Development of plaque on enamel

Intact human enamel was used to study the development of dental plaque. This procedure involved placing cylinders of surface enamel in an appliance that was worn by one subject up to seven days. By using a technique of slight demineralization of the enamel, pellicle and plaque could be sectioned along with the enamel for light and transmission microscopy. Scanning electron microscopic and microbiologic studies were also performed on the specimens. Microbiologic investigation of two day old samples from the one individual revealed the presence of streptococci and a smaller number of Neisseria. Streptococcus sanguis was the predominant streptococcal species. Early samples of dental plaque appeared to have more desquamated epithelial cells than seven day old plaques. Electron micrographs suggest that bacteria may digest these epithelial cells. An apparent distinction between bacteria adjacent to the enamel and bacteria adsorbed to the surface of the enamel was. noted. Adsorbed bacteria appeared to alter their morphology and excrete an extracellular material which later formed a pellicular layer. Seven day old samples characteristically showed an alignment of rods superior to the adsorbed cocci. The formation of dental plaque on enamel cylinders may better simulate "in vivo" conditions than previous techniques.