THE INFLUENCE OF SURFACE-ROUGHNESS AND SURFACE-FREE ENERGY ON SUPRAGINGIVAL AND SUBGINGIVAL PLAQUE-FORMATION IN MAN - A REVIEW OF THE LITERATURE

In the oral cavity, an open growth system, bacterial adhesion to the n on-shedding surfaces is for most bacteria the only way to survive. Thi s adhesion occurs in 4 phases: the transport of the bacterium to the s urface, the initial adhesion with a reversible and irreversible stage, the attachment by specific interactions, and finally the colonization in order to form a biofilm. Different hard surfaces are available in the oral cavity (teeth, filling materials, dental implants, or prosthe ses), all with different surface characteristics. In a healthy situati on, a dynamic equilibrium exists on these surfaces between the forces of retention and those of removal. However, an increased bacterial acc umulation often results in a shift toward disease. 2 mechanisms favour the retention of dental plaque: adhesion and stagnation. The aim of t his review is to examine the influence of the surface roughness and th e surface free energy in the adhesion process. Both in vitro and in vi vo studies underline the importance of both variables in supragingival plaque formation. Rough surfaces will promote plaque formation and ma turation, and high-energy surfaces are known to collect more plaque, t o bind the plaque more strongly and to select specific bacteria. Altho ugh both variables interact with each other, the influence of surface roughness overrules that of the surface free energy. For the subgingiv al environment, with more facilities for microorganisms to survive, th e importance of surface characteristics dramatically decreases. Howeve r, the influence of surface roughness and surface-free energy on supra gingival plaque justifies the demand for smooth surfaces with a low su rface-free energy in order to minimise plaque formation, thereby reduc ing the occurrence of caries and periodontitis.