The casting misfit: how to cope.

C onstructing a casting that seats well and is retentive and comfortable to the patient taxes even the most conscientious dentist. The final seating is dependent upon so many sequential elements that any single procedure may prove to be an unacceptable link, resulting in failure. We must face the fact that under average conditions, when the casting, whether extracoronal or intracoronal, comes from the laboratory, it will be elevated approximately 200 h on the prepared tooth. Occlusal adjusting is almost routine. Occlusal margins are not in apposition with the cavosurface angle. These problems and the attendant frustrations will be considered in their logical order: impressions, die materials, die-spacing or casting relief, choice of cements and liners, and the mixing of cements.