[Studies on oral sensation in patients with implant denture. 4. Ability of hardness discrimination]

The ability of hardness discrimination in 11 implant denture wearers was compared with those in 10 bridge wearers and 11 normal dentate subjects. The hardness discrimination was tested using silicone rubber blocks having rubber hardness that ranged at intervals of 10 degrees from 30 degrees to 70 degrees. Using a rubber block with rubber hardness of 50 degrees as a standard, the ability of discriminating rubber blocks of different hardness was examined. All the three groups examined had excellent ability of discriminating the rubber blocks of rubber hardness of 30 degrees and 70 degrees from the standard block. The ability to discriminate the rubber block of rubber hardness of 40 degrees from the standard block was only slightly lower than but almost the same as the ability of discriminating the hardness of 30 degrees and 70 degrees in all the three groups. However, the ability of discriminating the rubber block of rubber hardness of 60 degrees from the standard block was significantly lower in the implant denture wearers, compared to the normal dentate subjects and bridge wearers.