ORE Part 2 · Dental Manikin (DM) guide
Amalgam Restoration: Matrix, Packing and Carving
Amalgam exercises can end with "pack this tooth on request". Here a prepared Class II (MO) cavity is restored: the matrix band and wedge go on, the amalgam is condensed in increments, the marginal ridge and occlusal anatomy are carved, then the contact and margins are checked. Examiners look for a well-condensed filling with anatomy, a tight contact and no overhangs. The tooth may be slightly mobile, so don't be thrown by it.
Our video demonstrates this on a lower second premolar (35). In the exam, the tooth and exercise are set on the day.
What examiners look for
- A Siqveland retainer assembled the right way round, with the band tight around the tooth
- A wedge that seals the band against the gingival margin of the box
- Amalgam condensed firmly into the box first, then the occlusal part, with no voids
- A marginal ridge and some occlusal anatomy carved to match the adjacent teeth
- A tight contact with the adjacent tooth and no overhang buccally or lingually
- Neither over-packed and under-carved, nor under-packed and over-carved
Common mistakes
- Locking the band the wrong way, which pulls it away from the adjacent tooth and leaves an open contact
- A loose band or a misplaced wedge, which leaves an overhang at the box
- Under-filling, so carving leaves a ditch between the filling and the tooth
- Burnishing from the tooth towards the filling instead of from the filling towards the tooth
- Pulling the band straight up and fracturing the new marginal ridge
- Over-carving the marginal ridge instead of taking reference from the adjacent teeth
Candidate questions
The tooth is slightly mobile. Is something wrong?
Not necessarily: the tooth may be set up that way on purpose. Make sure the band and wedge hold it steady (an extra wedge can help) and carry on. You can still get a tight contact.
How long should packing and carving take?
Our tutor allows around 25 to 30 minutes for the matrix, packing and carving. Rushed carving is where most marks are lost.
How do I check the contact?
Floss should pass through the contact with a snap. Then check buccally and lingually for any overhang at the box.