Study of Framework about CAD/CAM System

Abstract

An accurate framework is getting improved owing to CAD/CAM systems. But, to make an accurate framework needs an accurate model, especially in the CAD/CAM systems. Therefore, we considered a positioning procedure to acquire an accurate models. When we make a framework in conventional method, sometimes a framework is not fi t to the fi xture, because of some reasons, such as an error during step of making a model and from characteristic of material. In case of those, if the frame was made by casting or titanium frame, we would be able to cut the frame and repair with soldering or laser soldering. And we could correct a frame. But if a framework was made from zirconium framework, there was no longer repair way, so we must go back to the first step. Therefore, the accurate model is required. A study of the report indicates how to delete an error. Primary, in step 1 method, the hole, which was opened to the individual impression tray, must be a minimum size and fi t to the mucosa, because if a tray was made far from mucosa, it means that the hole is bigger than previous tray. And when impression material was harden, impression coping should be attached using minimum resin to the hole, because this can help resistant from weight of plaster. And this can avoid a change of model. Secondary, in step 3 and 4 methods, owing to additional step of positioning, we can get two merits. One is that we can make sure conventional method fi tting by checking screw is smoothly going or not. And the another is that we can compensate incompatibility in this step because of cutting the resin frame. It is like a very similar to the fi nal step, because if fi nal framework was maddened from bad model of cause, we must do the same step like a positioning step. Tertiary, in step 7, because of using straw, it can avoid an error from an expansion action of a plaster and changing from weight of a plaster. Finally, because of positioning step, we can get more accurate model than conventional model.