1. Access cavity
preparation for maxillary
canines
Presented by-
Khushboo Chansoria
Kritika Sarkar

3. Parts of root canal system

4. Anatomy of apical root
• The classic concept is
based on 3 anatomic &
histologic landmarks:
Apical
Construction(AC), Cemen
to-dentinal junction &
apical foramen(AF).
• Acc to Kuttler’s
description of the
anatomy of root apex has
root canal tapering from
orifice to AC is 0.5mm-1
mm inside the AF.

5. Clinical significance
• The AC generally is considered the part of
root canal with smallest diameter also a
reference point used most often as apical
termination for shaping, cleaning &
obturation.
• Post-op discomfort generally is greater
when this area is violated by instruments
of filling materials & the healing may be
compromised.

6. • From the minor diameter the canal widens as
it approaches the AF (major diameter).
• The space between major & minor diameter
has been described as funnel shaped of
hyperbolic or having the shape of “morning
glory”.
• The mean distance between major & minor
diameter is 0.5mm in a young person &
0.67mm in an older individual (distance is
greater because of build-up of cementum.

7. Maxillary Canine
•Longest human tooth.
•Average tooth length is 26mm.
•A specimen of 33.5 mm in length
has been reported.
Developmental and anatomic
data
Average time of eruption-: 10-
12Years
Average age of calcification-:
13-15Years
Average tooth length-: 22-
27mm
Average crown length-: 10mm
Average root length-: 17mm
M-D of crown-: 7.5mm
M-D of crown at cervix-: 5.5mm
Labio-lingual diameter of
crown-: 8mm
Labio-lingual diameter at
cervix-: 7mm

8. 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.

9. 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

10. Incidence
Root
Straight : 39%
Distally curved : 32%
Palatally curved : 7%
Labially curved: 13%
“S-shaped” or bayonet curved Apical
foramen: 7%
Apical delta : 3%

11. Anatomic relationship in
situ
 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.
 Labial surface of the root
lies under the labial cortical
plate and may fuse with it-
most prominent bulge:
canine eminence
(fenestration & dehisence).

12. • An abscess originating in a
maxillary canine usually
perforates the labial
cortical plate below the
insertion of levator muscles
of the upper lip and drains
into buccal vestibule.
• If the perforation occurs
above the insertion the
abscess will drain into the
canine space and will cause
cellulites.
• Apical curettage may be
difficult during peri-
radicular procedures
because of length of tooth.

13. Objectives of access cavity
preparation
• Most important phase of non-surgical root
canal treatment.
• Without adequate access, instruments &
materials become difficult to handle in the
highly complex and variable root canal
system.

14. Objectives
To achieve a straight
line access to apical
To locate all root canal To conserve sound
foramen/ initial
orifices tooth structure
curvature of canal.

15. 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.
 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.

18. Access cavity
• Is defined as an endodontic coronal
preparation which enables unobstructed
access to the canal orifices, a straight line
access to apical foramen, complete control
over instrumentation and to
accommodate obturation technique.

19. Armamentarium
• Ruler
• X-ray film
• Pencil
• High speed handpiece
• High speed fissure bur or round bur
• Slow speed handpiece
• Slow speed long-shank #2, #4, #6 bur
• Endodontic explorer
• Slow speed long shank #4 or #6 round bur
• Irrigating syringe
• Sodium hypochlorite
• Irrigating needle (with 45 degree bend at tip)

21. Steps
Step 1: Visualization of likely internal anatomy
• Begin with an x-ray of the unprepared tooth. This
start x-ray is important in making a diagnosis, as
well as estimating the initial measurement of the
canals. Study the radiograph as a blueprint to
establish the:
– size,
– shape
– location of the pulp canal(s) and
– their relative positions.
• Palpation along the attached gingiva aids the
determination of root location.

23. Step 2:Pencil Access
• Outline the coronal access on the tooth in
pencil, using the coronal preparation
slides as a guide.
• The access outline for a maxillary canine is
similar to an upside-down triangle
shape, with the base of the triangle
parallel to the incisal edge.

25. Step 3: Cut Through Center
• First, remove all caries and
fillings that obstruct the
view or that can cause
leakage.
• Undermined enamel should
also be removed together
with any parts of the crown
that make accessibility to
the canal(s) difficult.
• Using a high-speed fissure
bur or round bur held
perpendicular to the lingual
surface, cut just through the
enamel in the center of the
pencil-marked area. A
common error is to begin
cavity too far gingivally. Do
not force the bur.

27. Step 4: Extend Access
• Extend the opening laterally to the
designated outline by maintaining the
point of the bur in the central cavity and
rotating the hand piece toward the incisal
so that the bur continues to parallel the
long axis of the tooth.

28. Step 5: Cut Through Dentin
• With a low-speed long-shank #4 or #6 bur
(depending on the size of the pulp
chamber), make a cut with the long axis of
the tooth and cut directly through the dentin
into the large pulp horn, or the largest area
of the pulp chamber.
• This procedure makes the access cavity walls
confluent with the lateral & the incisal walls
of the pulp chamber & renders the cavity a
lingual extension of pulp chamber with a
“straight line” penetration to the apical root
canal.
• The bur should be used with a pull stroke
from the chamber in and out.

29. Step 6: Explore Access
• Use the endodontic explorer to check for
the canal.
• If the explorer meets constant
resistance, the pulp chamber has not yet
been reached.

30. Step 7: Cut into Chamber
• Continue drilling apically through the
dentin.
• The operator will feel a slight drop as the
bur breaks through the roof and drops
into the pulp chamber.

31. Step 8: Explore Access
• When the pulp chamber has been
penetrated, probing with the explorer will
often produce a "catch" along the
ledges, or overhangs, created by the
lingual walls or roof of the pulp chamber.

32. Step 9: Remove Undercuts
• Expand the coronal cavity access slightly.
• Avoid perforating the floor of the pulp chamber.
• Penetrate the pulp chamber using a slow-speed
long-shank round bur (No. 4 or 6 Gates Glidden).
• Working from inside the chamber to outside in a
sweeping motion, remove undercuts, or lingual
and labial walls of pulp chamber.
• The access on the tooth is extended more toward
the cingulum. Additional beveling of the incisal
wall is also completed by working from inside to
outside to remove the lingual "shoulder" of the
canal, thus allowing for the continuous access from
the coronal cavity into the canal.

35. • The ideal access consists of smooth walls
without ledges. The use of fissure burs very
often creates ledges in the floor and walls
of the cavity access preparation, which
can make canal instrumentation more
difficult. Moreover, ledges in the dentin
can diminish the tensile strength of the
tooth.

36. • In general, the No. 2 is used for working
within the canals, while Nos. 4 and 6 are for
working within the chamber, using a
sweeping motion to avoid gouging the floor
of the pulp chamber and creating the illusion
of a canal which may lead to perforation.
• Remove debris from the chamber as you
proceed, using a No. 2, No. 4 or No. 6 bur to
eliminate pulpal horn debris and bacteria.
• If the canal or chamber is calcified, remove
dentin with the slowspeed hand piece and
appropriate bur.

37. • Step 10: Irrigate
• Irrigate periodically to flush out debris.
• Fill an irrigating syringe with "sodium
hypochlorite" and attach an irrigating needle, the
tip of which should be bent at approximately a 45
degree angle to the long axis of the needle.
• The distance from the bend to the tip of the needle
should equal 20 mm.
• Using this needle, gently flush fillings and debris
from the chamber.
• The needle should fit in the canal very loosely, and
the solution should be introduced very slowly, so
that it can run back out of the access opening and
is not forced through the apex.

38. Step 11: Straight-Line Access
• The resulting cavity should be smooth and
continuous, flowing from cavity margin to canal
orifice; this is referred to as straight-line access.
• The incisal wall meets the lingual surface of canine
in a butt joint to provide adequate thickness for a
restorative material because this tooth is heavily
involved in excursive occlusal guidance.
• Verify that you have achieved straight-line access
by rotating a file within the canal.
• The file should have direct and unimpeded access
to the canal, achieving 360 degrees of
unrestrained motion; you should be able to rotate
the file 360 degrees about the cavity outline
without encountering resistance within the pulp
chamber due to ledges or ridges.

40. Bibliography
• Pathways to pulp- Cohen
• Grossman’s endodontics
• Endodontics by John Ingle
• Textbook of endodontics by Nisha Garg
• Endodontics by Pittford
• Endodontology by Gunner
• Google.com
• Columbia.edu
• Universityofmichigan.edu
• Googlebooks.com