C SHAPED CANALS

1. C- SHAPED CANALS
DR. AMAL DEVADAS
POST GRADUATE
DEPT. OF CONSERVATIVE AND ENDODONTICS
1

2. CONTENTS
• INTRODUCTION
• HISTORY
• ETIOLOGY
• INCIDENCE
• ANATOMIC FEATURES
roots, pulp chamber, root canal system
• CLASSIFICATION
2

3. • DIAGNOSIS
preoperative R/F analysis, preoperative clinical diagnosis,
clinical diagnosis following access cavity preparations, clinical
& R/F diagnosis during working length determination
• MANAGEMENT
location & negotiation of canals, cleaning & shaping,
obturation, post endo restoration, endodontic surgery
• CONCLUSION
3

4. INTRODUCTION
• The traditional ‘one canal per root’ concept is being
challenged with observations from newer diagnostic
tools and current scientific literature.
• It is therefore important to be familiar with variations
in tooth anatomy to help in identification,
negotiation and management of aberrant canals.
4

5. • A thorough knowledge of the root canal anatomy
and its variations are required for achieving success
in root canal therapy, along with diagnosis,
treatment planning and clinical expertise.
• One such variation of the root canal system is the C-
shaped canal configuration.
• It is termed so because of the C-shaped cross-
sectional anatomical configuration of the root and
root canal.
5

6. • In contrast to normal anatomy, the orifice of a C-
shaped canal is ribbon-shaped and transcribes an arc
of 180 degree.
• The feature usually starts at mesiolingual line angle
of the chamber, curves buccally and ends at the
distal aspect.
6

7. Below the orifice level, the root structure can be
basically divided into two groups.
1. With three or more distinct canals below the orifice.
2. With single, ribbon-like, C-shaped canal from orifice
to apex.
7

8. • C-shaped canals often present a challenge in
debridement and obturation.
• Roots of this type of teeth may be fused in buccal or
lingual aspect and may have a conical or square
configuration.
• Fins or webs may be seen connecting individual root
canals.
• This seminar is an attempt to address the etiology,
classification, prevalence, diagnosis and management
of C-shaped canals.
8

9. HISTORY
• Historically, Keith & Knowles in 1911 were the first
authors to depict a C-shaped root canal.
• The C-shaped root was first analysed in detail by
Nakayama in 1941, who gave it the name ‘gutter-
shaped root’.
• In addition, Nakayama & Toda in 1941 reported on the
‘gutter- shaped root canal’, focusing on its morphology
and aspects of treatment.
9

10. • Tratman in 1950 stated that the C-shaped root
morphology can frequently be observed in
mandibular second molars from Asian individuals.
• This condition was described for the first time in
literature by Cooke and Cox in 1979.
• Manning in his description of root canal anatomy of
mandibular second molars, stated that C-shaped
roots and root canals were first documented in 1908
and 1911,
10

11. ETIOLOGY
• The most accepted theory for the formation of C-
shaped canal configuration is the failure of Hertwig’s
epithelial root sheath (HERS) to fuse on the buccal
or lingual root surface.
• This results in a conical or prism shaped root with a
thin interradicular ribbon-shaped isthmus connecting
them.
11

12. INCIDENCE
• The C-shaped canal configuration shows an ethnic
predilection.
• Studies in Chinese and mexican populations have
shown a preponderance of this condition in
mandibular second molars.
• The C-shaped anatomy has been found to be more
common in Asians than in whites.
12

13. 13
JOE — Volume 43, Number 9, September 2017

14. • C-shaped configuration prevalence among women was
16.5%, which was significantly higher than the 10.4%
prevalence recorded in male patients.
• Despite its high occurrence in mandibular second molars,
this variation has also been reported in mandibular and
maxillary first molars (0.12%),maxillary (4.7%) and
mandibular third molars (3.5%-4%), mandibular first and
second premolars (1%) and even in maxillary lateral
incisors.
14

15. • Bilateral incidence of C-shaped canals has been
reported in 70%-81% of cases
• Singla & Aggarwal reported this configuration in the
palatal canal of a maxillary second molar.
15

16. ANATOMIC FEATURES
• The following are the pertinent features in relation to
the external root anatomy and configuration of the
pulp chamber and the root canal system usually found
in C-shaped mandibular molars, though similar
features may be found in C-shaped maxillary molars
and mandibular premolars.
16

17. ROOTS
• A conical or square configuration is characteristic of
roots having a C-shaped canal.
• The root configuration of molars having this canal
shape may be represented by fusion of either the
facial or lingual aspect of the mesial and distal roots
• The roots display an occluso-apical groove on the
buccal or lingual surface, which represent the line of
fusion between mesial and distal roots.
17

18. • The surface opposite this radicular groove is convex
referred to the C-shaped roots of mandibular second
molars as being ‘gutter-shaped’.
18

19. PULP CHAMBER
• The pulp chambers of teeth with C-shaped canals
mostly have greater apico-occlusal width with a low
bifurcation.
• This results in a deep pulp chamber floor, which has
uncommon anatomical configuration.
• The connecting slit that gives the tooth its name of “C-
shaped” may have closure to the buccal or lingual.
19

20. • If the buccal portion of the mesial and distal roots
are fused, the slit goes through the area of fusion,
and so the “C” is closed to the lingual.
• If the lingual portion of the roots are fused, then the
“C” is closed to the buccal.
20

21. ROOT CANAL SYSTEM
• The root canal system of C-shaped canals shows
broad, fan-shaped communications from the coronal
to the apical third of the canal.
• The canals change shape from the coronal aspect of
the root.
• For example: A continuous C-shaped canal would
change to a semicolon configuration in the midroot
and then becomes continuous C-shape in the apical
third of the root or vice versa.
21

22. • Accessory and lateral canals, inter-canal
communications and apical delta can be found in a
prevalence of 11-41%, in the apical region of C-
shaped canals.
• Cross-sectional C-shaped canal morphology reveals
thinner lingual walls than buccal with the lowest
value measured being 0.26 mm.
• The varied intricacies in the C-shaped canal anatomy
are outlined in the section on classification
22

23. MANDIBULAR PREMOLARS
• All C-shaped premolars have shallow or deep radicular
grooves located on the external mesiolingual surface of
the root.
• These grooves usually start 3 mm below the cemento-
enamel junction (CEJ) and may or not extend to the apex.
• The mean depth of the grooves at some areas on the root
can be around 1.5 mm.
• This must be taken into consideration during cleaning
and shaping.
23

24. • The morphology of C-shaped canals in mandibular first
premolars may present one of the following four
features:
• Continuous C-shaped canal only,
• Semilunar buccal canal only,
• Combination of continuous C-shape and semi-lunar
buccal canal
• C-shaped canal interrupted by non-C-shaped canal
24

25. CLASSIFICATION
• A comprehensive classification of C-shaped canal
system is essential for its diagnosis and management.
• The earliest classification were proposed by Manning
and Melton et al.
• However, there was no clear distinction between the
categories in Melton’s classification.
25

26. • Besides, Melton’s and Manning’s classifications
describe only the appearances of the canal orifices,
but fail to describe how the C-shaped configuration
may vary along the root length
• Various other classifications were then proposed by
Al-Fouzan, Fan et al, Gao et al and Min et al.
26

27. Melton’s Classification
• Melton et al. in 1991 proposed the following
classification of C-shaped canals based on their cross-
sectional shape.
• Category I: continuous C-shaped canal running from
the pulp chamber to the apex defines a C-shaped
outline without any separation (C1).
• Category II: the semicolon-shaped (;) orifice in which
dentine separates a main C-shaped canal from one
mesial distinct canal (C2).
27

28. 28

29. • Category III: refers to those with two or more
discrete and separate canals:
• Subdivision I: C-shaped orifice in the coronal third
that divides into two or more discrete and separate
canals that join apically.
• Subdivision II: C-shaped orifice in the coronal third
that divides into two or more discrete and separate
canals in the mid root to the apex.
• Subdivision III: C-shaped orifice that divides into
two or more discrete and separate canals in the
coronal third to the apex (C3).
29

30. Fan’s Classification
• Fan et al in 2004 modified Melton’s classification into
Anatomic and Radiographic classification
Anatomic classification
• Category I (C1): uninterrupted “C” with no separation
or division
30

31. • Category II (C2): the canal shape resembled a
semicolon resulting from a discontinuation of the “C”
outline , but either angle α or β should be no less
than 60°.
31

32. • Category III (C3): 2 or 3 separate canals (Fig.1C and
D) and both angles, α and β, were less than 60°.
32

33. • Category IV (C4): only one round or oval canal in that
cross section.
• Category V (C5): no canal lumen could be observed
(which is usually seen near the apex only)
33

34. 34

35. Fan’s classification (Radiographic )
• Fan et al classified C-shaped roots according to their
radiographic appearance into three types.
• Type I: conical or square root with a vague,
radiolucent longitudinal line separating the root into
distal and mesial parts.
• Mesial and distal canals merged into one before
exiting at the apical foramen.
35

36. • Type II: conical or square root with a vague,
radiolucent longitudinal line separating the root into
distal and mesial parts.
• Mesial and distal canals continue on their own
pathway to the apex .
36

37. • Type III: conical or square root with a vague,
radiolucent longitudinal line separating the root into
distal and mesial parts.
• Of the mesial and distal canals, one canal curved to
and superimposed on this radiolucent line when
running toward the apex, and the other canal
continued on its own pathway to the apex.
37

38. Classification of pulp chamber floor, by fan
• Type I: a peninsula-like floor with a continuous
C-shaped orifice.
38

39. • Type II: a buccal, strip-like dentin connection exists
between the peninsula-like floor and the buccal wall of
the pulp chamber that separates the C-shaped groove
into mesial (M) and distal (D) orifices.
39

40. • Type III: only one mesial, strip-like dentin connection
exists between the peninsula-like floor and the M wall,
which separates the C-shaped groove into a small ML
orifice and a large MB-D orifice. The MB-D orifice was
formed by the merging of the MB orifice and the D
orifice.
40

41. • Type IV: Non-C-shaped floor.
• One distal canal orifice and one oval or two round
mesial canal orifices are present.
41

42. Coronal view of C-types: (A)C1-type mandibular molar, (B)C2-type mandibular molar, (C)C1-
type 3D printed resin
replica, (D)C2-type 3D printed resin replica. 42

43. DIAGNOSIS
Preoperative Radiographic Analysis
• A preoperative radiograph usually provides various clues in
the identification of any variation in root canal
morphology.
• However, there are differences in opinions on the value of
a preoperative radiograph in diagnosing a C-shaped case.
• Cooke & Cox were of the opinion that it is not possible to
diagnose C-shaped canals on preoperative radiographs.
43

44. • Conversely, some investigators described four
radiographic characteristics that can allow prediction
of the existence of this anatomical condition:
radicular fusion, radicular proximity, a large distal
canal or a blurred image of a third canal in between.
• When the communication or fin connecting the two
roots is very thin, it is not visible on the radiograph
and may thus give the appearance of two distinct
roots.
44

45. • The radiograph may also reveal a large and deep pulp
chamber, usually found in C-shaped molars.
• Wang et al. reported a higher incidence in the
recognition of C-shaped canals using a combination of
radiography and clinical examination under the
microscope (41.27%) than using the radiography
(34.64%) or clinical examination (39.18%) alone.
45

46. Preoperative clinical diagnosis
• The crown morphology of teeth with C-shaped
anatomy does not present with any special features
that can aid in the diagnosis.
• A longitudinal groove on lingual or buccal surface of
the root with a C-shaped anatomy may be present.
• Such narrow grooves may predispose the tooth to
localized periodontal disease, which may be the first
diagnostic indication.
46

47. Clinical diagnosis following access cavity preparations
• Some investigators asserted that since radiographic
diagnosis is difficult, clinical diagnosis of C-shaped
canals can be established only following access to the
pulp chamber.
• The pulpal floor in C-shaped teeth can vary from
peninsula like with a continuous C-shaped orifice to
non C-shaped floor.
47

48. • However, when a C-shaped canal orifice is observed,
say, under the operating microscope, one cannot
assume that such a shape continues throughout its
length.
• Clinical recognition of C-shaped canals is based on
the anatomy of the floor of the pulp chamber and
the persistence of hemorrhage.
48

49. • Fan et al. stated that, for a mandibular second molar
to qualify for a C-shaped canal system, it has to
exhibit all the following three features:
• a. Fused roots
• b. A longitudinal groove on lingual or buccal surface
of the root.
• c. At least one cross-section of the canal should
belong to the C1, C2, or C3 configuration, as per
Fan’s anatomic classification.
49

50. Clinical and radiographic diagnoses during working
length determination
• Working length radiographs are more helpful than
preoperative and final radiographs in diagnosing C-
shaped canals.
• In a true C-shaped canal, (single canal running from
the orifice to the apex) it is possible to pass an
instrument from the mesial to the distal aspect
without obstruction.
50

51. • In the semicolon type, (one distinct canal and a
buccal or lingual C-shaped canal) whenever an
instrument was inserted into any side of the C-
shaped canal, it always ends in the distal foramen of
the tooth and a file introduced in this canal could
probe the whole extension of the C.
• When negotiating the C-shaped canal, instruments
may be clinically centered.
51

52. • Radiographically, the instruments may either
converge at the apex or may appear to be exiting the
furcation, thus adding to the confusion and
troublesome task of determining whether a
perforation has occurred.
52

53. • Interpretation of more than one radiograph or use
of an apex locator gives a differential diagnosis of C-
shaped molars from furcation perforation.
• Film combinations - “preoperative and working
length radiographs” or “preoperative and final
radiographs” or “all three radiographs” make
radiographic interpretation more effective than
single radiographs in diagnosing the C-shape.
53

54. • Working length radiographs are more helpful while
preoperative radiographs are least effective.
• Newer imaging modalities like spiral CT and micro CT
aid in the diagnosis of C-shaped canals.
• Both are time consuming and have limited
application in in-vivo studies.
54

55. • Limited - volume CBCT with low radiation dose and
high resolution, on the other hand, is a precise and
nondestructive technique which allows for both
qualitative and quantitative evaluation of root canal
morphology in three dimensions
• Further, it gives greater diagnostic data with
reduction of subjectivity in interpretation, as the
problem of overlap, common in two dimensional
views is eliminated.
55

56. • Micro-computed tomography (micro-CT) is a non-
destructive, three-dimensional analytical method that
permits the accurate evaluation of root canal systems
prior and subsequent to enlarging and shaping by
superimposing pre- and post-instrumentation scanning
data.
56

57. • Recently, micro-CT has been used for evaluating the
amount and distribution of hard-tissue debris in
canal isthmi (Paqué et al. 2009) and the reduction of
hard-tissue debris after different final irrigation
regimens (Paqué et al. 2012, Freire et al. 2015, Keles
et al. 2016)
57

58. MANAGEMENT
• The high percentage of canal irregularities, such as
accessory to lateral canals, and apical delta in a C-
shaped canal makes it difficult to clean and seal the
entire canal system adequately.
• The wide fins and small surface area of these canals
preclude complete debridement using traditional
hand instrumentation techniques, which can lead to
failure of root canal therapy.
58

59. • Therefore, careful location and negotiation of the
canals and the meticulous mechanical and chemical
debridement of the pulp tissue should be carried out
in order to successfully treat a C-shaped canal.
59

60. Location and negotiation of canals
• After achievement of endodontic access and removal
of tissue from the pulp chamber, modifications in the
access design facilitates location and negotiation of
the complete canal system.
60

61. • When the orifice is continuous C-shape or arc like
Mesiobuccal- Distal (MB-D), the number of canals can
vary from one to three; when the orifice is oval or
flat, the number of canals may be one or two; and
when the orifice is round, there is usually only one
canal below the orifice.
61

62. • Hence, for continuous C-shape orifice, 3 initial files are
inserted, one at either end and one in the middle.
• When the orifice is oval, two files are inserted, that is,
one file at each end of the orifice and when the orifice
is round, one initial file is inserted.
• Calcifications present in the pulp chamber may
disguise the C-shape of the canal system.
• In such cases, several orifices may be probed that link
up on further instrumentation.
62

63. • There are also chances of missing out on canals
because of bifurcation, dentin fusion, and curvatures.
• Exploration should be carried out with small size
endodontic files, such as a no. 8, 10, 15 K-file with a
small, abrupt apically placed curve, to ensure that
these irregularities are not missed.
63

64. Cleaning and Shaping
• In most situations, the mesiobuccal and distal canal
spaces can be prepared utilizing a conventional
approach.
• Instrumentation of the isthmus above #25 size files
should be avoided to minimize the potential for strip
perforation.
• The orifice portion of the slit can be widened with
Gates Glidden drills to access all the irregularities.
64

65. • For narrow, interconnecting isthmus areas as in C1
(continuous C type) and C2 (semicolon type)
configurations, Gates Glidden drills should not be
used and cleaning should be carried out using #25 or
smaller instruments, with copious irrigation using
5.25% sodium hypochlorite.
65

66. • Abou-Rass et al. recommended anti-curvature filing
technique to avoid danger zones.
• Perforation of the thinner lingual walls can be
minimized by instrumentation directed buccally.
66

67. • Apical instrumentation should be limited to #30(0.06
taper)
• Following rotary instrumentation, filing using K-files
or H-files may be specifically directed towards the
isthmus areas to obtain better debridement
67

68. • Self-adjusting file (SAF) system is more efficacious
than the protaper system for shaping C-shaped
canals.
• Intracanal instruments are unable to access and
debride the entire portion of the large canal space,
making the role of irrigation more relevant.
• Canal irrigation techniques incorporating ultrasonics
is more effective in achieving adequate debridement.
68

69. • Deeper penetration with small instruments and
increased volume of irrigant allows more cleansability
in fan-shaped areas of the C-shaped canal.
• However, injudicious ultrasonic instrumentation
carries the risk of perforation.
• In C-shaped molars with a single apex, the
mesiolingual canal is separate and shorter than the
other canals.
69

70. • The mesiobuccal canal swings back and merges with
the distal canal and exits through a single foramen.
• This feature can result in over instrumentation of the
mesiolingual canal.
• Some authors have advocated the use of calcium
hydroxide as an intracanal medicament for a period
of 7-10 days.
70

71. • With regard to the management of C-shaped canal
configuration in mandibular premolars, many
complicating factors make them difficult to treat.
• Anatomically the diameter and width of mandibular
first premolar is much smaller than mandibular
second molars.
• The small size of mandibular first premolar limits the
coronal access to the complex root canal system,
which unlike the mandibular second molar, is found
apically.
71

72. Advanced file systems to be used in a C shaped canal
• Reciproc Blue (RB; VDW, Munich, Germany) is a new-
generation single-file system that prepares root canals
using reciprocal motion.
• The proprietary heat treatment procedure results in a
blue titanium oxide layer on the surface of the
instrument.
72

73. • When compared with Reciproc (VDW) instruments
made of M-Wire, Reciproc Blue is more flexible and
fatigue resistant due to the alteration of the alloy
molecular structure (De-Deus et al. 2017).
• The R25 file in the RB system created a larger taper in
the apical 3 mm (.08 taper) and smaller diameter
(0.25 mm),
73

74. • XP-endo Shaper (XP-S; FKG Dentaire, La Chaux-
deFonds, Switzerland) is a NiTi instrument made of
MaxWire alloy (Martensite-Austenite
Electropolishing-Flex, FKG Dentaire) that enhances
efficiency during canal shaping.
74

75. • At ambient temperature, XP-S is in the martensitic
phase and has a size 30, .01 taper.
• At body temperature, the file transforms into the
austenitic phase along with the changes of shape,
which can make the final canal preparation reach size
30.04 taper (Lacerda et al. 2017).
75

76. • The XP-S system is a single-file system and makes
serpentine movement inside the canals.
• According to the manufacturer, the XP-S has a small,
free-floating adaptive core that adapts to the root
canal anatomy, enables ideal shaping in difficult canal
systems, and decreases debris compaction in the
irregular regions of those canals
76

77. Best irrigation methods for C-shaped Canals
• The use of SNI alone has been reported to be
ineffective in removing tissue remnants and cleaning
the apical region of a root canal system (Thomas et al.
2014).
• The main reason is that fluid flow dynamics beyond
the needle tip is limited (Nielsen & Baumgartner
2007).
77

78. • In addition, entrapment of gas bubbles in the apical region
may also prevent irrigants from reaching the entire
working length, a phenomenon that has been referred to
as the ‘vapor lock effect’.
• Previous studies reported that ultrasonic activation of
irrigants significantly reduces debris within the canal space
(Lee et al. 2010a, 2010b).
• The good performance of PUI may be attributed to the
production of acoustic microwaves, cavitation and heat
generation (Macedo et al. 2014, Arslan et al. 2015).
78

79. • When XP-F is used in the austenite phase shape and
in rotation mode, its functional rotational diameter
may be expanded to a maximum of 6 mm, which is a
100-fold greater than an equivalent-sized file (Leoni
et al. 2017).
79

80. • During rotating in the root canal, XP-F is claimed by
the manufacturer to be capable of removing debris
by mechanically contacting canal areas that are not
previously attainable by other file systems, while
agitating the irrigant within the canal space by
continuous irrigation.
80

81. 81

82. • For RB and XP-S, 33.04% and 30.45%, respectively, of
the canal wall remained untouched.
• For both groups, the apical third had larger AUCW%
than the coronal third.
• Instrumentation with RB left more debris (2.8%) than
XP-S (1.1%) .
• The PUI and XP-F subgroups had higher mean red% of
AHTD than the SNI subgroup; the difference was
significant for RB but not for XP-S
82

83. Conclusion of the study
• Both RB and XP-S systems were associated with similar
AUCW after instrumenting C-shaped canals.
• RB left significantly higher levels of AHTD compared
with XP-S.
• PUI and XP-F irrigation removed more debris than SNI
when using the RB system.
83

84. OBTURATION
• Obtaining a three dimensional fill of a C-shaped canal
may prove to be a problem due to the various
intricacies present within the root canal system.
• If a cold condensation technique is adopted for
obturation, deeper penetration of condensation
instruments in several sites will be necessary.
84

85. • To ensure proper placement of the master cones in C-
shaped canals, Barnett recommended placing a large
diameter file in the most distal portion of the canal,
before seating the master cone in the mesial canal.
• The file is then withdrawn and the master cone of the
distal canal is seated, followed by placement of
accessory cones in the middle portion of the C-
shaped canal
85

86. • Sealing the buccal isthmus is difficult using lateral
condensation alone, as the isthmus cannot be
prepared with a flare to permit deeper placement of
the spreader.
• This makes application of gutta-percha,
thermoplasticized with electric spreaders or
spreaders heated in an open flame or delivered by
injectable systems more appropriate.
86

87. • Studies have shown that following the cleaning and
shaping, the remaining dentin thickness around the
canals is usually 0.2 to 0.3 mm.
• The resultant forces of compaction during obturation
can exceed the dentin canal resistance, which may
result in root fracture and perforation of the root.
• In this regard, the thermoplasticized gutta-percha
technique may prove to be more beneficial
87

88. • The aim of this technique is to move the gutta-percha
and sealer into the root canal system under a
hydraulic force.
• But in C-shaped canals the hydraulic forces can
dramatically decrease and can seriously compromise
the obturation quality due to the following reasons:
• (a) there are divergent areas that are frequently
unshaped, which may offer resistance to obturating
material flow
88

89. • (b) communications exist between the main canals of
the C-shape through which the entrapped filling
materials that should be captured between the
apical tug back area and the level of condensation
may pass from one canal to another.
• Regardless of the choice of obturation technique,
proper placement of sealer with ultrasonic
endodontic files is critical.
89

90. • Walid’s technique aimed to overcome these
problems by the simultaneous use of two pluggers to
down pack the main canals in a C-shaped canal.
• Two fine-medium cones were seated in the
mesiolingual and distal canals.
• No accessory cones should be placed in the fin
between them and a medium point was fitted in the
mesiobuccal canal.
• Three pluggers are used for obturation.
90

91. • Using Touch’N Heat (Sybron Endo/Analytic, Irvine,
CA) gutta-percha at the mesiolingual orifice level was
seared off where the largest plugger was placed,
while down packing the distal canal with the smallest
plugger.
• While packing the mesiolingual canal, the smallest
plugger used in the distal canal was held in place.
91

92. 92

93. • The resistance toward the passage of obturating
material from one canal to another was increased by
placing two master points and blocking the canal
entrance with a plugger
• This offers backpressure on entrapped filling materials
and enhances the seal.
93

94. 94

95. • Zapata et al. analyzed gutta-percha filled area of C-
shaped canals filled with Maggiore’s modified
MicroSeal technique with reference to the
radiographic features.
• They found that the apical third was less accurately
filled and concluded that C2 canals with a 60° angle
could be less difficult to fill than a 120° or 150° C2
canal.
95

96. • Martin developed the EndoTec II (Medidenta, Inc.
Woodside, NY) that combined the qualities of both
the ease and speed of lateral compaction as well as
the superior density gained by vertical compaction of
warm gutta-percha.
• Using the “zap and tap” maneuver, improved
compaction could be achieved while obturating a C-
shaped canal by using the device.
96

97. • This involves heating the EndoTec plugger for 4 to 5
seconds (zap) followed by moving the hot instrument
in and out in short continuous strokes (tap) 10 to 15
times.
97

98. • In 1989 Stephen Buchanan conceived a way to
radically simplify 3D obturation , the Continuous wave
compaction technique by combining the function of
schilders pluggers and masreilez’s electric heat carrier
into a single electric heat plugger.
• This new method collapsed schilders vertical
condensation down packing procedure from 3 to 5
heating and packing steps requiring 5 min per canal
into a down pack that required just 2 procedural steps
and less than 15 sec per canal to complete
98

99. 99

100. Conclusion of the study
• Continuous wave obturation was more effective than
lateral condensation in both C1- and C2-type, except
for the apical 2 mm section of C1-type, suggesting
the need for a modified CW technique.
100

101. POST ENDODONTIC RESTORATIONS
• The thin dentin cross section between the external
surface of the root and the internal canal system can
compromise the structural integrity of these teeth.
• The available undercuts of the deep pulp chamber
provide ample retention.
• Bonded amalgam or composite is the preferred core
buildup material for such teeth
• For resistance to root fracture, at least 1 mm of sound
tooth structure should be present around a post.
101

102. • Prefabricated or cast posts have a risk of creating a
strip perforation.
• No prefabricated post (circular or conical) would fit
the C-shaped canals
• Post placement is preferred in the tubular distal canal
to facilitate adaptation and stress distribution.
• Placement of posts or anti-rotational pins in the
mesiolingual and mesiobuccal areas of C-shaped root
can cause perforation.
102

103. ENDODONTIC SURGERY
• Hemisection or root amputation is contraindicated
pertaining to the absence of furca.
• The intercanal communications or fins make retro-
preparation and retro-filling after apicoectomy
extremely difficult.
• If surgical intervention is indicated for a molar with
C-shaped root canal anatomy, extraction followed by
extra oral retro filling and intentional replantation
should be considered
103

104. Prognosis
• A suspicion of furcal breakdown should be kept in
mind and evaluated in the follow-up radiographs since
it is the most difficult area to obturate and is
associated with the greatest risk of perforation.
• Furcal failures have a poor prognosis
104

105. CONCLUSION
• The intricacies present in the C-shaped anatomy pose
a challenge during negotiation, debridement and
obturation.
• However, with advances in the tools for diagnosis and
treatment, the condition should no longer be an
enigma for the clinician.
105

106. • The advent of rotary and hand instrumentation
assisted with ultrasonics as well as modified
obturation techniques have improved the prognosis
of this anatomical variant.
• It is appropriate to observe cautious optimism in the
success of the root canal treatment of a C-shaped
canal.
106

107. References
• Barnett F (1986) Mandibular molar with C-shaped canal.
Endodontics & Dental Traumatology 2, 79–81.
• Melton DC, Krell KV, Fuller MW. Anatomical and
histological features of C-shaped canals in mandibular
second molars. J Endod. 1991;17(8):384-88.
• Fan B, Cheung GS, Fan M, Gutmann JL, Bian Z. C-shaped
canal system in mandibular second molars: Part I–
Anatomical features. J Endod. 2004;30:899- 903.
107

108. • Walid N. The use of two pluggers for the obturation
of an uncommon C-shaped canal. J Endod.
2000;26:422-24.
• Buchanan LS (1994) The continuous wave of
condensation technique: a convergence of
conceptual and procedural advances in obturation.
Dentistry Today 13, 80–5.
108

109. • Kato A, Ziegler A, Higuchi N, et al. Aetiology,
incidence and morphology of the Cshaped root canal
system and its impact on clinical endodontics. Int
Endod J2014;47:1012–33.
• Singla M, Aggarwal V (2010) C-shaped palatal canal
in maxillary second molar mimicking two palatal
canals diagnosed with the aid of spiral computerized
tomography. Oral Surgery, Oral Medicine, Oral
Pathology, Oral Radiology,and Endodontology 109,
e92–5. 109

110. • C-shaped canal configuration : a review, merina
fernandez et al Journal of Conservative Dentistry,Jul-
Aug 2014 , Vol 17, Issue 4.
• Worldwide Prevalence of Mandibular Second Molar
C-Shaped Morphologies Evaluated by Cone-Beam
Computed Tomography, J.kottoor et al JOE — Volume
43, Number 9, September 2017
110

111. • Evaluation of several instrumentation techniques and
irrigation methods on the percentage of untouched
canal wall and accumulated dentine debris in C-
shaped canal, Y zhao et al, IEJ 52,1354-1365, 2019.
• Cohens, Pathways of pulp 10TH ED.
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