1. Access cavity preparation is the first and most important step in root canal treatment as it provides straight-line access to the root canals. 2. Anatomical landmarks like the cementoenamel junction and root development lines can help locate canal orifices. 3. The goals of access cavity preparation are to remove all caries, locate all root canals, and achieve a conservative cavity that provides direct access to the canals and apical foramen. 4. The shape and size of the access cavity varies between teeth based on their anatomy and number of canals. Proper identification of canal orifices is crucial for successful root canal treatment.

1. ACCESS CAVITY
PREPARATION
PRESENTED BY: DR NADEEM AASHIQ
2NDYEAR MDS

2. Of all the phases of anatomic study in the human system, one of the
most complex is the pulp cavity morphology.
- M.T.Barrett
A proper access is the most important step in non surgical endodontic
treatment
Without adequate access, instruments and materials become difficult
to handle
2

3. Access cavity preparation is defined as endodontic coronal
preparation which enables unobstructed access to the canal orifices,
a straight line access to the apical foramen, complete control over
instrumentation and accommodate obturation technique.
A PROPER CORONAL ACCESS FORMSTHE
FOUNDATION OF PYRAMID OF
ENDODONTIC TREATMENT
3

4. GOALS OF ACCESS CAVITY
PREPARATION
Removal of all
carious tooth
structure
To achieve
straight or direct
line access
To locate all root
canal orifices
To conserve
tooth structure
Complete de-
roofing of pulp
chamber
ACC. TOVERTUCCI
4

5. Guidelines for access cavity preparation
1.VISUALIZATION OFTHE LIKELY INTERNAL ANATOMY
Approx. Length of the canal
Location of pulp chambers
Coronal anatomy
Number of roots and canals
Thickness of the roots
Extent of root curvature
Changes in furcation area 5

6. 2. EVALUATION OFTHE CEMENTOENAMEL
JUNCTIONAND OCCLUSALANATOMIES
According to a study conducted by Krasner and Rankow,
cementoenamel junction was the most important
anatomic landmark for determining the location of the
pulp chambers and canal orifices.
The authors suggested guidelines/laws to determine the
number and location of orifice on the chamber floor
6

7. LAW OF CENTRALITY
The floor of the pulp chamber is always located at the
centre of the tooth at the level of CEJ
LAW OF CONCENTRICITY
The walls of pulp chamber are always concentric to
the external surface of the tooth at the level of CEJ
LAW OF CEJ
The distance from the external surface of the clinical
crown to the wall of the pulp chamber is the same
throughout the circumference of the tooth at the
level of CEJ.The CEJ is the most consistent,
repeatable landmark for locating the position of the
pulp chamber
7

8. FIRST LAW OF SYMMETRY :
Except for maxillary molars, canal
orifices are equidistant from a line
drawn in a mesiodital line drawn
through the pulp chamber floor
SECOND LAW OF SYMMETRY:
Except for maxillary molars, canal
orifices lie on the line perpendicular to
a line drawn in a mesiodistal direction
across the centre of the pulp chamber
floor
8

9. LAW OF COLOUR CHANGE :
The pulp chamber is always darker in colour than the
walls.
LAW OF ORIFICE LOCATION 1: The orifices of the root
canals are always located at the junction of the walls
and the floor
LAW OF ORIFICE LOCATION 2: The orifices of the root
canals are located at the vertices of the floor-wall
junction .
LAW OF ORIFICE LOCATION 3 : the orifices of the root
canals are always located at the terminus of the roots
developmental lines.
9

10. 3. Preparation of the access
cavity through lingual and
occlusal surfaces.
4. Removal of all defective old
restorations and caries before
entering the pulp chamber
5. Removal of unsupported
tooth structure
10

11. IDENTIFICATION OF ORIFICE
ANATOMIC
FAMILIARITY
Knowledge,
understanding and
appreciation of the root
canal anatomy
RADIOGRAPHS Angulated periapical
images
CBCT
VISION Magnification glasses
Illuminating devices
Headlamps
11

12. SURGICAL LENGTH BURS Long length burs improve the line
of sight along the shaft of the bur
and promotes safety when
searching for canal
ACCESS CAVITIES Axial walls should be flared flattened
and finished to provide straight line
access to the orifice
Dyes Methylene blue gets absorbed in the
orifice and isthmus area
12

13. 13

14. TRANSILLUMINATION
A fibre optic wand is
placed cervically to the
tooth so that the light is
perpendicular to the long
axis of the tooth
14

15. RED LINETEST
In a vital teeth, blood emanates from the orifice or an
isthmus area. Like a dye, blood serves to map and
visually aid in identification of the underlying anatomy
below the pulp chamber
WHITE LINETEST
In necrotic teeth, dentinal dust frequently moves into
any anatomical spaces such as orifice, fin or isthmus
when performing ultrasonic procedures without water
This dust forms a white dot or line that provides a
visible road map. Eg to locate MB2 canal.
15

16. PERIO PROBING Circumferentially probing around the tooth is
another important strategy for locating canal
Intersulcular probing can provide important
information as to the emergence profile of the
clinical crown and the oriental alignment of the
underlying root
COLOUR A dark narrow line on the pulpal floor of a multi
rooted tooth provides a visual trail of colour that
leads to the orifice
Orifice will appear darker in colour than the
surrounding dentin
MICRO OPENERS Micro openers are flexible stainless steel hand files
attached to an ergonomically designed off-set
handle
They provide unobstructed view for initially
penetrating and enlarging an offshoot that divides
deep within the canal
16

17. 17

18. STAGES OF ACCESS CAVITY
PREPARATION
PRETREATMENTASSESMENT
PREPARATIONOFTOOTH FOR
ENDODONTICTREATMENT
REMOVALOF ROOF OF PULP
CHAMBERAND CORONAL PULP
CREATINGA STRAIGHT LINE
ACCESS
18

19. PRETREATMENT ASSESSMENT
Adequate access for treatment  determines the treatment
planning
Once accessibility is confirmed  mentally visualise the
location of the pulp chamber.
The angulation and any rotation of the tooth or coronal
restoration in relation to the roots should be assessed as this
will have a bearing on the design of the access cavity.
The position of the cemento-enamel junction and furcation
should also be noted as these landmarks help indicate the
location of the level of the pulp floor and the probable position
of the canal entrances.
19

20. SIGNIFICANCE OF A STRAIGHT LINE ACCESS:
Freedom of endodontic instrumentation in the coronal cavity
and direct access to the apical canal
MOUSE HOLE EFFCT :
• If the lateral wall of the cavity has not been sufficiently
extended and the pulp horn portion of the orifice still remains
in the wall, the orifice will have the appearance of a “mouse
hole”
• This feature occurs due to extension of canal orifice into axial
wall
• It can be prevented by extending the lateral wall of the cavity,
thus removing all the intervening dentin from the orifice.
20

21. ARMAMENTARIUM FOR ACCESS CAVITY PREPARATION
ENDODONTIC SPOON
EXCAVATOR
ENDODONTIC EXPLORER
DIAMOND BURS WITH
ROUND CUTTING EDGE
FISSURE CARBIDE BURSWITH
NON-END CUTTING SAFETY
TIPS
MUELLER BUR
LN BURS
21

22. ADDITIONAL AIDS
MAGNIFICATION AND
ILLUMINATION AIDS
ENDODONTICTIPS
MICRO-OPENER
MICRO-DEBRIDER
Transmetal Bur:The transmetal bur is specifically designed
for cutting any type of metal .This bur has a saw-tooth
blade configuration, which provides efficiency while
reducing unwanted vibration, especially important when
entering pulpitic or so-called “hot teeth.” 22

23. Endodontic Coronal Cavity Preparation
Outline Form
Convenience
Form
Removal of the
Remaining
Carious Dentin
and Defective
Restorations
Cleansing of
the Cavity
23

24. 1. Outline Form
The outline form of the endodontic cavity must be correctly shaped and positioned
to establish complete access for instrumentation, from cavosurface margin to
apical foramen.
2. Convenience form
As conceived by Black, is a modification of the cavity outline form to establish
greater convenience in the placement of intracoronal restorations.
In endodontic therapy, however, this form provides more convenient and accurate
preparation and filling of the root canal. Four important benefits are gained
through convenience form modifications:
1. Unobstructed access to the canal orifice,
2. Direct access to the apical foramen,
3. Cavity expansion to accommodate filling techniques, and
4. Complete authority over them enlarging instrument 24

25. 3. Removal of remaining carious dentin and defective restorations
To eliminate mechanically as many bacteria as possible from the interior of the
tooth
To eliminate discoloured tooth structure that might lead to staining
To eliminate bacteria laden saliva leakage into the prepared cavity .
4. Cleansing of cavity
All caries, debris and necrotic pulp must be removed before beginning the
radicular preparation
Calcified and metallic debris  obstruct the canal
Soft debris  increases bacteria population in the canal
25

26. Tooth Tooth length Crown length Root length Number of roots Types of canals
Maxillary central
incisor
A = 23.00 10.5 12.5 One I
L= 28.0 12.0 16.0
S= 18.0 8.0 8.0
Maxillary lateral
incisor
A=22.5 9.0 13.5 One I
L=27.0 10.5 16.5
S=17.0 8.0 8.0
Maxillary cuspids A=27.0 9.5 16.5 One I
L=32.0 12.0 20.5
S=20.0 8.0 11.0
Mandibular
incisor
A=21.0 9.0 12.0 One I most frequent
L=25.0 10.5 14.5 II less frequent
S=16.0 7.0 9.0 III least frequent
Mandibular
cuspids
A=24.0 10.0 15.0 One; two, buccal
and lingual, rare
I most frequent
L=30.5 12.0 20.5 II less frequent
S= 20.0 8.5 11.5 III least frequent
26

27. Tooth Total length Crown length Root length Number of roots types of canals
Maxillary first
bicuspid
A=21.0 8.5 12.5 TWO most frequent
(60%)  buccal and
palatal
II most common
L=24.0 10.0 14.5
I less frequent
One (40%)
Three  rare
S=17.5 7.0 10.0
III least frequent
Maxillary second
bicuspid
A=21.0 8.5 12.5 One  85 % I most common
L=25.0 10.5 15.0
Two  15 % 
buccal and palatal
II less frequent
S=17.0 7.0 9.5
Mandibular first
bicuspid
A=21.5 7.5 14.5 One
Two  rare 
buccal and lingual
I most common
L=25.0 9.0 17.0
II less frequent
S=17.0 6.5 11.5
mandibular second
bicuspid
A=22.0 8.0 14.0 One
Two  buccal and
lingual  very rare
Three  two buccal
and one lingual 
extremely rare
I most common
L=25.0 10.0 17.0
II less frequent
S=17.0 6.0 11.5
III least frequent
27

28. 28

29. REMOVAL OF CARIES
AND PERMANENT
RESTORATIONS
INITIAL EXTERNAL
OUTLLINE FORM
PENETRATION OF
THE PULP CHAMBER
ROOF
COMPLETE ROOF
REMOVAL
IDENTIFIACTION OF
ALL CANAL ORFICES
REMOVAL OF
LINGUAL SHOULDER
AND ORIFICE AND
CORONAL FALRING
STRAIGHT LINE
ACCESS
DETERMINATION
VISULAL
INSPECTION OFTHE
CAVITY
REFINEMENT AND
SMOOTHENING OF
RESTORATIVE
MARGINS 29

30. 30

31. REMOVAL OF CARIES
AND PERMANENT
RESTORATIONS
INITIAL EXTERNAL
OUTLLINE FORM
PENETRATION OFTHE
PULP CHAMBER ROOF
COMPLETE ROOF
REMOVAL
IDENTIFIACTION OF
ALL CANAL ORFICES
REMOVAL OF
CERVICAL DENTIN
BULGE AND ORIFICE
AND CORONAL
FALRING
STRAIGHT LINE
ACCESS
DETERMINATION
VISULAL INSPECTION
OFTHE CAVITY
REFINEMENT AND
SMOOTHENING OF
RESTORATIVE
MARGINS 31

32. 32

33. 33

34. 34

35. Maxillary central incisors
Outline form-The inverted-triangular shaped access
cavity is cut with its base at the cingulum to give straight
line access.
Width of base depends on distance between mesial
and distal pulp horns.
Shape may change from triangular to slightly oval due
to less prominent pulp horns in older individuals.
35

36. The cingulum is chosen as a
starting point, because, in
contrast to the gingival
margin which can retract and
the incisal margin which can
abrade, this ridge remains
constant throughout the
patient’s life.
36

37. Maxillary lateral incisors
Shape of access cavity similar
to maxillary central
incisors,except that
Smaller in size
When pulp horns are
present,shape of access cavity is
rounded triangle
If pulp horns are missing, shape
is oval
37

38. Maxillary canine
Shape of access cavity
No pulp horn
Access cavity is oval in
shape with greater
diameter labiopalatally
38

39. 39

40. 40

41. 41

42. Maxillary first premolar
Oval shaped acess cavity-The two
horns are situated just within the
peaks of their cusps.
The orifices of the two canals are
also slightly more within the horns.
Thus, one can generally prepare a
good access cavity without involving
the cusps.
42

43. Maxillary second premolar
43

44. 44

45. 45

46. 46

47. 47

48. 48

49. Maxillary second molar
Mb2 less likely to be
present
Three canals form a
rounded triangle with base
towards buccal side.
Mesiobuccal orifice is
located more towards
mesial and buccal than first
molar.
49

50. Maxillary third molar
▪ Alavi et al. found that 50.9% of third
maxillary molars had three separate roots
of which 45.5% had two or more canals in
the mesiobuccal root.
About 45.7% had fused roots
2% had C-shaped canals
2% had four separate roots
▪ Modifications must be made in accessing
these teeth compared to first and second
molars to accommodate these anatomical
variations.
50

51. 51

52. 52

53. 53

54. Mandibular incisors
Access cavity of
mandibular central and
lateral incisors is almost
similar
Shape is long oval
with greater dimensions
directed incisogingivally
54

55. Mandibular canine
Shape of acces opening similar to
maxillary canine-oval, but,
Smaller in size
Root canal outline narrower in
mesiodistal dimension
Two canals may be present
55

56. 56

57. 57

58. 58

59. Mandibular first premolar
•Oval acess cavity,wider
mesiodistally
•Presence of 30 degree lingual
inclination of crown to root,hence
starting point of bur should be half
way up the lingual incline of
buccal cusp.
59

60. Mandibular second premolar
•Similar to mandibular first
premolar
•Enamel penetration initiated in
central groove due to small
lingual tilt
•Ovoid acess opening is wider
mesiodistally
60

61. 61

62. 62

63. 63

64. 64

65. Mandibular first molar
This tooth most frequently requires
endodontic treatment.
The access cavity, which should not
be triangular, rather trapezoidal or
quadrangular with rounded corners.
The classical triangular shape would
hamper the identification of the
second distal canal .
65

66. 66

67. Mandibular second molar
The access cavity of this tooth is
started from the central fossa, and it is
created according to the same rules used
for the first molar.
 Because of the slight distal angulation
of its roots, the access cavity can,
however, be less extensive in this case.
The shape of the access cavity
depends on whether there is one, two,
three, or four canals; it may be round to
oval, triangular, or quadrangular
67

68. C shaped canal
The incidence of C-shaped canals is
reported to be highest in the
mandibular second molar.THE MAIN
ANATOMIC FEATURE OF C - SHAPED
CANALS ISTHE PRESENCE OF A FIN
ORWEB-connecting the
individual root canals.
The ‘‘C-shaped
canal’’ by Cooke
and Cox in
1979.This canal
shape results
from the fusion
of the mesial and
distal roots on
either the buccal
or the lingual
root surface.
68

69. 69

70. RADIX ENTOMOLARIS AND RADIX PARAMOLARIS
▪ Supernumery roots in mandibular molars
▪ Radix entomolaris:Presence of an additional disto lingual root in mandibular
molars;extra root on the lingual side.
▪ Radix paramolaris:presence of additional disto buccalroot in mandibular
molars;extra root on buccal side.First reported by De Moor et al in 2004
70

71. Mandibular third molar
•The lower third molar may require endodontic therapy
for the same reasons as the upper third molar.
When it is the last distal abutment, this tooth acquires
great importance.
The most varied and bizarre root morphology can
correspond to an almost normal coronal appearance .
Nonetheless, this tooth can also be treated successfully
by endodontic means .
The same rules that apply to the other lower molars also
hold for its access cavity.
71

72. HEAVILY RESTOREDTEETH
TEETHWITH CALCIFIED
CANAL
CROWDEDTEETH
ROTATEDTEETH
72

73. 73

74. 74

75. 75

76. 1) Failure to identify and excavate all caries and to remove unsupported,
weak tooth structure or faulty restorations.
2) Failure to establish proper access to the pulp chamber space and root canal
system.
3) Failure to identify the angle of the crown to the root and the angle of the
tooth in the dental arch.
4) Failure to recognize potential problems in access openings through
crowned teeth or teeth with excessively large restorations.
76

77. PERFORATION at the labio cervical is caused by failure to complete
convenience extension toward the incisal, prior to the entrance of the shaft
of the bur.
77

78. LEDGE formation at the apical-labial curve is caused by failure to complete
the convenience extension. The shaft of the instrument rides on the cavity
margin and “shoulder”.
78

79. BIFURCATION of a canal is completely missed, caused by
failure to adequately explore the canal with a curved
instrument.
79

80. APICAL PERFORATION of an invitingly straight conical canal.
Failure to establish the exact length of the tooth leads to
trephination of the foramen.
APICAL PERFORATION of an invitingly straight conical canal. Failure to establish the exact length of the tooth leads to trephination of the foramen.
80

81. INCOMPLETE preparation and possible instrument breakage caused by total
loss of instrument control. Use only occlusal access, never buccal or
proximal access.
81

82. BROKEN INSTRUMENT twisted off in a “cross-over” canal. This frequent
occurrence may be avoided by extending the internal preparation to
straighten the canals (dotted line).
82

83. PERFORATION into furcation caused by using a longer bur and failing to realise that the
narrow pulp chamber had been passed. Measure the bur against the radiograph and the
depth to the pulpal floor marked on the shaft with Dycal
83

84. CONTRACTED ACCESS CAVITY
• Contracted endodontic cavities are considered to be an
alternative to traditional endodontic cavities in
maintaining the mechanical stability and subsequently the
long-term survival and function of endodontically treated
teeth.
• Since no restorative material or technique can replace the
mechanical characteristics of the lost dentin in stress-
bearing areas of the tooth, treatment steps directed
toward dentin conservation are essential as the primary
measure to reinforce root-filled teeth
Boveda & A Kishen. Endodontic topics 2015, 33, 169 – 186
84

85. Why do we need modifications
The long-term functional survival of initial endodontically treated permanent
teeth was reported as 97.1% after 8 years in a very large epidemiologic survey.
Coronal tooth fractures continue to remain important reasons for post
endodontic tooth repairs and extractions.
J Endod2004;30:846 .EndodDent Traumatol1990;6:49
85

86. Pericervical dentin (PCD)
PCD is the dentin near the alveolar crest.
While the apex of the root can be amputated, and the coronal third of the clinical crown
removed and replaced prosthetically, the dentin near the alveolar crest is irreplaceable.
This critical zone, roughly 4 mm above the Crestal bone and extending 4 mm apical to crestal
bone, is sacred for 3 reasons:
(1) ferrule, (2) fracturing, and (3) dentin tubule Orifice proximity from inside to out.
long-term retention of the tooth and resistance to fracturing are directly related to the amount
of residual tooth structure.
This regional dentin is significant for the distribution of functional stresses in teeth
J Endod. 2003;29:523-528
86

87. Contracted endodontic access prioritizes the removal of:
-restorative material ahead of tooth structure,
-enamel ahead of dentin, and
-occlusal tooth structure ahead of cervical dentin
It overlooks the traditional requirements of straight-line access
and complete unroofing of the pulp chamber while emphasizing
the importance of preserving the crucial Pericervical dentin
87

88. In the case of incisors, the conservation of
cingulum dentin(pericingulum dentin) is
suggested to improve the functional stress
distribution in teeth.
A contracted endodontic cavity preserves a
portion of the roof around the entire coronal
aspect of the pulp chamber. This dentin is
known as dentin roof strut or soffit.
88

89. 89

90. 90

91. 91

92. The endodontic cavity should be as small as possible while still achieving the
biological objectives of the root canal treatment and as wide as the anatomy
permits in a particular case.
• Generally, a contracted cavity is suggested to be slightly wider than the
coronal extension of the root canal. This permits the maintenance of some of
the roof (dentin soffit) around the entire coronal portion of the pulp chamber
92

93. CT GUIDED ENDODONTIC ACCESSOPENING
In these cases, preparing an adequate access and identifying the
canal orifice can be challenging and may create a massive loss of
tooth structure that Is associated with a higher risk of fracture and a
high failure rate (cveket Et al. 2006)
Therefore, preoperative planning is highly recommended and 3D
imaging may be a useful tool.
Templates can be produced by 3D-printing devices, based on
matched 3D surface scans with CBCT data (Kuhlet al. 2015)
93

94. Technique for CT-GEA
Preoperative cbct images are
stored
3d surface scans are performed
using intraoral 3d surface scanner
94

95. CBCT data is uploaded into a planning software (co
DiagnosticX).
The software allows the creation of a virtual image of a
commercially available bur.
In addition, a virtual sleeve for guidance is created for
planning purposes.
The virtual bur is superimposed on each tooth with the
aim of creating a direct access to the apical third of
the root canal.
the surface scans are uploaded to the implant planning
software 95

96. 96

97. Finally, a virtual template is designed by applying a tool
of the software.
Information on sleeve‘s position is considered in
the planning.
Exported stl-files allowed a 3D printer to produce the
templates
Templates are attached to the models, and their
correct and reproducible fitting is checked. Marks are
set through the template sleeves to indicate the region
of access cavity.
Enamel should be removed in the area using a
diamond bur until dentine is exposed. Then, the
specific bur is used to gain access to the root canal. 97

98. Disadvantages of CT-GEA
High price
More time required for access cavity preparation.
More exposure to radiation because of use full mouth CBCT and
optical surface scan.
98

99. NINJA ACCESS
99

100. TRUSS ACCESS
100

101. Modern molar endodontic access and directed
dentin conservation.
•David J Clark, John A Khademi
•Published 2010 in Dental clinics of North America
The authors believe that the current models of endodontic treatment
do not lead to long-term success, and that the traditional approach
to endodontic access is fundamentally flawed.
This article introduces a set of criteria that will guide the clinician in
treatment decisions to maintain optimal functionality of the tooth
and help in deciding whether the treatment prognosis is poor and
alternatives should be considered
101

102. 102

103. Preoperative view of tooth #19 in
a 20-year-old woman.
(A) The deroofing problem. The likely bur used by the
referring general dentist is a 56 carbide; one of the most
popular burs in dentistry,6 it is possibly the most
iatrogenic instrument in modern medicine. Red arrow
delineates the typical gouging. (B) Postoperative view
provided by the endodontist. Blue arrow indicates the
grossly excessive dentin removal of pericervical dentin
(PCD). This serious gouging is typical of round bur access.
Yellow arrow indicates the large canal flaring with
unacceptable dentin removal (blind funneling). (C) Green
circle highlights worsening lesion on mesial root ends.
103

104. Eighteen-month follow-up. Despite
generous access and aggressive canal
enlargement, the lesion on the mesial root
continues to enlarge.
A more appropriate access shape is overlayed. Partial
deroofing and maintenance of a robust amount of
PCD is demonstrated. A soffit that includes pulp
horns on mesial and distal is depicted.
104

105. Traditional parallel-sided access (left), compared with the Cala Lilly enamel preparation (right).
(Left) Unfavorable C factor and poor enamel rod engagement are typically present when removing
old amalgam or composite restorations or with traditional endodontic access of 90 to the occlusal
table. (Right) The enamel is cut back at 45 with the Cala Lilly shape. This modified preparation will
now allow engagement of nearly the entire occlusal surface.
105

106. Refernces :
1. Grossman’s endodontic practice 13th edition
2. Endodontic therapy. Franklin S.Weine, 6th edition
3. Cohen’s Pathways of pulp
4. Guidelines for Access Cavity Preparation in Endodontics A Peer-Reviewed Publication
Written by Ricardo Caicedo; Dr. Odon; Stephen Clark, DMD; Liliana Rozo, DDS and Joseph
Fullmer, BA
5. Access Opening and Canal Location, Endodontics Colleagues for Excellence; Spring 2010
106

107. 107