
Taurodontism•
Short root and larger than normal pulp chamber
Dens• Invaginatus
 Malformation due to an invagination of enamel
epitelium resulting in a chanel or lumen surrounded
by hard tissues within the tooth.
 Frequently occurs in the palatal surface of max. lateral
incisor

• Dens Evaginatus
 Is an extra cusp, usually in the central groove or
ridge of a posterior teeth and in the cingulum of the
central or lateral incisor
• Fusion
 Union in dentin and/or enamel between two or
more normal teeth
• Gemination
 Incomplete division of a tooth germ or a union
between normal and a supernumerary tooth

• Rhizomicry
 Length of the root is shorter than the height of the
crown
 Associated with osteoporosis
 Predominantly affecting maxillary incisors and
premolars

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.
64
Av. Tooth Length 23.5 mm
Av. Crown Length 10.5 mm
Av. Root Length 13 mm
Maxillary Central IncisorDr. Nithin Mathew - Root Canal Morphology & Access Preparation

65
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%
66
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.
67
Av. Crown Length 9 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
• Others are straight - 30%
• Lateral Canals (frequently) - 26%
69
Anomalies
• 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 & distal
surfaces
• Ovoid in cross section
• Usually single root canal system
• Root apex & apical foramen are displaced distolabially.
70
Av. Tooth Length 26 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%
• Palatally curved - 7%
• Lateral Canals - 24%
72
Anomalies
• Dilaceration
• Dens evaginvatus
• Supernumery Canine
• 2 canals / 2 roots

Access Cavity Preparation In MAXILLARY ANTERIOR TEETH
73
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 tooth
Preliminary cavity outline
funnelled and fanned
incisally with a fissure bur

74
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

75
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
76
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
77
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 root
surfaces
• Ovoid to hourglass in cross section
• Usually single root canal system, ovoid/ribbon
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Av. 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
• Middle Round
• Apical Round

• Roots
• Straight - 60%
• Lingually curved - 0%
• Lateral Canals - 5.2%
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Anomalies
• Fusion
• Gemination
• Talon’s Cusp
Canals
One canal, one foramen 70.1%
2 canals, 1 foramen 23.4%
2 canals, 2 formina 6.5%

Additional Canal Configurations – Mandibular Incisors
By Kartal et al
81
Type I
• Two separate canals extended from the pulp
chamber 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
82
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
• Middle Round
• Apical Round

• Roots
• Straight - 60%
• Lateral Canals - 13.9%
84
Anomalies
• Fusion
• Gemination
• Talon’s Cusp
Canals
One 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 root
surface.
Usually• single canal system
85
Av. Tooth Length 25 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%
• Bayonet curve - 2%
87
Anomalies
• Dilaceration
• 2 canals, 2 roots
• 2 canals in single root
• 2 canals in single apical foramen
Canals
One canal, one foramen 94%
2 canals, 2 formena 6%
Variation – Vertucci Type II & III

Cavity Preparation In MANDIBULAR ANTERIOR TEETH
88
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 tooth
Preliminary cavity outline
funnelled and fanned
incisally with a fissure bur

89
No: 2 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 round bur used
laterally and incisally to
eliminate pulp horn
debris

90
Final preparation: triangular
internal anatomy in young
teeth
Cavity preparation in
adult- ovoid

ERRORS In Cavity Preparation In MANDIBULAR ANTERIOR TEETH
91
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
92
Ledge formation at
apical labial curve
Discoloration of crown

Maxillary 1st Premolar
• Prominent developmental depressions on mesial and distal root
surfaces (mesial root concavity more prominent)
• Broader buccopalatally & narrow mesiodistally
• Kidney shaped cross section at CEJ
93
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

95
Anomalies
• 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 root
canal

Maxillary 2nd Premolar
Single• rooted form – most common
Broader• buccopalatally & narrow mesiodistally
Prominent• developmental depressions on mesial and distal root
surfaces
Single• canal system – 50.3%
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Maxillary 2nd PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

97
PULP CHAMBER
• Wider buccopalatally than Maxillary 1st premolar
• Pulp horn under each cusp, buccal pulp horn more
prominent
Cross-Section
• Cervical Ovoid
• Middle Round
• Apical Round

98
Anomalies
• 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
99
Access starting location point is on central groove between cusp tip

10
0
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

10
1
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
10
2
Under extended
preparation
Overextented
preparation
Faulty alignment of
access cavity
Perforation at
mesiocervical
indentation

10
3
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 than
mesial surface
• Ovoid / hourglass shape in cross section
10
4
Mandibular 1st PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

10
5
PULP CHAMBER
• 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

10
6
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 the
appearance 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
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7
Mandibular 2nd PremolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

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8
PULP CHAMBER
• Wider buccolingually
• Prominent Lingual pulp horn
Cross-Section
• Cervical Very narrow and ovoid
• Middle Less ovoid
• Apical Round

10
9
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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0
2ND PREMOLAR
1/3rd way up the lingual incline of buccal
cusp on a line connecting buccal cusp tip
and lingual groove between the lingual
cusps
Ist PREMOLAR
Halfway up the lingual incline on a line
connecting cusp tips
Mandibular premolar-tilted lingually to root and must be adjusted to this tilt

111
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 bur
Final 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
• 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 System
Mesiobuccal Root
• Have distal curvature – 78%
• Straight – 21%
• Bayonet – 1%
• Narrowest of 3 canals
• Apical foramen centrally located
Distobuccal Root
• Small
• Straight – 54%
• Distal curve – 17%
• Mesial curve – 19%
• Bayonet – 10%
• Apical foramen centrally located
Palatal Root
• Largest root & diameter, ovoid mesiodistally, tapers apically
• May curve buccally in the apical third
117

• 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 MB1
and palatal orifices ,within 3.5mm palatally and 2mm mesially
of MB1 orifice.
118

119
Anomalies
• Taurodontism
• Root fusion
• 2 palatal canals
• Single root and single canal
• 2 distal canals
• 2 palatal roots
• C-shaped canals

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 of
2/3 roots
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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 System
Mesiobuccal Root
• Broad buccolingually
• Prominent depression in mesial and distal surfaces
• 1 or 2 canals
Distobuccal Root
• Rounded / ovoid, single canal
• Orifice appears on same line joining mesiobuccal & palatal canals
Palatal Root
• Broad mesiodistally
• Ovoid, Single canal

12
2
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
12
3
• 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

12
4
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

12
5
Final finish & funnelling
of cavity walls with
tapered diamond point
Final 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
12
6
Underextended / Over extended preparation Perforation into furcation

12
7
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
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8
Mandibular 1st MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

12
9
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 System
Normally 2 mesial and 1 distal canal
Mesial 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%
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0 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
13
2
Mandibular 2nd MolarDr. Nithin Mathew - Root Canal Morphology & Access Preparation

13
3
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 the
mesiodistal midline, a search should be made
for another canal on the opposite side using
Krasner and Rankow's laws of anatomy

13
4 Mandibular 2nd Molar
Anomalies
• C-shaped canals
• Taurodontism
• Fused or single canal
• Supernumery roots – Radix Entomolaris

Access Cavity Preparation In MANDIBULAR MOLARS
13
5
• 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

13
6
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

13
7
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
13
8
Over-extended
preparation
Perforation into
furcation
Disoriented occlusal
outline form
Perforation at
mesiocervical – tilted to
mesial

ERRORS In Cavity Preparation In MANDIBULAR MOLARS
13
9
Failure of finding 2nd
distal canal
Perforation of distal rootLedge formation

Access Cavity Preparation In Teeth with Calcified Canals
14
0
Mandibular first molar
with a Class I restoration,
calcified canals, and
periradicular
radiolucencies
Excavation 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 the
canal used to be.
• Chasing apically along this colored route typically leads to a more open canal that can
be negotiated.
14
2

Apical Diameter - Cohen
14
3
Teeth Mean Value (µm)
Maxillary incisors 289.4
Mandibular incisors 262.5
Maxillary premolars 210
Mandibular premolars 268.25
Maxillary molars
Palatal 298
Mesiobuccal 235.05
Distobuccal 232.2
Mandibular molars
Mesial 257.5
Distal 392

Suggested Preparation Sizes - Ingle
14

14

CONCLUSION
Thorough• Knowledge of root canal anatomy & cavity preparation will enable the
clinician to produce endodontic treatments of high quality and considerable longevity.
• A successful treatment outcome depends on the complete debridement and
disinfection of all canals.
14

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
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Root Canal Morphology & Access Preparation

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