#27 What I Learned Today

Introduction to Operative Dentistry

Today in sim lab we performed amalgam restorations on teeth #5, #12, and #14. The type of amalgam that we used for the restoration was Tytin FC (firm condensation) 600 mg, which has modified spherical particles. The alloy material percentage breakdown is:

• 61% Ag
• 26% Sn
• 13% Cu

The overall mixture contains 44.5% mercury by weight. The capsule is triturated (mixed) at 4000 cpm for 7 seconds.

The amalgam is first brought to the preparation by an amalgam carrier and condensed. Small increments seem to work best, as spillage can occur if you use excess. Start with a small condenser to make sure the pulpal line angles are well condensed and increase in size from there. Remember to also move quickly.

Once the preparation is slightly overfilled, you begin to carve. You can use a number of different hand instruments; personally, I started with a lateral condenser (can be roughly described as christmas tree-shaped) and then used a cleiod side of the cleiod-discoid instrument to clean up the margins. At this time, you make sure to incorporate any occlusal anatomy into the carving as you are trying to replace the initial lost tooth structure. Also of important note, you want to always have part of the carving instrument lying on healthy tooth structure while you are working; this helps simulate proper tooth structure shape.

Towards the end, you can use a ball burnisher to run it along the surface. Another useful tip is to take wet cotton and rub it along the surface of the restoration; it helps give a nice smooth finish. Once you are done carving, you should check the occlusion by having a patient bite down and side-to-side on articulating paper. This will also you to check the contact points and ensure they are restored. If not, modification to the restoration might be necessary. One final go-over of the restoration should be done with a lateral condenser, to ensure a good finish after occlusion is checked.

Also note: In a real patient, dentin sealer should be added to block the dentin tubules and help close up the microscopic space that is found between tooth structure and amalgam (recall: amalgam doesn't bond to tooth!). This should last until the amalgam restoration corrodes from being in the oral environment; the corrosion products help form a better seal. It also helps with post-op sensitivity and discolouration.