Transmission electron microscopy of early plaque formation on dental materials in vivo

This in vivo study describes the ultrastructural pattern of early plaque formation on various dental materials. Test pieces of amalgam, casting alloys, titanium, ceramics, glass polyalkenoate cement, composite resins, unfilled resins, and bovine enamel were attached to the buccal and lingual surfaces of the upper first molars in 3 subjects using removable intraoral splints. Specimens were exposed to the oral environment over a period of 24 h and subsequently processed for transmission electron microscopic evaluation. Only less pronounced variations could be detected in the ultrastructural appearance of the early plaque formed on the different material surfaces. However, electron microscopic observations revealed distinct differences in early biofilm formation between buccally and lingually mounted test pieces. While the bacterial colonization of specimens worn in the lingual position remained limited to the adherence of individual micro-organisms in the area of surface irregularities, a multi-layer adherence of micro-organisms was observed on all specimens carried in buccal areas. It is concluded that early plaque formation on solid surfaces is influenced predominantly by the oral environment rather than by material-dependent parameters. These findings may be ascribed to the presence of the pellicle layer, which apparently masks any difference among materials, with regard to surface properties and biocompatibility.