Histochemical study of the formation of dental plaque in artificial fissures

— The development of fissure plaque was studied in artificial fissures of Mylar® foil implanted in the occlusal surface of mandibular molars of 10 dental students for periods of 1, 3, 7, 14, 21, 30 and 60 d. After removal the fissures were processed for histologic and histochemical examination. The early fissure content consisted mainly of remnants of animal and plant tissues and relatively few Gram-positive cocci and short rods. Filamentous bacteria were rarely seen, whereas yeast cells were found in most fissures. After 2 months the food particles were almost completely disintegrated and the microorganisms constituted the major part of the fissure content. No distinct change had occurred in the relative proportion of the various morphologic types of bacteria. Some bacterial aggregates and single bacteria showed presence of carbohydrates. The development and composition of the plaque in the artificial fissures seemed to resemble that of natural fissures, indicating that the location and the anatomic characteristics of the occlusal fissures are important factors in the establishment of this particular ecosystem.