[Fundamental studies of impression method. Part 4. Reproducibility of edentulous denture ridge by seating speed and holding pressure of impression tray].

In this study, the author attempted to explicate the infuluence of thedifference in the impression methods for the simulation models based on the hypothetical pressure-displaceability and the form of the alveolar ridge on the reproducibility of the measuring models. For this purpose, the reproducibility of the master cast were examined by use of the threedimensional position-reproducing apparatus, concerning the two factors the seating speed and the holding pressure of the tray. As a result of this study, the following conclusion was obtained. It has been made clear that the impression of dentulous alveolar ridge (the seating speed and holding pressure of the tray) influences the reproducibility of the simulation model. In the impression of the alveolar ridge possessing normal pressure-displaseability, the reproduceability of the measuring cast was the highest when the measurement was made with the tray atthe seating speed of 100 mm/min, and at the holding pressure of 2.0 kgf. Furthermore, it was suggested that when the tray is pressure-adjusted to the alveolar ridge at a standard or slower seating speed, the tray should be held with great pressure, and when the tray is pressure-adjusted speedily, the tray should be held with little pressure.