Scanning Electron Microscope Investigation of the in vitro Effects of a Bacteriolytic Enzyme on Human Dental Plaque

The in vitro effects of a bacteriolytic enzyme derived from Streptonzyces globisporus strain 1829 on dental plaque, which previously formed on plastic foil attached to the buccal surfaces of maxillary molar tooth in the subject, were evaluated by scanning electron microscopy. According to the lapse of time (days), the dental plaque became thicker and the plaque bacteria were more densely packed. In early plaque (day 1 or 2) the bacterial constituents in the dental plaque were relatively simple. Cocci and rods predominated in early plaque, and filamentous form bacteria (filaments) appeared occasionally in plaque of day 2. In older plaque (day 7), filaments predominated and occupied most of the area of the plaque surface. A few of these filaments were observed to be coated with cocci and rods giving a “corncob” appearance. By treatment with the bacteriolytic enzyme, the bacterial cells in early plaque were lysed in situ and formed net-like, honey-comb or sponge-like caves. Bacteria in older plaque did not reveal any alteration by the enzyme, but no cocci and rods were observed in the plaque and the bamboo basket-like structure formed by filaments was partially broken. It was suggested from the results that the bacteriolytic enzyme might affect the surface structure and bacterial constituent of dental plaque by lysing the enzymesensitive bacteria.