Access cavity preparation

Seminar On-: Access Cavity Preparation
Submitted To-:
Dr Anurag Singhal Submitted By-:
Dr Anurag Gurtu Kapil Yadav(25)
Dr Naveen Chhabra Shailendra Singh(44)
Dr Raju Chauhan 1

INTRODUCTION

The major factor involved in the development of
the apical periodontitis are loss of integrity of
coronal tooth substance and the entry of
microorganisms into the dentine and pulp
space.
The chemo-mechanical removal of
microorganisms, their substrate and products form
the dentine and pulp space is primary aim of root
canal treatment, with the second being the three
dimensional obliteration and sealing of the pulp
space to prevent bacterial recontamination.

3

A clear understanding of the anatomy of human
teeth becomes an essential prerequisite for
achieving the objectives of access, through
cleaning, disinfection, and obturation of the pulp
space.
in this seminar we have tried to describe the
access opening of the teeth.

4

• The access cavity preparation generally refers to the
part of the cavity from the occlusion table to the canal
orifice. (according to Stephen Cohen)
OBJECTIVES

Well designed access preparation is essential for a good
endodontic result. Without adequate access, instruments
and material becomes difficult to handle properly in the
highly complex and variable canal system.
• To achieve a straight or direct line access to the apical
foramen.
• To locate all root canal orifice.
• To conserve sound tooth structure.

5

• Well prepared and correct access cavity allow
complete irrigation, shaping ,cleaning and
quality obturation.
• Ideal access results in a straight entry into the
canal orifice, with the line angles forming a
funnel that drops smoothly into the canal.

GUIDELINES
It is essential for the completion of ideal access
preparation.
7. Visualization of internal anatomy because
internal anatomy dictates access shape. This
require evaluation of angled peri-apical
radiograph, examination of coronal and
cervical tooth anatomy.

6

2. Evaluation of CEJ and occlusal anatomy.
traditionally, access cavity is prepared in relation
to the occlusal anatomy. CEJ is the most
important anatomical landmark for determining
the location of pulp chamber and root
canal orifice.

7

According to Krasner and Rankow, five guidelines
or laws, of pulp chamber anatomy to help
clinicians determine the number and location of
orifices on the chamber floor

 First Law of Symmetry
It states that except for the maxillary molars, canal
orifices are equidistant from a line drawn in mesio-distal
direction through the pulp chamber floor.

 Second Law of Symmetry
It state that except for the maxillary molars, canal
orifices lie on line perpendicular to a line drawn in a
mesio-distal direction across the center of the pulp
chamber floor

8

 First Law of Orifice Location
It states that the orifices of the root canal are
always located at the junction of the walls and
the floor.
 Second Law of Orifice Location
It states that the orifices of the root canals are
always located at the angles in the floor-walls
junction.
 Third Law of Orifice Location
It states that the orifices of the root canals are
always located at the terminus of the root's
developmental fusion lines.
 Law of Color Change
It states that the pulp chamber floor is always
darker in color than the walls.
10

3. Preparation of the access cavity is through
lingual in anterior teeth and on the posterior teeth
through occlusal surface.

4. Removal of unsupported tooth structure.This
reduce the tooth's resistance to stress.

5. Creation of access cavity walls. So that
sufficient tooth structure must be removed to
allow instrument to be placed in a straight line
and easily into canal orifice.

11

6. Location, flaring and exploration
of all root canals orifices. A sharp
endodontic explorer used to
locate the canal orifice and to
determine their angle of
departure from the pulp chamber.

7. Magnification and illumination.
These are important in root canal
therapy, especially for
determining the location of canal,
curved and calcified canal and
debriding and removing tissue
from the pulp chamber.

12

8.Tapering of cavity walls and evaluation of space
adequacy for a coronal seal. A proper access
cavity has tapering walls and is widest at
occlusal surface. At least 3.5 mm of temporary
filling material is needed to provide an adequate
coronal seal for a short period.

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ANATOMY OF THE PULP CAVITY

 Pulp cavity is the central cavity within the tooth
and is entirely enclosed by dentin except at the
apical foramen.
 Pulp cavity may be divided into a coronal
portion, pulp chamber, radicular portion and root
canal.
 In anterior teeth the pulp chamber gradually
merges into root canal.
 In multirooted teeth, the pulp cavity consists of
a single pulp chamber and usually three root
canal.

14

 A pulp horn is an accentuation of the roof of the
pulp chamber directly under a cusp or
developmental lobe.
 Orifices are continuation with both pulp
chamber and root canal.
 A root canal may be divided into three sections
namely coronal, middle, apical third.
 Accessory canal or lateral canal is a lateral
branch of main root canal, generally occur in the
apical third or furcation area of a root.

15

 In most cases number of root canal depends
upon the number of roots of the tooth.
 In young age, apical foramen is funnel shaped
in a incompletely developed teeth.
 With the development of the root, the apical
foramen becomes narrower.
 The shape and size of pulp cavity is influenced
by age.
 In young people, pulp chamber is large and
with increase of age, it gets smaller.

17

The root canal system is highly complex and
canal may branch, divide and rejoin.
Vertucci et al identified and classified eight pulp
space configuration which are following as -:
 Type I : A single canal extends from the pulp
chamber to the apex.
 Type II : Two seprate canal leaves the pulp
chamber and join short of the apex to form
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.

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 Type IV : Two separate, distinct canals extend
from the pulp chamber to the apex.
 Type V : One canal leaves the pulp chamber and
divides and divides short of the apex into two
separate, distinct canals with separate apical
foramina.
 Type VI : Two separate canals leave the pulp
chamber, merge in the body of the root, and
redivide short of the apex to exit as two distinct
canals.
 Type VII : One canal leaves the pulp chamber,
divides and then rejoins in the body of root, and
finally redivides into two distinct canals short of
the apex.
19

 Type VIII : Three separate, distinct canals
extend from the pulp chamber to the apex.

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Access Cavity Preparations

Anterior access cavity preparations
Many of the same steps are used in similar tooth
types to prepare an access cavity.
The following discussion outlines the steps for
maxillary and mandibular anterior teeth.

1. Removal of Caries and Permanent
Restorations
 Caries is typically removed early, before the
pulp chamber is entered.
 This minimizes the risk of contamination of the
pulp chamber or root canal with bacteria.

22

 Removal of defective permanent restorations
also permits straight line access and prevents
the restorative fragments from becoming
lodged in the root canal system.
 If recurrent decay is detected or suspected,
the permanent restoration must be removed
entirely to prevent coronal contamination of
pulp chamber.
2. Initial External Outline Form
 Once caries and restoration have addressed,
the clinician create an initial external outline
opening on the lingual surface of the anterior
teeth

23

 For an intact tooth, the clinician should begin
in the center of lingual surface of anatomic
crown.
 No 2 or 4 round bur or tapered fissure bur is
used to penetrate the enamel and slightly into
the dentine with a high speed hand piece.

24

 The bur is directed perpendicular to the lingual
surface as the external outline opening is
created.
3. Penetration of the Pulp Chamber Roof
 Penetration of the pulp chamber roof is
continuing with the same round or tapered
fissure bur, we change the angle of the bur
from perpendicular to the lingual surface to
parallel to the long axis of the tooth.
 Penetration into the tooth is accomplished
along this roots long axis until the roof of the
pulp chamber is penetrated, frequently a drop-
in effect is felt when the penetration occurs.

25

Complete Roof Removal
 Once the pulp chamber has been penetrated,
the remaining roof is removed by catching the
end of a round bur under the lip of the dentin
roof and cutting on the bur ‘s removal stroke.
 Each tooth has a unique pulp chamber
anatomy, working in this manner allow the
internal pulp anatomy to dictate the external
outline form of the access opening.
 In vital cases pulp tissue hemorrhage can
impair the clinician”s ability to see the internal
anatomy.
 In such cases, as soon as enough roof has been
removed to allow instrument access,
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 The coronal pulp should be amputated at the
orifice level an endodontic spoon or round bur
and the chamber irrigated copiously with
sodium hypo chlorite.
 After hemorrhage has been controlled, allowing
visibility, all of the pulp chamber roof, with pulp
horns, must be removed and all internal walls
must be flared to lingual surface of the tooth.

27

Identification of All Canal Orifices
 After the pulp chamber has been unroofed, the canal
orifice are located with an endodontic explorer
 Positioning the explorer in an orifices allows the
clinician to check the shaft for clearance from the axial
walls an d determine the angle at which a canal depart
the main chamber.
Removal of lingual shoulder, orifice and coronal
flaring
 Once the orifice has been identified, the lingual shoulder
is removed.
 Lingual Shoulder-: this is the lingual shelf of dentin that
extends from the cingulum to a point approximately
2mm apical to the orifice.

28

Straight line access determination
 After the lingual shoulder has been removed
and the orifice, the clinician must determine
whether straight line has been achieved.
 Ideally, an endodontic file can approach the
apical foramen or the first point of the canal
curvature.
Visual inspection of the access cavity
 The clinician should inspect and evaluate the
access cavity using appropriate magnification
and illumination.

29

Refinement and smoothing of restorating
margins
 The final step in the preparation of an access
cavity is to refine and smooth cavosurface
margin.
 Rough margins can cause of coronal leakage.
 Proper restorative margins are important
because anterior teeth may not require a crown
as a final restoration

30

Posterior Access Cavity Preparation
 The process of preparing access cavity on
posterior teeth is similar to that for anterior
teeth, but enough difference exists to warrant a
separate discussion.
Removal of caries and permanent restoration
 Same as anterior teeth but in posterior teeth, the
root canal therapy require a typically have been
heavily restored or carious process is extensive.
 Such conditions, along with the complex pulp
anatomy of the posterior teeth, can make access
process challenging.

31

Initial external outline form
 The pulp chamber of posterior teeth is
positioned in the center of the tooth at the level
of CEJ.
 An access starting location must be determined
for an intact tooth.

32

 In maxillary premolar this point is on the central
groove between the cusp tip.
 In mandibular 1st premolar the starting location
is half way up the lingual incline of the buccal
cusp on the line connecting the cusp tip.
 In mandibular 2nd premolar the starting location
is one third the way up lingual incline of the
buccal cusp on a line connecting the buccal
cusp tip and lingual groove between the lingual
cusp.
 In maxillary and mandibular molar the starting
location is limit with mesial and distal boundary.
 The mesial boundary for both molar is a line
connecting the mesial cusp tip.
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 The distal boundary for both molar is a line
connecting the buccal and lingual groove.
 Penetration through the enamel into the dentin
is performed using a No 2 round bur for premolar
and No 4 round bur for molar.
 The bur is directed perpendicular to the occlusal
table and initial outline shape is created.
 The premolar and maxillary molar outline shape
is oval and widest in bucco-lingual dimension
and mesiodistal direction is widest in
mandibular molar.
 The final outline shape of molar is triangular or
rhomboidal.

35

Penetration of pulp chamber roof
 Continuing with a same round or tapered fissure
bur and angle of bur is changed same as anterior
teeth.
 In case of premolar the direction of penetration
angle is towards the mesio-distal and bucco-
lingual and in case of molar it is towards the
largest canal because pulp chamber space is
usually largest just occlusal to the orifice of this
canal.

37

Complete Roof Removal
 Round or tapered fissure bur is passed between
the orifices along the axial walls to remove the
roof of pulp chamber with pulp horns and create
the desired external ouline shape
simultaneously.
Identification of all Canal Orifices
 Ideally the orifices are located at the corner of
the final preparations to facilitate the shaping
and cleaning process.

38

Removal of the Cervical Dentin bulge and
Orifices
and Coronal flaring
 The cervical dentine bulge are shelves of dentin
that overhang orifices in posterior teeth.
 These bulge can be removed with carbide bur or
Gates-Glidden burs.

39

 After this the orifices and the coronal portion of
the canal can be flared with Gates-Glidden bur,
which are used in sweeping upward portion with
lateral pressure away from the furcation.
Straight Line Access preparation
 It is paramount to successful shaping.
 Files must have unimpeded access to the apical
foramen or the first point of canal curvature.

40

Visual inspection of the pulp chamber floor
Same as anterior access cavity preparations.
Refinement and smoothing of the
restorative
Margins
The restorative margins are refined and smoothed
to minimize the potential of coronal leakage.

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MORPHOLOGY AND ACCESS CAVITY
PREPARATION FOR MAXILLARY
CENTRAL INCISOR

Developmental and anatomic data

 Average time of eruption-: 7-8 Years
 Average age of calcification-: 10 Years
 Average tooth length-: 23.5mm
 Average crown length-: 10.5mm
 Average root length-:13mm
 M-D of crown-: 8.5mm
 M-D of crown at cervix-: 7mm
 Labio-lingual diameter of crown-: 7mm
 Labio-lingual diameter at cervix-: 6mm

42

Pulp chamber
 It is located in the centre of crown equidistant
from the dentinal wall.
 It is broad m-d, with its broadest part incisally.
 It has three pulp horns that corresponds to the
double mammelons in a young tooth.
Root and root canal
 It has one root with one root canal.
 Root canal is broad labio-palataly, conical
shape, and centrally located.
 In cross-section, canal is ovoid m-d in cervical
third, rounded in middle and apical third.

43

INCIDENCE

Root
o Straight : 75%
o Distally curved : 8%
o Mesially and palatally curved : 4%
o Labially curved: 9%
Apical foramen
o Centrally located in anatomic apex : 12%
o Apical delta : 1%

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Anatomic relationship in situ
 Labial surface of the root lies under the labial
cortical plate of the maxilla and may fuse with
it.
 It has an average of 2 degree of mesio-axial
inclination and 29 degree of palato-axial
angulations in its alveolus.
Access opening
 Shape, size and coronal extension of pulp
chamber are estimated by diagnostic
radiograph.
 Enamel is penetrated in the centre of the lingual
surface at an angle perpendicular to it, with a

46

number 4 round bur in high speed contra-angle.
 After penetration of the enamel, a No 4 carbide
bur in a slow speed contra-angle is directed
along the long axis of the tooth until the pulp
chamber is reached.
 A “drop” of the bur into the chamber may be felt
if the chamber is large enough.
 The overhanging enamel and dentin lingual
surface of the pulp chamber is removed with a
No 4 round bur in a slow speed contra-angle by
working from inside to outside following internal
anatomy.

47

 The lingual extension of the pulp chamber, with
a “straight line” penetration to the apical root
canal.
 Direct access can be verified by placing a
straight end of the endodontic explorer in the
canal orifice.
 The access shape is slightly triangular, with the
base of the triangle to the incisal edge.

48

Anatomic alteration in pulp

 The usual anatomic structure of the chamber in
the root canal may be altered in any tooth due to
deposition of reparative or secondary dentin.
 This alteration in anatomy may be due to
trauma, caries, restorative procedure, aging.
To escape this alteration we can use No 2 round
carbide bur.
 Enlarge the enamel portion of the access cavity
to an ovoid shape, with greatest diameter
incisogingivally.

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LATERAL INCISOR
MAXILLARY LATERAL INCISOR

 Average time of eruption-: 8-9Years
 Average age of calcification-: 11Years
 Average tooth length-: 22mm
 Average crown length-: 9mm
 Average root length-: 13mm

51

Pulp chamber
 The shape of the pulp chamber is similar to the
maxillary central incisor.
 It only has two pulp horn, corresponding to the
developmental mamelons.
Root and root canal
 Configuration of the root canal is conical but it
has a finer diameter than maxillary central
incisor.
 In cross-section, the canal is ovoid labio-
palataly in the cervical third and middle third,
round in apical third.

52

INCIDENCE

Root
o Straight : 30%
o Mesially and palatally curved : 3%
o Labial curved: 4%
o “S-shaped” or bayonet curved: 6%
Apical foramen
o Apical delta : 3%

53

 It has an average of 16 degree of mesio-axial
inclination and average of 29 degree of palato
axial angulations in its alveolus.

Access opening
 It is similar to that for a maxillary central incisor,
but is smaller and usually more ovoid.
 Except a No 2 round bur may be used instead of
a No 4. 54

CANINE


 Average age of calcification-: 13-15Years
 M-D of crown at cervix-: 5.5mm

55

Pulp chamber
 It has the largest pulp chamber than any single
rooted tooth.
 Labio-palatally triangular in shape, apex is
toward the single cusp and base toward the
cervical third of crown.
 Mesio-distally it is narrower and may resemble
like flame.
 In cross-section it is ovoid in shape, with greater
diameter labio-palatally.
 Only one pulp horn is present.

56

Root and root canal
 Single root canal of maxillary cuspid is larger
than that of maxillary incisor.
 It is wider labio-palatally than its mesio-distal
diameter, and on reaching middle third, it taper
gradually to an apical constriction.
 In cross-section, root canal is ovoid in the
cervical and middle third and generally round in
the apical third

57

INCIDENCE

Root
o Straight : 39%
o Palatally curved : 7%
Apical foramen
o Apical delta : 3%

58

 The root of maxillary cuspid is positioned in the
cancellous bone of the maxilla between the
nasal cavity and the maxillary sinus, called the
canine pillar.
 It has an average of 6 degree disto-axial
inclination and an average of 21 degree palato-
axial angulation in its alveolus.

59

Access opening

 External access outline form is oval or slot
shaped because no mesial or distal pulp horn
are present
 Mesio-distal slope is determined by the mesio-
distal width of pulp chamber.
 Inciso-gingival diameter is determined via
straight line access factor and removal of the
lingual shoulder.

60

 Incisal extension is approached with in 2-3 mm
of the incisal edge to allow for straight line
access.
 All internal walls funnel to the orifice.

61

PREPARATION FOR MAXILLARY 1ST
PREMOLAR


 M-D of crown-: 7mm
62

Pulp chamber
 It is narrow M-D, wider bucco-palatally.
 The buccal pulp horn is more prominent than the
palatal in young tooth.
 The floor of the pulp chamber is convex usually
with two canal orifices with one buccal and
other palatal, it lies deep in the coronal third of
the root.
 The roof of the pulp chamber is coronal to the
cervical line.
Root and root canal
 It may have one, two, or three roots and canals.

63

 It most often has two roots namely buccal and
palatal.
 The roots are considerably shorter and thinner
than the canine.
 The palatal orifice is slightly larger than buccal
orifice.
 In the cross-section at the CEJ, the palatal
orifice is wider bucco-lingually and kidney
shaped because of the mesial concavity.
 The tooth lies in the alveolar socket below the
maxillary sinus and is separated from it by a thin
layer of spongy and compact bone.
 It has an average of 10 degree of disto-axial
inclination with average of 6 degree of bucco-
axial angulation in its alveolus
64

INCIDENCE

Root( Single rooted)
o Straight : 38.4%
o Distally curved : 36.8%
o Buccally curved : 14.4%
o Palatally curved: 2.4%
Apical foramen
o Apical delta : 3%

65

Double Rooted Teeth

• Buccal Root • Palatal Root
o Straight : 27.8% o Straight : 44.4%
o Distally curved : 14% o Distally curved : 14%
o Buccally curved : 14% o Buccally curved : 27.8%
o Palatally curved: 36.2% o Palatally curved: 8.3%
o “S-shaped” or bayonet o “S-shaped” or bayonet
curved: 8% curved: 5.5%
Apical foramen Apical foramen
o Centrally located in o Centrally located in
anatomic apex : 12% anatomic apex : 12%
o Apical delta : 3.2% o Apical delta : 3.2%

66

Access opening
 The diagnostic radiograph is used for measuring
the shape and extension of the pulp chamber
mesially, distally and coronally.
 The access preparation is oval or slot shaped.
 It is also wide bucco-lingually, narrow mesio-
distally and centered mesio-distally between the
cusp tips.
 Using a No 2 round bur in a high speed contra
angle one penetrates the enamel in the center of
the occlusal surface and the bur is directed into
the long axis of the tooth.
 Than a No 2 round carbide bur in a slow speed
contra angle, align in the long axis of the tooth
is used to penetrate through the dentin into the
pulp chamber. 67

 Using the radiographic measurement, one
penetrate deep enough to remove the roof of the
pulp chamber without cutting into the chamber
floor.
 To remove the roof of the pulp chamber, one
should place the bur along the side of walls of
the chamber and cut occlusally.
 A tapered cylinder, self limiting diamond in slow
speed contra angle is used to remove the
remaining roof of the pulp chamber.
 The walls of the cavity are smoothened and
sloped slightly to the occlusal surface.
 The divergence of the access cavity creates a
positive seal for the temporary filling such as
cavity.
68

 The border of the ovoid access cavity should not
exceed beyond half the lingual inclined of the
facial cusp and half the facial incline of the
palatal cusp.
 Any loose debris is removed by irrigating the
access cavity with 5.2% sodiumhypochlorite
solution.
 Excess solution is removed by suction with 2 x 2
gauge.
 The anatomic dark lines in the pulpal floor
should be examined with an endodontic explorer.
 The orifice of the buccal canal lies beneath the
buccal cusp and the orifices of the palatal canal
lies beneath the palatal cusp.
69

Schematic
representation of three
canal access preparation.

70

PREPARATION FOR MAXILLARY 2ND
PREMOLAR


71

Pulp chamber
 It is like maxillary 1st premolar
 It is wider bucco-lingually than the maxillary 1st
pre molar and shows two pulp horn in this
projection, a buccal and a palatal.
 In cross-section, the pulp chamber has a narrow
ovoid shape.
Root and root canal
 Single rooted tooth but may be two or three root
and canal .
 The majority of canal may be curved.
 They may be curved distally, buccally, palatally
or bucco-palatally.

72

INCIDENCE
Root (single root 90.3%)
o Straight : 37.4%
o Distally curved : 33.9%
o Buccally curved : 15.7%
o Palatally curved: 2.4%
Apical foramen
o Apical delta : 3.2%
Only 2% have two well developed root.

73

 A single root is oval and wider bucco-lingually
than m-d.
 The canal remain oval from the pulp chamber
floor and taper rapidly to the apex.
Access cavity preparation
 Nearly identical to 1st maxillary premolar.
 If three canals are present, the external access
outline form are triangular in shape.

74

PREPARATION FOR MAXILLARY 1ST
MOLAR


 Average root length-: 12mm(b) 13mm(p)
75

Pulp chamber
 It has four pulp horns m-b, d-b, m-p, d-p, the
arrangement of the four pulp horn gives the
pulpal roof of a rhomboidal shape in cross-
section.
 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 canal are located in the
three angles of the floor.

76

 Palatal orifice is the largest, round or oval in
shape and easily accessible for exploration.
 The mesio-buccal orifice is under the mesio-
buccal is long bucco-palatally.
 The mesio-buccal orifice is located by
insinuating the tip of long shank explorer.
 The disto-buccal orifice is located slightly distal
and palatal to the mesio-buccal orifice and is
accessible from the mesial for exploration.
 The floor of the pulp chamber in the cervical
third of the root and the roof is in cervical third
of crown.

77

Root and root canal
 It has three root with usually 3 canal situated
mesio-buccally, disto-buccally, palatally.

 Mesio-buccal root
• It is broad in the bucco-palatal direction.
• Majority of the m-b roots have a distal curve and
some are “s” shaped or bayonet shaped.
• It has one root and one canal, it is narrowest of
the 3 canals, flattened in a m-d direction in the
orifice, but round in the apical third.

79

 Disto-buccal root
• It is small and is more or less round in shape.
• It may be straight (54%), distally curved mesial
curve or “s” shaped.
• It is a narrow, tapering canal sometimes
flattened in a mesio –distal direction , but
generally cone shaped.
 Palatal root
• It has larger diameter and is the longest root of
the maxillary 1st molar.
• It may be straight, curved buccally, mesially or
distally.
• Root may curve in the apical third toward buccal
side.
• The palatal canal is ovoid m-d and tapers toward
apex.

80

INCIDENCE

• Mesio-buccal Root • Disto-buccal Root
o Straight : 21% o Straight : 54%
o Buccally curved : 14% o Mesial curved : 20%
o “S-shaped” or bayonet o “S-shaped” or bayonet
curved: 1% curved: 10%
o Apical delta : 2%

81

• Palatal Root
o Straight : 40%
o Mesial curved : 4%
o Buccally curved: 55%
Apical foramen

82

Access opening
 Radiograph is used to determine the shape and
size as well as the extension of the pulp
chamber mesially, distally and coronally.
 The enamel is penetrated with No 4 round
carbide bur in a high speed contra angle by
positioning the instrument in the central fossa
and angling it toward palatal root.
 After penetration of the enamel No 4 round
carbide bur in slow speed is used in a slow
speed contra angle to penetrate dentin.
 The bur is angled toward the palatal root until
the pulp chamber is reached.

83

 A “drop” of the bur into the pulp chamber may
be felt if the chamber becomes large.
 The internal anatomy of the pulp chamber
guides the occlusal cutting.
 A tapered cylinder self limiting diamond in a
slow speed contra angle is used to remove the
remaining roof of the pulp chamber.
 The walls of the access cavity should be in good
confluence with the walls of pulp chamber and
should be slightly divergent to the occlusal
surface.
 The access opening should be triangular for
permitting direct access to the root canal
orifice.
85

 Any loose debris is removed by irrigating the
access cavity with 5.2% sodiumhypochlorite
solution.
 Excess solution is removed by suction with 2 x 2
gauge.
 The anatomic dark lines in the pulpal floor
should be examined with an endodontic
explorer.

86

PREPARATION FOR MAXILLARY 2ND
MOLAR


 Average root length-: 11mm(b) 12mm(p)
87

Pulp chamber
 Similar to maxillary 1st molar, except it is
narrower m-d.
 It is rhomboidal in shape.
 The roof of the pulp chamber is more
rhomboidal in cross-section,
 The floor of the pulp chamber is an obtuse
triangle in cross-section.
 The mesio-buccal and disto-buccal root canal
are closer together and appear to have a
common opening.

89

Root and root canal
 It has usually one canal in each root however ,
it may have two or three mesio-buccal canal,
one or two disto-buccal canal, or two palatal
canal.
 The three main orifice ( M-B, D-B, P) usually
form a flat triangle and sometimes a straight
line.
 The mesio-buccal canal orifice is located to the
buccal and mesial than 1st molar.
 Disto-buccal orifice approaches the mid point
between the m-b and palatal orifice
 Palatal orifice usually located at the most
palatal aspect of the root.
90

 Floor of the pulp chamber is convex which gives
the canal orifice a slight funnel shape.
 When four canal are present, access cavity
preparation has a rhomboid shape, if three
canal are present, it is a rounded triangle with
the base placed buccally.
 If two canal are present the access outline form
is oval and widest bucco-lingually.

91

INCIDENCE

• Mesio-buccal Root • Palatal Root
o Straight : 22% o Straight : usually
o Distally curved : usually o Buccally curved : 37%
o Apical delta : 3% o Apical delta : 3%
Distal Root
o Straight : usually
o Mesially curved : 17%
Apical foramen
o Centrally located in
anatomic apex : 16%
o Apical delta : 3%

92

 Same as 1st molar.

93

PREPARATION FOR MAXILLARY 3RD
MOLAR


 Labio-lingual diameter at cervix-: 9.5mm
94

It is considered as a strategic abutment after loss
of maxillary 1st and 2nd molars.

Pulp chamber
 Anatomic resemblance to maxillary 2nd molar.
 It may also have an odd shaped pulp chamber
with four or five root canal orifice.
 Conical chamber with only one root canal.
Roots and root canal
 Three well developed roots, fused root, one
conical root or four or more independent roots.
 Root may be straight, curved or dilacerated.
 One may find a “C shaped” pulp chamber with a
“C shaped root canal.
96

PREPARATION FOR MANDIBULAR
CENTRAL INCISOR


 Average root length-: 12.5mm

97

Pulp chamber
 It is small and flat m-d.
 Three distinct pulp horns present.
 Pulp chamber is wide and ovoid labio-lingually
and it tapers incisally.
Root and root canals
 It has one root which is flat and narrow mesio-
distally but wide labio-lingually.
 It may have a distal labial curvature.
 Canal is broad and cervical of middle third of
root in labio-lingual aspect, tapers toward apex.
 Canal is ovoid in labio-lingual direction in the
cervical third of root.

98

INCIDENCE

Root
o Straight : 60%
Apical foramen
o Apical delta : 5%

99

 It is ribbon shaped in labio-lingual direction in
middle third and round in the apical third.
 Apical foramen is central in root in 25%cases.
Anatomic relation in situ
 Average of 2 degree of m-d inclination of
average of 20 degree linguo-axial of tooth in its
alveolus.
Access opening
 Same as maxillary anterior teeth.

100

Mandibular lateral incisor

101

LATERAL INCISOR

 Labio-lingual diameter of crown-: 6.5mm
102

Pulp chambers
 Same as mandibular central incisor but it has
larger dimension.
Root and root canal
 Larger than mandibular central incisor.
 Majority of root are straight.
 It may also have distally , labially curved root as
central incisor but the distal curve is sharper.
 Average 17 degree of mesio-axial inclination of
20 degree of linguo-axial angulations of tooth in
its alveolus.
103

INCIDENCE

Same as mandibular central incisor except apical
foramen which is located centrally in 20% cases

104

Access opening
 Same as mandibular central incisor

105

CANINE

106

Pulp chamber
 It is small and flat mesio-distally.
 Three distinct pulp horn are present.
 It is wide and ovoid m-d and tapering incisally.
Root and root canal
 It is usually single rooted.
 It has straight root(68%) may have curved
root(20%)
 Sometimes a “S shaped” bayonate shaped curve
is also seen.
 It usually has a single canal and apical foramen.
 Root canal is broad in middle third and taper to
constriction in the apical third in labio-lingual
view.
107

INCIDENCE

Root
o Mesially curved : 1%
Apical foramen
o Apical delta : 8%

108

 In cross-section it is ovoid in middle third and
round in apical third.
 Lateral canal are present in 30% cases
 Average of 13 degree of mesio-axial inclination
of average of 15 degree of linguo-axial
angulations of tooth in its alveolus.
Access opening
 Similar to maxillary canine.

110

PREPARATION FOR MANDIBULAR 1st
PREMOLAR


111

Pulp chamber
 It is the transition tooth between anteriors and
posteriors.
 The m-d width is narrow.
 Bucco-lingually the pulp chamber is wide with
prominent buccal pulp horn that extend under a
well-developed buccal cusp.
 In cross-section the chamber is ovoid with the
greater diameter bucco lingually.
 Single canal is present.
 In young tooth a small lingual pulp horn is
present in the prominent buccal cusp and
smaller lingual cusp give the crown an 30
degree lingual tilt.
112

Root and root canal
 It has a short conical root which may divide in
the apical third into 2 or 3 roots.
 Root is usually straight (48%) but may be curved
also.
 One canal and and apical foramen is present.
 Canal is cone shaped and simple in outline.
 Root canal is m-d narrow and b-l broad and taper
towards the apical third.
 In cross-section, the cervical and middle third
are ovoid and apical third is conical.

114

INCIDENCE

Root
o Buccally curved : 2%
o Lingually curved: 7%
o Straight : 48%
Apical foramen

115

PREPARATION FOR MANDIBULAR 2ND
PREMOLAR


116

Pulp chamber
 Same as mandibular 1st premolar.
 Lingual pulp horn is more prominent under well
developed lingual cusp.
Root and root canal
 Single root but rarely two or three roots.
 Root is wider bucco-lingually than the counter
tooth.
 It may curve distally9(40%) and curve(30%).
 Single canal is present.
 Lateral canal in (48.3%) cases.

117

INCIDENCE

Root
o Buccally curved : 10%
o Lingually curved: 3%
o Straight : 39%
Apical foramen
o Centrally located in anatomic apex : 60.1%

118

 Similar to mandibular 1st premolar.
 Average 10 degree of disto-axial inclination of
root and average of 34 degree bucco-axial
angulations of tooth in its alveolus.
Access opening
 Same as mandibular 1st premolar.
 Enamel penetration is initiated in the central
fossa .
 Ovoid access cavity is wider m-d and dictated
by the wide pulp chamber.

120

PREPARATION FOR MANDIBULAR 1ST
MOLAR


121

Pulp chamber
 Roof of the pulp chamber is often rectangular.
 The mesial wall is straight and distal wall
converge round.
 Buccal and lingual walls converge to meet
mesial and distal wall to form a rhomboidal
floor.
 The roof of the pulp chamber has four pulp horns
m-b, m-l, d-b and d-l.
 The four pulp horns regress with age.
 The roof of the pulp chamber is located in
cervical third of crown just above the cervix

122

 Floor is located in the cervical third of the root.
 Three distinct orifice are present in the pulpal
floor m-b, m-l and distal.
 The m-b orifice is located under the m-b cusp
and difficult to find.
 It can be penetrated by a long shank explorer.
 The mesiobuccal and the mesio-lingual orifice
may be close under the mesio-buccal cusp.
 Distal orifice is oval in shape.
 The multiple orifice may be present in the distal
root or are found in buccal and lingual portion of
ovoid root canal.

124

Root and root canal
 Two roots mesial and distal.
 The roots are wide and flat, with a depression in
the middle of the root b-l.
 Sometimes third root is present.
 Mesial root is curved distally.
 Distal root is straight.
 Three canals are usually present.
 Mesial root may have two canals and apical
foramina.
 Distal root has one canal.
 In cross-section three canals are ovoid in
cervical and middle third and round in apical
third 125

INCIDENCE

• Mesial Root • Distal Root
Apical foramen o Mesially curved : 5%
o Centrally located in Apical foramen
anatomic apex : 22% o Centrally located in
o Apical delta : 10% anatomic apex : 20%
o Apical delta : 14%

In 5.3% cases a third root may be present which is either
mesially or distally,

126

 On average a 58 degree of bucco-axial
inclination of roots in the alveolus.
Access opening
 It follows the anatomy of the pulp chamber.
 The enamel and dentin are penetrated in central
fosa.
 The bur is angled toward the distal root, where
the pulp chamber is largest.
 It is trapezoidal in shape with round corners and
rectangular if second distal canal is present.

127

PREPARATION FOR MANDIBULAR 2ND
MOLAR


128

Pulp chamber
 It is smaller than the mandibular 1st molar.
 Root canal orifice are small and close to each
other.
Root and root canal
 It has mesial and distal root.
 Rarely three rooted.
 In the single rooted tooth root is straight but
may curve distally, lingually it is “S shaped” or
bayout shape
 In two rooted tooth mesial root curve distally,
straight and “S shaped” buccally.

130

INCIDENCE

• Mesial Root • Distal Root
o Buccally curved : 4% o Mesially curved : 10%
o “S-shaped”: 7% o Buccally curved: 4%
Apical foramen o “S-shaped: 6%
o Centrally located in anatomic Apical foramen
apex : 19% o Centrally located in anatomic
apex : 21%

In 27% cases a single root may be present and in 2% cases it is
three rooted.

131

 Three root canal may be present.
 The mesial root has one canal and foramina.
 The distal root has one canal and foramina.
 In cross-section all three root canal are small
and ovoid in cervical and middle third and round
in the apical third.
 On average -52 degree of bucco axial inclination
of the root in the alveolus.
 Same as 1st molar

133

PREPARATION FOR MANDIBULAR 3RD
MOLAR


134

Pulp chamber
 It is similar to mandibular 1st and 2nd molars.
 It is large and has an anatomic configuration of
a “c shaped” root canal orifice
Root and root canal
 Two roots with two canals are present.
 Three roots with three canals are generally
large and short.
 The alveolar socket may project to the lingual
plate of mandible.
 Apex of root is in close proximity of the mesio-
distal canal

135

Access opening
 It is same as the mandibular 1st and 2nd molars

136

Errors in access cavity preparation

• Poor access placement and inadequate mesial
extension may lead to uncovered mesial orifice.
• Inadequate extension of the distal access cavity
may leave the d-b canal unexposed.
• Gross over extension of the access cavity
weakens the coronal tooth structure and
compromises the final restoration.

137

• Failure to remove the roof of the pulp chamber
may lead to pulp horn mistaken as canal
orifice.
• Overzealous tooth removal due to improper
angulations of bur and failure to recognize the
lingual inclination of the tooth.
• Inadequate opening may lead to -:
1. Bur or file breakage
2. Coronal discoloration
3. Root perforation
4. Canal ledging
5. Apical transportation

139

• Furcation perforation leading to the weakening
of the tooth and periodontal problems.
• Common error in the teeth with full crown is
perforation of the mesial surface due to the
failure to recognize that tooth is tipped or
recognize the alignment of bur along the long
axis of tooth.
• Entering the wrong tooth is a very serious error
and may lead to the medico legal problems.
• Any improper motion and excessive pressure
may lead to bur and file breakage, broken
fragments may lead to excessive tooth removal.

140

Conclusion

• The aim of the access preparation is a good
endodontic result and with restoration of
normal structure and function of the tooth.

142

Access cavity preparation

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