This document discusses guidelines for access cavity preparation in endodontic treatment, including in special situations. It begins by outlining the objectives of achieving straight line access to canals and removing caries/defective restorations. Principles of access preparation include following the internal anatomy and removing remaining caries. Specific guidelines are provided for various tooth types, and locating additional canals like the MB2 in maxillary molars is discussed. Aids like microscopes and ultrasonic tips can help in complex cases.

1. Access preparation in special
situations

2. CONTENTS
 Introduction
 Pulp space anatomy
 Objectives of access cavity preparation
 Principles of access cavity preparation
 Access preparation guidelines
 Armamentarium
 Anatomy of the pulp chamber floor

3.  Access preparation
- In teeth with unusual canal morphology
- Tilted teeth
- Retreatment cases
- Primary teeth
- Through metal crowns
- Heavily restored tooth
- Calcified canals
 Conclusion
 References

4. Introduction
 Endodontic therapy is a micro neurologic surgical
procedure. A thorough understanding of the canal
anatomy followed by its complete debridement
and filling is essential for a successful outcome.
To achieve these objectives a well executed access
preparation is essential which provides a straight
line path to the apex and thereby increases the
success rate of endodontic therapy.

5. Objectives of access cavity
preparation
1. Straight line access
Benefits gained through this:
 unobstructed access to canal orifice
 direct access to apical foramen
 complete authority over enlarging instrument
 Ease of cleaning and shaping
 Quality obturation

6. 2. Removal of carious dentin and defective
restorations
 eliminate mechanically bacteria
 eliminate the discolored tooth structure that
may ultimately lead to staining the crown.
 eliminate the possibility of any bacteria
laden saliva leaking into the prepared cavity
3.Unroofing the pulp chamber
 maximum visibility
 location of canals
 exposure of pulp horns

7. Access preparation guidelines
1. Internal anatomy dictates the access shape
Visualization of the location of pulp space
- B-L angulations
- Coronal anatomy judged visually
- Cervical anatomy is tactically determined using
explorer
- Palpation to determine the tooth location and
direction
- Diagnostic radiograph

8. 2. Removal of any impinging restorative material.
3.Roof of the pulp chamber is perforated with a round
bur. For teeth with porcelain crowns, a water cooled
round diamond instrument should be used until dentin
is reached ,this prevent fracture of the thin dentin.
4. Once the pulp chamber is located, the round bur is
used to remove the roof of the pulp chamber from
underneath, the belly of the bur should be used to cut
on the out stroke.
5. A sharp DG 16 double explored is used to locate
canal orifices and to determine their angle of
departure form the main chamber.

9. 5.When canals are difficult to find the rubber dam
should not be placed until correct location has been
confirmed.
6. Access is through occlusal or lingual surface never
through proximal or gingival surface.
7. As part of access preparation , the unsupported cusps
of posterior teeth must be reduced.

10. Armamentarium
1.High speed handpiece.
2.Round bur no 2 , no 4.
Regular length 9 mm,
surgical length 12 mm.
3. Endoaccess bur
4. safe ended bur (BATT
fissure or taper fissure
burs)

11. Radiographs:
straight on periapical radiographs
walton’s projection : horizontal
angulation of 20 degrees

12. Accessory aids:
 fibre optic lighting
 operating microscopes
 carr tips
 stropko irrigator
 methylene blue
 DG- 16 explorer
 pathfinder
 microopener

13. Principles of access cavity
preparation
 Outline form
 convenience form
 removal of the remaining carious dentin
 toilet of the cavity

14. Outline form
Outline form
 complete access for instrumentation from cavity margin to
apical foramen. External form evolves from the internal
anatomy of the tooth established by the pulp
Three factors to be considered:
 size of the pulp chamber
 Shape of the pulp chamber
 No of individual root canals, their curvatures and their
positions

15. Convenience form:
Important benefits gained through
convenience form modifications
 Unobstructed access to the canal orifice
Direct access to the apical foramen
Cavity expansion to accommodate filling
techniques
Complete authority over the enlarging
instrument

16. Unobstructed access to the
canal orifice:
Shamrock preparation
(Luebke 1983) :
In the event of an
instrument impingent only
the portion of the wall
should be extended to free
the instrument. A
cloverleaf appearance may
evolve as the outline form

17. Removal of remaining carious dentin and
defective restorations:
Toilet of the cavity:
All of the caries, debris, and necrotic
material must be removed from the chamber
with round burs and spoon excavator before
the radicular cavity preparation is begun

18. Anatomy of the pulp chamber
 Krasner et al (JOE 2004)
proposes certain laws
which make for the
specific, consistent
location of landmarks.
Relationship of the pulp
chamber to the clinical
crown:
 LAW of Centrality: the
floor of the pulp chamber
is always located in the
center of the tooth at the
level of the CEJ

19.  Law of concentricity: the
walls of the pulp chamber
are always concentric to
the external surface of the
tooth at the level of the
CEJ
 Law of CEJ: CEJ is the
most, consistent,
repeatable landmark for
locating the position of the
pulp chamber.

20. Relationship on the pulp chamber floor:
The following observations were noted relative to all teeth:
 The floor of pulp chamber is always a darker color than the
surrounding dentinal walls.
 this color difference created a distinct junction where the
walls and the floor of the pulp chamber meet
 the orifices of the root canals are always located at the
junction of the walls and floor,
 the orifices of the root canals are located at the angles in
the floor wall junction

21. the orifices lay at the terminus of
developmental root fusion lines , if present
the developmental root fusion lines are
darker than the floor color
reparative dentin or calcifications are lighter
than the pulp chamber floor and often
obscure it and the orifices

22. The following observations
are noted relative to all
teeth except maxillary
molars:
Law of symmetry 1
 if a line is drawn in a
mesial –distal direction
across the center of the
floor of the pulp chamber,
the orifices of the canals
on either side of the line
are equidistant,

23. Law of symmetry 2:
 if a line is drawn in a
mesial-distal direction
across the center of
the floor of the pulp
chamber , the orifices
of the canals on either
side are perpendicular
to it.

24.  Law of color change:
the color of the pulp
chamber floor is
always darker than the
walls.

25.  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
angles in the floor-wall
junction

26.  Law of orifice location
-3: the orifices of the
root canals are located
at the terminus of the
root developmental
fusion lines.

27. Maxillary central incisor
 Pulp chamber is centrally
located
 Broadest incisally
 Has one root and one root
canal
 Access shape is triangular
and is begin in exact
centre of lingual surface
(Lingual conventional
access)

28.  Lingual cingulum
access:(mannan et al)
initial point of entry
lingual surface,
coronal to
cingulum.Opening
enlarged minimally to
remove the entire pulp
chamber roof cervico
incisally and MD

29. incisal straight line access:
 Initial point of entry-
incisal edge on the
lingual surface
 Extension- . cervically
to the centre of lingual
surface , incisally to
involve half the bucco
lingual width of the
incisal edge and
mesiodistally to include
the entire pulp chamber
roof.

30. Maxillary canines
 Pulp chamber largest of any
single rooted teeth
 B-L chamber is triangular in
shape , with the apex toward the
single cusp and a broad base in
the cervical third of the crown.
 Mostly single root and single
root canal
 Access cavity corresponds to
lingual crown shape is ovoid
 To achieve straight line access ,
cavity should be extended
incisally

31. Maxillary first premolar
Commonly two rooted
Pulp chamber is narrow M-D ,wide B-L
Pulp horn is under each cusp
Two canal orifices one under each cusp

32.  Access cavity is ovoid
which must be more
extensive in the bucco
lingual direction than
mesiodistal
 Border of this cavity
should not extend beyond
half the lingual incline of
the facial cusp and half the
facial incline of the lingual
cusp

33. Three rooted maxillary premolar
 incidence of 5 – 6% for 1st premolars
 1% for 2nd premolars
 common configuration is three separate roots, each
containing a single canal,
 2 roots with 2 canals in the buccal root that leaves the
chamber separately and merge to form a single canal short
of the foramen,
 2 roots with 2 canals in the buccal root that leave the
chamber as a single canal and divide into two separate and
distinct canals.
 Miniature maxillary molar – MB, DB, and palatal,

34.  General guideline for radiographic identification : in a
straight on radiograph if the mesial distal width of the mid
root image appears equal to or greater than the mesial
distal width of the crown image ( sieraski et al JOE 1989)
 Access modification : “ T” shape , mesial –distally
extending the buccal aspect of the outline form .This
allows good access to each of the two buccal canals.
 S-shaped canals – when 2 buccal canals arise from a
common narrow canal which originates from the pulp
chamber . a trough is created over and between the buccal
canals to eliminate the S- shape. Similar to preflaring.

35. Maxillary second premolar
 Similar to the first premolar in coronal
morphology varies mainly in root form
 Usually has one root
 May have two separate canals, two canals
anastomsoing to a single canal or two canals with
interconnections or webbing

36. Maxillary first molar
 Pulp chamber is largest in dental arch with four
pulp horns M-B, D-B, M-P, D-P
 Pulp chamber is rhomboidal in shape
 3 roots, palatal, mesiobuccal , distobuccal
 Orifices of root canals are located in the angles of
floor
 Palatal orifice is the largest, round or oval in shape

37.  Palatal root is the longest and has the largest
diameter, often curves toward the buccal in the
apical one third
 Distobuccal root is conical and usually straight
 Mesiobuccal root: Greene reported 2 orifices in
36% of first molars, pineda reported 42% of teeth
exhibited 2 canals and 2 apical foramina
 Stropko et al reported found MB 2 in 73.2% of
first molars before use of surgical operating
microscope and 93% after the introduction of
these devices

38.  The number of roots in maxillary molars can vary.
Christie et al reported 16 cases of maxillary
molars with two palatal roots .
 classified them according to the shape and root
separation as
 type 1: two widely divergent palatal roots, which
often are long and tortuous . Buccal roots often are
cow –horn shaped and less divergent. Four
separate root apices are seen on the radiograph ,
 Type 2: Four separate roots, but the roots often are
shorter, run parallel, and blunt root apices.

39.  Type 3: constricted in root morphology with MP
and DP canals encaged in a web of root dentin.
DB root slant alone and may even diverge to
distobuccal.
 While examining the preoperative radiographs if
the outlines of the roots are unclear, the root
canals show sharp density changes or the apices
cannot be well defined, then extra roots can be
suspected.

40. MB- 2 Canal
 Clinician should always assume two canals in the
mesiobuccal root until it is proven otherwise
 Access openings made rhomboidal in anticipation
of MB2 , most cases mesial marginal ridge was
infringed upon to achieve enough access to reveal
the mesially positioned and mesially inclined MB
2 canal

41. Location of MB-2 orifice
 MB2 orifice openings
were usually found mesial
to an imaginary line
between the MB1 and
palatal orifices and
commonly about 2 to 3
mm palatal to MB1
orifice.
 This imaginary line is an
arc with an apogee toward
the mesial, following the
contours of the mesial
surface of the
root.(stropko etal 1999)

42. Gorduysus et al 2001:MB 2 canals were
characterized by the presence of a subpulpal
groove extending palatally from the main
mesiobuccal canal that on probing with
sharp explorers and exploration disclosed an
orifice like spot.
Prevalence in 96% of teeth , however only
in 84% of molars a secondary orifice was
identified,

43.  Location of the MB-2 canal
relative to the mesiobucal
orifice, the MB-2 canal was
located either mesial to or
directly on the mesio palatal
line within 3.5 mm palatally
and 2 mm mesially from the
main mesiobuccal canal.
 The location of the MB 2 is
from the point from which it
could be negotiated , rather than
the location of its orifice

44. Subpulpal groove
Subpulpal groove: Acosta described a “Y”
shaped groove on the floor for the pulp
chamber of the permanent maxillary first
molar

45. Access cavity
 Access cavity is usually
triangular with round
corners extending toward
,but not including the MB
cusp tip, marginal ridge ,
oblique ridge.
 Access openings made
rhomboidal in anticipation
of MB2 .
 Access openings in case of
four rooted molars is
usually quadrangluar.

46. Aids for location of MB 2 orifice
 Slow speed Mueller burs
 Carr CT tips and
 Ruddle CPR
 SP- 1 ultrasonic tips
 Operating microscopes ,for
- orientation purposes at 6 X magnification ,
- 12 X to enhance what is seen at lower magnification,
- magnification at 26 X to confirm the openings
 stropko irrigator fitted with a blue micro tip

48. Procedure for locating MB2
Troughing with ultrasonic tips:
 Under magnification, the darker channels in the
floor of the pulp chamber are traced with the
unactivated tip of the instrument.
 In molars there is a slight groove that runs from
the palatal to the mesiobuccal tooth canals for the
presence of MB 2. If the channel deepens slightly
the instrument should be activated, and with a
gentle picking action the dentin should be
removed

49. To enhance vision the pulpal floor dried
with a stropko irrigator fitted with a blue
micro tip . This permitted precise and
regulated stream of air, or water to be
directed onto the desired site. Dryness was
essential for maximum visual inspection of
the anatomy occurring on the pulpal floor.

50.  Normal observation of
the pulpal floor
reveals the isthmus
appearing as a thin and
white or red line
unless it has calcified

51.  It was sometimes necessary to clean and shape the
MB 1 to observe the line emanating from deep
within the confines of the prepared canal.
 On occasion it necessary to trough to depths of 4
mm , or more to locate and instrument the
calcified and tortuous MB2 canal.
 A few times, troughing line did not lead to an
orifice or the line disappeared when instrumented
in an apical direction.

52.  MB 2 canal usually has a marked mesial incline
immediately apical to its orifice in the coronal 1 -3 mm,
 The ultrasonic or dental handpiece is inclined to the distal
as far as the access permits , to allow the first few
millimeters of this overlying “roof of calcified tissue to be
eliminated.
 After this refinement of the access preparation , a more
desired straight line access can be achieved
 On occasion ,MB2 shared an orifice with MB1 , when the
opening is oval in shape.
 Infrequently the MB 2 orifice was harbored within, or just
apical to that of the palatal canal

53.  other aids champagne bubble test with warmed 2.6%
NaOCl ,staining the chamber with 1% methylene blue, the
use of DG-16, looking for bleeding signs and obliquely
angled preoperative radiographs.
 Negotiating of the MB-2 canals is difficult due to the ledge
of dentin that frequently covers the orifice.
 Another complication is the tortuous pathway of some of
these canals that can include one or two abrupt curves in
the coronal portion.
 MB-2 invariably emerges from the pulp chamber floor at a
considerable mesial –buccal angle.

54. - A file inserted into the orifice is forced to bend
sharply toward the mesial buccal direction.
 Attempts to insert the file from the distal palatal
direction as the file travels just 1-2mm its tip
engages the canal wall at the next sharp bend.
 Countersinking: various amount of dentin must be
removed to uncover completely the orifice and
pursue the MB-2 canal 1-3 mm deeper into the
root,
 usually includes troughing along the mesiobuccal
subpulpal groove with a distinct orientation
toward the mesial direction to eliminate the
tortuous coronal portion of the canal.

55. Pathway of MB2
Pathway of the MB2 canal is as variable as
the location.
Coronal portion is usually tortuous.
Beyond this level the canal can be relatively
straight, turn slightly to distal and buccal or
turn sharply to buccal or palatal

56. Maxillary Second molars
 Narrower M-D
 Three roots are grouped closer together and sometimes
fused
 Roots usually shorter than 1st molar but not as curved,
occurrence of 4 canals less likely than 1st molar.
 The three orifices may form a flat triangle.

57.  Teeth with fused roots
occasionally have only
two canals, rarely only
one, two canalled teeth
usually have a buccal and
a lingual canal of equal
length and diameter, these
parallel root canal are
frequently superimposed
and can be imaged by
exposing the radiograph
from a distal angle.

58.  It is tipped to the distal or buccal or both which
can complicate access, especially when the
opening is limited or mouth is small.
 A distally tipped tooth may require exaggerated
convenience form to allow adequate access to MB
canal. Buccal tipping can confuse the perception
of long axis of the canals and lead to access errors

59. Mandibular incisors
 Smallest tooth in the arch
 Narrow and flat in BL dimension
 One root which is flat B-L ,
 Benjamin and Dowson et al prevalence of 2 canals in
mandibular incisors in 41.4%, of these only 1.3% had
separate foramina
 Incisor anatomy presents a challenge when making an
access because of its small size and high prevalence of two
canals

60.  Traditional access - lingual ,because of esthetics and
restorative reasons.
 Disadvantage: the lingual canal is difficult to locate and
instrument an artificial bulge of dentin remains making
detection and debridement of the lingual canal more
difficult.
 Janik advocated extending the lingual access more toward
the cingulum to aid in locating and debriding the lingual
canal.
 Clements and Gilboe labial endodontic access.
 Mauger et al JOE 1999, advocate access in the incisal or
facial edge of mandibular incisors.
 Using a straight line access from the incisal or facial edge
preserves the dentin in the cingulum area making for a
stronger tooth

61.  Amount of incisal wear is
a guide for the positioning
of access, in unworn
incisors the crown slopes
toward the lingual from
the long axis of the tooth.
In these teeth the ideal
access will be positioned
facially 68.1% of the time,
when teeth show extensive
or moderate incisal wear,
the access should he made
in the incisal edge 86.5%
of time

62. Mandibular Canine
 Ocassionally may have
two canals and roots
 Access cavity is ovoid and
may extend incisally for
access
 In case of 2 roots, the
second canal must be
opened and funneled in
concert with the first canal
to prevent packing of
dentin debris and loss of
access

63. Mandibular premolars
 1st premolar: well
developed buccal and
small lingual cusp. Access
prep ovoid in shape
 2nd premolar: well
developed buccal and
lingual cusp. Access is
ovoid in outline
 Three rooted ,mandibular
premolars the access
cavity is enlarged to a
triangular outline, with
three separate root canal

64. Mandibular first Molar
 Roof of the pulp chamber is rectangular in shape
 Four pulp horns MB, ML,DB, DL
 Usually has 2 roots and 3 canals with 2 canals in
mesial and one in distal
 Distal root canal is larger and may be wide B-L
 Mesial roots usually curved , with greatest
curvature in MB canal.
 3 orifices MB, ML and distal

65.  Mesiobuccal orifice under mesiobuccal
cusp,explored in a mesiobuccoapical direction
 ML orifice in a depression formed by mesial and
lingual walls explored from distobuccal direction
 Distal orifice is oval in shape , explored from
mesial direction
 Zattar et al JOE 1998 reported two root canal in
6.1%
 Three root canals in 67.4%
 Four root canals 26.5%

66. Smaller and shorter root present on the
distolingual aspect and may posses a sharp
hook toward the buccal that is not obvious
on the radiograph
orifice locations of the two distal canals
may be found in extreme buccal and lingual
locations
Traditional access form is triangular
Rectagular one is preferred to search for the
location of the second distal canal.

67.  Access opening
extends toward the
MB cusp to uncover
the MB canal,
lingually slightly
beyond the central
groove and distally
slightly beyond the
buccal groove

68. Mesial groove
 Presence of mesial groove between the
mesiobuccal and mesiolingual orifices in
mandibular molars ( Yesilsoy et al JOE 2002)
 84% mandibular first and second molars had a
mesial groove that could potentially allow pulpal
tissue and microorganisms to remain unaffected
by debridement procedures
 average groove depth of 1.05 mm.

69.  Area between the mesial orifices can be probed with an
endodontic explorer, the access preparation modified by
deepening this region, which can be performed with #1 or
#2 round bur or ultrasonic tip until no further probing of
this region is possible
 Use of DOM may aid in minimal hard tissue removal
 Overall modification of the mesial groove area may not
only decrease the contents in this space but may also
expose the area to more volume of irrigation

70. Mandibular Second Molar
 roots often sweep distally in a gradual curve.
 Most common finding is 2 separate roots , with 2
canals in the mesial root and one canal in the distal
 Existence of single rooted Mnd2M with a
continuous slit connecting two , three or four
canals was described by Cooke and Cox in 1979,
 C-shape consisted of a slit that went from the
mesiolingual canal to the mesiobuccal canal ,
continuing around the buccal to the distal canal or
canals

71.  Cooke and Cox et al classified them as follows:
 Cat 1: continuous C-shaped canal without
separation
 Cat 2: Semicolon ; shaped canal , dentin separates
one distinct canal from a buccal or lingual C-
shaped canal in the same section
 Cat 3: 2 or more distinct and separate canals
Access modification: orifice portion of slit widened
early in treatment

73. Access in retreatment cases
Missed canals:
 Radiographic method:
with different angulations.
 Transillumination
methods : with fiber –
optic bundles ,
illuminating light source
xenon of metal halide bulb
with a cable composed of
glass fibers.

74. Troughing method: White line
test
 Use of DOM and CT-4, is used
to create the initial trough, it is
used in a dusting or etching,
back and forth action with the
water turned off while the
assistant uses the stropko
irrigator to keep the operative
site free from dentinal dust and
pulpal debris,
 As a steady steam of air is
applied, any pulp tissue
becomes desiccated and turns
white

75.  Staining method: if white line is not visible ,
trough stained with a food dye or caries
indicator.
 Bubble test: action of sodium hypochlorite on
vital or necrotic tissue produces oxygen bubbles.
A single drop of NaOCl placed in troughing
groove reacts with pulp tissue and produces
Oxygen bubbles which may be seen under high
magnification.

76. Access in primary teeth
 Maxillary anterior teeth access is from the facial
surface , the only variation to the opening is more
extension to the incisal edge than the normal
lingual access to give a straight line approach
 Posterior teeth: similar to that of anterior except
length of the crowns, bulbous shapes of the
crowns, and the very thin dentinal wall of the
pulpal roots and floors. Depth of penetration is
less,

77. Access in tilted tooth
 May occur due to lose of adjacent teeth, malocclusion.
 Before access cavity preparation, it is essential to
determine the anatomic relationship of the crown to the
root and the angle of the root in the arch.
considered the following problems are encountered :
1.misidentification of canals,
2.inability to locate a canal,
3. missing extra canals.
4.Undermining and weakening coronal or radicular tooth
structure.
 Guideline: bur should be tilted, so that it is in line with the
long axis of tooth.

78. Access through complex
restorations
 Extensive coronal tooth loss requires many types of
restorations
 Subgingival caries requires complex restorative procedures
which result in the recession of coronal and radicular
canals.
 Achieving access in these teeth requires excavation of
filling materials, caries and calcified tooth structure
 Ideal access can only be achieved by total removal of all
restorative materials.

79. Endo Perio lesions
Gradual closure of internal spaces may be
observed as the attachment appartarus
demineralizes away from the root surfaces.
Height of pulp space moves apically,
making occlusal access difficult.
Periodontal patients may have caries on
exposed root surfaces, and require extensive
class V restorations.

80.  These restorations and
calcifications
accompanying them make
gaining occlusal access to
some canals impossible.
 In unusual cases, it may
become necessary to
remove the restorative
material and then locate,
clean and shape the orifice
from the buccal aspect

81. Access in teeth with crowns
Potential problem in access openings through crowned teeth
 Alters the original landmarks like cusp tips and central
grooves.
 Obscure the pulp chamber in radiographs.
 Root or crown structure under full crown may be rotated or
misaligned with normal tooth position and arch
configuration
 Presence of crowns may obscure fractures in the walls and
floor of the pulp chamber.
 Light penetration into an access opening is difficult

82. Following guidelines deserve special attention
during access preparations:
 All potential avenues of carious leakage under
crown margins must be determined and
eliminated.
 Bite-wing radiographs may assist in pulp chamber
location,
 Most crowns have extensive alloy or composite
buildups that often impede direct access and
chamber or orifice location

83. Visibility into the dark access openings in
crowns is limited.
Porcelain to metal crowns are subject to
fracture or craze lines during access
preparation. This is especially true for old
porcelain jacket crowns.
Newer, non precious alloys are very hard
and impede access preparations

84. The artificial occlusal or lingual anatomy of
a crown restoration does not serve as a
guide to the access opening entry.
The presence of crowns may obscure
fractures in the tooth structure, especially
the proximal walls or floor of the chamber.

85. Following difficulties are encountered:
Inadequate access opening:
Overzealous tooth removal
Inadequate caries removal
Misinterpretation of angulations
Procedural accidents

86.  Access cavities are prepared with coolants with
extra coarse dome ended cylinder .
 Friction generated heat can damaged adjacent soft
tissue, including the PDL.
 Once penetration of metal is accomplished , a
sharp round bur can be used.
 Metal filing and debris should be removed
frequently,
 As with naturally occurring crown –root
angulations, a thorough radiographic evaluation in
necessary to identify angled roots.

87.  Use of a fibreoptic system for increased visibility.
 prepare the initial access through the crown without a
rubber dam
 evaluate the shape of the alveolar process over the root
surface in the cervical area below the margin of the
crown.
 before cutting the access opening, measure the bur
against the radiograph to estimate the depth of
penetration relative to the position of furcation.
 use water spray and proceed slowly with high speed
diamond bur to protect any porcelain present.

88.  using a diamond bur, cut porcelain in a light
,shaving manner. Once the porcelain has been
penetrated ,switch to a sharp carbide bur to
complete access preparation
 after entry into pulp space, restrict all cutting to
a lateral or outstroke movement, irrigate often,
 flare the walls of the access opening to he
occlusal side for posterior or lingual side for ant
teeth to prevent contact with the intracanal
instruments,

89.  probe for possible avenues
of carious leakage or
fractures.
 If necessary , open the
coronal outline of the
access beyond a standard
size to facilitate canal
location and exploration.
 irrigate the prepared
access well before
entering any of the canals.

90. Access in calcified canals
 Success in negotiating small or calcified canals is
predicated on a proper access opening and
identification of the canal orifice or orifices.
 access preparation is initiated with the rotary
instrument directed toward the presumed location
of the pulpal space

91.  all the old restorative materials must be removed
 Using a long shanked no 4 or no 6 bur the
clinician explores the assumed location of the
main pulp chamber
 The endodontic explorer is used to examine the
pulpal floor, it is both an examining instrument
and a chipping tool , to flake away calcified dentin
 Reparative dentin is slightly softer than normal
dentin, a slight tug back in the area of the canal
orifice signals the presence of a canal.

92.  Failure to locate the orifice at this point, bur to be
removed from the handpiece and placed in the
excavation site. Packing cotton around the pellets
around the shaft maintains the position and
angulations of the bur, the radiograph exposed at
right angles through the tooth reveals the depth
and angulations of the search.
 At the smallest indication of space, the smallest
instrument is introduced.
 Magnification also plays a major role in orifice
location

94. Conclusion
 Access opening is a dynamic three dimensional
process. It is one of the keystones for achieving
success in endodontic therapy. A properly
prepared endodontic access can eliminate many of
the technical difficulties encountered during root
canal treatment.

95. References
 Pathways of the pulp –Cohen 7th and 8th edition
 Endodontics – Ingle 5th edition
 Problem solving in endodontics- Gutmann 3rd
edition
 Endodontic therapy- Weine 5th edition
 Endodontic practice –Grossman 11th edition
 Microscopes in endodontics – DCNA
 Journal references