[Mechanical analysis of the denture bases, using the photoelastic-coating method. 1. Influence of the coating on mechanical properties of the test denture].

The anterior palatal area may be related with the flexural rigidity and bending strength of the upper complete dentures. Therefore, the deformation of this area should be measured widely and continuously when new materials were applied to the dentures. The influence of the photoelastic coating on the mechanical properties of the upper complete dentures was investigated, prior to the measurement of surface strains on the denture bases by the photoelastic coatings. In this experiment, the uniform-moment bending method was employed simulating the occlusal situation. The flexural rigidity of the denture bases depended on the palatal materials in spite of the presence of the coating. The strains concentrated on the anterior palatal area were slightly decreased when the coating was bonded to the polished surface of the palate. The reinforcing effect was significant when the resin dentures of low elastic modulus were coated. The photoelastic-coating method was suitable for the qualitative analysis of the strain distribution of the denture base and selecting the test points to make strain measurement accurate.