The central fissure of a molar, premolar or cervicular margin of any tooth is the site for accumulation and colonization of oral organism. In addition to bacteria that attach to the pellicle, lymphocytes, leukocytes, desquamated epithelial cells dan clumps of mucin may lodge in any of these sites. Organisms attach to the pellicle and utilize the presence of debris in acid formation.In gingival or tonsillar inflammation, the number of lymphocytes and leukocytes increases. If microscopic analysis of a saliva sample reveals many lymphocytes, tonsillitis is present. However, an increase in leukocytes in saliva is indicative of gingival inflammation. These cells are called salivary corpuscles. At first, only a few bacteria are on the pellicle, but they rapidly grow into a thick plaque that contains a variety of microorganism. The initial plaque quickly changes in composition to include rods and filamentous organisms. These appear after a few days, as shown in figure 16-10.The composition of plaque depends also on the extent of gingival disease and whether the location of the plaque is supragingival or subgingival. The initial carious lesions affect the prismless zone of enamel because plaque bacteria cause dissolution of these surface crystals. A breakdown of enamel crystals is seen clinically as a brown spot on the tooths surface. Figure 16-11 shows a microscopic view of the loss of enamel rod structure. The enamel pellicle may overlie the area of an early lesion on the tooths surface and may be covered by plaque bacteria. Such a lesion may become filled with organic debris and bacteria. Crystals appear to dissolve in one area and be intact in an adjacent area of enamel. Plaque can best be seen when a disclosing solution (0.2% basic fuchsin or erythrosine red no. 3 dye) is used to determine whether all the plaque has been removed. The advantage of using no. 3 dye is that it does not permanently discolor composite restorations or clothing. The stain left after a quick rinsing reveals any remaining plaque deposits, as observed in figure 16-13. These visible deposits can be removed by further polishing.