专业英语 Unit 15new.docVIP

Unit Fifteen NORMAL ANATOMY AND HISTOLOGYOF THE ORAL MUCOSA ANATOMY The oral mucosa may be divided into areas corresponding to the anatomic configuration of the jaws and associated musculature. These areas are the gingiva, buccal mucosa, labial mucosa, tongue, hard palate, and soft palate. Gingiva The gingiva or gums refers to the tissue surrounding the teeth and covering the alveolar bone. The gingival tissue is tightly matted to the periosteum of the alveolar bone, and it covers that portion of the roots of the teeth that extends beyond the crest of alveolar tooth socket. The gingival tissue fills the interproximal spaces between the teeth so that usually spaces are not seen between teeth that are normally aligned in the dental arch. The portion of the gingiva that extends beyond the alveolar bone and attaches to the teeth is referred to as the marginal gingiva or free gingival margin, because it is relatively unsupported by hard tissue and forms a continuous band along the root-crown junction of the teeth. The gingival tissue attaches to the tooth surface just below the gingival margin, so that a sulcus or gingival crevice about l to 2 mm in depth is normally found beneath the gingival margin. The exact nature of the gingival attachment to tooth has not been established, but the attachment is firm, so that gingiva cannot be detached from a tooth unless considerable force is used to tear the tissue or a surgical knife is used to sever the tissue. The surface of the marginal gingiva is smooth; that of the attached gingiva is stippled. The gingival tissue appears a light pink color normally. Beyond the gingiva and separated from it by a clear demarcation is the alveolar mucosa. The line of demarcation of referred to as the mucogingival junction, and the alveolar mucosa beyond this junction is loose, delicate tissue not matted down to underlying bone. Numerous small blood vessels can be seen through this delicate mucosa. The alveolar