ANDREW MCCLENAGHAN / SCIENCE PHOTO LIBRARY. ANDREW MCCLENAGHAN / SCIENCE PHOTO LIBRARY.
Young woman using dental floss (a cotton thread which may be waxed or unwaxed) to clean particles of food from around her teeth & gingival crevices (the spaces between the gums & the surface of the teeth). Bacterial action on any food particles deposited in these areas leads to the formation of plaque, which eventually forms a hard deposit - tartar, which enlarges the gingival crevices & precipitates periodontal disease. Early symptoms include swollen & bleeding gums; ulceration may follow. If untreated the plaque spreads to & destroys the underlying periodontal membrane & alveolar bone: in this chronic stage the teeth become loosened & eventually fall out.
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