Do you have the basic idea? Its a very complicated appliance when it comes to the fabrication of the acrylic.
Start with the lower, and I suggest all the blocks are made using the doughy technique, makes it easier to form the shape and height. After applying the doughy and curing, trim the retainer as you notmally would and leave the blocks for the last step of the lower. The most important part is finding the right distal angle on the lower. If its not steep enough the patient won't be locked into protrusion and it will slip, if its too steep, then the patient won't engage efficiently. I suggest making the angles on a model trimmer, makes the angles identical to each other.
Once you finish the lower, wax the blocks and rub most of the wax off to give a very thin layer over the blocks, then make the upper off the lower. And thats it, very complicated appliance to try and explain in a nutshell in text.
Good Luck!!
Here is a link to a page with pictures.
Twin Block Pics
