ORE Part 2 · Dental Manikin (DM) guide
Putty Index for Crown Preparation
Before any crown preparation you make a putty index of the unprepared tooth, then use it to check your reduction as you go — the DM Guidance lists an index that isn't used as a fault. The skill is mixing the putty evenly, adapting it over the tooth and its neighbours without voids, and sectioning it cleanly through the middle of the tooth so it reseats accurately.
Our video demonstrates this on an upper first molar (26). In the exam, the tooth and exercise are set on the day.
What examiners look for
- Putty and activator mixed until the colour is even, with no streaks
- The index covers the tooth being prepared and at least one tooth either side
- Fully adapted, with no voids over the tooth being prepared
- Left in place until it has fully set
- Sectioned once through the middle of the tooth, in a clean cut
- Both parts reseat flush against the cusps, with no gaps
- Used to check the reduction during the preparation
Common mistakes
- Starting the crown preparation without making the index first
- Under-mixing, so streaks of activator remain
- Pressing the putty on without supporting it, so it shifts while you adapt it
- Removing it before it has set
- Sawing back and forth with the blade instead of one controlled cut
- Sectioning off-centre, so the index doesn't show the reduction where it matters
Candidate questions
When do I make the putty index?
Before you cut anything. It records the original shape of the tooth, so it has to be made on the unprepared tooth.
How do I know the putty has set?
Press a finger into it. If the mark disappears, it has set; if the mark stays, it's still setting.
Where should the index be sectioned?
Once, through the middle of the tooth being prepared, so the cut face shows the tooth's profile. Mark the line first and cut in one smooth movement rather than several strokes.