Method: Study subjects comprised 17 edentulous (mean age, 78.4 years) and 17 dentate patients (mean age, 29.5 years). The following three points of the maxilla mucosa were measured in all subjects as control: the median and lateral parts of the palate and their midpoint. During measurement, subjects were fitted with a jig manufactured from a plastic sheet. An ultrasonic thickness gauge with a strain gauge attached to the handle enabled simultaneous measurement of load and thickness. The probe touched the surface of the edentulous oral mucosa at the hard palate and load was slowly increased (1N/s). Subjects were instructed to press the button when the pressure applied to the edentulous oral mucosa changed from a feeling of ‘being pressed’ to ‘initial pain recognition’. Signals for the ultrasonic thickness gauge and strain gauge were recorded simultaneously. Thickness (mm) and elasticity (MPa) were assumed to be parameters associated with properties of the oral mucosa, while pressure (MPa), compressibility (%), and subsidence (mm) were assumed to be parameters associated with the pressure-pain threshold.
Result: The results for edentulous areas were as follows for the dentate subjects.
1. Thickness was significantly larger at the median (t-test, p<0.05).
2. Elasticity was significantly smaller in all parts (t-test, p<0.05).
3. All parameters associated with the pressure-pain threshold showed smaller values.
Conclusion: Edentulous oral mucosa tended to be thick, soft, and sensitive. Therefore, load capacity of edentulous oral mucosa is low.