Tuesday, December 3, 2013

Taking impression for Crown using putty and light body

In the last post, I was very excited about helping Dr.X for the Post and core. Now, I want to write about waht I have to do while the DDS is doing a crown preparation.
This is a video I found on youtube. In the dental office, there is a difference though. 

We use regular set light body. Dr.X doesn't use spacer. We do one step impression. 
Usually alginate impression is taken before crown prep. If a temporary crown is going to be made, the mould will be made as well.
Once the crown is prepared, Dr.X places a gingival retraction cord.  For the molars, it is usually one round around my thumb and for anteriors one round around my little finger, I just figured out.
If you have any other method of figuring the length of the cord, please share it.
 (I know, I am getting some views, but not sure it is from dental assistants though. So, dear readers, please share your ideas, if you don't mind).
When the dentist is packing the cord, I make the light body material ready to use.( we use the gun. So I load the cartridge and put a tip). Then the putty will be placed on a a paper pad with equal amount of base and catalyst. Before opening the putty, make sure to change the latex gloves and put vinyl gloves. (Putty won't set if mixed wearing latex gloves, right?)

I usually will have the same size tray used for the alginate impression, ready for the final impression. When the DDS gives the go ahead signal, start mixing the putty. ( I don't want to forget the cotton rolls....)Dr.X loves to get an indentation on the putty, as in the video. Dr.X place some of the light body in that indentation too. Then place the tray and take impression.
While the impression is getting set, I can make the lab box ready. The alginate impressions are wrapped in a wet paper towel and placed in a zip lock bag before putting in the box. When the putty impression is good to go, just spray the disinfectant on it and wash with water. Some dentists wanted to take bite registration with wax and some wants to take with another material. Send all impressions and bite registration to the lab.

Now, if they are making a temp crown, they are going to start now. So, I will have my temporary cement like tembond ready. Of course, articulating paper to check the bite is needed. 
Once again the steps are:
1. Alginate impression, Mould for temp. crown
2. crown prep.
3. Retraction cord placing
4. Final impression
5. Bite registration
6. making temporary crown
7. Cementing temporary crown
8. Checking bite registration
9.Prepare the lab box.

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