ORE Part 2 · Dental Manikin (DM) guide
Root Canal Treatment: Access and Canal Preparation
An endodontic access cavity and canal preparation on an anterior tooth — a triangular palatal access in the right position, a confirmed working length, coronal flaring with Gates Glidden burs, and a hand-file sequence taken to length with irrigation and recapitulation between sizes.
Our video demonstrates this on an upper incisor. In the exam, the tooth and exercise are set on the day.
What examiners look for
- A triangular access cavity confined to the middle third of the palatal surface, within the landmark grooves, preserving the cingulum
- The initial entry made with a small round bur at 45 degrees, then straightened once the "drop" into the pulp chamber is felt
- Straight-line access for the files — walls relieved on the way out of the cavity, never on the way in
- A working length properly determined (tooth length minus 1 mm from the radiographic apex) and confirmed before shaping
- Coronal flaring with Gates Glidden burs in descending sizes, then hand files used in sequence to the working length
- Irrigation after every file and recapitulation with a small file so the apex never blocks
Common mistakes
- Breaching the cingulum or wandering out of the middle third with the access
- Keeping the bur at 45 degrees after the drop instead of straightening to the canal's long axis
- Scraping walls on the inward stroke of the file — cut only as you withdraw
- Skipping sizes in the file sequence, or forcing a file that resists instead of watch-winding it to length
- Not irrigating and recapitulating between files, clogging the apical canal
- A working length more than a safe margin out from the reference — show the length radiograph to the examiner before continuing
What the official DM Guidance states
- Access cavity: adequate size, appropriate shape and position for the tooth, with direct line access to the canal and the pulp chamber roof completely removed
- Canal filled to 0.5–1.0 mm of the radiographic apex
- Master apical file consistent with the canal size (three sizes larger than the first file that binds)
- A smooth conical preparation tapering towards the apex, following the curvature of the tooth, with adequate coronal flare
- Dense gutta-percha condensed against the canal walls over the length of the root, without voids
- Adequate use of irrigants and recapitulation; radiographs justified and interpreted accurately
The exam may set an access cavity alone (a minor exercise, sometimes combined with rubber dam) or a full root canal treatment on a single canal.
Source: ORE Part 2 Dental Manikin (DM) Guidance, version 2.0, effective 1 March 2026, p. 16–18. Values marked “about” are approximate in the guidance. Check the current version before your exam. How to reach these, step by step, is in the course.
Candidate questions
Where exactly does the access cavity sit?
In the middle third of the palatal surface, a triangle bounded by the landmark grooves mesially and distally, with its gingival limit at the tip of the cingulum — the cingulum itself is preserved.
How is the working length set?
Measure the tooth to its radiographic apex, subtract 1 mm, confirm with a file in place on a length radiograph, and show it to the examiner before shaping. The course video walks through the measurement and the x-ray step.
What does "recapitulation" mean here?
Returning to a small file (the 15) and taking it to the full working length between larger sizes, with irrigation each time, so debris never packs the apical canal.