Endodontic Access Cavity Anatomy

Study Notes

In young patients, pulp chamber is larger in all three dimensions, requiring more extensive preparation.
In older patients, pulp has receded, and pulp chamber is smaller in all three dimensions.

Cavity walls are extended to allow easy instrument approach to the apical foramen.
Knowledge of internal anatomy of individual tooth is essential due to variations in canal anatomy.

Principle I: Preservation of Tooth Structure
Principle II: Convenience Form
- Unobstructed access to canal orifice
- Direct access to apical foramen
Principle III: Removal of Remaining Carious Dentin
- Eliminate mechanically as many bacteria as possible
- Eliminate discolored tooth structure
- Eliminate saliva leaking into the prepared cavity
Principle IV: Cleansing of the Cavity
- Removal of calcified or metallic debris
- Removal of soft debris
- Prevention of bacterial population and crown staining

I. Initial Penetration
- Round and tapered tungsten carbide bur
- Round and tapered diamond points
- Endo access bur
II. Unroofing the Pulp Chamber
- Endo access bur with a safe tip or non-cutting tip
- Round Bur
- Tapered fissure Bur
III. Canal Orifice Flaring Instruments
- Gates-Glidden drill
- Peeso Reamer
- NiTi rotary file
IV. Endodontic Pathfinders
- DG-16 Endodontic explorer
- Ultrasonic unit and tips
- NiTi pathfinder rotary file
V. Vision, Magnification, and Illumination
- Fiber optic light source
- Methyline blue
- Surgical operating microscope
- Binocular loupes
- DG-16 endodontic explorer

Maxillary Central Incisor
- Access cavity is oval or triangular in shape
- Removal of lingual shoulder is critical
Mandibular Incisors
- Access cavity is long oval with greater dimension incisogingivally
- Complete removal of lingual shoulder is critical
Mandibular Canine
- Access cavity is oval or slot-shaped
- One canal is present, but two canals could be present
Maxillary Molars
- Bur entry is determined by the mesial boundary and oblique ridge
- Place bur in Central groove between Mesial and Distal boundary and direct it Palatally
- Feel drop and de-roof using round, tapered fissure or safe tip bur
- Shape and size of the chamber guide the cutting
- Locate canal orifice with Endo explorer, remove ledge or obstruction if present
- Smoothen cavity walls and merge with pulp chamber diverging occlusally

Overzealous tooth preparation
Inadequate caries removal
Labial perforation
Furcal perforation
Root perforation due to misinterpretation of angulation
Debris falling into the orifices such as old amalgam restorations and dentin debris