Human dental plaque formation on plastic films. A quantitative SEM study.

The initial colonization of bacteria in previously clean teeth or artificial surfaces inserted in mouth has been reported to occur at various periods of time. Rönström et al., using light microscopy, saw that bacteria were present 10 seconds after prophylaxis. Bacterial culture studies have shown that microorganisms associated with the surface coating on tooth surfaces appeared within minutes after prophylaxis. Furthermore, Rönström et al. noted that the number of bacteria increased over a period of four hours. In contrast, ultrastructural investigations of early plaque have demonstrated bacterial colonization only within the first two hours of plaque development in a few samples obtained on a smooth surface and in most samples on a rough surface. However, microorganisms have been found regularly after four hours of plaque accumulation in subjects with healthy gingiva. The aim of the present investigation was to determine the earliest occurrence of bacterial colonization in situ and to observe the pattern of the initial formation of human dental plaque.