Fabrication of the devices for pressure welding
Previous studies have shown that the load on the palatal plate during pressure contact influences the retentive force. For this reason, a device was needed to define the loads. We fabricated palatal plates that were seated under standardized pressures using custom-made devices for pressure welding. In turn, the retentive force was measured using a digital force gauge at specific periods. The devices were made to maintain a constant pressure load with the placement of the palatal plate in the mouth and application of pressure. These devices for pressure welding were fabricated for each of the 10 palatal plate surfaces by moulding room temperature-cured resin (TrayResin®, Shofu, Kyoto, Japan). The pressure sensor (compact pressure contact load cell LMA-A®, Kyowa, Tokyo, Japan) was incorporated into the pressure welding device (Fig. 