Canal-specific file sequences
← Molar collection
41 preparation courses across 12 complete molars and 40 canals. The selected finishing sizes are 25/.04 for 14 courses, 30/.04 for 14 and 35/.04 for 13. MicroPath 17/.03 starts each sequence, followed by the selected ET .04 stages.
What the evidence supports
There is no single finishing size established by a canal name. Native calibre, curvature, wall anatomy, irrigation and the instrument design all matter. MB2 research demonstrates the cost of increasing taper in thin walls; it does not establish a universal ban on one tip size. The user-identified MB2 in ACTA0115 is deliberately restricted to ET25/.04 in this teaching lesson.
- AAE — Apical preparation has no universal standardized size; initial dimensions, anatomy and preservation of delicate curved roots affect selection. Irrigation remains necessary.
- MB2-low-taper — In a micro-CT comparison using MB2 sizes 20, 25 and 30, design and taper affected dentine removal and transportation; findings are not interchangeable between brands.
- MB2-25 — Size-25 MB2 preparations with different tapers/designs had different dentine preservation and perforation outcomes. A tip number alone does not establish safety.
- MB2-taper — At size 25, larger tapers improved wall preparation but increased dentine removal; MB2 wall reduction was greater than MB1/DB in this sample.
- palatal-width — Palatal canals in the study could have broad apical dimensions and thin curved coronal/middle walls. This supports separate assessment rather than applying an MB2 finish to every canal.
How these selections were made
Native oblique sections were sampled over the final visible 2 mm, excluding the illustrative terminal extension. The recorded widths are minimum Feret widths of the local connected lumen. They are approximate at the original 72 µm resolution; resampling adds no source detail. Narrow or strongly curved courses use a conservative smaller finish, intermediate courses use 30 and broader courses retain 35. These are explicit model-specific teaching choices within the preserved instrument set, rather than clinical prescriptions or thresholds derived from a trial. Broader oval canals may retain large untouched recesses. Increasing file size solely to colour every wall would misrepresent dentine conservation and cleaning.
ET25 uses the preserved artwork. ET20, ET30 and ET35 are the previously authorised nominal teaching derivatives. Their use does not transfer the clinical performance of another study instrument to EndoTech. These models do not establish manufacturer instructions, binding-file assessment or safe clinical preparation sizes.
| Model · ACTA | Canal | Selected sequence | Selection reason |
|---|
| 01 · 0003 | Root A · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 01 · 0003 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 01 · 0003 | Root C · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 03 · 0006 | Root A · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 03 · 0006 | Root B · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 03 · 0006 | Root B · canal 2 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 04 · 0027 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 04 · 0027 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 04 · 0027 | Root C · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 06 · 0002 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 06 · 0002 | Root A · canal 2 | 17 → 20 → 25 | Preserves the existing measured size restriction and apical endpoint. |
| 06 · 0002 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 07 · 0014 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 07 · 0014 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 07 · 0014 | Root B · canal 2 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 7 · 0014 | Root A · canal 1 · Pass 2 (green path) | 17 → 20 → 25 → 30 | Second preparation sequence in the same broad lumen; shared target and deduplicated total. Path colours do not indicate size. |
| 08 · 0040 | Root A · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 08 · 0040 | Root A · canal 2 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 08 · 0040 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 09 · 0056 | Root A · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 09 · 0056 | Root B · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 09 · 0056 | Root B · canal 2 | 17 → 20 → 25 | Fine native limb; ET25/.04 teaching finish. Local non-apical spur removed by lateral flute cutting; final 2 mm apical curve retained. |
| 10 · 0062 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 10 · 0062 | Root A · canal 2 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 10 · 0062 | Root A · canal 3 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 10 · 0062 | Root A · canal 4 | 17 → 20 → 25 | Fine native fourth trace. Conservative ET25/.04 teaching finish; unresolved terminal passage completed illustratively with changing native-derived contours. |
| 11 · 0093 | Root A · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 11 · 0093 | Root B · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 11 · 0093 | Root C · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 11 · 0093 | Root C · canal 2 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 12 · 0113 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 12 · 0113 | Root B · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 12 · 0113 | Root C · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 12 · 0113 | Root A · canal 2 | 17 → 20 → 25 | Fine native inner limb and shared isthmus; conservative ET25/.04 finish. Marked approach from the first3.45mm. Missing terminal passage is illustrative and uses changing native section contours. |
| 13 · 0115 | Root A · canal 1 | 17 → 20 → 25 → 30 → 35 | Broader original canal; retains the reviewed available ET35 geometric limit and avoids enlarging solely to make every recess touch. |
| 13 · 0115 | Root B · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 13 · 0115 | Root C · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
| 13 · 0115 | Root C · canal 2 · MB2 | 17 → 20 → 25 | User-identified MB2, narrow native course, shared root and evidence favouring dentine conservation. |
| 15 · 0036 | Root A · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 15 · 0036 | Root B · canal 1 | 17 → 20 → 25 → 30 | Intermediate native calibre or curved shared-root course; size 35 omitted for this lesson. |
| 15 · 0036 | Root C · canal 1 | 17 → 20 → 25 | Conservative narrow-course selection, native calibre and curvature; preserves low taper rather than forcing wall coverage. |
Rebuilt biological canal regions
ACTA0115 MB2 follows the user's red canal course and white external entry direction. The rejected diagonal bridge is removed. Its slender illustrative connection uses changing asymmetric sections drawn from the native fine fragment. The native 72 µm source remains unchanged; single-view depth is approximate. The MB2 sequence remains MicroPath17/.03, ET20/.04, ET25/.04.
ACTA0062 canals2 and3 have separately rebuilt terminal profiles, with native local contour and width variation blended through an overlap. Their selected nearby exits and apical targets are unchanged. The missing regions remain explicitly illustrative. Source comparison: Root Canal Anatomy Project, Marco Versiani.
ACTA 0115 · native contour continuity
The unprepared Model 13 apical reconstructions were revised on 20 October 2026 after review of their shape and surface transitions. Changing asymmetric native section contours and local calibre variation replace the smooth taper. Extended overlaps blend into the retained native canal; terminal additions avoid unsupported bulbs or collars. The original 72 µm scan, external root, selected endpoints and MB2 entry course are preserved. These missing regions remain illustrative.
ACTA 0062 · fourth canal
Model 10 now includes the fine fourth course omitted by the earlier single-level component cutoff. All four canals have individual preparation buttons. The fourth uses MicroPath17/.03 → ET20/.04 → ET25/.04. Its native trace disappears before the root surface; the separately authored terminal continuation and internal target remain illustrative. Native scans, the other three selected courses and source instruments are preserved. The presentation is roots upwards, as requested.
Coronal entry · Model 6
The Root B file approach was refitted on 20 October 2026 from 3.45 mm of the native coronal course. Its straight external assembly follows that entrance tangent through the chamber and blends into the deeper canal. File motion, contact, stock and cusp stop were regenerated together. Native canal geometry, terminal passages and apical targets are preserved. This is a teaching construction under Stephen’s first-3–4-mm rule.
Model 12 · fine inner branch
Root A canal 2 follows the fine inner limb identified in the marked views. Its entry follows the dominant course across the first 3.45 mm of native canal. It shares a native isthmus with Root A canal 1. The offered sequence is MicroPath 17/.03 → ET 20/.04 → ET 25/.04. The missing terminal passage is an explicitly illustrative continuation guided by changing native sections. All four preparations remain selectable.
Model 7 · two passes in one broad canal
Select Root A canal 1, then choose Pass 1 (red path) or Pass 2 (green path). Each uses MicroPath17/.03 → ET20/.04 → ET25/.04 → ET30/.04. Red and green identify the paths only. The original ribbon-shaped canal is preserved. Both passes share its apical target; their cumulative preparation and shared canal total remain visible without double counting. Complete both passes to finish this canal.
Model 9 · green-marked native limb
Root B canal 2 follows a fine native limb that converges into the existing terminal region. It uses MicroPath17/.03 → ET20/.04 → ET25/.04. The starting scan and irregular walls are preserved; no extra apical connector was added. The two earlier preparation courses remain available.