Relationship between aging and recovery of the underlying mucosa immediately after removal of pressure: the first molar region in the mandible.

To investigate changes in the characteristics of edentulous mucosa in the alveolar ridge with aging, we applied pressure to the mucosa of the alveolar ridge in subjects of various ages and evaluated the recovery amount and time after the pressure was removed. Twenty-three subjects ranging from 23 to 79 years of age, who had lost the first mandibular molar tooth, were selected. Displacing pressure was applied to the mucosa corresponding to the mandibular first molar region. After release the pressure, we measured the recovery amount of mucosa from its displacement, which was expressed as the movement of a target which had been placed on the mucosa as measured by an indirect displacement measurement device. The levels of displacement were set at 0.1 mm, 0.2 mm and 0.3 mm, and the time to achieve the selected displacement level was set at 1 second. The initial recovery of the mucosa immediately after the pressure has been released was designated as the initial recovery amount, and the time needed for recovering to 90% of the previous state was designated as the final recovery time. Then we investigated the relationships between the measures of the initial recovery amount, the final recovery time, and the subjects' ages. The initial recovery amount of mucosa was lower and the final recovery time was longer in older subjects, and this tendency was exaggerated when the displacement was increased.