Gingiva is divided into three main regions: the marginal gingiva, the attached gingiva, and the interdental gingiva.
These divisions are based on anatomical location and characteristics:
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Marginal Gingiva (Free Gingiva): This is the unattached portion of the gingiva that forms a collar around the tooth. It's separated from the attached gingiva by the free gingival groove in about 50% of individuals. It includes the gingival margin, which is the edge of the gingiva nearest the biting or chewing surface.
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Attached Gingiva: This is the firm, tightly bound gingiva that extends from the free gingival groove to the mucogingival junction. It's attached to the underlying bone and cementum via connective tissue fibers. The attached gingiva is usually stippled in appearance, resembling an orange peel.
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Interdental Gingiva (Interdental Papilla): This is the gingiva that occupies the interdental space between adjacent teeth. Its shape is determined by the contact relationship between the teeth and the contour of the cementoenamel junction (CEJ) of the adjacent teeth. When teeth are next to each other, the interdental gingiva forms a pointed or pyramidal shape. When there is a diastema (space) between teeth, the interdental gingiva is usually flat or saddle-shaped.
In summary, the gingiva, which protects the tooth-supporting structures, is divided into the marginal, attached, and interdental regions, each with distinct anatomical features and functions.