THE INFLUENCE OF SURFACE FREE-ENERGY AND SURFACE-ROUGHNESS ON EARLY PLAQUE-FORMATION - AN INVIVO STUDY IN MAN

Abstract Previous in vivo studies suggested that a high substratum surface free energy (s.f.e.) and an increased surface roughness facilitate the supragingival plaque accumulation. It is the aim of this clinical trial to explore the “relative” effect of a combination of these surface characteristics on plaque growth. 2 strips, one made of fluorethylenepropylene (FEP) and the other made of cellulose acetate (CA) (polymers with surface free energies of 20 and 58 erg/cm2, respectively) were stuck to the labial surface of the central incisors of 16 volunteers. Half the surface of each strip was smooth (Ra ± 0.1 μm) and the other half was rough (Ra ± 2.2 μm). The undisturbed plaque formation on these strips was followed over a period of 6 days. The plaque extension at day 3 and 6 was scored planimetrically from color slides. Finally, of 6 subjects samples were taken from the strips as well as from a neighbouring smooth tooth surface (s.f.e. 88 erg/cm2; Ra ± 0.14 μm). These samples were analysed with a light microscope to score the proportion of coccoid cells, and small, medium, and large rods or fusiform bacteria. At day 3, a significant difference in plaque accumulation was only obtained when a rough surface was compared with a smooth surface. However, at day 6, significantly less plaque was recorded on FEP smooth (19.4%) when compared with CA smooth (39.5%). Between FEP rough (96.8%) and CA rough (98.2%), no significant difference appeared. The latter were of course significantly higher than the scores of the smooth surfaces. Small differences in bacterial composition appeared: the highest % of coccoid cells was observed on FEP smooth (86.2%) and the lowest % on FEP rough (78.5%) and CA rough (82.8%). The results of this study suggested that the influence of the surface roughness on plaque accumulation and plaque composition is more prominent than the influence of the surface free energy. Copyright © 1990, Wiley Blackwell. All rights reserved