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Internal anatomy of permanent/ orthodontic course by indian dental academy
1. CONTENTS
• Introduction
• Learning objectives
• Normal tooth structure
• Components of pulp system
• Comparative study of deciduous and permanent tooth structure
• Techniques for vascularization of internal anatomy
• Detailed study of internal anatomy of permanent tooth
• Detailed study of internal anatomy of deciduous teeth
• Variation in normal pulpal structure and its significance
o Physiological
o Pathological
o Development
o Others
• Conclusion
• References
2. Introduction :
The alliance between endodontics and pulp anatomy is inflexible and inseparable.
As a cause of treatment failure lack of know ledge of pulp anatomy ranks second only
to error in diagnosis and treatment planning. This implies that an endodontist must be
thoroughly cognizant of the anatomic shapes its variation and its relationship to other
significant landmarks.
Leading objectives :
- Recognize error that may cause difficulties or failures in root canal treatment
owing to lack of knowledge or pulp anatomy.
- To know common shapes of root in cross section and common canal
configurations.
- To know average tooth length, number of roots and most common root
curvatures.
- Define pulp space and describe its major components.
- State the tenet of pulp-root anatomy.
- List and recognize the significance of iatrogenic or pathologic factors that may
alteration in pulp anatomy.
- To know location, morphology frequency and importance or accessory canals.
- To know the relationship between anatomic apex, radiographic apex and actual
location of apical foramen.
NORMAL TOOTH STRUCTURE :
A tooth can be broadly divided into
- Crown (coronal portion).
- Root (Radicular portion).
The various components of tooth are _________ the outer most layer or crown is
Enamel : It is the hardest calcified tissue in human body. It forms a protective covering
over the entire surface of crown. The shape and contour of the cusps receive their final
modeling in enamel.
Dentin : The dentin provides the bulk and general form of the tooth and is characterized
as a hard tissue with tubules throughout its thickness. Since it forms slightly before
enamel it determines the shape of crown including the cusp and ridges and the number
and size of roots.
Pulp : The dental pulp occupies the center of each tooth and consists of soft connective
tissue. Every person normally has a total or 52 pulp organs (32 permanent, 20 primary).
Each or these organs has a shape that conform to that of respective tooth.
Total volume of all permanent teeth pulp organ = 0.38 cc.
Mean volume of a single adult human pulp = 0.02 cc.
Cementum : Cementum is the mineralized dental tissue covering the anatomic roots of
human teeth. It furnishes a medium for the attachment or collagen fibres that bend the
tooth to the surrounding.
Periodontal ligament : The periodontal ligament is the connective tissue that surrounds
the root and connects it to the bone. It is continuous with the connective tissue or
gingiva and communicates with marrow spaces through vascular channels in the bone.
3. COMPONENTS OF PULP SYSTEM :
The pulp system can be classified into
- Coronal pulp
- Radicular pulp
Coronal pulp :
Each pulp organ is composed of a coronal pulp located centrally in the crowns of
teeth. The coronal pulp in young individuals resemble the shape of the outer surface of
the crown dentin. The coronal pulp has six surfaces – occlusal (roof), mesial, distal,
buccal, lingual and the floor.
The cervical region or pulp organ constricts as does the contour of the crown and
at this zone the coronal pulp joins the radicular pulp. Because of continuous deposition
of dentin the pulp becomes smaller with age. This is not uniform in all areas of coronal
pulp but progresses faster on floor than on roof or side walls.
Dentinal maps as anatomical lines present on floor joining orifices. An important
or coronal pulp is pulp horns.
Pulp horns : These are prolongations / projections in the roof of pulp chamber that
correspond to various major cusps or lobes.
A single pulp horn tends to correspond with each cusp in posterior teeth. Occlusal
irtent correspond to height of contour in younger teeth whereas in order teeth it leis
closer to cervical margin.
“Pulp horns represents what the dentist does not want to locate during restorative
procedures but does want to locate during access preparation.”
Clinical significance :
During access preparation the height and location of pulp horns may be more
accurately determined by measuring from cusp tip to pulp horn or chamber roof using a
bur and a handpiece.
RADICULAR PULP :
Radicular pulp is that pulp extending from the cervical region of the crown to
root apex. The radicular portion of the pulp are continuous with the periapical
connective tissue through the apical foramen.
Significantly most canals are curved in faciolingual direction which may not be
obvious on facial projection.
CANAL CONFIGURATIONS :
According to Weine :
Type – I : Single canal from pulp chamber to apex.
Type – II : Two separate canals leave the chamber to merge short of apex into one
canal.
Type – III : Two separate canals leaving the chamber to apex.
Type – IV : One canal leaving the pulp chamber but dividing short of apex into two
separate different foramina.
According to verticle :
Type I : A single canal extends from the pulp chamber to apex.
4. Type II : Two separate canals leave the pulp chamber and join short of the apex to form
one canal.
Type III : One canal leaves the pulp chamber and divides into two in the root; the two
then merge to exit as one canal.
Type IV : Two separate, distinct canals extend from the pulp chamber to apex.
Type V : One canal leaves the pulp chamber and divides short of the apex into two
separate distinct canals with separate apical foramen.
Type VI : Two separate leave the pulp chamber merge in the body of the root and
redivide short of the apex to exist as two distinct canals.
Type VII : One canal leaves the pulp chamber divides and then rejoins in the body of
the root and finally redivides into two distinct canals short of apex.
Type VIII : Three separate distinct canal extend from pulp chamber to apex..
According to grossman :
Type I : Single canal from pulp chamber to apex.
Type II : Two separate canals leaving the chamber.
Type III : One canal leaving the pulp chamber but dividing short of apex in two
separate different canals with separate apical foramen.
Type IV : Two separate canals leave the chamber to merge short of the apex into one
canal.
ACCESSORY CANALS :
Accessory canals are minute canals that extend in a hornontal vertical or lateral
direction from pulp to peridontium.
73.5% - apical 1/3rd
11.4% - middle 1/3rd
15.1% - cervical 1/3rd
These canals contain connective tissue and vessels but do not supply pulp with
collateral circulation.
Formation :
They are formed by entrapment of periodontal vessels of periodontal vessels in
Hertwigs epithelial root sheath during calcification.
Accessory canals have a mean diameter or 6 to 60 µm.
In anterior teeth Seltzer (1966) observed 34% incidence of accessory canals.
DETECTION OF ACCESSORY CANALS :
Thickening of periodontal ligament or development of a frank lesion in the lateral
wall of the root would reveal the presence of a lateral canal. So during examination
complete stretch or lamina dura all around root should be studied. Many times in
clinical practice the presence of these canals become noticeable only in post obturation
x-ray.
Clinical significance :
These act as avenues for interchange of / passage or irritants. Pulp may become
inflamed or necrotic from the presence of deep periodontal pockets which cause deep
periodontal pockets which cause exposure or the orifices of the canals thereby
permitting the ingress or toxic products into the pulp. Conversely breakdown products
5. or inflammatory pulp lesions may have an effect on the periodontal tissues via these
canals, causing inflammatory changes.
Furcation canals :
Accessory canals may also occur in bifurcation or trifurcation of multirooted
teeth. Vertucei and Williams called these furcation canals.
Formation :
These form as a result of entrapment of periodontal vessels during the fusion of
the diaphragm which becomes the pulp chamber floor.
Diameter or furcation opening – 4 – 720 µm. Mandibular teeth have a higher
incidence of foramen on both pulpal chamber floor and furcation surface.
N mandibular molar these canals occurs in three distinct patterns.
Clinical significance :
These canals may be the cause of primary endodontic lesions in the furcation of
multirooted teeth.
Isthumus :
Isthumus is a marrow ribbon shaped communication between two root canals that
contain pulp or pulpally derived tissue.
It is also called as transverse anastomasis (Vertucei 1984), corridor (Green 1973)
lateral connection (Pineda 1973).
Kim et al has identified five types or isthmi that can be found on believed root
surface.
Type I : It an incomplete isthmus, it is a faint communication between two canals.
Type II : It is characterized by two canals with a definite connection between them
(complete isthmus).
Type III : It is a very short complete isthmus between two canals.
Type VI : It, complete or incomplete isthmus between three or more canals.
Type V : It is marked by two or three canal opening without visible connections.
Occurrence :
Isthmi are found in 15% of anterior teeth in maxillary premolar they are found
16% at the 1mm resection level and in 52% at the 6mm resection level.
The prevalence isthmi increases in the misiobuccar root or maxillary first molar
from 30% to 50% as root is resected from 2 to 4 mm level. Eighty presence of mesial
root of mandibular first molar have isthmi at 3 to 4 mm resections level where as 15%
or distal roots have isthmi – 3mm level.
Clinical significance :
Presence of isthmus must be suspected whenever multiple canals are seen on a
resected root surface.
They must be prepared and failed during surgery as these isthmus acts as
reservoir or bacteria.
ANATOMY OF APICAL ROOT :
6. The classic concept of apical root anatomy is based on three anatomic and
histologic landmarks in the apical region of a root.
- Apical constriction
- Cementodentinal junction
- Apical foramen.
Apical constriction :
The apical constriction is considered the part of the root canal with the smallest
diameter.
It is also the reference point clinicians most often as the apical termination for
shaping, cleaning and obturation.
This is generally 0.5 – 1.5 mm inside the apical foramen.
From the apical constriction or minor apical diameter the canal widens as it
approaches the apical foramen or major apical diameter.
The space between the major and minor diameter has been described as funnel
shaped or hyperbolic or as having the shape or a morning glory.
The mean distance between the major and minor apical diameter is 0.5 mm in a
young person and 0.67 mm in older individual.
It is greater in older indivicial because of build up of cementum.
Apical foramen :
The apical foramen is the circumference or rounded edge like funnel or crater that
differentiates the termination of cemental canal from the exterior surface of root.
Diameter :
503 µ - (18-25 yrs)
681 µ - (over 55 yrs).
The apical foramen does not normally exit at the anatomic apex but is offset 0.5 –
3 mm. This correction is more marked in older teeth through cementum apposition.
Cementodentinal junction :
It is the point in the canal where cementum meets dentin. It is the point where the
pulp tissue ends periodontal tissue begins. It is not in the same area as apical
constriction but 1 mm from apical foramen.
Cementodentinal junction should be considered just a variable junction at which
two histologic. Tissues meet in the root canal. The extent or cementum deposition on
each wall of the root canal varies; one wall usually covered with a greater quality of
cementum than the other wall.
Apical delta :
The principal canal may or may not exit as a single apical foramen. In many
instances it may slit near the apex and exit in two or more smaller foramina. This Y
shaped branching of root canal near the apex is called apical delta.
Pulpal tissue :
Pulpal tissue can be categorized into
- Apical pulp tissue
- Coronal pulp tissue
7. Apical pulp tissue is mainly found in the apical end of root. Most probably
continuing into surrounding periapical region. Apical tissue is more fibrous and
contains fevers cells. Histochemical studies by Yamashi et al in 1986 demonstrated
large concentrations or glycogen in apical pulp tissue, a condition compatible with the
presence of anaerobic environment. In gross appearance the collagenous apical tissue is
whitish in colour. The fibrous tissue acts as a barrier against apical progression of pulpal
inflammation.
The coronal pulp tissue contains mainly cellular connector tissue and fever
collagen fibers.
COMPARATIVE STUDY OF STRUCTURE OF DECIDUOUS AND
PERMANENT TOOTH
Primary tooth Permanent tooth
- Pulp chamber larger in relation to
crown sire
- Pulp chamber smaller in relation to
crown sire.
- Pulpal outline follows the DEJ
more closely
- Pulpal outline follows DEJ less
closely.
- Pulp horns are closer to outer
surface. Mesial pulp horn extends
to a closer approximation of
surface than does the distal pulp
horns
- The pulp horn are comparatively
aware from outer surface.
- Floor or pulp chamber is porous.
Accessory canals in primary pulp
chamber leads directly into inter
radicular furcation
- Floor or pulp chamber does not
have any accessory canal.
- The roots are larger and more
slender in comparison to crown
size
- The roots are shorter and bulbous
in comparison to crown.
- Furcation is more towards cervical
area so that root trunk is smaller
- Placement of furcation is apical
these the root trunk is larger.
- The roots are narrower
mesiodistaly
- The roots are broader mesiodistally
- At cervical region the roots of
primary molar flare outward and
continue to flare, as they
approach the apices to
accommodate the permanent.
- Marked flaring or root is absent.
- Root canals are ribbon like. The
radicular pulp follows a thin
tirtuous and branching pulp.
- Root canals are well defined with
less branching.
- Roots have enlarged apical
foramens. Thus abundant blood
- Foramens are restricted reduced
blood supply favours calcific
8. supply response and healing by calcific
scar.
TECHNIQUES FOR STUDYING INTERNAL ANATOMY :
- Diagnostic measures
- Radiography
- Dyes, lirafrony (India ink, Haematonyless, chenese).
- Clearing (using xylene, berizone).
- SEM (scanning electron microscope).
- Dental operating microscope.
- fiberoptic endoscopy.
Diagnostic measures :
Diagnostic measures are important aid in localization or root canal orifices.
These include
- Examining the pulp chamber with a sharp explorer.
- Troughing grooves with ultrasonic tips.
- Staining the chamber floor with methylene blue.
- Performing the CHAMPAGNE BUBBLE TEST with sodium hypochlorite –
allowing the sodium hypochlorite to remain in the pulp chamber may aid in
location or a calcified root canal orifice. The bubbles may appear in solution
indicating the position of orifice.
Radiography : Inspite of the recent advances radiographs remain to be the primary and
most commonly used method for visualization. Careful evaluation of two or more
periapical radiographs exposed at different horizontal angulation helps in assessing the
number and position or canals.
Scanning election microscope :
It has been used to determine the number and size of main apical foramen and
their distance from the anatomic apex and the size of accessory foramina.
Dental operating microscope :
Introduction of dental operating microscope has lead to enhanced visibility and
lighting to the internal architecture. Light is significantly improved because light or a
microscope is parallel the line or sight. These have been found to be effective for
locating MB-2 canals in maxillary molar DOM makes canal easier to locate by
magnifying and illuminating the grooves in the pulpal floor and by distinguishing the
color differences of the dentin of floor and wells.
Fiberoptic endoscopy :
This helps immensely in a better visualization of root canal and periapical spaces.
This works in conjunction with a camera, light source and monitor currently there exists
two diameter sizes of flexible fiberoptic probes used in endodontic.
- 1.8 mm (30,000 visual fiber).
- 0.7 mm (10000 visual fiber).
9. A ring or much larger light transmitting fibre surrounds the visual fibres. The 0.7
mm fiberoptic probe is used for intra canal visualization and also to determine now well
a canal is prepared.
STRUCTURE OF INDIVIDUAL TOOTH
Maxillary central incisor
Average tooth length – 22.5 mm :
(Root length is 1½ times or crown length).
Pulp chamber : The pulp chamber of maxillary central incisor is equidistant from
dentinal walls. Pulp chamber is wider mesiodistally than labio lingually with broadest
pare incisally.
Three pulp horns corresponding to developmental Mamnelons are present. A
lingual shoulder is present which must be removed to gain access to lingual wall.
Division between pulp chamber and canals are indistinct.
Root canals :
The maxillary central incisor has one root with one root canal. It is broader
labioparatally conical in shape and centrally located.
Cross –section :
Cervical 1/3 - Triangular (young)
Oval (old)
Middle 1/3 - Ovoid
Apical - Round.
Lateral canals (24% or specimens) in apical third.
Root curvatures - Straight – 75%
Labial – 9%
Distal – 8%
Mesial – 4%
The palatal and labial curvatures may not be seen in routine radiographs unless
taken at different horizontal angles.
The apical foramen is centrally located in the anatomic apex in only 12% cases
and apical delta is present in 1% cases.
ANATOMIC RELATIONSHIP IN SITES L
The labial surface of the root of the maxillary central incisor lies under the labial
cortical plate of maxilla and may fuse with it. Because of proximity to the labial surface
fenestration / dehiscence may be seen.
The relationship between apex of maxillary control incisor and nasal floor
depends
- Height or face
- Length of the root
Maxillary control incisor 20
mesioaxial.
250
palatoaxial.
Inclination in the alveolous.
- Incisor canal parallel the long axis so its sever as guide for palatine injection.
Clinical significance :
10. Lingual shoulder should be removed for straight line access.
Outline of access cavity changes to more oval shape as tooth matures and pulp
horns recede.
11. MAXILLARY LATERAL INCISOR
Average tooth length : 22 mm :
Pulp chamber : The outline of pulp chamber is similar to central except it is smaller. It
has two or no pulp horns. It is broader mesiodistally with its broadest past incisally. The
division between root canal and pulp chamber is indistinct.
ROOT CANALS :
Maxillary lateral incisor has a single root and an single root canal but it has a
finer diameter.
CROSS SECTION :
Cervical 1/3rd
– Ovoid labiopalatally
Middle 1/3rd
– Ovoid
Apical 1.3rd
– Round
Lateral canals occur more frequently than central incisors.
Root curvature - Distal – 53%
Straight – 30%
Palatally – 4%
Bayonet – 6%
The apical foramen is centrally located in the anatomic apex in 22% or cases and
apical delta is present in only 3% of cases.
Anatomic relationship in sites :
The labial surface of root of the maxillary lateral under the cortical plate of
maxilla. Therefore fenestration dehiscence may be present. As this root curves distally it
may be center or cancellous lower pointing palatally.
Location in alveolus - 160
mesioaxial
290
palatoaxial
Clinical significance :
- Two or three canals have been reported.
- In cases of Dens invaginatez peg lateral, Talons cusp require modification in
access opening.
MAXILLARY CANINE
Tooth length – 26.5 mm :
Pulp chamber : The pulp chamber are largest of any single rooted teeth. no pulp horns
smallest pointed incisal edge corresponds to single cusp. The pulp chamber is wider
labiolingually than mesiodistally. Labiopalatally the pulp chamber is triangular shape
apex towards the single cusp broad base towards the cervical third. Mesiodistally it is
narrow resembling to flame.
ROOT CANAL :
The single root canal of maxillary canine larger than that of maxillary incisor. It
is wider labiopalatally. Gradually it tapers to an apical constriction.
CROSS SECTION :
Cervical 1/3 - Oval
Middle - Oval
12. Apical - Constricted
Lateral canals are present in 30% cases.
Root curvature - Straight – 39%
Distally – 32%
Palatally – 7%
Labally – 13%
Bayonet / s – 7%
Dilacerations – 2%.
The apical foramen is centrally located in anatomic apex 14% of cases and an
apical delta is present in only 3%.
13. ANATOMIC RELATIONSHIP IN SITES :
An abscess originating in the maxillary cuspid usually perforates labial cortical
plate.
- It below insertion of levatormuscle – Buccal vestibule.
- It above the insertion – canine space cellulites.
Apical curettage may be difficult ding periradicular procedures because of length of the
root.
Location in alveolus - 60
Destoaxial
210
Palatoaxial
Clinical significance :
- Buccal bone over canine immune disintegrates leading to fenestration. Slight
permanent apical sensitivity occasionally occurs after root canal therapy. This can
be corrected by apical root surgery.
- Apical curettage may be difficult.
MAXILLARY FIRST PREMOLAR
Tooth length – 20.6 mm :
Pulp chamber : The pulp chamber is wider bucco lingually and narrow mesiodistally.
It has a pulp horn under each cusp but both may be missed in routine radiographic
projections because of superimposition. Two pulp horns are present. Buccal is larger
than the palatal one. Roof of the pulp chamber coronal to cervical line. Floor is convex.
Usually below the cervical line. In cross section chamber is wide and ovoid in
buccopalatal direction.
ROOT CANALS :
- The maxillary first premolar has 2 roots in 54.6% cases. Out of this roots are
separated (21.9%) partially fused (32.7).
- Irrespective or whether it has one root / two root it has 2 canals at the apex in
69% cases.
- When fused root occur a groove summing in occlusoapical direction dividing root
into buccal and palatal portions.
- The palatal canal is larger of the two and is directly under palatal cusp and its
orifice can be penetrated by following the palatal wall of pulp chamber.
- Twenty six percent of these teeth have only one canal at the apex. Of these only
1% have 1 canal exiting at the apex whereas 18% have 2 orifices in the pulp
chamber that coalesce to form a single canal at apex. Transverse canals between
canals are common.
- Lateral canals may be present in 49.5% cases with 11% found in furcation
between buccal and palatal roots.
ROOT CURVATURES :
In single rooted - Straight – (38.4%)
Distal – 36.8%)
Buccally – (14.4%)
Palatally – (2.4%)
S or Bayonet (8%)
14. In double rooted
Buccal root Palatal root
Straight 27.8% Straight – 44%
Buccal – 14% Buccal curve 27.8%
Palatal – 36.2% Palatal – 8.3%
Distal – 14% Distal – 14%
S / Bayonet – 5.5%
The apical foramen is centrally located in 12% cases and an apical delta only in
3.2% cases.
15. ANATOMIC RELATIONSHIP IN SITES :
Relationship of first premolar socket to alveolar process varies with the number
of roots. If one root then the socket is in close relationship to buccal cortical plate. If
two roots are present then buccal is close to buccal cortical plate and palatal is centrally
located.
Clinical significance :
The outline form of cavity preparation varies with the number of canals.
- When two canals are present access opening is oval / slot shaped wide
buccolignually.
- But with three canals outline form becomes triangular base on buccal aspect.
Mesiobuccal and distobuccal corners directly on the orifice.
- Prone to mesio distal fracture so full coverage restoration is required after root
canal treatment.
MAXILLARY SECOND PREMOLAR
Tooth length – 21.5 mm :
Pulp chamber : Like maxillary first premolar the pulp chamber is narrow mesiodistally
but it is more wider buccopalatally than the first premolar. Two pulp horns are present.
Buccal (larger) and palatal. Roof is similar to maxillary first but is deeper than the first
if two canals are present.
If one root canal present then the canal orifice may be indistinct but if two canals
are present the two orifices will be visible.
ROOT CANALS :
Single root – 90.3%
2 well developed roots – 2%
Partially fused 2 roots – 7.7%.
Lateral canals are present in 59.5% of cases 1.6% occur in furcation area if two
roots occur.
CROSS SECTION :
Cervical – Ovoid and narrow
Middle 1/3 – Ovoid (1 canal); round (2 canal)
Apical 1/3 – Round.
Apical foramen is centrally located in 12% cases and an apical delta is present in
only 3.2% cases.
Root curvature - Distal – 33.9%
Bayonet – 13%
Buccal – 15.7%
Straight – 37.4%
ANATOMICAL RELATIONSHIP IN SITES :
There is a close relationship between the roots of premolar and maxillary sinus.
Clinical significance :
Depending on the number of canals the external outline form varies.
16. One canal : Buccolingual width corresponds to width between buccal and palatal pulp
horns.
Two canals : Access preparation is nearly identical to first premolar.
Three canals : The access outline form is same triangular shape.
MAXILLARY FIRST MOLAR
Average tooth length – 20.8 mm :
Pulp chamber : The pulp chamber of maxillary first molar is largest in the arch with
four pulp horns - Mesiobuccal
Distobuccal
Mesiopalatal
Distopalatal
The four walls forming the roof converge towards the floor where the lingual wall
almost disappear, the floor of the pulp chamber thus has a triangular form in cross-
section. The orifices of the root canals are located in the three angles of the floor.
Anatomic dark lines in the floor of the pulp chamber connect the orifices.
Palatal orifice : It is the largest round or oval in shape and easily accessible for
exploration.
Mesiobuccal orifice : This orifice is under the mesiobuccal cusp, long buccopalatally
and may have a depression at the palatal and in which fourth orifice may be present.
The mesiobuccal orifice is located by insinuating the tip of a long shank explorer startite
D-11 in a mesiobuccal –apical inclination into point angle at the juncture of buccal wall,
mesial wall, and subpulpal floor of the pulp chamber.
Distobuccal orifice : It is located slightly distal and palatal to mesiobuccal orifice and
is accessible from mesial for exploration.
The floor chamber is in cervical third of root canal roof is in the cervical third of
crown.
Root canals :
It has 3 roots with usually 3 canals situated mesiobuccally distobuccally and
palatally.
Palatal root : Largest and longest of the three it offers the easiest access. It can contain
1-3 canals. It is flat ribbon like wider mesiodistally.
Lateral canals are present in 40% of these roots and apical deltas are only seen in
4%. Apical foramen is centrally located in only 18% cases.
Distobuccal root : It is small and is more or less round in shape. If usually has a single
root canal which is narrow tapering canal sometimes flattened in mesiodistal direction.
Lateral canals are present in 36% of cases. Apical deltas are present in only 2%.
The apical foramen is centrally located in 19% or these teeth.
Mesiobuccal root : It has generated more research investigation than any other root in
the mouth. It is narrowest of the three. Flattened in mesiodistal direction at orifice but
round in apical third but round in apical third. In 64% of cases it has 1 canal and 1
foramen and oval and wider buccolingually.
It two or more canals are present it becomes more circular.
17. MB – 2 (Meseobuccal – 2) is generally present mescal to or directly on a line joining
MB – 1 and palates orifice (3.6 mm palatally and 2 mm mescal to MR – 1 orifice).
Not all MB–2 orifices read to canals (only 84%).
Root curvatures :
Meseobuccal Distobuccal Palatal
Distal – 78% Straight – 54% Straight – 48%
Straight – 21% Distal – 17% Buccally – 55%
s/tayonet – 1% s/ Bayonet – 10% Distally – 1%
Anatomic relationship insitu :
There is close relationship of maxi. first molar with maxillary sinus. This close
relationship may produce more ness in maxillary teeth due to maxillary sinusitis
conversely infection of the sinus may result from pulpal disease.
Clinical significance :
• Pulp stones may be present in the pulp chamber which must be identified and
removed during access preparation.
• Generally a concavity exists on the distal aspect or mesiobuccal root which
makes this wall thin. The clinician must take care not instrument excessively elase a
strip perforation may occur.
• Negotiation or MB-2 is often difficult is a redge or dentin covers its orifice. The
orifice has a mesiobuccal inclination on the pulpal floor and canal’s pathway often
takes one or two abrupt curves in coronal past or root. These can be eliminated by
throughing and countersinking by ultrasonic tips.
Maxillary second molar :
Tooth length – 20 mm
Pulp chamber – Similar to maxillary first molar except it is narrower
mesiodistally. Because of this narrower dimension the roof of the pulp chamber is
rhomboidal in cross section and the floor is an obtuse triangle in cross section and
mesiobuccal and distobuccal canals are closer together and may appear to have a
common opening but they are readily distinguishable from each other. Sometimes all
three are in a straight time.
Root canals :
The maxillary second molar has 3 roots which are closely grouped. Because of
this close grouping buccal roots may fuse and occasionally all three may fuse. Studies
have reported this characteristic in 46% cases.
• It 3 roots are present one usually sees 3 canal with a fourth canal is less
frequently than in the maxillary first molar.
• It the buccal roots fuse to form 1 buccal root the tooth may have 2 canals (1
buccal, 1 palatal).
• A tooth with only 1 root usually has only 1 conical root canal.
Fever lateral canals are present in the roots or furcation. In only16% foramena are
centrally located and only apical deltas are seen in 3% roots.
18. Anatomic Relationship Insitu :
The maxillary second molar is usually more closely related to maxillary sinus
than the maxillary first molar.
Clinical significance :
Access cavity varies number of canals
Four – Rhomboidal
Three – Triangular
Two – Ovoid widest in buccopalatal direction
Mesial marginal ridge should not be involved.
To enhance radiographic risibility especially when interferences arises from
molar process a more perpendicular and distoangular radiograph may be exposed.
Maxillary third molar :
Tooth length – 17 mm
Pulp chamber : The maxillary third molar anatomically resembles the second molar.
The pulp chamber can be similar to that of second molar but it may vary greatly. This
may have odd shaped chamber with four or five root canal orifices or a conical chamber
with only on root canal.
Root canals :
It may have three well developed roots that are closely grouped. It may also have
fused roots, one conical roots or four or more independent roots. The roots may be
straight curved or dilacerated and they may fully or partially developed.
Root canals vary from 1 to 4 or even five depending on the number of roots. One
may find a C-shaped pulp chamber with a C-shaped root canal.
Anatomic Relationship Insitue :
The maxillary third molar is closely related to maxillary sinus and maxillary
tuberosity.
Mandibular central incisor :
Tooth length – 20.7 mm
Pulp chamber : Smallest tooth in the arch. The pulp chamber is small and flat
mesiodistally. The three distinct pulp horns present in recently erupted tooth become
calcified and disappear early in life because of constant masticatory stimulus.
Labiolingually the pulp chamber is wide ovoid in cross section in cervical third of
the crown and tapers incisally.
19. Root canals :
The mandibular central incisor has 1 root flat and narrow mesiodistaly but wide
labiolingually.
The canal configuration varies
• 1 canal exiting in 1 Apical foramen – 70%
• 2 canal existing in 1 Apical foramen – 5%
• 1 canal bifurcating, into 2 coming together and exiting into 1 apical foramen –
22%
• 2 canals may exit in 2 foramen – 3%
Cross section :
Cervical 1/3 – ovoid
Middle 1/3 – ribbon shaped in labiolingual direction due to flatness or root in this
region (clinical significance)
Apical 1/3 – round
Root curvature :
Straight – 60%
Distal – 23%
Labial – 13%
Lateral canals are present in 20% cases apical deltas in 5%. The apical foramen is
situated centrally in the root 25% or cases.
Anatomic relationship in situ :
The roots of the anterior teeth are broad labiolingually occupy most of the
alveolar process and the labial and lingual surfaces f the roots therefore fuse with labial
and lingual cortical plates.
Location alveolus – 20
mesioaxial
200
linguoaxial
Clinical significance :
Because of small six and internal anatomy may be most difficult tooth for access
opening. Complete removal of lingual shoulder critical often the second canal is
present. For this one should extend preparation into lingulum gingivally.
Mandiublar lateral incisor :
Average toothy length – 20.7 mm.
Pulp chamber : The configuration of pulp chamber of mandibular lateral incisor is
similar to mandibular central but the lateral tooth has larger dimension.
Root canals :
Although the root of mandibular lateral incisor is larger than that of mandibular
central it has basically same configuration. The incidence of double root canals at the
apex is about the same as in central incisor and their anatomy in cross section also
similar. Lateral canals are present in 18% cases; only 6% have apical diction. The apical
foramen is in the center of radiographic apex in 200
% cases.
Location in alveolus – 170
mesioaxial
200
linguoaxial
20. Root curvature – Straight (Majority)
Distal sharper)
Clinical significance :
Germination and fusion are common in mandibular anterior teeth.
Mandibular canine :
Tooth length – 25.7 mm
Pulp chamber : The mandibular canine resembles maxillary canine but it is smaller in
dimensions. The pulp chamber is narrow mesiodistally. When viewed labiolungually
chamber narrows to a point in the incisal third of crown but it is wide in the cervical
third.
Only one pulp horn is present in the adult tooth. In cross section pulp chamber is
ovoid in cervical third.
Root canals :
Although the tooth usually has a single root it may have two (2.3%) cases and
two canals (‘labially; lingually). These canals are narrow mesiodistally wider
labiolingually.
Variable canal configuration present are
• 1 canal exiting in 1 apical foramen - 78%
• 2 canal come together and exit in 1 foramen – 5%
• 1 canal bifurcates and coalesces to exit in 1 apical foramen – 18%
• 2 canals exit in 2 apical foramen – 2%.
When one root canal is present, a labiolingual view shows a canal that is broad in the
middle third and tapers to a constriction in to apical third.
CROSS SECTION :
Cervical 1/3 – ovoid
Middle 1/3 – ovoid
Apical – round
Root curvature :
Straight – 68%
Distal – 20%
Mesial – 1%
Labial – 7%
S/Bayonet – 2%
Lateral canals are present in 30% cases apical deltas in 8Z%. Apical foramen is
centrally located in 30% of these teeth.
Anatomic Relationship Insitu :
Location in alveolus – 130
mesioaxial
150
linguoaxial
Clinical significance :
• Lingual shoulder must be removed to gain access to second canal / lingual wall.
• Incisal extension can approach incisal edge for straighten access.
21. Mandibular first premolar :
Tooth length – 21.6 mm
Pulp chamber : It is a transitional tooth between anterior and posterior tooth. The
mesiodistal width of the pulp chamber is narrow. Buccolingually the pulp chamber is
wide with a prominent buccal pulp horn that extends under a well developed buccal
cusp. In young tooth one sees a small lingual pulp horn that disappears with age and
may give pulp chamber an appearance of a cuspid. The prominent buccal cusp and the
smaller lingual cusp give the crown of about a tilt or 300
.
Root canals :
The mandibular first premolar has a short conical root. This root may divide in
apical third into 2 or 3 roots. Narrow mesiodistally broader labiolingually.
Canal configuration :
• 1 canal exiting in 1 foramen - 70%
• 1 canal bifurcurating into two then uniting to exist in 1 foramen – 4%
• 1 canal bifurcates into two and exists into two foramen 24%.
• 2 canals exit in 2 foramen – 1.5%
• 3 canals exit in 2 foramen – 2%.
CROSS SECTION :
Cervical 1/3 – ovoid
Middle 1/3 – ovoid
Apical 1/3 – round
Lateral root curvature :
Straight – 48%
Distally – 35%
Buccally – 2%
Lingually – 7%
Bayonet/S – 7%
Lateral canals are present in 44.3% and apical deltas are found in 5.7%. Apical
foramen is centrally located in only 15%, or teeth.
Anatomic relationship in situ :
The mental canal and foramen are sometimes close to root apex of mandibular first
premolar. The radiographic appearance may suggest periapical pathoses.
Location in alveolus : 140
distoaxial
100
linguoaxial
Clinical significance :
• Befurcation / Trefurcation are the most common anomalies.
Mandibular second premolar
Tooth length – 22.3 mm
Pulp chamber : The pulp chamber is similar to 1st
premolar except the lingual horn is
more prominent under a well developed lingual cusp.
Root canals :
22. The mandibular second premolar usually has a single root but on rare occasions 2
to 3 are present. The root has a greater girth and is wider buccolingually usually 1 canal
exists in 1apical foramen in 97.5%
In 2.5% cases a single canal may bifurcate exiting in 2 foramina.
Root curvature :
Distally – 40%
Straight – 39%
Buccal – 10%
Lingual – 3%
Bayonet – 7%
Anatomical relationship in situ :
Mandibular second premolar is in close relationship to mental foramen.
Location in alveolus – 100
distoaxial
340
buccoaxial
Clinical significance :
• Because the crown typically has less lingual inclination less extension up to
buccal cusp incline is required to gain straight line access.
• As the lingual half is more well developed so access extension typically is
halfway up the lingual cusp incline.
• In case two lingual cusps are present the access is centred mesiodistally on a line
connecting buccal cusp and the lingual groove between the lingual cusp tips.
Mandibular first molar :
Average tooth length – 21 mm.
Pulp chamber : The roof of the pulp chamber is often rectangular in shape. The mesial
wall is straight, the distal wall I round and buccal and lingual walls converge to meet the
mesial and distal walls and to form a shomboidal floor. The roof of the pulp chamber
has four pulp horns; mesiobuccal mesiolingual, distobuccal and distolingual. The roof is
located in the cervical third of crown just above the cervix of tooth and the floor is
located in the cervical third of root.
Three distinct orifices
Mesiobuccal : It is present under the mesiobuccal orifice is under the mesiobuccal cusp
and is usually difficult to find if not enough tooth structure is removed. A long shank
starlite D-11 explorer is inserted in mesiobucco apical inclination into the point angle
created at the juncture of mesial wall, buccal wall and ssubpulpal floor of pulp chamber.
Mesiolingual : It is located in a depression formed by mesial and lingual wall. The
orifice can be explored in a distobuccal direction. A groove generally connects the
mesiobuccal and mesiolingual canals.
Distal : The distal orifice which is oval in shape with the widest diameter
buccolingually. The opening is generally located distal to the buccal groove. The orifice
usually can be explosed from the mesial with either an endodontic explorer or small K
file. If the file takes a sharp turn in a distobuccal or distolingual direction the clinician
should search for yet another orifice.
23. ROOT CANALS
Usually 2 well differentiated rots are present in mandibular first molar 1 mesial
and 1 distal. Both the roots are wide and flat buccolingually with a depression in the
middle of the root buccolingually
This anatomic characteristic may accentuated in the mesial root. A third root is
found in some cases either distally or medially. Although two roots are present 3 canals
are usually these.
Canal configuration for mesial root :
• 2 canals that exit in 2 foramen – 41%
• 2 canals that coalesce to exit in 1 foramen -28%.
• 2 canal that coalesce to form 1 again bifurcate and exit in 2 foramina – 10%
• 1 canal hat exits in 1 foramen – 12%
• 1 canal that bifurcates and exists in two foramen – 8%.
Canal configuration for Distal root
• 1 canal exiting in 1 foramen – 70%
• 1 anal bifurcation existing in 2 foramina 8%
• 2 canals coalescing and exiting in 1 foramen – 15%.
• 2 canals 2 foramina 5%
When 2 canals are present in either root they may converge toward and exit in 1
foramen or they may have inter connecting lateral canals between them that form a
single ribbon canal ending in 1 foramen.
CROSS SECTION
Cervical 1/3 – Ovoid
Middle 1/3 – Ovoid
Apical 1/3 – Round
Root curvature :
Measure Distal
Distally – 84% Straight – 74%
Straight – 16% Distal – 21%
Mesial – 5%
Lateral canals are present in furcation in 23% cases, in mesial root 45% and distal
root 30%. Apical deltas are present in mesial root 10% and distal root in 14%.
Anatomic relationship in sites :
The mesial root of the mandibular terse molar is in close prormity to buccal
cortical plate where as distal root is centrally located. 580
buccoacial in alcohols.
Chemical significance :
• Pulp stones may be present.
Mandibular second molar
Average tooth length – 19.8mm
24. Pulp chamber : The pulp chamber is smaller than that or mandibular first molar and
the root canal orifices are smaller and closer together.
Root canals : Majority or mandibular second molars have
2 roots (71%)
1 root (27%)
3 roots (2%)
Three root canals are usually present in mandibular second molars. Most frequent
vacation is presence or only 2 canals. When the mescal root or the mandibular second
molar has two canals they often join near the apex to root as single foramen.
Cross section :
Cervical - ovoid
Middle - ovoid
Apical - round
Root curvatures :
In single rooted It 2 rooted
Straight – 53% Mesial Distal
Distally – 2.6% Distally – 61% Straight – 58%
Lingually - 2% Straight – 27% Distally – 18%
Bayonet – 19% Buccaly – 4% Messally – 10%
Bayonet – 7% Bucally – 4%
Bayonet – 6%
Lateral canals are present – [Meseal root (45%)
Distal root (34%)].
Apical delta [Meseal (6%)
Distal (7%)]
Lateral canals are present in furcation area in 11% cases.
Anatomic relation slup in siter :
The meseal root is more untrally located and the distal root is closer to lingual
cortical plate.
Clinical significance :
The appear of this tooth very close to mandibular canal the clinician must take
care not to allow instruments or felling material to invade this space because paresthesia
may result.
Mandibular Third Molar
Tooth length – 18.5 mm
Pulp chamber : The pulp chamber resembles the pulp chamber or mandibular first and
second molars. It is large and possess many anomalous configuration such c-shaped root
canal orifices may occur.
Root canals :
The mandibular third molar usually has two roots and two canals but occasionally
one root and one canal or three roots and three canals may be present. The root canals
are generally large and short.
25. Anatomic Relationship in Setir :
The alveolar socket may project onto the lingual plate or the mandible. The apex
or the root may be in close proximity to mandibular canal.
Clinical significance :
The anatomy of mandibular third molar is very unpredictable therefore access
cavity can take any or the several shapes.
DETAILED TOOTH STRUCTURE OF DECIDUOUS TEETH
Maxillary first molar
Pulp cavity : The pulp cavity of maxillary first molar consists of 3-4 pulp horns. These
pulp horns are more sharply pointed then the corresponding cusps.
Mescobuccal pulp norms largest pulp horn with its apex slightly mesial to the
body of the pulp chamber. Distobuccal occupies the distobuccal angle. Occlusally it
appears a roughly triangular with rounded corners.
Six
MB > ML > DB
The mesiolingual part is obtual whereas the mesiobuccal and distobuccal are
acute.
Roots :
Usually Maxillary first molar consorts of three roots.
Mesiobuccal
Distobuccal – shortest
Lingual – longest averages in lingual direction.
Maxillary second molar
Pulp cavity : The pulp cavity consists of a pulp chamber and three pulp canals. The
pulp chamber conforms to the general outline or the tooth and has four pulpal horns a
fifth horn projecting from the lingual aspect of the mescolingual horn may be present
and when present is small. Mesiobuccal pulp horn and largest. It extends occlusally
above other cusps and is pointed. Meseolngual is second in sine but slightly longer than
the distobuccal. When combined with fifth pulp horn it appears quite bukky.
Projections on the incisal border. The chamber tapers cervicaly in mesiodistal
diameter but is widest at cervical ridge labiolingually. There is no distinct demarcation
between pulp chamber and canal.
Maxillary lateral incisors are quite similar in contour to maxillary central incisors
except that they are not as wide mesiodistally. Their cervioincisal length is almost same.
The labial surface is little more flattened the ungulum is not so pronounced and blends
with the lingual marginal ridges. In lateral incisor there is slight demarcation between
the pulp chamber and the canal especially on the labial and lingual aspects.
Root :
The root is single and conical in shape. It is fairly regular in form ending in a well
rounded apex.
26. The distobuccal is third in size. Its general contour is such that it joins the
mesiolingual pulp horn as slight elevation and separates a central pit and a distal pit
corresponding to occlusal outline of the tooth in this area.
Destolingual pulp horn is smallest and shortest and extends only slightly above
the occlusal level.
Root canals :
There are three pulp canals corresponding to the three roots. These leave the floor
of the chamber at the mesiobuccal and distobuccal corners and from the lingual area.
The root canals follow the general contour of the roots.
MAXILLARY PRIMARY INCISOR
Pulp cavity : The pulp cavity confirms to the general outside surface of the tooth. The
pulp chamber has three slight projection
MANDIBULAR FIRST PRIMARY MOLAR
Pulp chamber : The pulp chamber viewed from the occlusal is rhomboidal shape and
closely follows the contour of the surface of crown. It has four pulpal horns.
Mesiobuccal pulpal horn is the largest and occupies a considerable part of the
pulp chamber. It is rounded and connects with the mesiolingual pulpal horn in a high
ridge making the mesial area especially vulnerable to mechanical exposure.
Distobuccal pulp horn is second in area but lacks the height of the mesial horn.
Mesiolingual pulp horn because of the contour of the pulp chamber lies slightly
mesial to corresponding cusp. Although it is third in size it is second in height.
MAXILLARY PRIMARY CUSPID
Pulp cavity : The pulp cavity conforms to the general surface contour of the tooth.
There is a central pulpal horn projecting incisally considerably further that the
remainder of the pulp. Because of the greater length of the distal surface this horn is
larger than the mesial projection. There is very little demaseation between the pulp
chamber and the canal.
Roots :
The root of maxillary cuspid is long thick in diameter and slightly flattened on its
mesial and distal surfaces. The root is tapering however there is a slight increase in
diameter as it progresses from the cervical margin. The apex of the tooth is rounded.
The distolingual pulp horn is smallest. It is more pointed than the buccal horns
and small compared to other three pulp horns.
Roots / canals :
There are three pulp canals. A mesiobuccal and mesiolingual are confluent and
leave the chamber widened buccolingually in the form of a ribbon. The two pulp canals
soon separate to form a buccal and lingual which gradually taper to apical foramen.
Distal pulp canal projects in ribbon fashion from the floor of the chamber in the
distal aspect. This canal is wide buccolingaully and may be constricted in center
reflecting the outside contour of the root.
MANDIBULAR SECOND MOLAR
Pulp cavity : The pulp cavity is made up of a chamber and three canals. The pulp
chamber has five pulp horns.
27. Corresponding to five cusps. The roof of the chamber being extremely concave
towards the apices.
Mesiobuccal and mesiolingual pulpal horns are largest. Mesiolingual pulpal horns
slightly less pointed but of same height. These horns are connected by a higher ridge of
pulpal tissue that is found connecting the distal horns of the pulp.
Distobuccal pulp horn is not as large as the mesiobuccal pulpal horn but
somewhat larger than either distolingual or distal horn.
Distal pulpal horn is the shortest and smallest occupies a position distal to
distobuccal horn and its distal inclination carries the apex distal to distolingual horn.
Roots :
The two mesial pulp canals are confluent as they leave the floor of the pulp
chamber through a common orifice that is wide buccolingually but narrow
mesiodistally. The root of the lateral incisor is longer and also tapers towards the apex.
MANDIBULAR PRIMARY CUSPID :
Pulp cavity : The pulp chamber follows the external contour of the tooth being
approximately as wide mesiodistally as labiolingually there is no differentiation
between chamber and canal.
Roots / canals :
The root is single with a broader labial than lingual diameter. The mesial and
distal surfaces are slightly flattened. The root tapers Aa a rather pointed apex.
The canal soon divides into a larger mesiobuccal and a smaller mesiolingual
canal.
The distal canal is somewhat constricted in the center. All three canals taper as
they approach the apical foramen.
MANDIBULAR PRIMARY INCISOR
Pulp cavity : The pulp cavity conforms to the general surface contour of the tooth. The
pulp chamber is widest mesiodistally at the roof of the chamber. Labiolingually the
chamber is widest at the ungulum.
There is a definite demarcation between the pulp chamber and canal in central
incisor which is not present in lateral incisor.
Roots / canals :
The root of the central incisor is only slightly flattened on its mesial and distal
aspects and tapers towards the apex.
VARIATIONS TO NORMAL PULPAL STRUCTURE AND ITS
SIGNIFICANCE
Factors
1) Physiological
2) Developmental
3) Pathological
Physiological :
28. Age : Although dentin formation occurs with age on all surfaces it occurs
predominantly in certain areas. As in case of molars the roof and floor of the chamber
show more dentin formation eventually making the chamber almost disc like in
configuration.
Clinical significance : With gradual deposition of dentin there is a change in internal
anatomy which leads to difficulty in locating chamber and canals.
PATHOLOGICAL FACTORS
Irritants :
Anything that exposes dentin to oral cavity can potentially stimulate increased
dentin formation at the base of tubules in the underlying pulp. Causes of such dentin
exposure include caries periodontal disease, abrasion, erosion, attraction cavity
preparation, root planning and cusp fractures. Vital pulp therapy such as pulpotomy
pulp capping or placement of irritating material in a deep cavity may cause increase
dentin formation occlusion. Calcific metamorphosis resorption or other unusual
configuration in chamber a canal. These tertiary dentin formation tend to occurs directly
under involved tubules.
Clinical significance : It is imperative clinician study radiograph and usually examine
the tooth. Failure to do so may result in serious error lost time and inadequate treatment.
Calcifications :
Calcification can take two basic forms within the pulp – pulp stones true false,
diffuse calcification.
Pulp stones are usually found in pulp chamber whereas diffuse calcification
within the radicular pulp.
These calcifications may form either normally or in response to irritation.
Pulp stones are often seen on radiograph diffuse calcification are visible only
histologically.
Clinical significance : Pulp stones may reach considerable size and alter the internal
anatomy. They may often make the process of orifice locating challenging. These large
pulp stones may be free or attached and are removed during access preparation.
INTERNAL RESORPTION :
Internal resorption is an unusual form of tooth resorption that begins centrally
within the tooth apparently initiated in most cases by a percussion inflammatory
hyperplasia of the pulp.
Most resorption ar small and not detectable on radiograph or during canal
preparation. When visible radiographically they are usually extensive and often
perforate.
Clinical significance : Internal resorption usually create operative difficulties.
DEVELOPMENTAL FACTORS
Dens in dente / dens invaginaties :
The dens in dente is a developmental variation which is thought to arise as a
result of an invagination in the surface of tooth crown before calcification has occlusal
29. causes may include localized external pressure, focal growth retardation and focal
growth stimulation.
Permanent lateral incisors are the teeth more frequently involved. Such teeth are
predisposed to decay because of anatomic malformation and pulp disease before the
root apex is fully developed.
DENS EVAGINATUS :
It is a developmental condition that appears clinically as an accessory cusp or a
globule or enamel on the occlusal surface between buccal and lingual cusps of
premolar.
The pathogenesis is thought to be proliferation and evagination of an area of inner
enamel epithelium and subjacent odontogenic mesenchyme into the dental organ during
early tooth development.
These malformation often contain an extension of pulp which may get exposed
when the fragile tubercle fractures.
HIGH PULP HORNS :
Occasionally a pulp horn extends for into the cusp resulting in premature
exposure by caries or accidental exposure during cavity preparation.
Lingual groove :
Usually found in maxillary lateral incisor a lingual groove appears as a surface
infolding of dentin oriented from cervical toward the apical direction.
This results in a deep narrow periodontal defect that occasionally communicates
with pulp causing an endodontic / periodontal problem.
Dilacerations :
The term dilacerations refers to an angulation or sharp bend or curve in the root
or crown or a formed tooth. Many or these curvatures are found in a faccolingual plane
and are not obvious on standard radiographic projections.
Other variations :
A not uncommon variation is the C-shaped canal. This usually occurs in
mandibular molars.
The C-shaped canal was first reported in 1979 most C shaped canals occurs in
mandibular second molar.
C – shaped canals are so named because of cross sectional morphology of their
roots and root canals instead of having discrete orifices the pulp chamber of a molar
with a C-shaped canal system is a single ribbon orifice with an are of 1800
or more.
It starts at the mesiolingual line angle and sweeps around either to the buccal or
lingual to end at distal aspect of pulp chamber.
Below the orifice the root structure can show a wide range of anatomic variations.
These can be classified into two basic types.
1. Those with a single ribbon like C-shaped canal from orifice to apex.
2. Those with three or more distinct canals below the usual C shaped orifice.
Most common is the second type.
30. Significant Ethmic variation can be seen the anatomy is much more common in
Asians and Caucasians.
Teeth with C-shaped anatomy pose a considerable technical challenge however
use of DOM, sonic and ultrasonic instrumentation and plasticized techniques have made
treatment successful.