A new experimental restoration model in man for studying enamel reactions

A new model of experimental restoration is suggested for testing the marginal imperfections of composite resin, for examining the surface morphology of composite restorations and of sound, etched and remineralized enamel. Enamel-dentine samples with standardized cavities and composite restorations were placed on lower removable partial dentures using the etching technique. After 12 and 28 days the specimens were examined in a scanning electron microscope (SEM), operated at 15 kV. After 12 days the examination of the conventional composite resin by SEM showed extremely rough structures. The use of the enamel etch techniques produces acceptable marginal conditions with tags and some minor gaps. Etching the enamel emphasizes its prismatic structure and reveals the typical pattern of demineralization, involving prism cores and the preferential dissolution of prism peripheries. After 12 days the SEM appearance of uncovered etched enamel suggested that incomplete remineralization had occurred. After 28 days the mineral recoating, which had progressed further, predominantly involved prism-orientated repair. The experimental model described here is more accurate, highly standardizable and easily accessible, compared with conventional clinical and replica techniques.