THE CLINICAL MEANING OF THE SURFACE-ROUGHNESS AND THE SURFACE FREE-ENERGY OF INTRAORAL HARD SUBSTRATE ON THE MICROBIOLOGY OF THE SUPRAGINGIVAL AND SUBGINGIVAL PLAQUE - RESULTS OF IN-VITRO AND IN-VIVO EXPERIMENTS

In the oral cavity, which may be considered as an open growth system, most bacteria can only survive if they adhere to the hard surfaces (te eth, filling materials, dental implants, or prostheses). Such bacteria l adhesion occurs in four phases: transport to the surface, initial ad hesion with a reversible and irreversible stage, attachment by specifi c interactions and finally colonization. During this process the rough ness and the free energy of the surfaces play a key role. The reductio n in roughness of a surface will result in a dramatic retardation of p laque formation and maturation. A reduction in surface free energy of the substratum will result in a decrease in plaque growth rate, a decr ease in plaque retention capacity of the surface and in the selection of specific organisms. Although both parameters interact with each oth er, the influence of surface roughness is dominant. The importance of both parameters justifies the demand for smooth surfaces with a low su rface free energy in order to prevent plaque formation, thereby reduci ng the occurrence of gingival inflammation.