41467Re: Head Cast
- Apr 3, 2009I also recommend Techniques of 3-Dimensional Makeup by Lee Baygan. It has very detailed instructions and pictures. Check it out first, so that you know what you are getting into.
If you are going to use alginate, I recommend Jeltrate Regular set. Make sure you ask for a measuring scoop and water measure, because they don't always come with the alginate. (Tip) You can use ice water, instead of room temperature water to give yourself more working time.
As to what type of plaster to use, the terminology can be kind of confusing. The major difference between plaster of paris and the types of plaster used to pour up dental models is the water to powder ratio. Plaster of paris has a w/p ratio of 50ml water/100gm powder. Whereas dental stone has a w/p ratio of about 30ml water/100gm powder. The less water you need, the stronger the plaster. So you want to use a product with a w/p ratio of 28-30ml water/100gm powder with a compressive strength after 1hour of 4,500 psi and a 24hour compressive strength of 8,000 psi. (Tip) Although you can separate the plaster model from the alginate impression after about 1.5 - 2 hours, it's better to wait 24 hours before making anything on your plaster model, because the compressive strength almost doubles over that time.
I've used Modern Materials Denstone(Heraeus Kulzer), but there are other good brands out there. Make sure you get "Regular Set". You can get Denstone in white or yellow. Orthodontists like white, because the models look pretty when they are presenting the case and price tag to the patient. Dental lab technicians prefer yellow or buff color, because it's a lot easier on the eyes, particularly when you are working under high intensity lights. It also contrasts nicely with the white plaster used for the mold of the denture or facial prosthesis.
You can check out prices at darbydental.com and henryscheindental.com
Hope this helps,
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