[Vital staining and phase contrast microscopy results of plaque smears]

The information about the vitality of the plaque is limited. Only motile bacteria can be distinguished as alive. Vital staining allows to differentiate between living nonmotile rods and dead, previously motile rods. With increasing severity of the periodontal destruction, the proportion of alive respectively motile rods and vibrions increases. The vital staining shows very clearly the relation between destruction and living rods.