Access opening – A quick notes
It is the first step in root canal treatment of a teeth. Let us know various types of access opening methods / approaches. The access cavity preparation generally refers to the part of the cavity from the occlusal table to the canal orifices.
Objectives
- To remove all caries
- To conserve sound tooth structure
- To completely unroof the pulp chamber
- To remove all coronal pulp tissue (vital or necrotic)
- To locate all root canal orifices
- To achieve straight- or direct-line access to the apical foramen or to the initial curvature of the canal
- To establish restorative margins to minimize marginal leakage of the restored tooth
- Visualization of the Likely Internal Anatomy
- Determination of the point of penetration
- Assessment of occlusal and external root form
- Radiographic measurement of the depth of the pulp chamber roof from the occlusal table
- Assessment of complicating factors
- Radiographic assessment
- Evaluation of the Cementoenamel Junction and Occlusal Anatomies
Guidelines
- Preparation of the Access Cavity Through the Lingual and Occlusal Surfaces
- Removal of All Defective Restorations and Caries Before Entry Into the Pulp Chamber
- Removal of Unsupported Tooth Structure
- Creation of Access Cavity Walls That Do Not Restrict Straight- or Direct-line Passage of Instruments to the Apical Foramen or Initial Canal Curvature
- Delay of Dental Dam Placement Until Difficult Canals Have Been Located and Confirmed
- Location, Flaring, and Exploration of All Root Canal Orifices
- Inspection of the Pulp Chamber, Using Magnification and Adequate Illumination
- Tapering of Cavity Walls and Evaluation of Space Adequacy for a Coronal Seal
Newer designs of access cavity preparation
- Conservative endodontic access cavity
- Ultra conservative access cavity / ‘Ninja’
- Orifice – directed dentin conservation access cavity / Truss
- Caries driven
- Restorative driven
- Cala lilly enamel preparation
- Image guided endodontic access
- Dynamically guided endodontic access
- Micro guided endodontic access
Conservative access cavity
- By David Clark and John Khademi
- Lessen the tooth structure removal
- Helps the long time survival & function of root canal treated tooth
- Here, the teeth are accessed at the central fossa and they are extended out to discover canal orifices. This aids in protecting the pericervical dentin and a part of the chamber floor
Ultra conservative access cavity/ Ninja method
- Here, an oblique projection is made towards the central fossa of the root canal orifices
- This projection is made parallel with the enamel cut of 90 degree or more to the occlusal plane
- This makes simpler to discover the canal orifices from different visual angulations
- Limited line of vision, incomplete removal of infected pulpal tissue is the main limitation leading to failure of endodontic treatment
Orifice- Directed Dentin Conservation Access Cavity / ‘Truss’
- Separate cavities are made to approach the canals
- The point of this methodology is to preserve dentin with the minimally invasive approach i.e. leaving a truss of dentin between the two cavities that have been prepared
- The restricting components of this methodology which are past the operator’s control are position of tooth, patients mouth opening capability, degree of calcification & other patient related variables
Caries driven
Entry into the pulp chamber is carried out by extracting caries and maintaining all the remaining structure of the tooth
Cala lilly enamel preparation
- Usually, unfavourable C factor and weak enamel rod engagement are present when eliminating old amalgam or composite restoration or with the traditional endodontic access cavity
- Enamel in the form of cala lilly is cut back at 45
Dynamically Guided Endodontic Access
- Dr. Charles M introduced it for the first time for implants
- CBCT is used to design an access cavity
- Overhead cameras are used to trace the location of patients jaw and clinicians bur in three dimensional space
- After looking at the software interface, the clinician provides input about the bur location
Article by: Dr. Siri P.B.
