2. CONTENTS
INTRODUCTION
COMPONENTS OF ROOT CANAL SYSTEM
CLASSIFICATION OF ROOT CANAL SYSTEM
OBJECTIVES OF ACCESS CAVITY PREPARATION
PRINCIPLES OF ACCESS CAVITY PREPARATION
MORPHOLOGY OF ACCESS CAVITY PREPARATION FOR INDIVIDUAL TEETH
ANTERIOR ACCESS CAVITY PREPARATION
POSTERIOR ACCES CAVITY PREPARATION
CHALLENGES IN ACCESS CAVITY PREPARATION
ERRORS IN ACCESS CAVITY PREPARTION
NEWER CONCEPTS IN ACCESS CAVITY PREPARATION AND CASE REPORT
3. CONTENTS COVERED IN PART -1
INTRODUCTION
COMPONENTS OF ROOT CANAL SYSTEM
CLASSIFICATION OF ROOT CANAL SYSTEM
OBJECTIVES OF ACCESS CAVITY PREPARATION
PRINCIPLES OF ACCESS CAVITY PREPARATION
4. CONTENTS TO BE COVERED IN PART -2
ANTERIOR ACCESS CAVITY PREPARATION
POSTERIOR ACCES CAVITY PREPARATION
MORPHOLOGY OF ACCESS CAVITY PREPARATION FOR INDIVIDUAL TEETH
CHALLENGES IN ACCESS CAVITY PREPARATION
ERRORS IN ACCESS CAVITY PREPARTION
NEWER CONCEPTS IN ACCESS CAVITY PREPARATION AND CASE REPORT
6. REMOVAL OF CARIES AND PERMANENT
RESTORATIONS
• Removal of caries and old faulty restorations has to be
removed as early as possible ,before entering into the pulp
chamber which helps in minimizing further contamination
of bacteria into the pulp chambers
• Removal of defective permanent restorations helps
to gain a straight line access to the apical end of the
tooth
7. STEPS INVOLVED IN ANTERIOR ACCESS
CAVITY PREPARATION
• Initial external outline form
• Penetration of the pulp chamber roof
• Complete roof removal
• Identification of all canal orifices
• Removal of lingual shoulder and coronal flaring
• Straight line access determination
• Refining and smoothing restorative margins
8. INITIAL EXTERNAL OUTLINE FORM
>An initial outline preparation is made primarily on the lingual surface of the anteriors at the center of
the tooth
#2 or #4 no. round bur is used primarly to penetrate and remove the enamel layer and enter in to
dentin (approximate 1mm ) . The initial outline form is almost made in a shape and geometry that of
final access cavity preparations ( two thirds to three fourths size of final access cavity preparation )
The bur is directed perpendicular to the lingual surface of the tooth for the initial external outline
form
9. PENETRATION OF THE PULP CHAMBER ROOF
>The angle of the bur is been changed
from perpendicular to lingual surface to
parallel to the long axis of the tooth
>penetration into the tooth is accomplished along
the root long axis of the root until the roof of the
pulp chamber is penetrated .usually a DROP-
EFFECT can be felt once the bur penentrares the
pulp chamber of the tooth
10. 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
withdrawal stroke
All pulp chamber roof , including the pulp
horns ,must be removed and all internal
walls must be flared to the lingual surface of
the tooth. Complete roof removal is confirmed
with a #17 operative explorer if no “catches”
are discovered as the explorer tip is
withdrawn from the pulp chamber along the
mesial ,distal and facial walls
11. IDENTIFICATION OF ALL CANAL ORIFICES
• After the pulp chamber are unroofed the canal orifices are
located with canal orifices
• While probing the pulp chamber floor, explorer often
penetrates or dislodges the calcific deposits blocking an
orifice.
• It also can be used to evaluate straight line access
12. REMOVAL OF THE LINGUAL SHOULDER
AND ORIFICE AND CORONAL FLARING
Once the orifices has been identified and confirmed
, the lingual shoulder is removed .
This structure is the lingual shelf of dentin that
extends from the cingulum to a point
approximately 2mm apical to the orifice
The lingual shoulder can be removed with a
tapered safety –tip diamond or carbide bur or with
gates-glidden burs
13. • When Gates-Glidden burs are used the largest one can be
passively be placed 2mm apical to the orifice is used first.
• During rotation, the bur is leaned against the lingual
shoulder and withdrawn .
• The clinician can increase the size of these BURS sequentially
, depending on the size of the canal , and repeat the shaping
of the lingual wall until the lingual shoulder of the dentin
has been eliminated
14. STRAIGHT LINE ACCESS DETERMINATION
Ideally, an endodontic file can approach the
apical foramen or the first point of canal
curvature undeflected
Deflected instruments also lack access the
critical areas of the canal and therefore do not
shape and clean effectively . Attempts to shape
and clean without straight line access often
lead to procedural errors such as ledging
,transportation and zipping
15. The final position of the incisal wall of
the access cavity is determined by two
factors
1. Complete removal of the pulp horns
2. Straight line access
16. REFINEMENT AND SMOOTHENING OF
RESTORATIVE MARGINS
• The final step is access cavity preparation is to refine and smoothen the restorative
margins to avoid coronal leakage through permanent or temporary restoration
• Butt joints are indicated rather than beveled margins which produce thin composite
edges that can fracture under excursive functional load and ultimately result in
coronal leakage
18. INITIAL EXTERNAL OUTLINE FORM
• As that of anterior teeth , pulp chamber of posterior teeth is positioned in the center of
the tooth at the level of CEJ
*The access starting location is different for different individual tooth.
• 1. maxillary premolars -- point at central grooves in between the cusp tips
• 2.maxillary 1st molar --
• 3. maxillary 2nd molar --
• 4. mandibular premolars --
• 5. mandibular 1st molar --
• 6. mandibular 2nd molar --
21. Crowns of mandibular pre-molars are tilted lingually relative to their
roots, and the starting location must be adjusted to compensate for this
tilt by angulating the bur towards the lingual side
22. MOLARS
• To determine starting location of molars access cavity preparation the
clinicians must establish mesial and distal boundaries limitations so
that sound tooth structure is prevented and which further helps in
longevity and strength of the tooth
• Evaluation of the bitewing radiographs is the accurate method of
assessing the mesio distal extension of the pulp chamber
23. MAXILLARY MOLARS
• Mesial boundary -- a line connecting the
mesial cusp tips i.e mesio buccal and mesio
lingual
• Distal boundary – the oblique ridge
MANDIBULAR
MOLARS
• Mesial boundary – a line
connecting the mesial cusp tips
• Distal boundary – the line
connecting the buccal and
lingual grooves
24. *Penetration through the enamel into the dentin (approximately 1mm) is
performed with a #2 round bur for premolars and #4 round bur for molars
• The bur is directed perpendicular to the occlusal table , and an initial outline
shape is created at about one half to three fourths as projected canal size
• The premolar shape is oval and widest in buccolingual dimension
• The molar shape is also oval initially , it is widest in buco -lingual dimensions
for maxillary molars and in a mesio distal direction for mandibular molars
• The lingual outline shape for molars is triangular ( for three canals) or
rhomboid (for four canals ) however , the canal orifices dictate the position of
the corners of these geometric shapes . Therefore , until the orifices have been
located the initial outline form should be left as an oval
25. In molars the penetration angle should be
towards the largest canal because the pulp
chamber space usually is the largest just
occlusal to the orifice of this canal . Therefore
in maxillary molars the penetration angle is
towards the palatal orifice , and in mandibular
molar it is towards the distal orifice
A round bur , a tapered fissure bur , or a
safety –tip diamond or carbide bur is used to
remove the roof of the pulp chamber
completely , including all pulp horns.
26.
27. IDENTIFICATION ALL CANAL ORIFICES
• In the posterior tooth with multiple canals the canal orifices play an important role in
determining the final extension of external outline form of access cavity
• Ideally orifices are located at the corners of the final preparations to facilitate the
shaping and cleaning process
• Internally the access cavity should have all the orifices positioned entirely on the pulp
floor and should not extend into an axial wall
28. Extension of an orifice into the axial wall creates a mouse hole effect which indicates the
internal Under extension and impedes straight line access . In such cases the orifice must
be repositioned Onto the pulp floor without interference from axial walls
29. REFINEMENT AND SMOOTHING RESTORATIVE
MARGINS
• In both interim and permanent restorations , the restoration margins
to be refined and smoothened to minimize the potential for the coronal
leakage of the of the restoration
• The final restoration of choice for the posterior tooth that have
undergone the root canal therapy is a crown or inlay .
33. MAXILLARY CENTRAL INCISOR
* A newly erupted central incisor has three pulp horns, and
the pulp chamber is wide mesiodistally than buccolingually
• In cross –section , the root canal at the cej is triangular in
young teeth and oval in older teeth.
• It gradually becomes round as it approaches the apical
foramen
35. The external access outline form
for the maxillary central incisor
is a rounded triangle with its
base toward the incisal aspect
The width of the triangular base
is determined by distance
between the mesial and distal
pulp horns
36. MAXILLARY LATERAL INCISOR
*The pulp chamber outline of the maxillary lateral incisor is similar to that of
maxillary central incisor ,however, it is smaller , and two or no pulp horns may be
present
*This tooth is wider mesiodistally than buccolingually
* Normally only one root canal is present , but two and three canals have been
reported
37. *The external access outline form for the maxillary lateral incisor may be a rounded
triangle or an oval, depending on the prominence of the mesial and distal pulp horns
*when the horns are prominent , the rounded triangular shape is compressed mesiodistally
relative
To a central incisor , producing a more slender triangle
* The outline form usually is oval if the mesial and distal pulp horns are not prominent
38. MAXILARY CANINE
• The access cavity is wider labiolingually than mesiodistally
• It has no pulp horns
• It its smallest pointed incisal edge corresponds to single cusp tip
• The pulp chamber outline at CEJ is oval. From this point it is
oval through out the midroot and till apex. , where it becomes
constricted
41. MAXILLARY FIRST PREMOLAR
* The pulp chamber of the maxillary first premolar is wider
buccolingually than mesio distally
• In the buccolingual dimension the chamber outline shows a buccal and
a palatal pulp horn the buccal pulp horn usually is larger .
• From the floor, two root canals take on a round shape at midroot and
rapidly taper to their apices, Usually ending in extremely narrow
curved root canals
42. * The maxillary first premolars may have
one ,two or three roots and canals
* Most often it has two root canals
* When these canals are present , the
external outline form becomes triangular
with the base on the buccal aspect
The mesio buccal and distobuccal corners
of the triangle should be positioned
directly over the corresponding canal
orifices
43. MAXILLARY SECOND PREMOLAR
* The root canal system of the maxillary second premolar is wider buccolingually
than mesiodistally .this tooth may have one two or three roots and canals
* Two or three canals can occur in a single root
* Buccal and a palatal pulp horn are present in which buccal horn is larger
* when two canals are present , the maxillary second premolars access preparation is
nearly identical that of the first premolar ,because this tooth usually has one root ,if
two canals are present , they are nearly parallel to each other and external outline
form must have a greater buccolingual extension to permit straight line access to
these canals than with the first premolars
With two roots and diverging canals .
* If three canals are present , the external access outline form is the same triangular
shape illustrated in first premolar
44. MAXILLARY FIRST MOLARS
• The maxillary first molars is the largest tooth in volume and one of the
most complex in root canal anatomy .the pulp chamber is widest in
buccolingual dimension , and four pulp horns are present (mesio buccal ,
mesio palatal, distobuccal and disto palatal)
• The pulp chambers cervical outline form has a rhomboid shape , sometimes
with rounded corners . The mesio buccal angle is an acute angle ,
distobuccal angle is an obtuse angle and palatal angles are basically right
angles
45. • The three individual roots of the maxillary first molar (i.e.
mesiobuccal root, distobuccal root, and palatal root ) form a tripod
• The palatal root is the longest , has the largest diameter and
generally offers the easiest access.it can contain one,two or three root
canals
• The distobuccal root is conical and may have one or two canals
46.
47.
48. • Because the maxillary first molar almost always has four canals ,the access cavity has a
rhomboid shape ,with the corners corresponding to the four orifices (MB-1, MB-2, DB
AND P)
• The access cavity should not extend into the mesial marginal ridge . Distally ,the
preparation can invade the mesial portion of the oblique ridge , but it should not
penetrate through the ridge .
• The buccal wall should be parallel to a line connexting the MB-1 and DB orifices and not
to the buccal surface of the tooth
49. MAXILLARY SECOND MOLARS
The distinguishing morphologic feature of maxillary second molar is that its
three roots are grouped closer together and are sometimes fused .also ,they
generally are shorter than the roots of the first molar and not as curved
The second molar usually has one canal in each root , however it may have two
or three mesiobuccal canals ,one or two distobuccal canals ,or two palatal canals
50. • If only three canals are present , the access cavity is a rounded triangle with the base
to the buccal aspect
• If only two canals are present , the access outline form is oval and widest in the
buccolingual Dimension
