Loading 3D view…
M1 step 4 of 6 · Tapered diamond
Axially reduce walls
Reduce the buccal and lingual walls with the bur held along the line of draw, so its own taper makes the wall. Read each wall on its own.
Your last prep
No prep scored yet. Your first score is free with an account.
Score a prep free- Target
- Axial taper: ≤ 12° per wall
- Why
- Taper is scored per wall; a wall past the band loses retention.
- Watch
- Tilting the bur on the buccal and lingual walls is the usual over-taper.
After the lesson: Retake the photos and score again on the 5 checkpoints.
Check 1 of 1 · Axial taper
A wall reads 14° per wall. Which band is it in?
Sources and 3D credits
Sources: Crown-prep criteria sheet, zirconia molar (#3), 2026–27 season, pp. 1–2 (checked 2026-10-28) · Clinical candidate manual 2026–27, p. 14 (scoring overview), p. 16 (taper, line of draw) (checked 2026-10-28) · Cast-metal crown criteria sheet, 2025 season, criteria page (checked 2026-11-11)
3D model: molar30.glb: teeth #29–#31, jaw bone and gum. BodyParts3D, © 2008 Life Science Integrated Database Center (DBCLS); modified by Osler Press. CC BY-SA 2.1 JP · source
3D viewer code. three.js authors. MIT · source
3D viewer code. three.js authors. MIT · source
Step 4: Axially reduce walls
No prep scored yet · target ≤ 12° per wall
Loading 3D view…
TOOLTapered diamond
CHECKPOINTAxial taper: ≤ 12° per wall
WHYTaper is scored per wall; a wall past the band loses retention.
Do
Reduce the buccal and lingual walls with the bur held along the line of draw, so its own taper makes the wall. Read each wall on its own.
WatchTilting the bur on the buccal and lingual walls is the usual over-taper.
Check 1 of 1 · Axial taper
A wall reads 14° per wall. Which band is it in?
Sources: Crown-prep criteria sheet, zirconia molar (#3), 2026–27 season, pp. 1–2 (checked 2026-10-28) · Clinical candidate manual 2026–27, p. 14 (scoring overview), p. 16 (taper, line of draw) (checked 2026-10-28) · Cast-metal crown criteria sheet, 2025 season, criteria page (checked 2026-11-11)
3D model: molar30.glb: teeth #29–#31, jaw bone and gum. BodyParts3D, © 2008 Life Science Integrated Database Center (DBCLS); modified by Osler Press. CC BY-SA 2.1 JP · source
3D viewer code. three.js authors. MIT · source
3D viewer code. three.js authors. MIT · source
Outline · 8 parts
✓Criteria card✓Anatomy in 3D3Steps1Depth-orient occlusal grooves2Reduce occlusal table following anatomy3Add functional cusp bevel4Axially reduce walls5Open proximal surfaces with guarded bur6Finish continuous chamfer and verify clearance with putty index4Within vs outside5Check6Guided cut7Cut and score8Recall: day 3 and day 10Practice feedback against the 2026–27 published crown-prep criteria (molar). Not an exam or admissions result; your program and examiners decide.