Endodontic Anatomy and Access Preparation
Endodontic Anatomy and Access Preparation tests canal morphology, chamber landmarks, and the access that lets you find every canal without destroying tooth structure.
Core rules
- Access is a straight-line pathway to the canal orifices after complete caries and restoration removal and unroofing of the pulp chamber.
- Know tooth-specific anatomy: maxillary first molars commonly have MB1, MB2, DB, and palatal canals; mandibular incisors may have two canals; C-shaped systems occur in mandibular second molars.
- Use magnification, transillumination, staining, and troughing to locate orifices; do not gouge the furcation or perforate the chamber floor.
- Preserve pericervical dentine and the chamber-floor map; overcutting weakens the tooth and complicates retreatment.
- Confirm canal location with radiographs and an apex locator, not by depth alone.
Worked example
In a maxillary first molar, after deroofing, three orifices are visible. The MB2 orifice lies mesial to the MB1 line, often under a dentine shelf. Troughing between MB1 and the palatal canal with a fine ultrasonic tip, under magnification, exposes MB2 without cutting into the furcation. Missing it would leave untreated anatomy and risk failure.
Traps that cost marks
Incomplete deroofing; mistaking a pulp stone for a canal; cutting a ledge instead of troughing; assuming every maxillary molar has four canals; and ignoring curvature when choosing access and files.