Gold Crowns

We have been spending countless hours in our Dental Materials class learning about the properties of various alloys, the chemical make up of investment materials, and the differences between hygroscopic, thermal, and setting expansions. Quite boring actually, but all very related to the process of making gold crowns.

On Monday we all drove up to a local dental lab on the South Hill of Spokane to cast our very own gold crown. These are the basic steps...... I think it is a pretty cool process.

1. Impressions of the mouth are taken and casts are made.
2. We wax up a crown that has proper occlusal and proximal contacts i.e. the crown functions properly in the mouth and of course it has superb anatomy.
3. We then attach a wax sprue - it is a piece of wax (like a funnel) that attaches to our waxed up tooth.

4. We put our wax up w/ sprue into a metal ring and then fill the ring with an investment material that can withstand high temperatures and let it set.

- A cool side note here: The investment materials has been engineered to expand 1.7% during this process. This is important, because when the hot gold cools it will shrink 1.7% - leaving the crown at the exact proportions it should be. Pretty cool.

5. Bake the ring in an oven - This melts out all the wax, leaving a negative copy of our crown in the investment material with a tunnel (from the sprue) leading into the empty cavity.

6. Next you take the hot investment filled ring and place it on a massive centrifuge.

7. Place your $300 worth of gold penny weights (yes, we pay for this) down and torch them until they are super melted, shiny, and liquid.

8. When everything is ready to go, the stop pin on the centrifuge is released and everything spins super fast.

Notice in the picture above our instructor's hand carefully holding the gas hose away from the centrifuge. A good friend of mine accidentally let his hose drop into the centrifuge while it was spinning - a horrible noise and smell ensued...... The Dental Tech who was in the other room, without even seeing what happened, yelled "you drop the hose in the centrifuge?" as if she knew those sounds all to well ....... Ahhh it was a classic and priceless moment. My friend's face was bright red with embarrassment and I had a massive smile strung across my face while I soaked it all in. Finally, I'm not alone in the massive (but hilarious) mistake category - I'm referring to my infamous flame ball incident from fall quarter.


9. The centrifugal force of the centrifuge forces the hot liquid gold into the crown cavity. Let it cool and then do a lot of refining and polishing to make it pretty and viola.... you have a gold crown.

Here is most of the gang at the dental lab-


Camille sporting her sweet safety shades and getting ready to throw down her $300 dollars worth of gold.... All the while singing "Gold Digger " by Kanye........ okay that last part is false, but c'mon.... with those shades, its gotsta be true.

Picture of the final product - Kind of a blurry but you get the idea




My "good friend" moments before the incident...... :)


This year has produced some fantastically great times.