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Access Cavity Designs and Techniques
1.
2. Outline
bjectives
w of Access
nciples of access cavity preparation
allenging Access Cavity Preparation
portance of Radiograph in Endodontics
w Designs in Access Cavity Preparation
aditional vs Contracted Access Cavity
w Techniques (Guided and Navigated Access
Outline
3. • Remove all caries when present.
• Conserve sound tooth structure.
• Deroof the pulp chamber completely.
• Remove all coronal pulp tissue (vital or necrotic).
• Achieve straight- or direct-line access
• apical foramen
• initial curvature of the canal.
• Achievement of convenience form
• Cavity toilet
Objectives OF ACCESS
Cavity
Objectives OF ACCESS
Cavity
5. 1) direct vision of the floor of the pulp chamber
and canal openings
1) direct vision of the floor of the pulp chamber
and canal openings
6. 2) Facilitate the introduction of canal
instruments into the root canal openings
2) Facilitate the introduction of canal
instruments into the root canal openings
7. 3) Provide direct access to the apical one third of the canal
for both preparation instruments and canal filling
instruments
3) Provide direct access to the apical one third of the canal
for both preparation instruments and canal filling
instruments
√
8. 4) Provide a positive support for temporary fillings
4) Provide a positive support for temporary fillings
√
9. 5)Permit the removal of all the chamber
content
5)Permit the removal of all the chamber
content
23. • Teeth with minimal or no clinical crown
• Heavily Restored Teeth (Including those with full
coronal coverage)
• Access in Teeth with Calcified Canals
• Crowded or Rotated Teeth
Challenging Access Preparation
24. 1) Teethwith minimalor no clinical
crown
• Access cavity preparation when
the anatomic crown is missing
1) Teethwith minimalor no clinical
crown
• An endodontic explorer fails to
penetrate the calcified pulp
chamber
25. • A long-shank round bur is
directed in the assumed long axis
of the root
• Perforation of the root wall,
resulting from failure to consider
root angulation
26. • Palpation of the buccal root
anatomy without a dental dam in
place to determine root angulation
• Correct bur angulation after repair
of the perforation with mineral
trioxide aggregate (MTA).
• (Cohen)
27. HeavilyRestored Teeth
(Including those with full coronal coverage)
• Original crown contour of the tooth
Heavily Restored Teeth
(Including those with full coronal coverage)
• A full veneer crown is used to change the
original crown contour for esthetic purposes.
• Access perforation resulting from reliance on
the full veneer crown contour rather than the
long axis of the root.
28. • In a heavily restored maxillary second
molar that requires root canal therapy,
the clinician may attempt access to the
canals
• Pretreatment radiographs demonstrate
three important factors:
• (1) a reinforcing pin is in place(arrow);
• (2) at least two thirds of the coronal
portion is restorative material;
• (3) the mesiobuccal canal appears
calcified (arrow).
29. • A safer, more conservative approach is to remove the
amalgam, the pin, and any old cements.
• Careful excavation, using enhanced vision, results in
access to the pulp chamber.
• The clinician now can perform sound root canal therapy,
followed by internal reinforcement and full coverage.
31. • Extensive class V restoration
necessitated by root caries
and
• Periodontal disease that led
to canal calcification (arrow).
B, Access to the canal is
occluded by calcification.
Removal of the facial
restoration may be required
to obtain access from the
buccal surface.
Class V
Class V
32. • Mandibular molar with what
appears to be almost complete
• calcification of the pulp
chamber and root canals.
However, pathosis is
• present, which indicates the
presence of bacteria and some
necrotic tissue
• in the apical portion of the
roots
Calcified Canals:
Calcified Canals:
35. • Access cavity on
crowded mandibular
anterior teeth.
• The access
preparation is cut
through the buccal
surface on the canine
Crowded or Rotated Teeth:
Crowded or Rotated Teeth:
40. A) CBCT image
showing the missed
canal in the
mandibular molar
B) Missed canal seen
on axial view.
Extra Canal
Extra Canal
C) Cross sectional view showing missed canal.
D) 3D reconstruction showing osteolytic lesion with mandibular first
molar
50. PCD
• is the dentin near the
alveolar crest , This critical
zone, roughly 4 mm above
the crestal bone and
extending 4 mm apical to the
crestal bone .
Clark & khademi(2010)
Clark & khademi(2010)
53. In the conservative access cavity premolars were accessed 1 mm buccal to
the central fossa, and cavities extended apically , maintaining part of the
chamber roof and lingual shelf. Molars were accessed at the mesial quarter
of the central fossa, and cavities extended apically and distally while
maintaining part of the chamber roof.
CAC
CAC
54. • The access ‘‘ninja’’ outline is derived from the oblique projection toward
the central fossa of the root canal orifices on the occlusal plane. By doing
this, localization of all the root canal orifices is possible even from
different visual angulations because the endodontic access is parallel with
the enamel cut at 90 or more to the occlusal table
NINJA AC
NINJA AC
76. Guided endodontics
• Guided endodontic procedures are a promising technique offering a
highly predictable outcome and lower risk of iatrogenic damage.
Minimally invasive treatment can be performed, and chair side time
can be reduced.
77. • We can illustrate the steps of CBCT guided endodontics through the
following case report that was published on 8 October 2015 on
onlinelibrary.wiley.com.
• A 15‐year‐old male patient presented with pain of his upper right central
incisor. He had a history of trauma 7 years prior to the upper anterior
region.
78. Slight, hardly visible discoloration of the maxillary right central incisor
secondary to trauma
79. Radiograph of the same tooth showing almost complete PCC and a widened
periodontal ligament space at the periapex
80. CBCT showing apical periodontitis and PCC. The root canal
is visible in the apical part of the root
85. Template positioned on the maxillary teeth to check its correct
and reproducible fitting
86. Clinical application: After the removal of enamel, the bur was guided through the
sleeve to gain access to the apical third of the root canal. The sleeve's mechanical
stop indicates that the bur reached the planned position
87. View of the endodontic access cavity after root canal location
90. Limitations of guided endodontics
•In many cases intra oral radiography is used during follow-up. Given the
2D nature of the image, the deviation of the access cavity underestimated
in terms of its bucco-lingual position as well as the healing of per apical
lesions. (Ali & Arslan, 2019)
•When planning for guide access cavity ,it should be noted that it can be
used only in straight portion of the canal and not beyond the curvature.
•It should be mentioned that reduced mouth opening could impose
limitations when trying to implement this technique in posterior region.
91. Dynamic navigation endodontics
• Promising technology designed to guide the placement of
drills/implants in real time, based on information generated from the
patient’s computed tomography (CT).
• In endodontics, dynamic navigation is used for localization of
calcified canals as well root-end resection surgeries. Treatment
planning and surgery can be performed in the same appointment.
92. Advantages of this technology over static CBCT
guided endodontics
• No waiting period is required for a 3D printed or milled drill guide to
be delivered from the lab.
• No guide rings are required .so it is easy to plan and execute multiple
drill path in multi canalled posterior teeth.
• Any treatment changes if needed are allowed to be made at the time
of surgery. So drills can be updated as new information is acquired
during the procedure
93. Components of dynamic navigation system
Navident Unit Used for Dynamic Navigation (ClaroNav,
Toronto, Canada)
94. Navident planning screen. In this case used for planning the endodontic access cavity (appears in yellow)
through the calcified pulp chamber directly into the radiographically visible coronal entrance to the
canal. The operator adjusts the yellow “implant” image, which will be used for the guidance (diameter,
length, position and direction) until they are satisfied that this is the best path to take. Axial, coronal and
sagittal views are aligned to set up the correct path for the bur to follow
95. Head-Tracker. This unit is used for maxillary teeth. The Head-Tracker is securely placed on the
patient head. The pattern on the tracker is identified by the stereoscopic camera on the Navident
unit and used as a reference point for the software
96. Tracer Tool. This instrument is used to trace landmarks (between 3 and 6) such as existing teeth in the patient,
that are identified in the CBCT that has been preloaded into the Navident software. This enables the software to
register (“merge”) the CBCT image to the actual physical patient’s jaw.
97. • Following this step, the high-speed handpiece, also tracked by the system,
is calibrated in a short two-step process: the axis is calibrated first,
followed by calibration of the drill’s tip.
• This lets the system continuously track the bur’s direction and position,
and to report it to the user on the Navident screen.
99. The Calibrator is a multi tool calibration device that enables the calibration of low and high speed handpiece
driven burs and drills and other rigid dental instruments. The quick calibration process done using this tool is used
for determining the drill tip position and location in relation to the optical tracking tag installed on the handpiece.
This way the navigation system can adapt to the particular angulation and length of the drill to be used when
preparing the access cavity and have it represented correctly on the navigation screen. Each time a bur is changed
in the handpiece, its length is quickly calibrated by the user
100. Navident navigation screen. Drill’s image (green) following the pre-planned path for locating the canal on the CBCT
image in the different views all the views on the screen show proper alignment
101. This is the actual view the operator follows during active dynamic navigation. The operator aligns the head of the hand
piece and the tip of the bur into the center circle (“Bulls eye”). The main center circle has a diameter of 1.0mm. Each
Orange circle is separated by 1 mm orange intervals. The green bar on the right shows the distance (in mm) left to drill
to the pointed tip of the planned trajectory (in yellow). Here we are 4 mm away from the predetermined target
