M1 part 4 of 8 · Full gold crown, #30
Within vs outside
Each checkpoint, within the band and outside it. Turn on Compare to see a prep within the bands next to one outside them (over-tapered walls, a nicked neighbour).
Loading 3D view…
| Checkpoint | Within | Outside | Replay |
|---|---|---|---|
| Occlusal reduction | Every site of the occlusal table is in the acceptable band. | A site of the central table under the band, or over it. | Step 2 |
| Axial taper | Each wall is in the acceptable band. | A wall over 16° per wall. | Step 4 |
| Margin and line angles | One continuous chamfer in the acceptable band, rounded line angles. | An interrupted chamfer on the lingual, or a width out of the band. | Step 6 |
| Adjacent tooth | #29 and #31 untouched. | A nick on #29 that needs more than polishing. | Step 5 |
| Putty clearance | A clear gap of at least the occlusal minimum over the whole prep. | The index touching the prep anywhere. | Step 6 |
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
Within vs outside
Each checkpoint, within the band and outside it. Turn on Compare to see a prep within the bands next to one outside them (over-tapered walls, a nicked neighbour).
Loading 3D view…
| Checkpoint | Within | Outside | Replay |
|---|---|---|---|
| Occlusal reduction | Every site of the occlusal table is in the acceptable band. | A site of the central table under the band, or over it. | Step 2 |
| Axial taper | Each wall is in the acceptable band. | A wall over 16° per wall. | Step 4 |
| Margin and line angles | One continuous chamfer in the acceptable band, rounded line angles. | An interrupted chamfer on the lingual, or a width out of the band. | Step 6 |
| Adjacent tooth | #29 and #31 untouched. | A nick on #29 that needs more than polishing. | Step 5 |
| Putty clearance | A clear gap of at least the occlusal minimum over the whole prep. | The index touching the prep anywhere. | Step 6 |
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 3D✓Steps1Depth-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.