[On the viscoelastic properties of the palatal mucosa analyzed for the displacement of maxillary complete denture].
The condition of palatal mucosa caused by wearing a maxillary complete denture closely resembles a closed hydrostatic system. To clarify the viscoelastic properties of the palatal mucosa under such a condition, we measured as a function of the degree of denture displacement during biting movements. For this work, we developed three dimensional movement-measuring equipment. The following results were obtained: 1. The displacement of the maxillary complete denture during biting movements (loading and unloading of occlusal forces) could be approximated by an empirical formula of exponential function. This formula expressed the delayed elasticity characteristics of the viscoelasticity of the palatal mucosa. 2. Observation of the denture's displacement revealed that the movement of the palatal mucosa after occlusal forces are unloaded could be regarded as creep according to a Voigtian two-element model. 3. Denture displacement differed between occlusal force loading and unloading: dentures took longer to return to the original position during occlusal force unloading. 4. This time delay, indicating the degree of delayed elasticity of the palatal mucosa, was substantially shorter than the reported value based on local compression tests. Our study clearly shows that when a maxillary complete denture is worn, movement of the palatal mucosa approximates a closed system, and differs from localized open systems.
Hada
M
M
1st Department of Prosthetic Dentistry, Tokushima University, School of Dentistry.
Imai
M
M
Ooishi
A
A
Matsumoto
N
N
D001696:Biomechanical Phenomena; D001732:Bite Force; D003799:Dental Stress Analysis; D003781:Denture Retention; D003827:Denture, Complete, Upper; D004548:Elasticity; D006801:Humans; D009061:Mouth Mucosa / Q000502:physiology*; D010159:Palate; D014783:Viscosity